Leonardo Santagada via llvm-dev
2018-Jan-25 18:46 UTC
[llvm-dev] [lldb-dev] Trying out lld to link windows binaries (using msvc as a compiler)
I see that there is an auxsymbol per section symbol, and also on the yaml representation there is a checksum, selection and unused all of them I have no idea how to fill in, also this aux symbol might have some important information for me to patch on the other symbols. Can you find the part in llvm that it writes those? because at least for auxsymbol the yaml part of the code threats as a binary blob so there is no info on what they should be. On Thu, Jan 25, 2018 at 7:15 PM, Zachary Turner <zturner at google.com> wrote:> If you run obj2yaml against a very simple object file, you'll see > something like this at the end: > ``` > symbols: > - Name: '@comp.id' > Value: 17130443 > SectionNumber: -1 > SimpleType: IMAGE_SYM_TYPE_NULL > ComplexType: IMAGE_SYM_DTYPE_NULL > StorageClass: IMAGE_SYM_CLASS_STATIC > - Name: '@feat.00' > Value: 2147484048 <(21)%204748-4048> > SectionNumber: -1 > SimpleType: IMAGE_SYM_TYPE_NULL > ComplexType: IMAGE_SYM_DTYPE_NULL > StorageClass: IMAGE_SYM_CLASS_STATIC > - Name: .drectve > Value: 0 > SectionNumber: 1 > SimpleType: IMAGE_SYM_TYPE_NULL > ComplexType: IMAGE_SYM_DTYPE_NULL > StorageClass: IMAGE_SYM_CLASS_STATIC > SectionDefinition: > Length: 47 > NumberOfRelocations: 0 > NumberOfLinenumbers: 0 > CheckSum: 0 > Number: 0 > ... > ``` > > There's a structure called coff::symbol which basically represents each > one of these records. It looks like this: > > ``` > struct symbol { > char Name[NameSize]; > uint32_t Value; > int32_t SectionNumber; > uint16_t Type; > uint8_t StorageClass; > uint8_t NumberOfAuxSymbols; > }; > ``` > > So you'll need to create one for the debug$H section and stick it into the > list. This particular list doesn't have to be in any special order, so you > can just put it at the end (although it's probably not that much harder to > insert into the middle, and it will make for a good test that you've done > it right. The output can be diffed against clang-cl object file and be > identical this way). So write all the normal symbols as you probably > already are, then write one for the .debug$H section. Initialize the > fields to the same thing that you see when you run obj2yaml against an > object file generated by clang-cl for the .debug$H section. > > This structure doesn't contain any kind of file pointers or offsets, so > all you really need to fix up are the "SectionNumber" fields. Basically as > you are writing the existing symbols, you would do somethign like: > > for (const auto &Sym : ObjFile.symbols()) { > if (Symbol->SectionNumber >= DebugHInsertionIndex) > ++Symbol->SectionNumber; > writeSymbol(Sym); > } > writeSymbol(DebugHSym); > > > On Thu, Jan 25, 2018 at 9:57 AM Leonardo Santagada <santagada at gmail.com> > wrote: > >> Any idea on how to create this new symbol there? I saw that there is a >> symbol pointing to each section, but didn't understand the format, and >> yaml2obj doesn't check it or do anything with the list. >> >> On Thu, Jan 25, 2018 at 6:56 PM, Leonardo Santagada <santagada at gmail.com> >> wrote: >> >>> YES, THANK YOU... I WAS THINKING THIS BUT COMPLETELY FORGOT. >>> >>> sorry for the caps... long day of working on this, and using vs 2017, >>> which adds a new section type .chks64 that I couldn't find documentation >>> anywhere was difficult. I highly recommend everyone to just not using vs >>> 2017 until 15.8 or something, our internal bug list is gigantic. >>> >>> On Thu, Jan 25, 2018 at 6:52 PM, Zachary Turner <zturner at google.com> >>> wrote: >>> >>>> Actually I already have a theory that even though you are adding the >>>> section to the section table, you might not be adding a *symbol* for the >>>> section to the symbol table. So the existing symbols (which reference >>>> sections by index) will all be wrong because you've inserted a new >>>> section. Still though, obj2yaml would expose that. >>>> >>>> On Thu, Jan 25, 2018 at 9:50 AM Zachary Turner <zturner at google.com> >>>> wrote: >>>> >>>>> Yea as long as you compare clang-cl object file with automatically >>>>> generated .debug$H section against clang-cl object file without .debug$H >>>>> but added after the fact with llvm-objcopy, that should expose the problem >>>>> I think when you run obj2yaml on them. >>>>> >>>>> On Thu, Jan 25, 2018 at 9:49 AM Leonardo Santagada < >>>>> santagada at gmail.com> wrote: >>>>> >>>>>> I did reorder my sections, so that .debug$H is in the correct place, >>>>>> but now I get some errors on dubplicate symbols, I created a folder with >>>>>> examples: >>>>>> >>>>>> https://www.dropbox.com/sh/nmvzi44pi0boe76/ >>>>>> AAA0f47O5PCJ9JiUc6wVuwBra?dl=0 >>>>>> >>>>>> t.obj is generated by vs 2015 and it links fine with lld-link.exe, >>>>>> but tout.obj gives this errors: >>>>>> >>>>>> lld-link.exe /DEBUG:GHASH tout.obj >>>>>> LLD-LINK.EXE: error: duplicate symbol: __local_stdio_printf_options >>>>>> in tout.obj and in LIBCMT.lib(default_local_stdio_options.obj) >>>>>> LLD-LINK.EXE: error: duplicate symbol: __local_stdio_printf_options >>>>>> in tout.obj and in libvcruntime.lib(undname.obj) >>>>>> >>>>>> I'm using PEView from http://wjradburn.com/software/ to look at the >>>>>> files and can't see anything wrong, except some valid differences in the >>>>>> offsets being used for the data (so pointer to data is different between >>>>>> them). >>>>>> >>>>>> I will look into yaml2obj now to see if I see anything else weird >>>>>> going on. >>>>>> >>>>>> >>>>>> On Thu, Jan 25, 2018 at 6:41 PM, Zachary Turner <zturner at google.com> >>>>>> wrote: >>>>>> >>>>>>> I'm pretty confident that cl is not putting anything strange in the >>>>>>> .debug$T sections. We've done a lot of testing and never seen anything >>>>>>> except CodeView type records in a .debug$T. My hunch is that your objcopy >>>>>>> patch is probably not doing the right thing in one or more of the section >>>>>>> headers, and this is confusing the linker. >>>>>>> >>>>>>> One idea might be to build a simple object file with clang-cl but >>>>>>> without the magic -mllvm -emit-codeview-ghash-section, then run your >>>>>>> llvm-objcopy on it. Then build the same object file passing -mllvm >>>>>>> -emit-codeview-ghash-section. Then run obj2yaml on both and diff the >>>>>>> results. They should be byte-for-byte identical. That should give you a >>>>>>> clue about if objcopy is doing something wrong. >>>>>>> >>>>>>> On Thu, Jan 25, 2018 at 2:21 AM Leonardo Santagada < >>>>>>> santagada at gmail.com> wrote: >>>>>>> >>>>>>>> Don't worry, I definetly want to perfect this to generate legal obj >>>>>>>> files, this is just to speed up testing. >>>>>>>> >>>>>>>> Now after patching all the obj files I get this errors when linking >>>>>>>> a small part of our code base (msvc 2017 15.5.3, lld and llvm-objcopy >>>>>>>> 7.0.0): >>>>>>>> lld-link.exe : error : relocation against symbol in discarded >>>>>>>> section: $LN8 >>>>>>>> lld-link.exe : error : relocation against symbol in discarded >>>>>>>> section: $LN43 >>>>>>>> lld-link.exe : error : relocation against symbol in discarded >>>>>>>> section: $LN37 >>>>>>>> >>>>>>>> I'm starting to guess that cl.exe might be putting some random >>>>>>>> comdat or other discardable symbols in the .debug$T and clang doesn't? I >>>>>>>> will try to debug this and see what more I can uncover. >>>>>>>> >>>>>>>> Linking works perfectly without my llvm-objcopy pass to add >>>>>>>> .debug$H? >>>>>>>> >>>>>>>> >>>>>>>> On Thu, Jan 25, 2018 at 1:53 AM, Zachary Turner <zturner at google.com >>>>>>>> > wrote: >>>>>>>> >>>>>>>>> It might not influence LLD, but at the same time we don't want to >>>>>>>>> upstream something that is producing technically illegal COFF files. Also >>>>>>>>> good to hear about the planned changes to your header files. Looking >>>>>>>>> forward to hearing about your experiences with clang-cl. >>>>>>>>> >>>>>>>>> On Wed, Jan 24, 2018 at 10:41 AM Leonardo Santagada < >>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>> >>>>>>>>>> Hi, >>>>>>>>>> >>>>>>>>>> I finally got my first .obj file patched with .debug$H to look >>>>>>>>>> somewhat right. I added the new section at the end of the file so I don't >>>>>>>>>> have to recalculate all sections (although now I probably could position it >>>>>>>>>> in the middle, knowing that each section is: SizeOfRawData + (last.Header.NumberOfRelocations >>>>>>>>>> * (4+4+2)) and the $H needs to come right after $T in the file). That >>>>>>>>>> although illegal based on the coff specs doesn't seem its going to >>>>>>>>>> influence lld. >>>>>>>>>> >>>>>>>>>> Also we talked and we are probably going to do something similar >>>>>>>>>> to a bunch of windows defines and a check for our own define (to guarantee >>>>>>>>>> that no one imported windows.h before win32.h) and drop the namespace and >>>>>>>>>> the conflicting names. >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On Tue, Jan 23, 2018 at 12:46 AM, Zachary Turner < >>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>> >>>>>>>>>>> That's very possible that a 3rd party indirect header include is >>>>>>>>>>> involved. One idea might be like I suggested where you #define _WINDOWS_ >>>>>>>>>>> in win32.h and guarantee that it's always included first. Then those other >>>>>>>>>>> headers won't be able to #include <windows.h>. but it will probably >>>>>>>>>>> greatly expand the amount of stuff you have to add to win32.h, as you will >>>>>>>>>>> probably find some callers of functions that aren't yet in your win32.h >>>>>>>>>>> that you'd have to add. >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> On Mon, Jan 22, 2018 at 3:28 PM Leonardo Santagada < >>>>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>>>> >>>>>>>>>>>> Ok some information was lost on getting this example to you, >>>>>>>>>>>> I'm sorry for not being clear. >>>>>>>>>>>> >>>>>>>>>>>> We have a huge code base, let's say 90% of it doesn't include >>>>>>>>>>>> either header, 9% include win32.h and 1% includes both, I will try to >>>>>>>>>>>> discover why, but my guess is they include both a third party that includes >>>>>>>>>>>> windows.h and some of our libs that use win32.h. >>>>>>>>>>>> >>>>>>>>>>>> I will try to fully understand this tomorrow. >>>>>>>>>>>> >>>>>>>>>>>> I guess clang will not implement this ever so finishing the >>>>>>>>>>>> object copier is the best solution until all code is ported to clang. >>>>>>>>>>>> >>>>>>>>>>>> On 23 Jan 2018 00:02, "Zachary Turner" <zturner at google.com> >>>>>>>>>>>> wrote: >>>>>>>>>>>> >>>>>>>>>>>>> You said win32.h doesn't include windows.h, but main.cpp >>>>>>>>>>>>> does. So what's the disadvantage of just including it in win32.h anyway, >>>>>>>>>>>>> since it's already going to be in every translation unit? (Unless you >>>>>>>>>>>>> didn't mean to #include it in main.cpp) >>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> I guess all I can do is warn you how bad of an idea this is. >>>>>>>>>>>>> For starters, I already found a bug in your code ;-) >>>>>>>>>>>>> >>>>>>>>>>>>> // stdint.h >>>>>>>>>>>>> typedef int int32_t; >>>>>>>>>>>>> >>>>>>>>>>>>> // winnt.h >>>>>>>>>>>>> typedef long LONG; >>>>>>>>>>>>> >>>>>>>>>>>>> // windef.h >>>>>>>>>>>>> typedef struct tagPOINT >>>>>>>>>>>>> { >>>>>>>>>>>>> LONG x; // long x >>>>>>>>>>>>> LONG y; // long y >>>>>>>>>>>>> } POINT, *PPOINT, NEAR *NPPOINT, FAR *LPPOINT; >>>>>>>>>>>>> >>>>>>>>>>>>> // win32.h >>>>>>>>>>>>> typedef int32_t LONG; >>>>>>>>>>>>> >>>>>>>>>>>>> struct POINT >>>>>>>>>>>>> { >>>>>>>>>>>>> LONG x; // int x >>>>>>>>>>>>> LONG y; // int y >>>>>>>>>>>>> }; >>>>>>>>>>>>> >>>>>>>>>>>>> So POINT is defined two different ways. In your minimal >>>>>>>>>>>>> interface, it's declared as 2 int32's, which are int. In the actual >>>>>>>>>>>>> Windows header files, it's declared as 2 longs. >>>>>>>>>>>>> >>>>>>>>>>>>> This might seem like a unimportant bug since int and long are >>>>>>>>>>>>> the same size, but int and long also mangle differently and affect overload >>>>>>>>>>>>> resolution, so you could have weird linker errors or call the wrong >>>>>>>>>>>>> function overload. >>>>>>>>>>>>> >>>>>>>>>>>>> Plus, it illustrates the fact that this struct *actually is* a >>>>>>>>>>>>> different type from the one in the windows header. >>>>>>>>>>>>> >>>>>>>>>>>>> You said at the end that you never intentionally import >>>>>>>>>>>>> win32.h and windows.h from the same translation unit. But then in this >>>>>>>>>>>>> example you did. I wonder if you could enforce that by doing this: >>>>>>>>>>>>> >>>>>>>>>>>>> // win32.h >>>>>>>>>>>>> #pragma once >>>>>>>>>>>>> >>>>>>>>>>>>> // Error if windows.h was included before us. >>>>>>>>>>>>> #if defined(_WINDOWS_) >>>>>>>>>>>>> #error "You're including win32.h after having already included >>>>>>>>>>>>> windows.h. Don't do this!" >>>>>>>>>>>>> #endif >>>>>>>>>>>>> >>>>>>>>>>>>> // And also make sure windows.h can't get included after us >>>>>>>>>>>>> #define _WINDOWS_ >>>>>>>>>>>>> >>>>>>>>>>>>> For the record, I tried the test case you linked when >>>>>>>>>>>>> windows.h is not included in main.cpp and it works (but still has the bug >>>>>>>>>>>>> about int and long). >>>>>>>>>>>>> >>>>>>>>>>>>> On Mon, Jan 22, 2018 at 2:23 PM Leonardo Santagada < >>>>>>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>>>>>> >>>>>>>>>>>>>> It is super gross, but we copy parts of windows.h because >>>>>>>>>>>>>> having all of it if both gigantic and very very messy. So our win32.h has a >>>>>>>>>>>>>> couple thousands of lines and not 30k+ for windows.h and we try to have >>>>>>>>>>>>>> zero macros. Win32.h doesn't include windows.h so using ::BOOL wouldn't >>>>>>>>>>>>>> work. We don't want to create a namespace, we just want a cleaner interface >>>>>>>>>>>>>> to windows api. The namespace with c linkage is the way to trick cl into >>>>>>>>>>>>>> allowing us to in some files have both windows.h and Win32.h. I really >>>>>>>>>>>>>> don't see any way for us to have this Win32.h without this cl support, so >>>>>>>>>>>>>> maybe we should either put windows.h in a compiled header somewhere and not >>>>>>>>>>>>>> care that it is infecting everything or just have one place we can call to >>>>>>>>>>>>>> clean up after including windows.h (a massive set of undefs). >>>>>>>>>>>>>> >>>>>>>>>>>>>> So using can't work, because we never intentionally import >>>>>>>>>>>>>> windows.h and win32.h on the same translation unit. >>>>>>>>>>>>>> >>>>>>>>>>>>>> On Mon, Jan 22, 2018 at 7:08 PM, Zachary Turner < >>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>> >>>>>>>>>>>>>>> This is pretty gross, honestly :) >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Can't you just use using declarations? >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> namespace Win32 { >>>>>>>>>>>>>>> extern "C" { >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> using ::BOOL; >>>>>>>>>>>>>>> using ::LONG; >>>>>>>>>>>>>>> using ::POINT; >>>>>>>>>>>>>>> using ::LPPOINT; >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> using ::GetCursorPos; >>>>>>>>>>>>>>> } >>>>>>>>>>>>>>> } >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> This works with clang-cl. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> On Mon, Jan 22, 2018 at 5:39 AM Leonardo Santagada < >>>>>>>>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Here it is a minimal example, we do this so we don't have >>>>>>>>>>>>>>>> to import the whole windows api everywhere. >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> https://gist.github.com/santagada/ >>>>>>>>>>>>>>>> 7977e929d31c629c4bf18ebb987f6be3 >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> On Sun, Jan 21, 2018 at 2:31 AM, Zachary Turner < >>>>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Clang-cl maintains compatibility with msvc even in cases >>>>>>>>>>>>>>>>> where it’s non standards compliant (eg 2 phase name lookup), but we try to >>>>>>>>>>>>>>>>> keep these cases few and far between. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> To help me understand your case, do you mean you copy >>>>>>>>>>>>>>>>> windows.h and modify it? How does this lead to the same struct being >>>>>>>>>>>>>>>>> defined twice? If i were to write this: >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> struct Foo {}; >>>>>>>>>>>>>>>>> struct Foo {}; >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Is this a small repro of the issue you’re talking about? >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 3:44 PM Leonardo Santagada < >>>>>>>>>>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> I can totally see something like incremental linking with >>>>>>>>>>>>>>>>>> a simple padding between obj and a mapping file (which can also help with >>>>>>>>>>>>>>>>>> edit and continue, something we also would love to have). >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> We have another developer doing the port to support >>>>>>>>>>>>>>>>>> clang-cl, but although most of our code also goes trough a version of >>>>>>>>>>>>>>>>>> clang, migrating the rest to clang-cl has been a fight. >From what I heard >>>>>>>>>>>>>>>>>> the main problem is that we have a copy of parts of windows.h (so not to >>>>>>>>>>>>>>>>>> bring the awful parts of it like lower case macros) and that totally works >>>>>>>>>>>>>>>>>> on cl, but clang (at least 6.0) complains about two struct/vars with the >>>>>>>>>>>>>>>>>> same name, even though they are exactly the same. Making clang-cl as broken >>>>>>>>>>>>>>>>>> as cl.exe is not an option I suppose? I would love to turn on a flag >>>>>>>>>>>>>>>>>> --accept-that-cl-made-bad-decisions-and-live-with-it and >>>>>>>>>>>>>>>>>> have this at least until this is completely fixed in our code base. >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> the biggest win with moving to cl would be a better more >>>>>>>>>>>>>>>>>> standards compliant compiler, no 1 minute compiles on heavily templated >>>>>>>>>>>>>>>>>> files and maybe the holy grail of ThinLTO. >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 10:56 PM, Zachary Turner < >>>>>>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> 10-15s will be hard without true incremental linking. >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> At some point that's going to be the only way to get any >>>>>>>>>>>>>>>>>>> faster, but incremental linking is hard (putting it lightly), and since our >>>>>>>>>>>>>>>>>>> full links are already really fast we think we can get reasonably close to >>>>>>>>>>>>>>>>>>> link.exe incremental speeds with full links. But it's never enough and I >>>>>>>>>>>>>>>>>>> will always want it to be faster, so you may see incremental linking in the >>>>>>>>>>>>>>>>>>> future after we hit a performance wall with full link speed :) >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> In any case, I'm definitely interested in seeing what >>>>>>>>>>>>>>>>>>> kind of numbers you get with /debug:ghash after you get this llvm-objcopy >>>>>>>>>>>>>>>>>>> feature implemented. So keep me updated :) >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> As an aside, have you tried building with clang instead >>>>>>>>>>>>>>>>>>> of cl? If you build with clang you wouldn't even have to do this >>>>>>>>>>>>>>>>>>> llvm-objcopy work, because it would "just work". If you've tried but ran >>>>>>>>>>>>>>>>>>> into issues I'm interested in hearing about those too. On the other hand, >>>>>>>>>>>>>>>>>>> it's also reasonable to only switch one thing at a time. >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 1:34 PM Leonardo Santagada < >>>>>>>>>>>>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> if we get to < 30s I think most users would prefer it >>>>>>>>>>>>>>>>>>>> to link.exe, just hopping there is still some more optimizations to get >>>>>>>>>>>>>>>>>>>> closer to ELF linking times (around 10-15s here). >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 9:50 PM, Zachary Turner < >>>>>>>>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> Generally speaking a good rule of thumb is that >>>>>>>>>>>>>>>>>>>>> /debug:ghash will be close to or faster than /debug:fastlink, but with none >>>>>>>>>>>>>>>>>>>>> of the penalties like slow debug time >>>>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 12:44 PM Zachary Turner < >>>>>>>>>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> Chrome is actually one of my exact benchmark cases. >>>>>>>>>>>>>>>>>>>>>> When building blink_core.dll and browser_tests.exe, i get anywhere from a >>>>>>>>>>>>>>>>>>>>>> 20-40% reduction in link time. We have some other optimizations in the >>>>>>>>>>>>>>>>>>>>>> pipeline but not upstream yet. >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> My best time so far (including other optimizations >>>>>>>>>>>>>>>>>>>>>> not yet upstream) is 28s on blink_core.dll, compared to 110s with /debug >>>>>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 12:28 PM Leonardo Santagada < >>>>>>>>>>>>>>>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 9:05 PM, Zachary Turner < >>>>>>>>>>>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> You probably don't want to go down the same route >>>>>>>>>>>>>>>>>>>>>>>> that clang goes through to write the object file. If you think yaml2coff >>>>>>>>>>>>>>>>>>>>>>>> is convoluted, the way clang does it will just give you a headache. There >>>>>>>>>>>>>>>>>>>>>>>> are multiple abstractions involved to account for different object file >>>>>>>>>>>>>>>>>>>>>>>> formats (ELF, COFF, MachO) and output formats (Assembly, binary file). At >>>>>>>>>>>>>>>>>>>>>>>> least with yaml2coff >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> I think your phrase got cut there, but yeah I just >>>>>>>>>>>>>>>>>>>>>>> found AsmPrinter.cpp and it is convoluted. >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> It's true that yaml2coff is using the COFFParser >>>>>>>>>>>>>>>>>>>>>>>> structure, but if you look at the writeCOFF >>>>>>>>>>>>>>>>>>>>>>>> function in yaml2coff it's pretty bare-metal. The logic you need will be >>>>>>>>>>>>>>>>>>>>>>>> almost identical, except that instead of checking the COFFParser for the >>>>>>>>>>>>>>>>>>>>>>>> various fields, you'll check the existing COFFObjectFile, which should have >>>>>>>>>>>>>>>>>>>>>>>> similar fields. >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> The only thing you need to different is when >>>>>>>>>>>>>>>>>>>>>>>> writing the section table and section contents, to insert a new entry. Since >>>>>>>>>>>>>>>>>>>>>>>> you're injecting a section into the middle, you'll also probably need to >>>>>>>>>>>>>>>>>>>>>>>> push back the file pointer of all subsequent sections so that they don't >>>>>>>>>>>>>>>>>>>>>>>> overlap. (e.g. if the original sections are 1, 2, 3, 4, 5 and you insert >>>>>>>>>>>>>>>>>>>>>>>> between 2 and 3, then the original sections 3, 4, and 5 would need to have >>>>>>>>>>>>>>>>>>>>>>>> their FilePointerToRawData offset by the size of the new section). >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> I have the PE/COFF spec open here and I'm happy that >>>>>>>>>>>>>>>>>>>>>>> I read a bit of it so I actually know what you are talking about... yeah it >>>>>>>>>>>>>>>>>>>>>>> doesn't seem too complicated. >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> If you need to know what values to put for the >>>>>>>>>>>>>>>>>>>>>>>> other fields in a section header, run `dumpbin /headers foo.obj` on a >>>>>>>>>>>>>>>>>>>>>>>> clang-generated object file that has a .debug$H section already (e.g. run >>>>>>>>>>>>>>>>>>>>>>>> clang with -emit-codeview-ghash-section, and look at the properties of the >>>>>>>>>>>>>>>>>>>>>>>> .debug$H section and use the same values). >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> Thanks I will do that and then also look at how the >>>>>>>>>>>>>>>>>>>>>>> CodeView part of the code does it if I can't understand some of it. >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> The only invariant that needs to be maintained is >>>>>>>>>>>>>>>>>>>>>>>> that Section[N]->FilePointerOfRawData =>>>>>>>>>>>>>>>>>>>>>>>> Section[N-1]->FilePointerOfRawData + >>>>>>>>>>>>>>>>>>>>>>>> Section[N-1]->SizeOfRawData >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> Well, that and all the sections need to be on the >>>>>>>>>>>>>>>>>>>>>>> final file... But I'm hopeful. >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> Anyone has times on linking a big project like >>>>>>>>>>>>>>>>>>>>>>> chrome with this so that at least I know what kind of performance to expect? >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> My numbers are something like: >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> 1 pdb per obj file: link.exe takes ~15 minutes and >>>>>>>>>>>>>>>>>>>>>>> 16GB of ram, lld-link.exe takes 2:30 minutes and ~8GB of ram >>>>>>>>>>>>>>>>>>>>>>> around 10 pdbs per folder: link.exe takes 1 minute >>>>>>>>>>>>>>>>>>>>>>> and 2-3GB of ram, lld-link.exe takes 1:30 minutes and ~6GB of ram >>>>>>>>>>>>>>>>>>>>>>> faslink: link.exe takes 40 seconds, but then 20 >>>>>>>>>>>>>>>>>>>>>>> seconds of loading at the first break point in the debugger and we lost DIA >>>>>>>>>>>>>>>>>>>>>>> support for listing symbols. >>>>>>>>>>>>>>>>>>>>>>> incremental: link.exe takes 8 seconds, but it only >>>>>>>>>>>>>>>>>>>>>>> happens when very minor changes happen. >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> We have an non negligible number of symbols used on >>>>>>>>>>>>>>>>>>>>>>> some runtime systems. >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 11:52 AM Leonardo Santagada >>>>>>>>>>>>>>>>>>>>>>>> <santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> Thanks for the tips, I now have something that >>>>>>>>>>>>>>>>>>>>>>>>> reads the obj file, finds .debug$T sections and global hashes it (proof of >>>>>>>>>>>>>>>>>>>>>>>>> concept kind of code). What I can't find is: how does clang itself writes >>>>>>>>>>>>>>>>>>>>>>>>> the coff files with global hashes, as