How to use AVX/pclmulqdq on Mac OS X

gcc assembly osx-lion macports avx
Conrado picture Conrado · Mar 23, 2012 · Viewed 8.7k times · Source

I am trying to compile a program that uses the pclmulqdq instruction present in new Intel processors. I've installed GCC 4.6 using macports but when I compile my program (which uses the intrinsic _mm_clmulepi64_si128), I get

/var/folders/ps/sfjmtgx5771_qbqnh4c9xclr0000gn/T//ccEAWWhd.s:16:no such
instruction: `pclmulqdq $0, %xmm0,%xmm1'

It seems that GCC is able to generate the correct assembly code from the instrinsic, but the assembler does not recognize the instruction.

I've installed binutils using macports, but the problem persists. How do I know which assembler gcc is using? The XCode assembler probably does not support it, but the binutils assembler should.

Answer

capisce picture capisce · Oct 13, 2013

A simpler solution that fixed this problem for me was adding -Wa,-q to the compiler flags. From the man pages for as (version 1.38):

-q

     Use the clang(1) integrated assembler instead of the GNU based system assembler.

The -Wa part passes it from the compiler driver to the assembler, much like -Wl passes arguments to the linker.

Related questions

Error "no such instruction" while assembling project on Mac OS X

I used homebrew to install GCC 4.7.0 and my project's make is failing at assembly-time. I can successfully take code from .c -> .s, but .s -> .o fails. To view the brew formula used to install GCC, please …

Read More
How do you get assembler output from C/C++ source in gcc?

How does one do this? If I want to analyze how something is getting compiled, how would I get the emitted assembly code?

Read More
Why doesn't GCC optimize a*a*a*a*a*a to (a*a*a)*(a*a*a)?

I am doing some numerical optimization on a scientific application. One thing I noticed is that GCC will optimize the call pow(a,2) by compiling it into a*a, but the call pow(a,6) is not optimized and will actually …

Read More