assigned to @rengolin

Hi Nico,

Clang is not very good at passing -Wa flags down at the moment. Is this a Clang error or an assembler error? Can you paste the "clang -v" output?

Sure, but it's easy to try yourself too:

thakis@yearofthelinuxdesktop:/src/chrome/src$ third_party/llvm-build/Release+Asserts/bin/clang -Wa,-masm=fpu -v test.S
clang version 3.5.0 (trunk 214024)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.6.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.3
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64
clang: error: unsupported argument '-masm=fpu' to option 'Wa,'
thakis@yearofthelinuxdesktop:/src/chrome/src$ third_party/llvm-build/Release+Asserts/bin/clang -Wa,-masm=fpu -v test.S -###
clang version 3.5.0 (trunk 214024)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.6.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.3
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64
clang: error: unsupported argument '-masm=fpu' to option 'Wa,'
"/usr/local/google/home/thakis/src/chrome/src/third_party/llvm-build/Release+Asserts/bin/clang" "-cc1" "-triple" "x86_64-unknown-linux-gnu" "-E" "-disable-free" "-main-file-name" "test.S" "-mrelocation-model" "static" "-mdisable-fp-elim" "-fmath-errno" "-masm-verbose" "-mconstructor-aliases" "-munwind-tables" "-target-cpu" "x86-64" "-target-linker-version" "2.22" "-v" "-dwarf-column-info" "-resource-dir" "/usr/local/google/home/thakis/src/chrome/src/third_party/llvm-build/Release+Asserts/bin/../lib/clang/3.5.0" "-internal-isystem" "/usr/local/include" "-internal-isystem" "/usr/local/google/home/thakis/src/chrome/src/third_party/llvm-build/Release+Asserts/bin/../lib/clang/3.5.0/include" "-internal-externc-isystem" "/usr/include/x86_64-linux-gnu" "-internal-externc-isystem" "/include" "-internal-externc-isystem" "/usr/include" "-fdebug-compilation-dir" "/usr/local/google/home/thakis/src/chrome/src" "-ferror-limit" "19" "-fmessage-length" "121" "-mstackrealign" "-fobjc-runtime=gcc" "-fdiagnostics-show-option" "-fcolor-diagnostics" "-o" "/tmp/test-01b1ce.s" "-x" "assembler-with-cpp" "test.S"
"/usr/local/google/home/thakis/src/chrome/src/third_party/llvm-build/Release+Asserts/bin/clang" "-cc1as" "-triple" "x86_64-unknown-linux-gnu" "-filetype" "obj" "-main-file-name" "test.S" "-target-cpu" "x86-64" "-fdebug-compilation-dir" "/usr/local/google/home/thakis/src/chrome/src" "-dwarf-debug-producer" "clang version 3.5.0 (trunk 214024)" "-o" "/tmp/test-bede9c.o" "/tmp/test-01b1ce.s"
"/usr/bin/ld" "-z" "relro" "--hash-style=gnu" "--build-id" "--eh-frame-hdr" "-m" "elf_x86_64" "-dynamic-linker" "/lib64/ld-linux-x86-64.so.2" "-o" "a.out" "/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crt1.o" "/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crti.o" "/usr/lib/gcc/x86_64-linux-gnu/4.6/crtbegin.o" "-L/usr/lib/gcc/x86_64-linux-gnu/4.6" "-L/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu" "-L/lib/x86_64-linux-gnu" "-L/lib/../lib64" "-L/usr/lib/x86_64-linux-gnu" "-L/usr/lib/gcc/x86_64-linux-gnu/4.6/../../.." "-L/usr/local/google/home/thakis/src/chrome/src/third_party/llvm-build/Release+Asserts/bin/../lib" "-L/lib" "-L/usr/lib" "/tmp/test-bede9c.o" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "/usr/lib/gcc/x86_64-linux-gnu/4.6/crtend.o" "/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crtn.o"

Err, pretend that there's a -target arm-linux-androideabi on that command too (it doesn't change anything)

Doesn't matter the target, this is a Clang issue when dealing with -Wa flags. I could keep adding flags to -Wa but we need some planning first, as so far, not much is actually accepted in there. We need to consult the Clang experts.

Nico,

I'm adding the following Wa flags to be passed directly to the target:

-mcpu
-mfpu
-march
-mfloat-abi

as they are the most common assembler flags I know (and that the kernel also uses). However, I don't know what the -masm you mention does, and GCC/GAS doesn't seem to recognise it either.

Is this related to Microsoft Asm? If so, I shall not do that one now, and another bug shall be created.

Hi Nico,

I'm back looking at those bugs. Did you work around this one by adding ".fpu neon" to the ASM files, or is this still holding Chromium builds?

If the latter, I'd recommend you to work around, so we can fix this one properly after the other, more complicated, fixes. If the former, then we need to mark this as not blocking the Chromium bug and close that, since this is the last issue.

cheers,
--renato

Patches proposed:

• http://reviews.llvm.org/D11147
• http://reviews.llvm.org/D11148

Fixed in r243352 / r243353

mentioned in issue #22065