that might help me understand how to >>>>>>>>>>>>>>>>>>>>>>>>> create the .debug$H section, how to update the file section count and how >>>>>>>>>>>>>>>>>>>>>>>>> to properly write this back. >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> The code on yaml2coff is expecting to be working >>>>>>>>>>>>>>>>>>>>>>>>> on the yaml COFFParser struct and I'm having quite a bit of a headache >>>>>>>>>>>>>>>>>>>>>>>>> turning the COFFObjectFile into a COFFParser object or compatible... >>>>>>>>>>>>>>>>>>>>>>>>> Tomorrow I might try the very non efficient path of coff2yaml and then >>>>>>>>>>>>>>>>>>>>>>>>> yaml2coff with the hashes header... but it seems way too inefficient and >>>>>>>>>>>>>>>>>>>>>>>>> convoluted. >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> On Fri, Jan 19, 2018 at 10:38 PM, Zachary Turner < >>>>>>>>>>>>>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, Jan 19, 2018 at 1:02 PM Leonardo >>>>>>>>>>>>>>>>>>>>>>>>>> Santagada <santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, Jan 19, 2018 at 9:44 PM, Zachary Turner >>>>>>>>>>>>>>>>>>>>>>>>>>> <zturner at google.com> wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, Jan 19, 2018 at 12:29 PM Leonardo >>>>>>>>>>>>>>>>>>>>>>>>>>>> Santagada <santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi, >>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> No I didn't, I used cl.exe from the visual >>>>>>>>>>>>>>>>>>>>>>>>>>>>> studio toolchain. What I'm proposing is a tool for processing .obj files in >>>>>>>>>>>>>>>>>>>>>>>>>>>>> COFF format, reading them and generating the GHASH part. >>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> To make our build faster we use hundreds of >>>>>>>>>>>>>>>>>>>>>>>>>>>>> unity build files (.cpp's with a lot of other .cpp's in them aka munch >>>>>>>>>>>>>>>>>>>>>>>>>>>>> files) but still have a lot of single .cpp's as well (in total something >>>>>>>>>>>>>>>>>>>>>>>>>>>>> like 3.4k .obj files). >>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> ps: sorry for sending to the wrong list, I was >>>>>>>>>>>>>>>>>>>>>>>>>>>>> reading about llvm mailing lists and jumped when I saw what I thought was a >>>>>>>>>>>>>>>>>>>>>>>>>>>>> lld exclusive list. >>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> A tool like this would be useful, yes. We've >>>>>>>>>>>>>>>>>>>>>>>>>>>> talked about it internally as well and agreed it would be useful, we just >>>>>>>>>>>>>>>>>>>>>>>>>>>> haven't prioritized it. If you're interested in submitting a patch along >>>>>>>>>>>>>>>>>>>>>>>>>>>> those lines though, I think it would be a good addition. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> I'm not sure what the best place for it would >>>>>>>>>>>>>>>>>>>>>>>>>>>> be. llvm-readobj and llvm-objdump seem like obvious choices, but they are >>>>>>>>>>>>>>>>>>>>>>>>>>>> intended to be read-only, so perhaps they wouldn't be a good fit. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> llvm-pdbutil is kind of a hodgepodge of >>>>>>>>>>>>>>>>>>>>>>>>>>>> everything else related to PDBs and symbols, so I wouldn't be opposed to >>>>>>>>>>>>>>>>>>>>>>>>>>>> making a new subcommand there called "ghash" or something that could >>>>>>>>>>>>>>>>>>>>>>>>>>>> process an object file and output a new object file with a .debug$H section. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> A third option would be to make a new tool for >>>>>>>>>>>>>>>>>>>>>>>>>>>> it. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> I don't htink it would be that hard to write. >>>>>>>>>>>>>>>>>>>>>>>>>>>> If you're interested in trying to make a patch for this, I can offer some >>>>>>>>>>>>>>>>>>>>>>>>>>>> guidance on where to look in the code. Otherwise it's something that we'll >>>>>>>>>>>>>>>>>>>>>>>>>>>> probably get to, I'm just not sure when. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>> I would love to write it and contribute it back, >>>>>>>>>>>>>>>>>>>>>>>>>>> please do tell, I did find some of the code of ghash in lld, but in fuzzy >>>>>>>>>>>>>>>>>>>>>>>>>>> on the llvm codeview part of it and never seen llvm-readobj/objdump or >>>>>>>>>>>>>>>>>>>>>>>>>>> llvm-pdbutil, but I'm not afraid to look :) >>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> Luckily all of the important code is hidden >>>>>>>>>>>>>>>>>>>>>>>>>> behind library calls, and it should already just do the right thing, so I >>>>>>>>>>>>>>>>>>>>>>>>>> suspect you won't need to know much about CodeView to do this. >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> I think Peter has the right idea about putting >>>>>>>>>>>>>>>>>>>>>>>>>> this in llvm-objcopy. >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> You can look at one of the existing CopyBinary >>>>>>>>>>>>>>>>>>>>>>>>>> functions there, which currently only work for ELF, but you can just make a >>>>>>>>>>>>>>>>>>>>>>>>>> new overload that accepts a COFFObjectFile. >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> I would probably start by iterating over each of >>>>>>>>>>>>>>>>>>>>>>>>>> the sections (getNumberOfSections / getSectionName) looking for .debug$T >>>>>>>>>>>>>>>>>>>>>>>>>> and .debug$H sections. >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> If you find a .debug$H section then you can just >>>>>>>>>>>>>>>>>>>>>>>>>> skip that object file. >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> If you find a .debug$T but not a .debug$H, then >>>>>>>>>>>>>>>>>>>>>>>>>> basically do the same thing that LLD does in PDBLinker::mergeDebugT >>>>>>>>>>>>>>>>>>>>>>>>>> (create a CVTypeArray, and pass it to GloballyHashedType::hashTypes. >>>>>>>>>>>>>>>>>>>>>>>>>> That will return an array of hash values. (the format of .debug$H is the >>>>>>>>>>>>>>>>>>>>>>>>>> header, followed by the hash values). Then when you're writing the list of >>>>>>>>>>>>>>>>>>>>>>>>>> sections, just add in the .debug$H section right after the .debug$T section. >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> Currently llvm-objcopy only writes ELF files, so >>>>>>>>>>>>>>>>>>>>>>>>>> it would need to be taught to write COFF files. We have code to do this in >>>>>>>>>>>>>>>>>>>>>>>>>> the yaml2obj utility (specifically, in yaml2coff.cpp in the function >>>>>>>>>>>>>>>>>>>>>>>>>> writeCOFF). There may be a way to move this code to somewhere else >>>>>>>>>>>>>>>>>>>>>>>>>> (llvm/Object/COFF.h?) so that it can be re-used by both yaml2coff and >>>>>>>>>>>>>>>>>>>>>>>>>> llvm-objcopy, but in the worst case scenario you could copy the code and >>>>>>>>>>>>>>>>>>>>>>>>>> re-write it to work with these new structures. >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> Lastly, you'll probably want to put all of this >>>>>>>>>>>>>>>>>>>>>>>>>> behind an option in llvm-objcopy such as -add-codeview-ghash-section >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> -- >>>>>>>>>>>>>> >>>>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> -- >>>>>>>>>> >>>>>>>>>> Leonardo Santagada >>>>>>>>>> >>>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> >>>>>>>> Leonardo Santagada >>>>>>>> >>>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> >>>>>> Leonardo Santagada >>>>>> >>>>> >>> >>> >>> -- >>> >>> Leonardo Santagada >>> >> >> >> >> -- >> >> Leonardo Santagada >> >-- Leonardo Santagada -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20180125/918f371e/attachment.html>
Zachary Turner via llvm-dev
2018-Jan-25 19:01 UTC
[llvm-dev] [lldb-dev] Trying out lld to link windows binaries (using msvc as a compiler)
I haven't really dabbled in this part of the COFF format personally, so
hopefully I'm not leading you astray :)
But I checked the code for coff2yaml, and I see this:
} else if (Symbol.isSectionDefinition()) {
// This symbol represents a section definition.
assert(Symbol.getNumberOfAuxSymbols() == 1 &&
"Expected a single aux symbol to describe this
section!");
const object::coff_aux_section_definition *ObjSD
reinterpret_cast<const object::coff_aux_section_definition *>(
AuxData.data());
So it looks like you need exactly 1 aux symbol for each section symbol.
I then scrolled up in this function to figure out where AuxData comes from,
and it comes from COFFObjectFile::getSymbolAuxData. I think that function
holds the clue to what you need to do. It looks like you need to set
coff::symbol::NumberOfAuxSymbols to 1, and then there is a comment in
getSymbolAuxData which says:
// AUX data comes immediately after the symbol in COFF
Aux = reinterpret_cast<const uint8_t *>(Symbol.getRawPtr()) +
SymbolSize;
So I think you just need to write the bytes immediately after the
coff::symbol. The thing you need to write looks like a
coff::coff_aux_section_definition structure.
For the CheckSum, look at WinCOFFObjectWriter::writeSection. It looks like
its a CRC32 of the actual section contents, which you can generate with a
couple of lines of code:
JamCRC JC(/*Init=*/0);
JC.update(DebugHContents);
AuxSymbol.CheckSum = JC.getCRC();
Hope this helps
On Thu, Jan 25, 2018 at 10:46 AM Leonardo Santagada <santagada at
gmail.com>
wrote:
>
> I see that there is an auxsymbol per section symbol, and also on the yaml
> representation there is a checksum, selection and unused all of them I have
> no idea how to fill in, also this aux symbol might have some important
> information for me to patch on the other symbols. Can you find the part in
> llvm that it writes those? because at least for auxsymbol the yaml part of
> the code threats as a binary blob so there is no info on what they should
> be.
>
> On Thu, Jan 25, 2018 at 7:15 PM, Zachary Turner <zturner at
google.com>
> wrote:
>
>> If you run obj2yaml against a very simple object file, you'll see
>> something like this at the end:
>> ```
>> symbols:
>> - Name: '@comp.id'
>> Value: 17130443
>> SectionNumber: -1
>> SimpleType: IMAGE_SYM_TYPE_NULL
>> ComplexType: IMAGE_SYM_DTYPE_NULL
>> StorageClass: IMAGE_SYM_CLASS_STATIC
>> - Name: '@feat.00'
>> Value: 2147484048 <(21)%204748-4048>
>> SectionNumber: -1
>> SimpleType: IMAGE_SYM_TYPE_NULL
>> ComplexType: IMAGE_SYM_DTYPE_NULL
>> StorageClass: IMAGE_SYM_CLASS_STATIC
>> - Name: .drectve
>> Value: 0
>> SectionNumber: 1
>> SimpleType: IMAGE_SYM_TYPE_NULL
>> ComplexType: IMAGE_SYM_DTYPE_NULL
>> StorageClass: IMAGE_SYM_CLASS_STATIC
>> SectionDefinition:
>> Length: 47
>> NumberOfRelocations: 0
>> NumberOfLinenumbers: 0
>> CheckSum: 0
>> Number: 0
>> ...
>> ```
>>
>> There's a structure called coff::symbol which basically represents
each
>> one of these records. It looks like this:
>>
>> ```
>> struct symbol {
>> char Name[NameSize];
>> uint32_t Value;
>> int32_t SectionNumber;
>> uint16_t Type;
>> uint8_t StorageClass;
>> uint8_t NumberOfAuxSymbols;
>> };
>> ```
>>
>> So you'll need to create one for the debug$H section and stick it
into
>> the list. This particular list doesn't have to be in any special
order, so
>> you can just put it at the end (although it's probably not that
much harder
>> to insert into the middle, and it will make for a good test that
you've
>> done it right. The output can be diffed against clang-cl object file
and
>> be identical this way). So write all the normal symbols as you
probably
>> already are, then write one for the .debug$H section. Initialize the
>> fields to the same thing that you see when you run obj2yaml against an
>> object file generated by clang-cl for the .debug$H section.
>>
>> This structure doesn't contain any kind of file pointers or
offsets, so
>> all you really need to fix up are the "SectionNumber" fields.
Basically as
>> you are writing the existing symbols, you would do somethign like:
>>
>> for (const auto &Sym : ObjFile.symbols()) {
>> if (Symbol->SectionNumber >= DebugHInsertionIndex)
>> ++Symbol->SectionNumber;
>> writeSymbol(Sym);
>> }
>> writeSymbol(DebugHSym);
>>
>>
>> On Thu, Jan 25, 2018 at 9:57 AM Leonardo Santagada <santagada at
gmail.com>
>> wrote:
>>
>>> Any idea on how to create this new symbol there? I saw that there
is a
>>> symbol pointing to each section, but didn't understand the
format, and
>>> yaml2obj doesn't check it or do anything with the list.
>>>
>>> On Thu, Jan 25, 2018 at 6:56 PM, Leonardo Santagada <santagada
at gmail.com
>>> > wrote:
>>>
>>>> YES, THANK YOU... I WAS THINKING THIS BUT COMPLETELY FORGOT.
>>>>
>>>> sorry for the caps... long day of working on this, and using vs
2017,
>>>> which adds a new section type .chks64 that I couldn't find
documentation
>>>> anywhere was difficult. I highly recommend everyone to just not
using vs
>>>> 2017 until 15.8 or something, our internal bug list is
gigantic.
>>>>
>>>> On Thu, Jan 25, 2018 at 6:52 PM, Zachary Turner <zturner at
google.com>
>>>> wrote:
>>>>
>>>>> Actually I already have a theory that even though you are
adding the
>>>>> section to the section table, you might not be adding a
*symbol* for the
>>>>> section to the symbol table. So the existing symbols
(which reference
>>>>> sections by index) will all be wrong because you've
inserted a new
>>>>> section. Still though, obj2yaml would expose that.
