llvm dev - Jun 2016 - [cfe-dev] How to debug if LTO generate wrong code?

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
type relocation entries in my firmware image, which not happen in the clang LTO
build. I wish I could enforce the clang normal build not to use the
R_X86_64_GOTPCREL relocation type but to use R_X86_64_PC32 or R_X86_64_PLT32
instead. How could I do it?
Does it reproduce with clang trunk?

Cheers,
Rafael

Yes. I use the trunk, and my version is below. I could try the latest version
tomorrow. And if you need, I could give the reproduce build steps on my Uefi
firmware tomorrow. Thank you!
clang version 3.9.0 (trunk 271203)


Steven Shi
Intel\SSG\STO\UEFI Firmware

Tel: +86 021-61166522
iNet: 821-6522

> -----Original Message-----
> From: Rafael Espíndola [mailto:rafael.espindola at gmail.com]
> Sent: Tuesday, June 07, 2016 11:05 PM
> To: Shi, Steven <steven.shi at intel.com>
> Cc: Mehdi Amini <mehdi.amini at apple.com>; Umesh Kalappa
> <umesh.kalappa0 at gmail.com>; llvm-dev <llvm-dev at
lists.llvm.org>; cfe-
> dev at lists.llvm.org; afish at apple.com; Lu, Hongjiu <hongjiu.lu at
intel.com>
> Subject: Re: [cfe-dev] [llvm-dev] How to debug if LTO generate wrong code?
> 
> 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 type
> relocation entries in my firmware image, which not happen in the clang LTO
> build. I wish I could enforce the clang normal build not to use the
> R_X86_64_GOTPCREL relocation type but to use R_X86_64_PC32 or
> R_X86_64_PLT32 instead. How could I do it?
> 
> Does it reproduce with clang trunk?
> 
> Cheers,
> Rafael

See:

https://llvm.org/bugs/show_bug.cgi?id=24964


> -----Original Message-----
> From: Shi, Steven
> Sent: Tuesday, June 07, 2016 8:13 AM
> To: Rafael Espíndola <rafael.espindola at gmail.com>
> Cc: Mehdi Amini <mehdi.amini at apple.com>; Umesh Kalappa
> <umesh.kalappa0 at gmail.com>; llvm-dev <llvm-dev at
lists.llvm.org>; cfe-
> dev at lists.llvm.org; afish at apple.com; Lu, Hongjiu <hongjiu.lu at
intel.com>
> Subject: RE: [cfe-dev] [llvm-dev] How to debug if LTO generate wrong code?
> 
> Yes. I use the trunk, and my version is below. I could try the latest
version
> tomorrow. And if you need, I could give the reproduce build steps on my
> Uefi firmware tomorrow. Thank you!
> clang version 3.9.0 (trunk 271203)
> 
> 
> Steven Shi
> Intel\SSG\STO\UEFI Firmware
> 
> Tel: +86 021-61166522
> iNet: 821-6522
> 
> 
> > -----Original Message-----
> > From: Rafael Espíndola [mailto:rafael.espindola at gmail.com]
> > Sent: Tuesday, June 07, 2016 11:05 PM
> > To: Shi, Steven <steven.shi at intel.com>
> > Cc: Mehdi Amini <mehdi.amini at apple.com>; Umesh Kalappa
> > <umesh.kalappa0 at gmail.com>; llvm-dev <llvm-dev at
lists.llvm.org>; cfe-
> > dev at lists.llvm.org; afish at apple.com; Lu, Hongjiu
> > <hongjiu.lu at intel.com>
> > Subject: Re: [cfe-dev] [llvm-dev] How to debug if LTO generate wrong
code?
> >
> > 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 type relocation entries in my firmware image,
> which
> > not happen in the clang LTO build. I wish I could enforce the clang
> > normal build not to use the R_X86_64_GOTPCREL relocation type but to
> > use R_X86_64_PC32 or
> > R_X86_64_PLT32 instead. How could I do it?
> >
> > Does it reproduce with clang trunk?
> >
> > Cheers,
> > Rafael