[llvm-dev] How to pass march flag to GCC Assembler arch64-linux-gnu-as

Sri via llvm-dev llvm-dev at lists.llvm.org
Mon Oct 26 10:31:48 PDT 2015

I am trying to build chromium and at this moment, They see some issues with
internal one so recommended to use the flag -fno-integrated-as.
Here is my exact build command (with -v and  --save-temps):

$ clang  -Igen -I../../include -target aarch64-linux-gnu
-march=armv8-a+crypto -fno-integrated-as
--sysroot=./debian_jessie_arm64-sysroot -O2 -c MyFile.S -o MyFile.o -v
clang version 3.8.0 (trunk 247874)
Target: aarch64--linux-gnu
Thread model: posix
Found candidate GCC installation:
Selected GCC installation:
Candidate multilib: .;@m64
Selected multilib: .;@m64
 "clang" -cc1 -triple aarch64--linux-gnu -E -disable-free -main-file-name
MyFile.S -mrelocation-model static -mthread-model posix -mdisable-fp-elim
-fmath-errno -masm-verbose -no-integrated-as -mconstructor-aliases
-fuse-init-array -target-cpu generic -target-feature +neon -target-feature
+crypto -target-abi aapcs -v -dwarf-column-info -coverage-file MyFile.o
-resource-dir ../lib/clang/3.8.0 -I gen -I ../../include -isysroot
./debian_jessie_arm64-sysroot -internal-isystem
./debian_jessie_arm64-sysroot/usr/local/include -internal-isystem
../lib/clang/3.8.0/include -internal-externc-isystem
-internal-externc-isystem ./debian_jessie_arm64-sysroot/include
-internal-externc-isystem ./debian_jessie_arm64-sysroot/usr/include -O2
-fno-dwarf-directory-asm -fdebug-compilation-dir ./out/Release
-ferror-limit 19 -fmessage-length 205 -fallow-half-arguments-and-returns
-fno-signed-char -fobjc-runtime=gcc -fdiagnostics-show-option
-fcolor-diagnostics -vectorize-loops -vectorize-slp -o MyFile.s -x
clang -cc1 version 3.8.0 based upon LLVM 3.8.0svn default target

#include "..." search starts here:
#include <...> search starts here:
End of search list.
 "/usr/bin/aarch64-linux-gnu-as" -I gen -I ../include -o MyFile.o MyFile.s
Error: selected processor does not support `pmull v0.1q,v20.1d,v20.1d'

Manually running  /usr/bin/aarch64-linux-gnu-as -march=armv8-a+crypto -I
gen -I ../include -o MyFile.o MyFile.s works fine without any errors


On Mon, Oct 26, 2015 at 12:05 PM, Tim Northover <t.p.northover at gmail.com>

> On 26 October 2015 at 09:52, Sri via llvm-dev <llvm-dev at lists.llvm.org>
> wrote:
> > I am passing "-march=armv8-a+crypto" to clang command but how do i
> promote
> > the same flag to assembler arch64-linux-gnu-as through clang?
> You could certainly argue Clang should be forwarding that argument
> automatically (assuming you did specify it to Clang itself) as part of
> supporting -fno-integrated-as. Not that I think we really encourage
> -fno-integrated-as; what problems are you having with the internal
> one?
> Until someone fixes that issue though, you can use
> "-Wa,-march=armv8-a+crypto" to give an argument to the assembler
> manually.
> Tim.

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