>>>>>
>>>>> On Thu, Jan 25, 2018 at 9:50 AM Zachary Turner <zturner
at google.com>
>>>>> wrote:
>>>>>
>>>>>> Yea as long as you compare clang-cl object file with
automatically
>>>>>> generated .debug$H section against clang-cl object file
without .debug$H
>>>>>> but added after the fact with llvm-objcopy, that should
expose the problem
>>>>>> I think when you run obj2yaml on them.
>>>>>>
>>>>>> On Thu, Jan 25, 2018 at 9:49 AM Leonardo Santagada <
>>>>>> santagada at gmail.com> wrote:
>>>>>>
>>>>>>> I did reorder my sections, so that .debug$H is in
the correct place,
>>>>>>> but now I get some errors on dubplicate symbols, I
created a folder with
>>>>>>> examples:
>>>>>>>
>>>>>>>
>>>>>>>
https://www.dropbox.com/sh/nmvzi44pi0boe76/AAA0f47O5PCJ9JiUc6wVuwBra?dl=0
>>>>>>>
>>>>>>> t.obj is generated by vs 2015 and it links fine
with lld-link.exe,
>>>>>>> but tout.obj gives this errors:
>>>>>>>
>>>>>>> lld-link.exe /DEBUG:GHASH tout.obj
>>>>>>> LLD-LINK.EXE: error: duplicate symbol:
__local_stdio_printf_options
>>>>>>> in tout.obj and in
LIBCMT.lib(default_local_stdio_options.obj)
>>>>>>> LLD-LINK.EXE: error: duplicate symbol:
__local_stdio_printf_options
>>>>>>> in tout.obj and in libvcruntime.lib(undname.obj)
>>>>>>>
>>>>>>> I'm using PEView from
http://wjradburn.com/software/ to look at the
>>>>>>> files and can't see anything wrong, except some
valid differences in the
>>>>>>> offsets being used for the data (so pointer to data
is different between
>>>>>>> them).
>>>>>>>
>>>>>>> I will look into yaml2obj now to see if I see
anything else weird
>>>>>>> going on.
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Jan 25, 2018 at 6:41 PM, Zachary Turner
<zturner at google.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> I'm pretty confident that cl is not putting
anything strange in the
>>>>>>>> .debug$T sections. We've done a lot of
testing and never seen anything
>>>>>>>> except CodeView type records in a .debug$T. My
hunch is that your objcopy
>>>>>>>> patch is probably not doing the right thing in
one or more of the section
>>>>>>>> headers, and this is confusing the linker.
>>>>>>>>
>>>>>>>> One idea might be to build a simple object file
with clang-cl but
>>>>>>>> without the magic -mllvm
-emit-codeview-ghash-section, then run your
>>>>>>>> llvm-objcopy on it. Then build the same object
file passing -mllvm
>>>>>>>> -emit-codeview-ghash-section. Then run
obj2yaml on both and diff the
>>>>>>>> results. They should be byte-for-byte
identical. That should give you a
>>>>>>>> clue about if objcopy is doing something wrong.
>>>>>>>>
>>>>>>>> On Thu, Jan 25, 2018 at 2:21 AM Leonardo
Santagada <
>>>>>>>> santagada at gmail.com> wrote:
>>>>>>>>
>>>>>>>>> Don't worry, I definetly want to
perfect this to generate legal
>>>>>>>>> obj files, this is just to speed up
testing.
>>>>>>>>>
>>>>>>>>> Now after patching all the obj files I get
this errors when
>>>>>>>>> linking a small part of our code base (msvc
2017 15.5.3, lld and
>>>>>>>>> llvm-objcopy 7.0.0):
>>>>>>>>> lld-link.exe : error : relocation against
symbol in discarded
>>>>>>>>> section: $LN8
>>>>>>>>> lld-link.exe : error : relocation against
symbol in discarded
>>>>>>>>> section: $LN43
>>>>>>>>> lld-link.exe : error : relocation against
symbol in discarded
>>>>>>>>> section: $LN37
>>>>>>>>>
>>>>>>>>> I'm starting to guess that cl.exe might
be putting some random
>>>>>>>>> comdat or other discardable symbols in the
.debug$T and clang doesn't? I
>>>>>>>>> will try to debug this and see what more I
can uncover.
>>>>>>>>>
>>>>>>>>> Linking works perfectly without my
llvm-objcopy pass to add
>>>>>>>>> .debug$H?
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Thu, Jan 25, 2018 at 1:53 AM, Zachary
Turner <
>>>>>>>>> zturner at google.com> wrote:
>>>>>>>>>
>>>>>>>>>> It might not influence LLD, but at the
same time we don't want to
>>>>>>>>>> upstream something that is producing
technically illegal COFF files. Also
>>>>>>>>>> good to hear about the planned changes
to your header files. Looking
>>>>>>>>>> forward to hearing about your
experiences with clang-cl.
>>>>>>>>>>
>>>>>>>>>> On Wed, Jan 24, 2018 at 10:41 AM
Leonardo Santagada <
>>>>>>>>>> santagada at gmail.com> wrote:
>>>>>>>>>>
>>>>>>>>>>> Hi,
>>>>>>>>>>>
>>>>>>>>>>> I finally got my first .obj file
patched with .debug$H to look
>>>>>>>>>>> somewhat right. I added the new
section at the end of the file so I don't
>>>>>>>>>>> have to recalculate all sections
(although now I probably could position it
>>>>>>>>>>> in the middle, knowing that each
section is: SizeOfRawData +
>>>>>>>>>>> (last.Header.NumberOfRelocations *
(4+4+2)) and the $H needs to come right
>>>>>>>>>>> after $T in the file). That
although illegal based on the coff specs
>>>>>>>>>>> doesn't seem its going to
influence lld.
>>>>>>>>>>>
>>>>>>>>>>> Also we talked and we are probably
going to do something similar
>>>>>>>>>>> to a bunch of windows defines and a
check for our own define (to guarantee
>>>>>>>>>>> that no one imported windows.h
before win32.h) and drop the namespace and
>>>>>>>>>>> the conflicting names.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On Tue, Jan 23, 2018 at 12:46 AM,
Zachary Turner <
>>>>>>>>>>> zturner at google.com> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> That's very possible that a
3rd party indirect header include
>>>>>>>>>>>> is involved. One idea might be
like I suggested where you #define
>>>>>>>>>>>> _WINDOWS_ in win32.h and
guarantee that it's always included first. Then
>>>>>>>>>>>> those other headers won't
be able to #include <windows.h>. but it will
>>>>>>>>>>>> probably greatly expand the
amount of stuff you have to add to win32.h, as
>>>>>>>>>>>> you will probably find some
callers of functions that aren't yet in your
>>>>>>>>>>>> win32.h that you'd have to
add.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On Mon, Jan 22, 2018 at 3:28 PM
Leonardo Santagada <
>>>>>>>>>>>> santagada at gmail.com>
wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>> Ok some information was
lost on getting this example to you,
>>>>>>>>>>>>> I'm sorry for not being
clear.
>>>>>>>>>>>>>
>>>>>>>>>>>>> We have a huge code base,
let's say 90% of it doesn't include
>>>>>>>>>>>>> either header, 9% include
win32.h and 1% includes both, I will try to
>>>>>>>>>>>>> discover why, but my guess
is they include both a third party that includes
>>>>>>>>>>>>> windows.h and some of our
libs that use win32.h.
>>>>>>>>>>>>>
>>>>>>>>>>>>> I will try to fully
understand this tomorrow.
>>>>>>>>>>>>>
>>>>>>>>>>>>> I guess clang will not
implement this ever so finishing the
>>>>>>>>>>>>> object copier is the best
solution until all code is ported to clang.
>>>>>>>>>>>>>
>>>>>>>>>>>>> On 23 Jan 2018 00:02,
"Zachary Turner" <zturner at google.com>
>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> You said win32.h
doesn't include windows.h, but main.cpp
>>>>>>>>>>>>>> does. So what's
the disadvantage of just including it in win32.h anyway,
>>>>>>>>>>>>>> since it's already
going to be in every translation unit? (Unless you
>>>>>>>>>>>>>> didn't mean to
#include it in main.cpp)
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I guess all I can do is
warn you how bad of an idea this is.
>>>>>>>>>>>>>> For starters, I already
found a bug in your code ;-)
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> // stdint.h
>>>>>>>>>>>>>> typedef int
int32_t;
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> // winnt.h
>>>>>>>>>>>>>> typedef long LONG;
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> // windef.h
>>>>>>>>>>>>>> typedef struct tagPOINT
>>>>>>>>>>>>>> {
>>>>>>>>>>>>>> LONG x; // long
x
>>>>>>>>>>>>>> LONG y; // long
y
>>>>>>>>>>>>>> } POINT, *PPOINT, NEAR
*NPPOINT, FAR *LPPOINT;
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> // win32.h
>>>>>>>>>>>>>> typedef int32_t LONG;
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> struct POINT
>>>>>>>>>>>>>> {
>>>>>>>>>>>>>> LONG x; // int x
>>>>>>>>>>>>>> LONG y; // int y
>>>>>>>>>>>>>> };
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> So POINT is defined two
different ways. In your minimal
>>>>>>>>>>>>>> interface, it's
declared as 2 int32's, which are int. In the actual
>>>>>>>>>>>>>> Windows header files,
it's declared as 2 longs.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> This might seem like a
unimportant bug since int and long are
>>>>>>>>>>>>>> the same size, but int
and long also mangle differently and affect overload
>>>>>>>>>>>>>> resolution, so you
could have weird linker errors or call the wrong
>>>>>>>>>>>>>> function overload.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Plus, it illustrates
the fact that this struct *actually is*
>>>>>>>>>>>>>> a different type from
the one in the windows header.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> You said at the end
that you never intentionally import
>>>>>>>>>>>>>> win32.h and windows.h
from the same translation unit. But then in this
>>>>>>>>>>>>>> example you did. I
wonder if you could enforce that by doing this:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> // win32.h
>>>>>>>>>>>>>> #pragma once
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> // Error if windows.h
was included before us.
>>>>>>>>>>>>>> #if defined(_WINDOWS_)
>>>>>>>>>>>>>> #error "You're
including win32.h after having already
>>>>>>>>>>>>>> included windows.h.
Don't do this!"
>>>>>>>>>>>>>> #endif
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> // And also make sure
windows.h can't get included after us
>>>>>>>>>>>>>> #define _WINDOWS_
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> For the record, I tried
the test case you linked when
>>>>>>>>>>>>>> windows.h is not
included in main.cpp and it works (but still has the bug
>>>>>>>>>>>>>> about int and long).
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Mon, Jan 22, 2018 at
2:23 PM Leonardo Santagada <
>>>>>>>>>>>>>> santagada at
gmail.com> wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> It is super gross,
but we copy parts of windows.h because
>>>>>>>>>>>>>>> having all of it if
both gigantic and very very messy. So our win32.h has a
>>>>>>>>>>>>>>> couple thousands of
lines and not 30k+ for windows.h and we try to have
>>>>>>>>>>>>>>> zero macros.
Win32.h doesn't include windows.h so using ::BOOL wouldn't
>>>>>>>>>>>>>>> work. We don't
want to create a namespace, we just want a cleaner interface
>>>>>>>>>>>>>>> to windows api. The
namespace with c linkage is the way to trick cl into
>>>>>>>>>>>>>>> allowing us to in
some files have both windows.h and Win32.h. I really
>>>>>>>>>>>>>>> don't see any
way for us to have this Win32.h without this cl support, so
>>>>>>>>>>>>>>> maybe we should
either put windows.h in a compiled header somewhere and not
>>>>>>>>>>>>>>> care that it is
infecting everything or just have one place we can call to
>>>>>>>>>>>>>>> clean up after
including windows.h (a massive set of undefs).
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> So using can't
work, because we never intentionally import
>>>>>>>>>>>>>>> windows.h and
win32.h on the same translation unit.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Mon, Jan 22,
2018 at 7:08 PM, Zachary Turner <
>>>>>>>>>>>>>>> zturner at
google.com> wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> This is pretty
gross, honestly :)
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Can't you
just use using declarations?
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> namespace Win32
{
>>>>>>>>>>>>>>>> extern
"C" {
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> using ::BOOL;
>>>>>>>>>>>>>>>> using ::LONG;
>>>>>>>>>>>>>>>> using ::POINT;
>>>>>>>>>>>>>>>> using
::LPPOINT;
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> using
::GetCursorPos;
>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> This works with
clang-cl.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Mon, Jan 22,
2018 at 5:39 AM Leonardo Santagada <
>>>>>>>>>>>>>>>> santagada at
gmail.com> wrote:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Here it is
a minimal example, we do this so we don't have
>>>>>>>>>>>>>>>>> to import
the whole windows api everywhere.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
https://gist.github.com/santagada/7977e929d31c629c4bf18ebb987f6be3
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Sun, Jan
21, 2018 at 2:31 AM, Zachary Turner <
>>>>>>>>>>>>>>>>> zturner at
google.com> wrote:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
Clang-cl maintains compatibility with msvc even in cases
>>>>>>>>>>>>>>>>>> where
it’s non standards compliant (eg 2 phase name lookup), but we try to
>>>>>>>>>>>>>>>>>> keep
these cases few and far between.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> To help
me understand your case, do you mean you copy
>>>>>>>>>>>>>>>>>>
windows.h and modify it? How does this lead to the same struct being
>>>>>>>>>>>>>>>>>> defined
twice? If i were to write this:
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> struct
Foo {};
>>>>>>>>>>>>>>>>>> struct
Foo {};
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Is this
a small repro of the issue you’re talking about?
