similar to: [cfe-dev] How to debug if LTO generate wrong code?

Hi Mehdi, GCC LTO seems support large code model in my side as below, if the code model is linker specific, does the GCC LTO use a special linker which is different from the one in GNU Binutils? I'm a bit surprised if both OS X ld64 and gold plugin do not support large code model in LTO. Since modern system widely use the 64bit, the code need to run in high address (larger than 2 GB) is a

Hi Mehdi, Should I apply your attached patch on my llvm3.8 source firstly? Or should I use the latest llvm SVN trunk instead? Steven Shi Intel\SSG\STO\UEFI Firmware Tel: +86 021-61166522 iNet: 821-6522 From: mehdi.amini at apple.com [mailto:mehdi.amini at apple.com] Sent: Monday, May 30, 2016 2:13 PM To: Shi, Steven <steven.shi at intel.com> Cc: Umesh Kalappa <umesh.kalappa0 at

On Mon, May 30, 2016 at 02:12:09AM +0000, Shi, Steven via llvm-dev wrote: > Hi Joerg, > My firmware case is I need load my firmware to run in high address > which is hardware required. It is not that my firmware really need > large static data and text code. My firmware modules are shared library > (like a DLL) built with "-fpic", and firmware loader will load them to >

We don't use cl::opt in gold, instead we parse the -plugin-opts that gold passes the plugin (see process_plugin_option). Cheers, Rafael On 30 May 2016 at 02:13, Mehdi Amini <mehdi.amini at apple.com> wrote: > > On May 29, 2016, at 5:44 PM, Shi, Steven <steven.shi at intel.com> wrote: > > (And I doubt the GNU linker supports LTO with LLVM). > [Steven]: I’ve pushed

(And I doubt the GNU linker supports LTO with LLVM). [Steven]: I’ve pushed GNU Binutils ld to support LLVM gold plugin, see detail in this bug https://sourceware.org/bugzilla/show_bug.cgi?id=20070. The new GNU ld linker works well with LLVM/Clang LTO when build IA32 code in my side. And from the ld owner input in the bug comments, the current X64 LLVM LTO issue is in llvm LTO plugin. The fact

Hi Steven, > On May 29, 2016, at 11:28 PM, Shi, Steven <steven.shi at intel.com> wrote: > > Hi Mehdi, > Should I apply your attached patch on my llvm3.8 source firstly? Or should I use the latest llvm SVN trunk instead? I wrote it on trunk, but I expect it to be fairly easy to port on 3.8. This is really just quickly plumbing an option on the TargetMachine creation. --

Hi, > On May 29, 2016, at 7:36 AM, Shi, Steven <steven.shi at intel.com> wrote: > > Hi Mehdi, > After deeper debug, I found my firmware LTO wrong code issue is related to X64 code model (-mcmodel=large) is always overridden as small (-mcmodel=small) if LTO build. And I don't know how to correctly specific the large code model for my X64 firmware LTO build. Appreciate if

Hi Mehdi, The llvm3.8 gold-plugin.cpp is very different from the latest one on trunk. Your patch has compiling failure on llvm3.8 as below. I will try it on latest trunk later. Thank you help anyway! Building CXX object tools/gold/CMakeFiles/LLVMgold.dir/gold-plugin.cpp.o cd /home/jshi19/llvm38releasebuild/tools/gold && /home/jshi19/clang38/bin/clang++ -DGTEST_HAS_RTTI=0

> On May 29, 2016, at 5:10 PM, Shi, Steven <steven.shi at intel.com> wrote: > > Hi Mehdi, > GCC LTO seems support large code model in my side as below, if the code model is linker specific, does the GCC LTO use a special linker which is different from the one in GNU Binutils? I don't know anything about GCC. (And I doubt the GNU linker supports LTO with LLVM). > I’m a

Hi Mehdi, After deeper debug, I found my firmware LTO wrong code issue is related to X64 code model (-mcmodel=large) is always overridden as small (-mcmodel=small) if LTO build. And I don't know how to correctly specific the large code model for my X64 firmware LTO build. Appreciate if you could let me know it. You know, parts of my Uefi firmware (BIOS) have to been loaded to run in high

