[PATCH] D103184: [AArch64] handle -Wa,-march=

[Jian Cai via Phabricator via cfe-commits]

jcai19 added inline comments.


================
Comment at: clang/lib/Driver/ToolChains/Arch/AArch64.cpp:217
+  // after -march. And while only using the the value of last -march, it
+  // includes all the options passed via -Wa,-march.
+  success = true;
----------------
joerg wrote:
> This comment is confusing. `-march` is a driver option and the GCC driver will internally convert it into the equivalent of `-Wa,-march` before passing the total command line to GNU as.
Thanks for the clarification! I haven't checked GCC implementation so the comment is likely not accurate. I did make the following observation from below command and its output. It seems all the -Wa.-march values passed (armv8.3-a and armv8.4a) showed up in COLLECT_AS_OPTIONS, as well as in COLLECT_GCC_OPTIONS. On the other hand, only the last value of -march (armv8.2-a) showed up in COLLECT_GCC_OPTIONS, and the -march value was placed before all the -Wa,-march values in COLLECT_GCC_OPTIONS. WDYT?

$ aarch64-linux-gnu-gcc -Wa,-march=armv8.1-a -march=armv8.2-a -march=armv8.3-a -Wa,-march=armv8.4-a -c foo.s -o gcc.o -###
Using built-in specs.
COLLECT_AS_OPTIONS='-march=armv8.1-a' '-march=armv8.4-a'
COLLECT_GCC=aarch64-linux-gnu-gcc
Target: aarch64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 10.2.1-6+build2' --with-bugurl=file:///usr/share/doc/gcc-10/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-10 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-libquadmath --disable-libquadmath-support --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --without-target-system-zlib --enable-multiarch --enable-fix-cortex-a53-843419 --disable-werror --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=aarch64-linux-gnu --program-prefix=aarch64-linux-gnu- --includedir=/usr/aarch64-linux-gnu/include --with-build-config=bootstrap-lto-lean --enable-link-mutex
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 10.2.1 20210110 (Debian 10.2.1-6+build2) 
COLLECT_GCC_OPTIONS='-march=armv8.3-a' '-c' '-o' 'gcc.o' '-mlittle-endian' '-mabi=lp64'
 /usr/lib/gcc-cross/aarch64-linux-gnu/10/../../../../aarch64-linux-gnu/bin/as -EL "-march=armv8.3-a" "-mabi=lp64" "-march=armv8.1-a" "-march=armv8.4-a" -o gcc.o foo.s
COMPILER_PATH=/usr/lib/gcc-cross/aarch64-linux-gnu/10/:/usr/lib/gcc-cross/aarch64-linux-gnu/10/:/usr/lib/gcc-cross/aarch64-linux-gnu/:/usr/lib/gcc-cross/aarch64-linux-gnu/10/:/usr/lib/gcc-cross/aarch64-linux-gnu/:/usr/lib/gcc-cross/aarch64-linux-gnu/10/../../../../aarch64-linux-gnu/bin/
LIBRARY_PATH=/usr/lib/gcc-cross/aarch64-linux-gnu/10/:/usr/lib/gcc-cross/aarch64-linux-gnu/10/../../../../aarch64-linux-gnu/lib/../lib/:/lib/aarch64-linux-gnu/:/lib/../lib/:/usr/lib/aarch64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc-cross/aarch64-linux-gnu/10/../../../../aarch64-linux-gnu/lib/:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-march=armv8.3-a' '-c' '-o' 'gcc.o' '-mlittle-endian' '-mabi=lp64'



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  https://reviews.llvm.org/D103184/new/

https://reviews.llvm.org/D103184