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Sat,
Jan 20, 2018 at 3:44 PM Leonardo Santagada <
>>>>>>>>>>>>>>>>>>
santagada at gmail.com> wrote:
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> I
can totally see something like incremental linking
>>>>>>>>>>>>>>>>>>>
with a simple padding between obj and a mapping file (which can also help
>>>>>>>>>>>>>>>>>>>
with edit and continue, something we also would love to have).
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> We
have another developer doing the port to support
>>>>>>>>>>>>>>>>>>>
clang-cl, but although most of our code also goes trough a version of
>>>>>>>>>>>>>>>>>>>
clang, migrating the rest to clang-cl has been a fight. From what I heard
>>>>>>>>>>>>>>>>>>> the
main problem is that we have a copy of parts of windows.h (so not to
>>>>>>>>>>>>>>>>>>>
bring the awful parts of it like lower case macros) and that totally works
>>>>>>>>>>>>>>>>>>> on
cl, but clang (at least 6.0) complains about two struct/vars with the
>>>>>>>>>>>>>>>>>>>
same name, even though they are exactly the same. Making clang-cl as broken
>>>>>>>>>>>>>>>>>>> as
cl.exe is not an option I suppose? I would love to turn on a flag
>>>>>>>>>>>>>>>>>>>
--accept-that-cl-made-bad-decisions-and-live-with-it and have this at least
>>>>>>>>>>>>>>>>>>>
until this is completely fixed in our code base.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> the
biggest win with moving to cl would be a better more
>>>>>>>>>>>>>>>>>>>
standards compliant compiler, no 1 minute compiles on heavily templated
>>>>>>>>>>>>>>>>>>>
files and maybe the holy grail of ThinLTO.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On
Sat, Jan 20, 2018 at 10:56 PM, Zachary Turner <
>>>>>>>>>>>>>>>>>>>
zturner at google.com> wrote:
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
10-15s will be hard without true incremental linking.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
At some point that's going to be the only way to get
>>>>>>>>>>>>>>>>>>>>
any faster, but incremental linking is hard (putting it lightly), and since
>>>>>>>>>>>>>>>>>>>>
our full links are already really fast we think we can get reasonably close
>>>>>>>>>>>>>>>>>>>>
to link.exe incremental speeds with full links. But it's never enough and
>>>>>>>>>>>>>>>>>>>>
I will always want it to be faster, so you may see incremental linking in
>>>>>>>>>>>>>>>>>>>>
the future after we hit a performance wall with full link speed :)
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
In any case, I'm definitely interested in seeing what
>>>>>>>>>>>>>>>>>>>>
kind of numbers you get with /debug:ghash after you get this llvm-objcopy
>>>>>>>>>>>>>>>>>>>>
feature implemented. So keep me updated :)
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
As an aside, have you tried building with clang instead
>>>>>>>>>>>>>>>>>>>>
of cl? If you build with clang you wouldn't even have to do this
>>>>>>>>>>>>>>>>>>>>
llvm-objcopy work, because it would "just work". If you've tried
but ran
>>>>>>>>>>>>>>>>>>>>
into issues I'm interested in hearing about those too. On the other hand,
>>>>>>>>>>>>>>>>>>>>
it's also reasonable to only switch one thing at a time.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
On Sat, Jan 20, 2018 at 1:34 PM Leonardo Santagada <
>>>>>>>>>>>>>>>>>>>>
santagada at gmail.com> wrote:
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
if we get to < 30s I think most users would prefer it
>>>>>>>>>>>>>>>>>>>>>
to link.exe, just hopping there is still some more optimizations to get
>>>>>>>>>>>>>>>>>>>>>
closer to ELF linking times (around 10-15s here).
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
On Sat, Jan 20, 2018 at 9:50 PM, Zachary Turner <
>>>>>>>>>>>>>>>>>>>>>
zturner at google.com> wrote:
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
Generally speaking a good rule of thumb is that
>>>>>>>>>>>>>>>>>>>>>>
/debug:ghash will be close to or faster than /debug:fastlink, but with none
>>>>>>>>>>>>>>>>>>>>>>
of the penalties like slow debug time
>>>>>>>>>>>>>>>>>>>>>>
On Sat, Jan 20, 2018 at 12:44 PM Zachary Turner <
>>>>>>>>>>>>>>>>>>>>>>
zturner at google.com> wrote:
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
Chrome is actually one of my exact benchmark cases.
>>>>>>>>>>>>>>>>>>>>>>>
When building blink_core.dll and browser_tests.exe, i get anywhere from a
>>>>>>>>>>>>>>>>>>>>>>>
20-40% reduction in link time. We have some other optimizations in the
>>>>>>>>>>>>>>>>>>>>>>>
pipeline but not upstream yet.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
My best time so far (including other optimizations
>>>>>>>>>>>>>>>>>>>>>>>
not yet upstream) is 28s on blink_core.dll, compared to 110s with /debug
>>>>>>>>>>>>>>>>>>>>>>>
On Sat, Jan 20, 2018 at 12:28 PM Leonardo Santagada <
>>>>>>>>>>>>>>>>>>>>>>>
santagada at gmail.com> wrote:
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
On Sat, Jan 20, 2018 at 9:05 PM, Zachary Turner <
>>>>>>>>>>>>>>>>>>>>>>>>
zturner at google.com> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
You probably don't want to go down the same route
>>>>>>>>>>>>>>>>>>>>>>>>>
that clang goes through to write the object file. If you think yaml2coff
>>>>>>>>>>>>>>>>>>>>>>>>>
is convoluted, the way clang does it will just give you a headache. There
>>>>>>>>>>>>>>>>>>>>>>>>>
are multiple abstractions involved to account for different object file
>>>>>>>>>>>>>>>>>>>>>>>>>
formats (ELF, COFF, MachO) and output formats (Assembly, binary file). At
>>>>>>>>>>>>>>>>>>>>>>>>>
least with yaml2coff
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
I think your phrase got cut there, but yeah I just
>>>>>>>>>>>>>>>>>>>>>>>>
found AsmPrinter.cpp and it is convoluted.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
It's true that yaml2coff is using the COFFParser
>>>>>>>>>>>>>>>>>>>>>>>>>
structure, but if you look at the writeCOFF
>>>>>>>>>>>>>>>>>>>>>>>>>
function in yaml2coff it's pretty bare-metal. The logic you need will be
>>>>>>>>>>>>>>>>>>>>>>>>>
almost identical, except that instead of checking the COFFParser for the
>>>>>>>>>>>>>>>>>>>>>>>>>
various fields, you'll check the existing COFFObjectFile, which should have
>>>>>>>>>>>>>>>>>>>>>>>>>
similar fields.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
The only thing you need to different is when
>>>>>>>>>>>>>>>>>>>>>>>>>
writing the section table and section contents, to insert a new entry. Since
>>>>>>>>>>>>>>>>>>>>>>>>>
you're injecting a section into the middle, you'll also probably need to
>>>>>>>>>>>>>>>>>>>>>>>>>
push back the file pointer of all subsequent sections so that they don't
>>>>>>>>>>>>>>>>>>>>>>>>>
overlap. (e.g. if the original sections are 1, 2, 3, 4, 5 and you insert
>>>>>>>>>>>>>>>>>>>>>>>>>
between 2 and 3, then the original sections 3, 4, and 5 would need to have
>>>>>>>>>>>>>>>>>>>>>>>>>
their FilePointerToRawData offset by the size of the new section).
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
I have the PE/COFF spec open here and I'm happy
>>>>>>>>>>>>>>>>>>>>>>>>
that I read a bit of it so I actually know what you are talking about...
>>>>>>>>>>>>>>>>>>>>>>>>
yeah it doesn't seem too complicated.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
If you need to know what values to put for the
>>>>>>>>>>>>>>>>>>>>>>>>>
other fields in a section header, run `dumpbin /headers foo.obj` on a
>>>>>>>>>>>>>>>>>>>>>>>>>
clang-generated object file that has a .debug$H section already (e.g. run
>>>>>>>>>>>>>>>>>>>>>>>>>
clang with -emit-codeview-ghash-section, and look at the properties of the
>>>>>>>>>>>>>>>>>>>>>>>>>
.debug$H section and use the same values).
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
Thanks I will do that and then also look at how the
>>>>>>>>>>>>>>>>>>>>>>>>
CodeView part of the code does it if I can't understand some of it.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
The only invariant that needs to be maintained is
>>>>>>>>>>>>>>>>>>>>>>>>>
that Section[N]->FilePointerOfRawData
=>>>>>>>>>>>>>>>>>>>>>>>>>
Section[N-1]->FilePointerOfRawData + Section[N-1]->SizeOfRawData
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
Well, that and all the sections need to be on the
>>>>>>>>>>>>>>>>>>>>>>>>
final file... But I'm hopeful.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
Anyone has times on linking a big project like
>>>>>>>>>>>>>>>>>>>>>>>>
chrome with this so that at least I know what kind of performance to expect?
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
My numbers are something like:
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
1 pdb per obj file: link.exe takes ~15 minutes and
>>>>>>>>>>>>>>>>>>>>>>>>
16GB of ram, lld-link.exe takes 2:30 minutes and ~8GB of ram
>>>>>>>>>>>>>>>>>>>>>>>>
around 10 pdbs per folder: link.exe takes 1 minute
>>>>>>>>>>>>>>>>>>>>>>>>
and 2-3GB of ram, lld-link.exe takes 1:30 minutes and ~6GB of ram
>>>>>>>>>>>>>>>>>>>>>>>>
faslink: link.exe takes 40 seconds, but then 20
>>>>>>>>>>>>>>>>>>>>>>>>
seconds of loading at the first break point in the debugger and we lost DIA
>>>>>>>>>>>>>>>>>>>>>>>>
support for listing symbols.
>>>>>>>>>>>>>>>>>>>>>>>>
incremental: link.exe takes 8 seconds, but it only
>>>>>>>>>>>>>>>>>>>>>>>>
happens when very minor changes happen.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
We have an non negligible number of symbols used on
>>>>>>>>>>>>>>>>>>>>>>>>
some runtime systems.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
On Sat, Jan 20, 2018 at 11:52 AM Leonardo
>>>>>>>>>>>>>>>>>>>>>>>>>
Santagada <santagada at gmail.com> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
Thanks for the tips, I now have something that
>>>>>>>>>>>>>>>>>>>>>>>>>>
reads the obj file, finds .debug$T sections and global hashes it (proof of
>>>>>>>>>>>>>>>>>>>>>>>>>>
concept kind of code). What I can't find is: how does clang itself writes
>>>>>>>>>>>>>>>>>>>>>>>>>>
the coff files with global hashes, as that might help me understand how to
>>>>>>>>>>>>>>>>>>>>>>>>>>
create the .debug$H section, how to update the file section count and how
>>>>>>>>>>>>>>>>>>>>>>>>>>
to properly write this back.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
The code on yaml2coff is expecting to be working
>>>>>>>>>>>>>>>>>>>>>>>>>>
on the yaml COFFParser struct and I'm having quite a bit of a headache
>>>>>>>>>>>>>>>>>>>>>>>>>>
turning the COFFObjectFile into a COFFParser object or compatible...
>>>>>>>>>>>>>>>>>>>>>>>>>>
Tomorrow I might try the very non efficient path of coff2yaml and then
>>>>>>>>>>>>>>>>>>>>>>>>>>
yaml2coff with the hashes header... but it seems way too inefficient and
>>>>>>>>>>>>>>>>>>>>>>>>>>
convoluted.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
On Fri, Jan 19, 2018 at 10:38 PM, Zachary Turner
>>>>>>>>>>>>>>>>>>>>>>>>>>
<zturner at google.com> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
On Fri, Jan 19, 2018 at 1:02 PM Leonardo
>>>>>>>>>>>>>>>>>>>>>>>>>>>
Santagada <santagada at gmail.com> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
On Fri, Jan 19, 2018 at 9:44 PM, Zachary Turner
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
<zturner at google.com> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
On Fri, Jan 19, 2018 at 12:29 PM Leonardo
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Santagada <santagada at gmail.com> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
No I didn't, I used cl.exe from the visual
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
studio toolchain. What I'm proposing is a tool for processing .obj files in
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
COFF format, reading them and generating the GHASH part.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
To make our build faster we use hundreds of
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
unity build files (.cpp's with a lot of other .cpp's in them aka munch
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
files) but still have a lot of single .cpp's as well (in total something
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
like 3.4k .obj files).
