llvm dev - Jan 2015 - [LLVMdev] [compiler-rt] -fno-lto warnings during build

Hi all

I came across a minor issue while trying to compile the latests LLVM with
compiler-rt.

At some point during the build (I am using clang-3.5) I get :

clang-3.5: error: argument unused during compilation: '-fno-lto'

The command that fails (I am using -Werror) is:

/home/compteam/opt/clang-build/3.5/bin/clang  -D_GNU_SOURCE
-D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
-fPIC -Wall -W -Wno-unused-parameter -Wwrite-strings
-Wmissing-field-initializers -pedantic -Wno-long-long
-Wcovered-switch-default -Werror -fcolor-diagnostics
-ffunction-sections -fdata-sections -Wall -Werror -g
-Iprojects/compiler-rt/lib/tsan
-I/home/compteam/slave0/build_folder/src/projects/compiler-rt/lib/tsan
-Iinclude -I/home/compteam/slave0/build_folder/src/include
-I/home/compteam/slave0/build_folder/src/projects/compiler-rt/lib/tsan/..
    -m64 -fPIC -fno-builtin -fno-exceptions -fomit-frame-pointer
-funwind-tables -fno-stack-protector -fvisibility=hidden
-fno-function-sections -fno-lto -O3 -gline-tables-only -Wno-gnu
-Wno-variadic-macros -Wno-c99-extensions -Wno-non-virtual-dtor -fPIE
-fno-rtti -Wframe-larger-than=512 -Wglobal-constructors -MMD -MT
projects/compiler-rt/lib/tsan/CMakeFiles/clang_rt.tsan-x86_64.dir/rtl/tsan_rtl_amd64.S.o
-MF
"projects/compiler-rt/lib/tsan/CMakeFiles/clang_rt.tsan-x86_64.dir/rtl/tsan_rtl_amd64.S.o.d"
-o
projects/compiler-rt/lib/tsan/CMakeFiles/clang_rt.tsan-x86_64.dir/rtl/tsan_rtl_amd64.S.o
  -c
/home/compteam/slave0/build_folder/src/projects/compiler-rt/lib/tsan/rtl/tsan_rtl_amd64.S

My understanding is that -fno-lto is not required while assembling a
file, so I think the warning is correct. Should this option be
filtered out for Asm files. I think this is related with the
configuration in lib/tsan/CMakeLists.txt. Is it a suitable place to
try to fix this? Any thoughts?

Many thanks!

Samuel
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We changed clang trunk to avoid the warning. Sorry about the issue.

On 20 January 2015 at 19:25, Samuel F Antao <sfantao at us.ibm.com>
wrote:
> Hi all
>
> I came across a minor issue while trying to compile the latests LLVM with
> compiler-rt.
>
> At some point during the build (I am using clang-3.5) I get :
>
> clang-3.5: error: argument unused during compilation: '-fno-lto'
>
> The command that fails (I am using -Werror) is:
>
> /home/compteam/opt/clang-build/3.5/bin/clang  -D_GNU_SOURCE
> -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -fPIC
> -Wall -W -Wno-unused-parameter -Wwrite-strings -Wmissing-field-initializers
> -pedantic -Wno-long-long -Wcovered-switch-default -Werror
> -fcolor-diagnostics -ffunction-sections -fdata-sections -Wall -Werror -g
> -Iprojects/compiler-rt/lib/tsan
> -I/home/compteam/slave0/build_folder/src/projects/compiler-rt/lib/tsan
> -Iinclude -I/home/compteam/slave0/build_folder/src/include
> -I/home/compteam/slave0/build_folder/src/projects/compiler-rt/lib/tsan/..
> -m64 -fPIC -fno-builtin -fno-exceptions -fomit-frame-pointer
-funwind-tables
> -fno-stack-protector -fvisibility=hidden -fno-function-sections -fno-lto
-O3
> -gline-tables-only -Wno-gnu -Wno-variadic-macros -Wno-c99-extensions
> -Wno-non-virtual-dtor -fPIE -fno-rtti -Wframe-larger-than=512
> -Wglobal-constructors -MMD -MT
>
projects/compiler-rt/lib/tsan/CMakeFiles/clang_rt.tsan-x86_64.dir/rtl/tsan_rtl_amd64.S.o
> -MF
>
"projects/compiler-rt/lib/tsan/CMakeFiles/clang_rt.tsan-x86_64.dir/rtl/tsan_rtl_amd64.S.o.d"
> -o
>
projects/compiler-rt/lib/tsan/CMakeFiles/clang_rt.tsan-x86_64.dir/rtl/tsan_rtl_amd64.S.o
> -c
>
/home/compteam/slave0/build_folder/src/projects/compiler-rt/lib/tsan/rtl/tsan_rtl_amd64.S
>
> My understanding is that -fno-lto is not required while assembling a file,
> so I think the warning is correct. Should this option be filtered out for
> Asm files. I think this is related with the configuration in
> lib/tsan/CMakeLists.txt. Is it a suitable place to try to fix this? Any
> thoughts?
>
> Many thanks!
>
> Samuel
>
>
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>