> On May 29, 2016, at 5:44 PM, Shi, Steven <steven.shi at intel.com> wrote: > > (And I doubt the GNU linker supports LTO with LLVM). > [Steven]: I’ve pushed GNU Binutils ld to support LLVM gold plugin, see detail in this bug https://sourceware.org/bugzilla/show_bug.cgi?id=20070 <https://sourceware.org/bugzilla/show_bug.cgi?id=20070>. The new GNU ld linker works well with

On 31 May 2016 at 01:08, Shi, Steven <steven.shi at intel.com> wrote: > Hi Mehdi, > What's the default code model for x86_64 Mac OS X App? Andrew showed me some example code of Mac OS X App as below, which looks to use the small code model but can run at >4GB high address. Small, but PIC. > For example if you read a global like this the compiler will generate this code.

> On May 17, 2016, at 11:21 AM, Umesh Kalappa <umesh.kalappa0 at gmail.com> wrote: > > Steven, > > As mehdi stated , the optimisation level is specific to linker and it > enables Inter-Pro opts passes ,please refer function To be very clear: the -O option may trigger *linker* optimizations as well, independently of LTO. -- Mehdi > >

OK, I get it. Adding "-pie" link option can force 64bits relocation address (e.g. EM_X86_64), instead of the 32bits one (e.g. R_X86_64_32S). I only used -fpic and -fpie in clang LTO compile option, and forgot add the "-pie" link option in ld. So my clang + ld LTO executable was still not position independent. Thank you all! Steven Shi Intel\SSG\STO\UEFI Firmware Tel: +86

On 7 June 2016 at 10:54, Shi, Steven <steven.shi at intel.com> wrote: > Hi Rafael, > I finally enable the clang LTO build with small code model and PIE, and my clang LTO Uefi firmware works now. Thank you! But I have one more issue on the clang normal build (without LTO) now. I find the small code model + "-fpie" build option will let clang generate some R_X86_64_GOTPCREL

On 05/30/16 01:34 PM, Rafael Espíndola <rafael.espindola at gmail.com> wrote: > > We don't use cl::opt in gold, instead we parse the -plugin-opts that > gold passes the plugin (see process_plugin_option). > What about that: $ grep ParseCommandLineOptions tools/gold/gold-plugin.cpp // ParseCommandLineOptions () expects argv[0] to be program name. Lazily cl::

Hi Umesh, Thank you for the suggestion. I can use the "Brute force method " to narrow down the LTO wrong instructions here and there, but I still don't know why these wrong instructions are generated, and how to let Clang LTO don't generate those wrong instructions. I suspect the wrong code is caused by some LTO wrong optimization pass, so I hope to disable all optimizations in

I didn't try to compile it locally (I don't have/use gold), but you should be able to fix the 3 errors fairly easily (looks like missing includes mostly). -- Mehdi > On May 30, 2016, at 5:11 AM, Shi, Steven <steven.shi at intel.com> wrote: > > Hi Mehdi, > Your patch cannot compile with gold-plugin.cpp in latest trunk either, the failure is same as llvm3.8 as below.

Hello, I'm enabling clang LTO to improve code size of Uefi standard (http://www.uefi.org/) firmware (https://github.com/tianocore/edk2), which is mostly C code. My project is in https://github.com/shijunjing/edk2 branch llvm : https://github.com/shijunjing/edk2/tree/llvm. I find my most firmware modules work well after enable LTO, but some X64 modules will not run (e.g. hang with CPU

Hi Richard, Thank you for the info. I build my code in Ubuntu-64bits with simply commands: “clang X64.c”, then run “./a.out” to see the output. If I replace my va_list, va_start, va_arg va_end with __builtin_ms_va_list, __builtin_ms_va_start, __builtin_ms_va_arg, __builtin_ms_va_end, my code will build fail in Ubuntu with below message. Do you suggest I should build it in windows and not in