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
ps: sorry for sending to the wrong list, I
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
was reading about llvm mailing lists and jumped when I saw what I thought
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
was a lld exclusive list.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
A tool like this would be useful, yes. We've
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
talked about it internally as well and agreed it would be useful, we just
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
haven't prioritized it. If you're interested in submitting a patch
along
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
those lines though, I think it would be a good addition.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
I'm not sure what the best place for it would
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
be. llvm-readobj and llvm-objdump seem like obvious choices, but they are
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
intended to be read-only, so perhaps they wouldn't be a good fit.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
llvm-pdbutil is kind of a hodgepodge of
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
everything else related to PDBs and symbols, so I wouldn't be opposed to
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
making a new subcommand there called "ghash" or something that could
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
process an object file and output a new object file with a .debug$H section.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
A third option would be to make a new tool for
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
it.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
I don't htink it would be that hard to write.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you're interested in trying to make a patch for this, I can offer some
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
guidance on where to look in the code. Otherwise it's something that
we'll
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
probably get to, I'm just not sure when.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
I would love to write it and contribute it
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
back, please do tell, I did find some of the code of ghash in lld, but in
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
fuzzy on the llvm codeview part of it and never seen llvm-readobj/objdump
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
or llvm-pdbutil, but I'm not afraid to look :)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
Luckily all of the important code is hidden
>>>>>>>>>>>>>>>>>>>>>>>>>>>
behind library calls, and it should already just do the right thing, so I
>>>>>>>>>>>>>>>>>>>>>>>>>>>
suspect you won't need to know much about CodeView to do this.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
I think Peter has the right idea about putting
>>>>>>>>>>>>>>>>>>>>>>>>>>>
this in llvm-objcopy.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
You can look at one of the existing CopyBinary
>>>>>>>>>>>>>>>>>>>>>>>>>>>
functions there, which currently only work for ELF, but you can just make a
>>>>>>>>>>>>>>>>>>>>>>>>>>>
new overload that accepts a COFFObjectFile.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
I would probably start by iterating over each of
>>>>>>>>>>>>>>>>>>>>>>>>>>>
the sections (getNumberOfSections / getSectionName) looking for .debug$T
>>>>>>>>>>>>>>>>>>>>>>>>>>>
and .debug$H sections.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you find a .debug$H section then you can just
>>>>>>>>>>>>>>>>>>>>>>>>>>>
skip that object file.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you find a .debug$T but not a .debug$H, then
>>>>>>>>>>>>>>>>>>>>>>>>>>>
basically do the same thing that LLD does in PDBLinker::mergeDebugT
>>>>>>>>>>>>>>>>>>>>>>>>>>>
(create a CVTypeArray, and pass it to GloballyHashedType::hashTypes. That
>>>>>>>>>>>>>>>>>>>>>>>>>>>
will return an array of hash values. (the format of .debug$H is the
>>>>>>>>>>>>>>>>>>>>>>>>>>>
header, followed by the hash values). Then when you're writing the list of
>>>>>>>>>>>>>>>>>>>>>>>>>>>
sections, just add in the .debug$H section right after the .debug$T section.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
Currently llvm-objcopy only writes ELF files, so
>>>>>>>>>>>>>>>>>>>>>>>>>>>
it would need to be taught to write COFF files. We have code to do this in
>>>>>>>>>>>>>>>>>>>>>>>>>>>
the yaml2obj utility (specifically, in yaml2coff.cpp in the function
>>>>>>>>>>>>>>>>>>>>>>>>>>>
writeCOFF). There may be a way to move this code to somewhere else
>>>>>>>>>>>>>>>>>>>>>>>>>>>
(llvm/Object/COFF.h?) so that it can be re-used by both yaml2coff and
>>>>>>>>>>>>>>>>>>>>>>>>>>>
llvm-objcopy, but in the worst case scenario you could copy the code and
>>>>>>>>>>>>>>>>>>>>>>>>>>>
re-write it to work with these new structures.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
Lastly, you'll probably want to put all of this
>>>>>>>>>>>>>>>>>>>>>>>>>>>
behind an option in llvm-objcopy such as -add-codeview-ghash-section
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
--
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
Leonardo Santagada
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
--
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
Leonardo Santagada
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
--
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
Leonardo Santagada
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> --
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
Leonardo Santagada
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> --
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Leonardo
Santagada
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> --
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Leonardo Santagada
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>>
>>>>>>>>>>> Leonardo Santagada
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>>
>>>>>>>>> Leonardo Santagada
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>>
>>>>>>> Leonardo Santagada
>>>>>>>
>>>>>>
>>>>
>>>>
>>>> --
>>>>
>>>> Leonardo Santagada
>>>>
>>>
>>>
>>>
>>> --
>>>
>>> Leonardo Santagada
>>>
>>
>
>
> --
>
> Leonardo Santagada
>
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Leonardo Santagada via llvm-dev
2018-Jan-26 15:27 UTC
[llvm-dev] [lldb-dev] Trying out lld to link windows binaries (using msvc as a compiler)
I'm so close I can almost smell it :) I know how bad the code looks, I don't intend to submit this, but if you want to try it out its at: https://gist.github.com/santagada/544136b1ee143bf31653b1158ac6829e I'm seeing: lld-link.exe: error: duplicate symbol: "<redacted_unmangled>" (<redacted>) in <internal> and in <redacted_filename>.obj, looking at the .yaml dump the symbols are all similar to this: - Name: <redacted> Value: 0 SectionNumber: 0 SimpleType: IMAGE_SYM_TYPE_NULL ComplexType: IMAGE_SYM_DTYPE_FUNCTION StorageClass: IMAGE_SYM_CLASS_WEAK_EXTERNAL WeakExternal: TagIndex: 134 Characteristics: IMAGE_WEAK_EXTERN_SEARCH_LIBRARY On Thu, Jan 25, 2018 at 8:01 PM, Zachary Turner <zturner at google.com> wrote:> I haven't really dabbled in this part of the COFF format personally, so > hopefully I'm not leading you astray :) > > But I checked the code for coff2yaml, and I see this: > > } else if (Symbol.isSectionDefinition()) { > // This symbol represents a section definition. > assert(Symbol.getNumberOfAuxSymbols() == 1 && > "Expected a single aux symbol to describe this section!"); > const object::coff_aux_section_definition *ObjSD > reinterpret_cast<const object::coff_aux_section_definition *>( > AuxData.data()); > > So it looks like you need exactly 1 aux symbol for each section symbol. > > I then scrolled up in this function to figure out where AuxData comes > from, and it comes from COFFObjectFile::getSymbolAuxData. I think that > function holds the clue to what you need to do. It looks like you need to > set coff::symbol::NumberOfAuxSymbols to 1, and then there is a comment in > getSymbolAuxData which says: > > // AUX data comes immediately after the symbol in COFF > Aux = reinterpret_cast<const uint8_t *>(Symbol.getRawPtr()) + > SymbolSize; > > So I think you just need to write the bytes immediately after the > coff::symbol. The thing you need to write looks like a > coff::coff_aux_section_definition structure. > > For the CheckSum, look at WinCOFFObjectWriter::writeSection. It looks > like its a CRC32 of the actual section contents, which you can generate > with a couple of lines of code: > > JamCRC JC(/*Init=*/0); > JC.update(DebugHContents); > AuxSymbol.CheckSum = JC.getCRC(); > > Hope this helps > > On Thu, Jan 25, 2018 at 10:46 AM Leonardo Santagada <santagada at gmail.com> > wrote: > >> >> I see that there is an auxsymbol per section symbol, and also on the yaml >> representation there is a checksum, selection and unused all of them I have >> no idea how to fill in, also this aux symbol might have some important >> information for me to patch on the other symbols. Can you find the part in >> llvm that it writes those? because at least for auxsymbol the yaml part of >> the code threats as a binary blob so there is no info on what they should >> be. >> >> On Thu, Jan 25, 2018 at 7:15 PM, Zachary Turner <zturner at google.com> >> wrote: >> >>> If you run obj2yaml against a very simple object file, you'll see >>> something like this at the end: >>> ``` >>> symbols: >>> - Name: '@comp.id' >>> Value: 17130443 >>> SectionNumber: -1 >>> SimpleType: IMAGE_SYM_TYPE_NULL >>> ComplexType: IMAGE_SYM_DTYPE_NULL >>> StorageClass: IMAGE_SYM_CLASS_STATIC >>> - Name: '@feat.00' >>> Value: 2147484048 <(21)%204748-4048> >>> SectionNumber: -1 >>> SimpleType: IMAGE_SYM_TYPE_NULL >>> ComplexType: IMAGE_SYM_DTYPE_NULL >>> StorageClass: IMAGE_SYM_CLASS_STATIC >>> - Name: .drectve >>> Value: 0 >>> SectionNumber: 1 >>> SimpleType: IMAGE_SYM_TYPE_NULL >>> ComplexType: IMAGE_SYM_DTYPE_NULL >>> StorageClass: IMAGE_SYM_CLASS_STATIC >>> SectionDefinition: >>> Length: 47 >>> NumberOfRelocations: 0 >>> NumberOfLinenumbers: 0 >>> CheckSum: 0 >>> Number: 0 >>> ... >>> ``` >>> >>> There's a structure called coff::symbol which basically represents each >>> one of these records. It looks like this: >>> >>> ``` >>> struct symbol { >>> char Name[NameSize]; >>> uint32_t Value; >>> int32_t SectionNumber; >>> uint16_t Type; >>> uint8_t StorageClass; >>> uint8_t NumberOfAuxSymbols; >>> }; >>> ``` >>> >>> So you'll need to create one for the debug$H section and stick it into >>> the list. This particular list doesn't have to be in any special order, so >>> you can just put it at the end (although it's probably not that much harder >>> to insert into the middle, and it will make for a good test that you've >>> done it right. The output can be diffed against clang-cl object file and >>> be identical this way). So write all the normal symbols as you probably >>> already are, then write one for the .debug$H section. Initialize the >>> fields to the same thing that you see when you run obj2yaml against an >>> object file generated by clang-cl for the .debug$H section. >>> >>> This structure doesn't contain any kind of file pointers or offsets, so >>> all you really need to fix up are the "SectionNumber" fields. Basically as >>> you are writing the existing symbols, you would do somethign like: >>> >>> for (const auto &Sym : ObjFile.symbols()) { >>> if (Symbol->SectionNumber >= DebugHInsertionIndex) >>> ++Symbol->SectionNumber; >>> writeSymbol(Sym); >>> } >>> writeSymbol(DebugHSym); >>> >>> >>> On Thu, Jan 25, 2018 at 9:57 AM Leonardo Santagada <santagada at gmail.com> >>> wrote: >>> >>>> Any idea on how to create this new symbol there? I saw that there is a >>>> symbol pointing to each section, but didn't understand the format, and >>>> yaml2obj doesn't check it or do anything with the list. >>>> >>>> On Thu, Jan 25, 2018 at 6:56 PM, Leonardo Santagada < >>>> santagada at gmail.com> wrote: >>>> >>>>> YES, THANK YOU... I WAS THINKING THIS BUT COMPLETELY FORGOT. >>>>> >>>>> sorry for the caps... long day of working on this, and using vs 2017, >>>>> which adds a new section type .chks64 that I couldn't find documentation >>>>> anywhere was difficult. I highly recommend everyone to just not using vs >>>>> 2017 until 15.8 or something, our internal bug list is gigantic. >>>>> >>>>> On Thu, Jan 25, 2018 at 6:52 PM, Zachary Turner <zturner at google.com> >>>>> wrote: >>>>> >>>>>> Actually I already have a theory that even though you are adding the >>>>>> section to the section table, you might not be adding a *symbol* for the >>>>>> section to the symbol table. So the existing symbols (which reference >>>>>> sections by index) will all be wrong because you've inserted a new >>>>>> section. Still though, obj2yaml would expose that. >>>>>> >>>>>> On Thu, Jan 25, 2018 at 9:50 AM Zachary Turner <zturner at google.com> >>>>>> wrote: >>>>>> >>>>>>> Yea as long as you compare clang-cl object file with automatically >>>>>>> generated .debug$H section against clang-cl object file without .debug$H >>>>>>> but added after the fact with llvm-objcopy, that should expose the problem >>>>>>> I think when you run obj2yaml on them. >>>>>>> >>>>>>> On Thu, Jan 25, 2018 at 9:49 AM Leonardo Santagada < >>>>>>> santagada at gmail.com> wrote: >>>>>>> >>>>>>>> I did reorder my sections, so that .debug$H is in the correct >>>>>>>> place, but now I get some errors on dubplicate symbols, I created a folder >>>>>>>> with examples: >>>>>>>> >>>>>>>> https://www.dropbox.com/sh/nmvzi44pi0boe76/ >>>>>>>> AAA0f47O5PCJ9JiUc6wVuwBra?dl=0 >>>>>>>> >>>>>>>> t.obj is generated by vs 2015 and it links fine with lld-link.exe, >>>>>>>> but tout.obj gives this errors: >>>>>>>> >>>>>>>> lld-link.exe /DEBUG:GHASH tout.obj >>>>>>>> LLD-LINK.EXE: error: duplicate symbol: __local_stdio_printf_options >>>>>>>> in tout.obj and in LIBCMT.lib(default_local_stdio_options.obj) >>>>>>>> LLD-LINK.EXE: error: duplicate symbol: __local_stdio_printf_options >>>>>>>> in tout.obj and in libvcruntime.lib(undname.obj) >>>>>>>> >>>>>>>> I'm using PEView from http://wjradburn.com/software/ to look at >>>>>>>> the files and can't see anything wrong, except some valid differences in >>>>>>>> the offsets being used for the data (so pointer to data is different >>>>>>>> between them). >>>>>>>> >>>>>>>> I will look into yaml2obj now to see if I see anything else weird >>>>>>>> going on. >>>>>>>> >>>>>>>> >>>>>>>> On Thu, Jan 25, 2018 at 6:41 PM, Zachary Turner <zturner at google.com >>>>>>>> > wrote: >>>>>>>> >>>>>>>>> I'm pretty confident that cl is not putting anything strange in >>>>>>>>> the .debug$T sections. We've done a lot of testing and never seen anything >>>>>>>>> except CodeView type records in a .debug$T. My hunch is that your objcopy >>>>>>>>> patch is probably not doing the right thing in one or more of the section >>>>>>>>> headers, and this is confusing the linker. >>>>>>>>> >>>>>>>>> One idea might be to build a simple object file with clang-cl but >>>>>>>>> without the magic -mllvm -emit-codeview-ghash-section, then run your >>>>>>>>> llvm-objcopy on it. Then build the same object file passing -mllvm >>>>>>>>> -emit-codeview-ghash-section. Then run obj2yaml on both and diff the >>>>>>>>> results. They should be byte-for-byte identical. That should give you a >>>>>>>>> clue about if objcopy is doing something wrong. >>>>>>>>> >>>>>>>>> On Thu, Jan 25, 2018 at 2:21 AM Leonardo Santagada < >>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>> >>>>>>>>>> Don't worry, I definetly want to perfect this to generate legal >>>>>>>>>> obj files, this is just to speed up testing. >>>>>>>>>> >>>>>>>>>> Now after patching all the obj files I get this errors when >>>>>>>>>> linking a small part of our code base (msvc 2017 15.5.3, lld and >>>>>>>>>> llvm-objcopy 7.0.0): >>>>>>>>>> lld-link.exe : error : relocation against symbol in discarded >>>>>>>>>> section: $LN8 >>>>>>>>>> lld-link.exe : error : relocation against symbol in discarded >>>>>>>>>> section: $LN43 >>>>>>>>>> lld-link.exe : error : relocation against symbol in discarded >>>>>>>>>> section: $LN37 >>>>>>>>>> >>>>>>>>>> I'm starting to guess that cl.exe might be putting some random >>>>>>>>>> comdat or other discardable symbols in the .debug$T and clang doesn't? I >>>>>>>>>> will try to debug this and see what more I can uncover. >>>>>>>>>> >>>>>>>>>> Linking works perfectly without my llvm-objcopy pass to add >>>>>>>>>> .debug$H? >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On Thu, Jan 25, 2018 at 1:53 AM, Zachary Turner < >>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>> >>>>>>>>>>> It might not influence LLD, but at the same time we don't want >>>>>>>>>>> to upstream something that is producing technically illegal COFF files. >>>>>>>>>>> Also good to hear about the planned changes to your header files. Looking >>>>>>>>>>> forward to hearing about your experiences with clang-cl. >>>>>>>>>>> >>>>>>>>>>> On Wed, Jan 24, 2018 at 10:41 AM Leonardo Santagada < >>>>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>>>> >>>>>>>>>>>> Hi, >>>>>>>>>>>> >>>>>>>>>>>> I finally got my first .obj file patched with .debug$H to look >>>>>>>>>>>> somewhat right. I added the new section at the end of the file so I don't >>>>>>>>>>>> have to recalculate all sections (although now I probably could position it >>>>>>>>>>>> in the middle, knowing that each section is: SizeOfRawData + (last.Header.NumberOfRelocations >>>>>>>>>>>> * (4+4+2)) and the $H needs to come right after $T in the file). That >>>>>>>>>>>> although illegal based on the coff specs doesn't seem its going to >>>>>>>>>>>> influence lld. >>>>>>>>>>>> >>>>>>>>>>>> Also we talked and we are probably going to do something >>>>>>>>>>>> similar to a bunch of windows defines and a check for our own define (to >>>>>>>>>>>> guarantee that no one imported windows.h before win32.h) and drop the >>>>>>>>>>>> namespace and the conflicting names. >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> On Tue, Jan 23, 2018 at 12:46 AM, Zachary Turner < >>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>> >>>>>>>>>>>>> That's very possible that a 3rd party indirect header include >>>>>>>>>>>>> is involved. One idea might be like I suggested where you #define >>>>>>>>>>>>> _WINDOWS_ in win32.h and guarantee that it's always included first. Then >>>>>>>>>>>>> those other headers won't be able to #include <windows.h>. but it will >>>>>>>>>>>>> probably greatly expand the amount of stuff you have to add to win32.h, as >>>>>>>>>>>>> you will probably find some callers of functions that aren't yet in your >>>>>>>>>>>>> win32.h that you'd have to add. >>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> On Mon, Jan 22, 2018 at 3:28 PM Leonardo Santagada < >>>>>>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>>>>>> >>>>>>>>>>>>>> Ok some information was lost on getting this example to you, >>>>>>>>>>>>>> I'm sorry for not being clear. >>>>>>>>>>>>>> >>>>>>>>>>>>>> We have a huge code base, let's say 90% of it doesn't include >>>>>>>>>>>>>> either header, 9% include win32.h and 1% includes both, I will try to >>>>>>>>>>>>>> discover why, but my guess is they include both a third party that includes >>>>>>>>>>>>>> windows.h and some of our libs that use win32.h. >>>>>>>>>>>>>> >>>>>>>>>>>>>> I will try to fully understand this tomorrow. >>>>>>>>>>>>>> >>>>>>>>>>>>>> I guess clang will not implement this ever so finishing the >>>>>>>>>>>>>> object copier is the best solution until all code is ported to clang. >>>>>>>>>>>>>> >>>>>>>>>>>>>> On 23 Jan 2018 00:02, "Zachary Turner" <zturner at google.com> >>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>> >>>>>>>>>>>>>>> You said win32.h doesn't include windows.h, but main.cpp >>>>>>>>>>>>>>> does. So what's the disadvantage of just including it in win32.h anyway, >>>>>>>>>>>>>>> since it's already going to be in every translation unit? (Unless you >>>>>>>>>>>>>>> didn't mean to #include it in main.cpp) >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> I guess all I can do is warn you how bad of an idea this >>>>>>>>>>>>>>> is. For starters, I already found a bug in your code ;-) >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> // stdint.h >>>>>>>>>>>>>>> typedef int int32_t; >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> // winnt.h >>>>>>>>>>>>>>> typedef long LONG; >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> // windef.h >>>>>>>>>>>>>>> typedef struct tagPOINT >>>>>>>>>>>>>>> { >>>>>>>>>>>>>>> LONG x; // long x >>>>>>>>>>>>>>> LONG y; // long y >>>>>>>>>>>>>>> } POINT, *PPOINT, NEAR *NPPOINT, FAR *LPPOINT; >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> // win32.h >>>>>>>>>>>>>>> typedef int32_t LONG; >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> struct POINT >>>>>>>>>>>>>>> { >>>>>>>>>>>>>>> LONG x; // int x >>>>>>>>>>>>>>> LONG y; // int y >>>>>>>>>>>>>>> }; >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> So POINT is defined two different ways. In your minimal >>>>>>>>>>>>>>> interface, it's declared as 2 int32's, which are int. In the actual >>>>>>>>>>>>>>> Windows header files, it's declared as 2 longs. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> This might seem like a unimportant bug since int and long >>>>>>>>>>>>>>> are the same size, but int and long also mangle differently and affect >>>>>>>>>>>>>>> overload resolution, so you could have weird linker errors or call the >>>>>>>>>>>>>>> wrong function overload. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Plus, it illustrates the fact that this struct *actually is* >>>>>>>>>>>>>>> a different type from the one in the windows header. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> You said at the end that you never intentionally import >>>>>>>>>>>>>>> win32.h and windows.h from the same translation unit. But then in this >>>>>>>>>>>>>>> example you did. I wonder if you could enforce that by doing this: >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> // win32.h >>>>>>>>>>>>>>> #pragma once >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> // Error if windows.h was included before us. >>>>>>>>>>>>>>> #if defined(_WINDOWS_) >>>>>>>>>>>>>>> #error "You're including win32.h after having already >>>>>>>>>>>>>>> included windows.h. Don't do this!" >>>>>>>>>>>>>>> #endif >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> // And also make sure windows.h can't get included after us >>>>>>>>>>>>>>> #define _WINDOWS_ >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> For the record, I tried the test case you linked when >>>>>>>>>>>>>>> windows.h is not included in main.cpp and it works (but still has the bug >>>>>>>>>>>>>>> about int and long). >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> On Mon, Jan 22, 2018 at 2:23 PM Leonardo Santagada < >>>>>>>>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> It is super gross, but we copy parts of windows.h because >>>>>>>>>>>>>>>> having all of it if both gigantic and very very messy. So our win32.h has a >>>>>>>>>>>>>>>> couple thousands of lines and not 30k+ for windows.h and we try to have >>>>>>>>>>>>>>>> zero macros. Win32.h doesn't include windows.h so using ::BOOL wouldn't >>>>>>>>>>>>>>>> work. We don't want to create a namespace, we just want a cleaner interface >>>>>>>>>>>>>>>> to windows api. The namespace with c linkage is the way to trick cl into >>>>>>>>>>>>>>>> allowing us to in some files have both windows.h and Win32.h. I really >>>>>>>>>>>>>>>> don't see any way for us to have this Win32.h without this cl support, so >>>>>>>>>>>>>>>> maybe we should either put windows.h in a compiled header somewhere and not >>>>>>>>>>>>>>>> care that it is infecting everything or just have one place we can call to >>>>>>>>>>>>>>>> clean up after including windows.h (a massive set of undefs). >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> So using can't work, because we never intentionally import >>>>>>>>>>>>>>>> windows.h and win32.h on the same translation unit. >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> On Mon, Jan 22, 2018 at 7:08 PM, Zachary Turner < >>>>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> This is pretty gross, honestly :) >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Can't you just use using declarations? >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> namespace Win32 { >>>>>>>>>>>>>>>>> extern "C" { >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> using ::BOOL; >>>>>>>>>>>>>>>>> using ::LONG; >>>>>>>>>>>>>>>>> using ::POINT; >>>>>>>>>>>>>>>>> using ::LPPOINT; >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> using ::GetCursorPos; >>>>>>>>>>>>>>>>> } >>>>>>>>>>>>>>>>> } >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> This works with clang-cl. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> On Mon, Jan 22, 2018 at 5:39 AM Leonardo Santagada < >>>>>>>>>>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> Here it is a minimal example, we do this so we don't have >>>>>>>>>>>>>>>>>> to import the whole windows api everywhere. >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> https://gist.github.com/santagada/ >>>>>>>>>>>>>>>>>> 7977e929d31c629c4bf18ebb987f6be3 >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> On Sun, Jan 21, 2018 at 2:31 AM, Zachary Turner < >>>>>>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> Clang-cl maintains compatibility with msvc even in cases >>>>>>>>>>>>>>>>>>> where it’s non standards compliant (eg 2 phase name lookup), but we try to >>>>>>>>>>>>>>>>>>> keep these cases few and far between. >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> To help me understand your case, do you mean you copy >>>>>>>>>>>>>>>>>>> windows.h and modify it? How does this lead to the same struct being >>>>>>>>>>>>>>>>>>> defined twice? If i were to write this: >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> struct Foo {}; >>>>>>>>>>>>>>>>>>> struct Foo {}; >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> Is this a small repro of the issue you’re talking about? >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 3:44 PM Leonardo Santagada < >>>>>>>>>>>>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> I can totally see something like incremental linking >>>>>>>>>>>>>>>>>>>> with a simple padding between obj and a mapping file (which can also help >>>>>>>>>>>>>>>>>>>> with edit and continue, something we also would love to have). >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> We have another developer doing the port to support >>>>>>>>>>>>>>>>>>>> clang-cl, but although most of our code also goes trough a version of >>>>>>>>>>>>>>>>>>>> clang, migrating the rest to clang-cl has been a fight. From what I heard >>>>>>>>>>>>>>>>>>>> the main problem is that we have a copy of parts of windows.h (so not to >>>>>>>>>>>>>>>>>>>> bring the awful parts of it like lower case macros) and that totally works >>>>>>>>>>>>>>>>>>>> on cl, but clang (at least 6.0) complains about two struct/vars with the >>>>>>>>>>>>>>>>>>>> same name, even though they are exactly the same. Making clang-cl as broken >>>>>>>>>>>>>>>>>>>> as cl.exe is not an option I suppose? I would love to turn on a flag >>>>>>>>>>>>>>>>>>>> --accept-that-cl-made-bad-decisions-and-live-with-it >>>>>>>>>>>>>>>>>>>> and have this at least until this is completely fixed in our code base. >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> the biggest win with moving to cl would be a better >>>>>>>>>>>>>>>>>>>> more standards compliant compiler, no 1 minute compiles on heavily >>>>>>>>>>>>>>>>>>>> templated files and maybe the holy grail of ThinLTO. >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 10:56 PM, Zachary Turner < >>>>>>>>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> 10-15s will be hard without true incremental linking. >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> At some point that's going to be the only way to get >>>>>>>>>>>>>>>>>>>>> any faster, but incremental linking is hard (putting it lightly), and since >>>>>>>>>>>>>>>>>>>>> our full links are already really fast we think we can get reasonably close >>>>>>>>>>>>>>>>>>>>> to link.exe incremental speeds with full links. But it's never enough and >>>>>>>>>>>>>>>>>>>>> I will always want it to be faster, so you may see incremental linking in >>>>>>>>>>>>>>>>>>>>> the future after we hit a performance wall with full link speed :) >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> In any case, I'm definitely interested in seeing what >>>>>>>>>>>>>>>>>>>>> kind of numbers you get with /debug:ghash after you get this llvm-objcopy >>>>>>>>>>>>>>>>>>>>> feature implemented. So keep me updated :) >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> As an aside, have you tried building with clang >>>>>>>>>>>>>>>>>>>>> instead of cl? If you build with clang you wouldn't even have to do this >>>>>>>>>>>>>>>>>>>>> llvm-objcopy work, because it would "just work". If you've tried but ran >>>>>>>>>>>>>>>>>>>>> into issues I'm interested in hearing about those too. On the other hand, >>>>>>>>>>>>>>>>>>>>> it's also reasonable to only switch one thing at a