Re: PATCH: Add SSSE3 builtin tests

["H. J. Lu" <hjl at lucon dot org>]

On Sun, Dec 17, 2006 at 05:53:56PM +0100, Jan Hubicka wrote:
> Hi,
> > 
> > Many (all?) of these tests are failing for me on i686-pc-linux-gnu on
> > RedHat 4.3, due to the new SSSE3 instructions not being recognized by
> > the native assembler, based upon binutils 2.15.92.0.2.
> > 
> > /tmp/ccBMbto1.s: Assembler messages:
> > /tmp/ccBMbto1.s:66: Error: no such instruction: `pabsd (%eax),%mm0'
> > /tmp/ccBMbto1.s:148: Error: no such instruction: `pabsd vals(%ebx),%xmm0'
> > FAIL: gcc.target/i386/ssse3-pabsd.c (test for excess errors)
> > 
> > We either need to make these compile only tests when assembler support
> > isn't available, or do something similar to what we do with
> > HAVE_AS_IX86_FFREEP, where the compiler emits .word directives
> > for assemblers that don't support the new mnemonics (such as the
> > Solaris native assembler and older versions on binutils).
> 
> I really don't think hand encoding all those hounders of instructions is
> an option. FREEP instruction is a bit special by being missing in x86
> ISA specification (as long as I can remember) but being supported by all
> CPUs anyway.  So it is sensible to not expect non-GNU assembler to know it.
> SSE ISA is however documented and rather complex.
> 
> I think we only can declare that for GCC SSExy support an capable
> assembler is required.  We can either keep current shape of failing on
> unknown instruction (that i think is pretty instructive to end user that
> he needs better assembler) in testsuite or arrange HAVE_AS_SSSE3 macro
> set by configure that will make __SSSE3___ definition in
> TARGET_CPU_CPP_BUILTINS to disappear and conditionalize testsuite tests
> on those with friendly #error message within the ???intrin.h header.
> Disadvantage of this is that user after discovering that he needs update
> on assembler will also need rebuild GCC itself.
> 

I'd rather leave it ASIS since it tells users that his/her gcc may
generate assembly code his/her assembler can't handle. We will run
into the same issue when we add SSE4 builtin tests. I will make sure
that Linux binutils will support SSE4 before gcc does.

If people really don't want to know there is a problem with their
assemblers, I can implment HAVE_AS_SSSE3 and let SSSE3 tests check
it. People don't need to rebuild gcc.


H.J.