similar to: [LLVMdev] Changing the design of GlobalAliases to represent what is actually possible in object files.

> I agree that this accurately summarizes both (1) what’s expressible in > current object file formats and (2) what we’re likely to want to need from > global aliases. > >> The tool we have in llvm for creating these extra labels is the GlobalAlias. >> >> One way of representing the above uses is to be explicit: a label is >> created with a specific value or at

On Fri, May 23, 2014 at 3:06 PM, Rafael Avila de Espindola <rafael.espindola at gmail.com> wrote: > > > Sent from my iPhone > >> On May 23, 2014, at 17:51, Eric Christopher <echristo at gmail.com> wrote: >> >> I'm not there yet, but at some point I'm going to need the notion of a >> global callable function like symbol that's resolved at

>> > For example, it would not be possible to define an absolute symbol to be >> > the offset between two symbols. In some restricted circumstances — >> > if both symbols are global variables in the same section and defined >> > in the same translation unit — this could be worked around. >> > >> > But I’ll gladly admit that I don’t have a use

I'm not there yet, but at some point I'm going to need the notion of a global callable function like symbol that's resolved at runtime. I've not given it much thought but I may need a new callable entity here (this is for the gnu ifunc stuff). Don't even know if this fits into the discussion, but since we were talking about weird symbols... -eric On Fri, May 23, 2014 at 1:26

On 24 October 2016 at 16:54, Peter Collingbourne via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > > On Mon, Oct 24, 2016 at 1:36 PM, Friedman, Eli <efriedma at codeaurora.org> > wrote: >> >> On 10/24/2016 1:07 PM, Peter Collingbourne via llvm-dev wrote: >> >> On Mon, Oct 10, 2016 at 8:12 PM, Peter Collingbourne <peter at pcc.me.uk> >>

> * Calling getBaseObject() on a GlobalIFunc returns its resolver function. I still don't understand how it can happen looking to the code ( https://github.com/llvm/llvm-project/blob/master/llvm/lib/IR/Globals.cpp#L430). I believe it should return nullptr (the same as if you call it from GlobalAlias that refers to GlobalIFunc). I don't have a strong opinion here because deriving

I was working on https://reviews.llvm.org/D81911 to try and fix https://bugs.llvm.org/show_bug.cgi?id=46340 . Through the review process we happened upon a design limitation or perhaps a potential mis-modelling of GlobalIFunc in the IR object hierarchy, which leads to some problems in LTO flows. To summarize, as it currently stands (and in the hopes of faithfully representing the conclusions of

After discussing with Nick Lewycky in the IRC channel, here comes a less aggressive patch. We were worried that a constant pointer could alias with a GlobalValue. Also, if one pointer could be a GlobalValue and the other a GlobalAlias with the GlobalValue as aliasee. However, I was not able to produce a test where this happens wihout the getUnderlyingObject() returning the same value. It

On Oct 30, 2013, at 12:35 PM, Rafael Espíndola <rafael.espindola at gmail.com> wrote: > A long time ago (before r97733) we used to model the weakref attribute > by outputting a new declaration and a weak alias to it. This was > fairly buggy and we now implement weakref directly in clang, with the > same logic an assembler uses to implement .weakref (which is what gcc >

On 30 October 2013 15:50, Chris Lattner <clattner at apple.com> wrote: > > On Oct 30, 2013, at 12:35 PM, Rafael Espíndola <rafael.espindola at gmail.com> wrote: > >> A long time ago (before r97733) we used to model the weakref attribute >> by outputting a new declaration and a weak alias to it. This was >> fairly buggy and we now implement weakref directly in

Dan Gohman wrote: > On Nov 4, 2009, at 6:43 AM, Hans Wennborg wrote: > >> Here is another change I'd like to suggest to the BasicAliasAnalysis. >> >> LLVM fails to remove the dead store in the following code: >> >> %t = type { i32 } >> >> define void @f(%t* noalias nocapture %stuff ) { >> %p = getelementptr inbounds %t* %stuff, i32 0,

> On Oct 24, 2016, at 1:07 PM, Peter Collingbourne <peter at pcc.me.uk> wrote: > > On Mon, Oct 10, 2016 at 8:12 PM, Peter Collingbourne <peter at pcc.me.uk <mailto:peter at pcc.me.uk>> wrote: > The specific change I have in mind is to allow !range metadata on GlobalObjects. This would > be similar to existing !range metadata, but it would apply to the

> On Oct 25, 2016, at 9:09 AM, Chandler Carruth via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > On Mon, Oct 24, 2016 at 10:48 PM Chris Lattner via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote: > >> On Oct 24, 2016, at 1:07 PM, Peter Collingbourne <peter at pcc.me.uk <mailto:peter at pcc.me.uk>> wrote:

On Tue, Oct 25, 2016 at 5:49 AM, Rafael Espíndola < rafael.espindola at gmail.com> wrote: > >>> @foo = globalconst i32 42 > >>> > >>> > >>> This is equivalent to writing "foo = 42" in assembly? > >> > >> > >> Yes. > > > > > > Back in the day the idea was to use an alias whose ConstantExpr

Hi, In order to find out-of-bound accesses to global objects with AddressSanitizer ( http://code.google.com/p/address-sanitizer/wiki/AddressSanitizer) I need to create redzones to the left and to the right of every global variable. I tried the following: Before: @Extern = global [10 x i8] zeroinitializer, align 1 After: %0 = type { [32 x i8], [10 x i8], [54 x i8] } @Extern_asan_redzone =

On 10/24/2016 1:07 PM, Peter Collingbourne via llvm-dev wrote: > On Mon, Oct 10, 2016 at 8:12 PM, Peter Collingbourne <peter at pcc.me.uk > <mailto:peter at pcc.me.uk>> wrote: > > The specific change I have in mind is to allow !range metadata on > GlobalObjects. This would > be similar to existing !range metadata, but it would apply to the >

A long time ago (before r97733) we used to model the weakref attribute by outputting a new declaration and a weak alias to it. This was fairly buggy and we now implement weakref directly in clang, with the same logic an assembler uses to implement .weakref (which is what gcc prints). One thing that was left from that old implementation is that we still have alias to declarations and they are a

Hi, I am trying to compile a dynamic loader using LLVM. Part of the IR for this loader looks like this: @_rtld_local = hidden alias %struct.rtld_global* @_rtld_global @_rtld_global = unnamed_addr global %struct.rtld_global { ... } The purpose of _rtld_local is to allow _rtld_global to be referenced without using the GOT, as this global is accessed before the dynamic loader initialises the GOT.

I see. Is there a pre-existing way to do this in LLVM? Cheers, ~Siddharth. On Thu, 17 Aug 2017 at 02:12 Craig Topper <craig.topper at gmail.com> wrote: > ConstantExprs are immutable, they can't be changed once they are created. > And a ConstantExpr can reference other ConstantExprs. So replacing all uses > of a Value in a ConstantExpr would require creating a new immutable

Hi, I wanted to see if there was a way in IR to emit a local alias such that I would get: ``` .type _ZTVSt13bad_exception, at object # @_ZTVSt13bad_exception .globl _ZTVSt13bad_exception _ZTVSt13bad_exception: *.L_ZTVSt13bad_exception:* .long 0 # 0x0 .long (_ZTISt13bad_exception.rtti_proxy-.L_ZTVSt13bad_exception)-8 .long