time. >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 1:34 PM Leonardo Santagada < >>>>>>>>>>>>>>>>>>>>> santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> if we get to < 30s I think most users would prefer it >>>>>>>>>>>>>>>>>>>>>> to link.exe, just hopping there is still some more optimizations to get >>>>>>>>>>>>>>>>>>>>>> closer to ELF linking times (around 10-15s here). >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 9:50 PM, Zachary Turner < >>>>>>>>>>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> Generally speaking a good rule of thumb is that >>>>>>>>>>>>>>>>>>>>>>> /debug:ghash will be close to or faster than /debug:fastlink, but with none >>>>>>>>>>>>>>>>>>>>>>> of the penalties like slow debug time >>>>>>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 12:44 PM Zachary Turner < >>>>>>>>>>>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> Chrome is actually one of my exact benchmark cases. >>>>>>>>>>>>>>>>>>>>>>>> When building blink_core.dll and browser_tests.exe, i get anywhere from a >>>>>>>>>>>>>>>>>>>>>>>> 20-40% reduction in link time. We have some other optimizations in the >>>>>>>>>>>>>>>>>>>>>>>> pipeline but not upstream yet. >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> My best time so far (including other optimizations >>>>>>>>>>>>>>>>>>>>>>>> not yet upstream) is 28s on blink_core.dll, compared to 110s with /debug >>>>>>>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 12:28 PM Leonardo Santagada >>>>>>>>>>>>>>>>>>>>>>>> <santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 9:05 PM, Zachary Turner < >>>>>>>>>>>>>>>>>>>>>>>>> zturner at google.com> wrote: >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> You probably don't want to go down the same route >>>>>>>>>>>>>>>>>>>>>>>>>> that clang goes through to write the object file. If you think yaml2coff >>>>>>>>>>>>>>>>>>>>>>>>>> is convoluted, the way clang does it will just give you a headache. There >>>>>>>>>>>>>>>>>>>>>>>>>> are multiple abstractions involved to account for different object file >>>>>>>>>>>>>>>>>>>>>>>>>> formats (ELF, COFF, MachO) and output formats (Assembly, binary file). At >>>>>>>>>>>>>>>>>>>>>>>>>> least with yaml2coff >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> I think your phrase got cut there, but yeah I just >>>>>>>>>>>>>>>>>>>>>>>>> found AsmPrinter.cpp and it is convoluted. >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> It's true that yaml2coff is using the COFFParser >>>>>>>>>>>>>>>>>>>>>>>>>> structure, but if you look at the writeCOFF >>>>>>>>>>>>>>>>>>>>>>>>>> function in yaml2coff it's pretty bare-metal. The logic you need will be >>>>>>>>>>>>>>>>>>>>>>>>>> almost identical, except that instead of checking the COFFParser for the >>>>>>>>>>>>>>>>>>>>>>>>>> various fields, you'll check the existing COFFObjectFile, which should have >>>>>>>>>>>>>>>>>>>>>>>>>> similar fields. >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> The only thing you need to different is when >>>>>>>>>>>>>>>>>>>>>>>>>> writing the section table and section contents, to insert a new entry. Since >>>>>>>>>>>>>>>>>>>>>>>>>> you're injecting a section into the middle, you'll also probably need to >>>>>>>>>>>>>>>>>>>>>>>>>> push back the file pointer of all subsequent sections so that they don't >>>>>>>>>>>>>>>>>>>>>>>>>> overlap. (e.g. if the original sections are 1, 2, 3, 4, 5 and you insert >>>>>>>>>>>>>>>>>>>>>>>>>> between 2 and 3, then the original sections 3, 4, and 5 would need to have >>>>>>>>>>>>>>>>>>>>>>>>>> their FilePointerToRawData offset by the size of the new section). >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> I have the PE/COFF spec open here and I'm happy >>>>>>>>>>>>>>>>>>>>>>>>> that I read a bit of it so I actually know what you are talking about... >>>>>>>>>>>>>>>>>>>>>>>>> yeah it doesn't seem too complicated. >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> If you need to know what values to put for the >>>>>>>>>>>>>>>>>>>>>>>>>> other fields in a section header, run `dumpbin /headers foo.obj` on a >>>>>>>>>>>>>>>>>>>>>>>>>> clang-generated object file that has a .debug$H section already (e.g. run >>>>>>>>>>>>>>>>>>>>>>>>>> clang with -emit-codeview-ghash-section, and look at the properties of the >>>>>>>>>>>>>>>>>>>>>>>>>> .debug$H section and use the same values). >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> Thanks I will do that and then also look at how >>>>>>>>>>>>>>>>>>>>>>>>> the CodeView part of the code does it if I can't understand some of it. >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> The only invariant that needs to be maintained is >>>>>>>>>>>>>>>>>>>>>>>>>> that Section[N]->FilePointerOfRawData =>>>>>>>>>>>>>>>>>>>>>>>>>> Section[N-1]->FilePointerOfRawData + >>>>>>>>>>>>>>>>>>>>>>>>>> Section[N-1]->SizeOfRawData >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> Well, that and all the sections need to be on the >>>>>>>>>>>>>>>>>>>>>>>>> final file... But I'm hopeful. >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> Anyone has times on linking a big project like >>>>>>>>>>>>>>>>>>>>>>>>> chrome with this so that at least I know what kind of performance to expect? >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> My numbers are something like: >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> 1 pdb per obj file: link.exe takes ~15 minutes and >>>>>>>>>>>>>>>>>>>>>>>>> 16GB of ram, lld-link.exe takes 2:30 minutes and ~8GB of ram >>>>>>>>>>>>>>>>>>>>>>>>> around 10 pdbs per folder: link.exe takes 1 minute >>>>>>>>>>>>>>>>>>>>>>>>> and 2-3GB of ram, lld-link.exe takes 1:30 minutes and ~6GB of ram >>>>>>>>>>>>>>>>>>>>>>>>> faslink: link.exe takes 40 seconds, but then 20 >>>>>>>>>>>>>>>>>>>>>>>>> seconds of loading at the first break point in the debugger and we lost DIA >>>>>>>>>>>>>>>>>>>>>>>>> support for listing symbols. >>>>>>>>>>>>>>>>>>>>>>>>> incremental: link.exe takes 8 seconds, but it only >>>>>>>>>>>>>>>>>>>>>>>>> happens when very minor changes happen. >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> We have an non negligible number of symbols used >>>>>>>>>>>>>>>>>>>>>>>>> on some runtime systems. >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> On Sat, Jan 20, 2018 at 11:52 AM Leonardo >>>>>>>>>>>>>>>>>>>>>>>>>> Santagada <santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for the tips, I now have something that >>>>>>>>>>>>>>>>>>>>>>>>>>> reads the obj file, finds .debug$T sections and global hashes it (proof of >>>>>>>>>>>>>>>>>>>>>>>>>>> concept kind of code). What I can't find is: how does clang itself writes >>>>>>>>>>>>>>>>>>>>>>>>>>> the coff files with global hashes, as that might help me understand how to >>>>>>>>>>>>>>>>>>>>>>>>>>> create the .debug$H section, how to update the file section count and how >>>>>>>>>>>>>>>>>>>>>>>>>>> to properly write this back. >>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>> The code on yaml2coff is expecting to be working >>>>>>>>>>>>>>>>>>>>>>>>>>> on the yaml COFFParser struct and I'm having quite a bit of a headache >>>>>>>>>>>>>>>>>>>>>>>>>>> turning the COFFObjectFile into a COFFParser object or compatible... >>>>>>>>>>>>>>>>>>>>>>>>>>> Tomorrow I might try the very non efficient path of coff2yaml and then >>>>>>>>>>>>>>>>>>>>>>>>>>> yaml2coff with the hashes header... but it seems way too inefficient and >>>>>>>>>>>>>>>>>>>>>>>>>>> convoluted. >>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, Jan 19, 2018 at 10:38 PM, Zachary Turner >>>>>>>>>>>>>>>>>>>>>>>>>>> <zturner at google.com> wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, Jan 19, 2018 at 1:02 PM Leonardo >>>>>>>>>>>>>>>>>>>>>>>>>>>> Santagada <santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, Jan 19, 2018 at 9:44 PM, Zachary >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Turner <zturner at google.com> wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, Jan 19, 2018 at 12:29 PM Leonardo >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Santagada <santagada at gmail.com> wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi, >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> No I didn't, I used cl.exe from the visual >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> studio toolchain. What I'm proposing is a tool for processing .obj files in >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> COFF format, reading them and generating the GHASH part. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> To make our build faster we use hundreds of >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> unity build files (.cpp's with a lot of other .cpp's in them aka munch >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> files) but still have a lot of single .cpp's as well (in total something >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> like 3.4k .obj files). >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> ps: sorry for sending to the wrong list, I >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> was reading about llvm mailing lists and jumped when I saw what I thought >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> was a lld exclusive list. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> A tool like this would be useful, yes. We've >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> talked about it internally as well and agreed it would be useful, we just >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> haven't prioritized it. If you're interested in submitting a patch along >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> those lines though, I think it would be a good addition. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> I'm not sure what the best place for it would >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> be. llvm-readobj and llvm-objdump seem like obvious choices, but they are >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> intended to be read-only, so perhaps they wouldn't be a good fit. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> llvm-pdbutil is kind of a hodgepodge of >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> everything else related to PDBs and symbols, so I wouldn't be opposed to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> making a new subcommand there called "ghash" or something that could >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> process an object file and output a new object file with a .debug$H section. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> A third option would be to make a new tool >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> for it. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> I don't htink it would be that hard to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> write. If you're interested in trying to make a patch for this, I can >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> offer some guidance on where to look in the code. Otherwise it's something >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> that we'll probably get to, I'm just not sure when. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> I would love to write it and contribute it >>>>>>>>>>>>>>>>>>>>>>>>>>>>> back, please do tell, I did find some of the code of ghash in lld, but in >>>>>>>>>>>>>>>>>>>>>>>>>>>>> fuzzy on the llvm codeview part of it and never seen llvm-readobj/objdump >>>>>>>>>>>>>>>>>>>>>>>>>>>>> or llvm-pdbutil, but I'm not afraid to look :) >>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> Luckily all of the important code is hidden >>>>>>>>>>>>>>>>>>>>>>>>>>>> behind library calls, and it should already just do the right thing, so I >>>>>>>>>>>>>>>>>>>>>>>>>>>> suspect you won't need to know much about CodeView to do this. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> I think Peter has the right idea about putting >>>>>>>>>>>>>>>>>>>>>>>>>>>> this in llvm-objcopy. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> You can look at one of the existing CopyBinary >>>>>>>>>>>>>>>>>>>>>>>>>>>> functions there, which currently only work for ELF, but you can just make a >>>>>>>>>>>>>>>>>>>>>>>>>>>> new overload that accepts a COFFObjectFile. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> I would probably start by iterating over each >>>>>>>>>>>>>>>>>>>>>>>>>>>> of the sections (getNumberOfSections / getSectionName) looking for .debug$T >>>>>>>>>>>>>>>>>>>>>>>>>>>> and .debug$H sections. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> If you find a .debug$H section then you can >>>>>>>>>>>>>>>>>>>>>>>>>>>> just skip that object file. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> If you find a .debug$T but not a .debug$H, then >>>>>>>>>>>>>>>>>>>>>>>>>>>> basically do the same thing that LLD does in PDBLinker::mergeDebugT >>>>>>>>>>>>>>>>>>>>>>>>>>>> (create a CVTypeArray, and pass it to GloballyHashedType::hashTypes. >>>>>>>>>>>>>>>>>>>>>>>>>>>> That will return an array of hash values. (the format of .debug$H is the >>>>>>>>>>>>>>>>>>>>>>>>>>>> header, followed by the hash values). Then when you're writing the list of >>>>>>>>>>>>>>>>>>>>>>>>>>>> sections, just add in the .debug$H section right after the .debug$T section. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> Currently llvm-objcopy only writes ELF files, >>>>>>>>>>>>>>>>>>>>>>>>>>>> so it would need to be taught to write COFF files. We have code to do this >>>>>>>>>>>>>>>>>>>>>>>>>>>> in the yaml2obj utility (specifically, in yaml2coff.cpp in the function >>>>>>>>>>>>>>>>>>>>>>>>>>>> writeCOFF). There may be a way to move this code to somewhere else >>>>>>>>>>>>>>>>>>>>>>>>>>>> (llvm/Object/COFF.h?) so that it can be re-used by both yaml2coff and >>>>>>>>>>>>>>>>>>>>>>>>>>>> llvm-objcopy, but in the worst case scenario you could copy the code and >>>>>>>>>>>>>>>>>>>>>>>>>>>> re-write it to work with these new structures. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> Lastly, you'll probably want to put all of this >>>>>>>>>>>>>>>>>>>>>>>>>>>> behind an option in llvm-objcopy such as -add-codeview-ghash-section >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> -- >>>>>>>>>>>> >>>>>>>>>>>> Leonardo Santagada >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> -- >>>>>>>>>> >>>>>>>>>> Leonardo Santagada >>>>>>>>>> >>>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> >>>>>>>> Leonardo Santagada >>>>>>>> >>>>>>> >>>>> >>>>> >>>>> -- >>>>> >>>>> Leonardo Santagada >>>>> >>>> >>>> >>>> >>>> -- >>>> >>>> Leonardo Santagada >>>> >>> >> >> >> -- >> >> Leonardo Santagada >> >-- Leonardo Santagada -------------- next part -------------- An HTML attachment was scrubbed... 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