Re: [PATCH v5 0/8] BaseTools: add support for GCC5 in LTO mode

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 2 August 2016 at 16:39, Michael Zimmermann <sigmaepsilon92@gmail.com> wrote:
> Sry for the late reply but I tried your latest gcc-lto branch to make sure
> my answers are still correct.
> I tested it with all configurations(StdLib:X64/ARM, Ovmf:X64, ArmVirtPkg:ARM
> with both RELEASE and DEBUG).
> In StdLib are many warnings actually. That's because of
> -Wunused-const-variable and -Wmisleading-indentation.
> Also I had to apply the commit to fix 'Unsupported ELF EM_X86_64 relocation
> 0x4.' for X64.
>

Only 0x4 or 0x9 or others as well? This is relevent since 0x4 is a PLT
relocation which can be fixed up easily. The GOT based ones are
trickier since they involve a GOT entry with an absolute symbol
address that needs to be fixed up by the PE/COFF loader

> '-b RELEASE -a ARM -t GCC5 -p AppPkg/AppPkg.dsc' is the only configuration I
> can't get to compile with gcc6(DEBUG works):
> /tmp/ccYJi1bO.ltrans0.ltrans.o: In function `memmove':
> <artificial>:(.text+0x3670): multiple definition of `memmove'
> /media/Data/repositories/git/efidroid/testing/linuxtoolchain/edk2/Build/AppPkg/RELEASE_GCC5/ARM/ArmPkg/Library/CompilerIntrinsicsLib/CompilerIntrinsicsLib/OUTPUT/CompilerIntrinsicsLib.lib(memmove.obj):(.text+0x0):
> first defined here
> /tmp/ccYJi1bO.ltrans0.ltrans.o: In function `memset':
> <artificial>:(.text+0x3674): multiple definition of `memset'
> /media/Data/repositories/git/efidroid/testing/linuxtoolchain/edk2/Build/AppPkg/RELEASE_GCC5/ARM/ArmPkg/Library/CompilerIntrinsicsLib/CompilerIntrinsicsLib/OUTPUT/CompilerIntrinsicsLib.lib(memset.obj):(.text+0x10):
> first defined here

Interesting. I wonder where the first memmove resp. memset are coming
from. Are you linking with libgcc are sth like that?

> /media/Data/repositories/git/efidroid/prebuilts/gcc/linux-x86/arm/gcc-linaro-6.1.1~linaro-gcc-6-branch@f3888e76-20160721-x86_64_arm-eabi/bin/../lib/gcc/arm-eabi/6.1.1/../../../../arm-eabi/bin/ld:
> printf.obj: plugin needed to handle lto object
> /media/Data/repositories/git/efidroid/prebuilts/gcc/linux-x86/arm/gcc-linaro-6.1.1~linaro-gcc-6-branch@f3888e76-20160721-x86_64_arm-eabi/bin/../lib/gcc/arm-eabi/6.1.1/../../../../arm-eabi/bin/ld:
> puts.obj: plugin needed to handle lto object
> /media/Data/repositories/git/efidroid/prebuilts/gcc/linux-x86/arm/gcc-linaro-6.1.1~linaro-gcc-6-branch@f3888e76-20160721-x86_64_arm-eabi/bin/../lib/gcc/arm-eabi/6.1.1/../../../../arm-eabi/bin/ld:
> internal error
> /media/Data/repositories/git/abe/_build/snapshots/binutils-gdb.git~linaro_binutils-2_26-branch/ld/ldlang.c
> 6299
> collect2: error: ld returned 1 exit status
> make: *** [GNUmakefile:417:
> /media/Data/repositories/git/efidroid/testing/linuxtoolchain/edk2/Build/AppPkg/RELEASE_GCC5/ARM/AppPkg/Applications/Main/Main/DEBUG/Main.dll]
> Error 1
>

Not sure what's going on here ...

> Also, I only did compilation tests, I didn't try to run any of the produced
> binaries.
>
> this is the fixed branch:
> https://github.com/M1cha/edk2/commits/edk2-master-gcc6
> it's based on your gcc5-lto-v6 branch.
>

Thanks for the report. I will look into this.