On Thu, Jul 26, 2012 at 03:42:24PM -0700, Ronald S. Bultje wrote:
> On Thu, Jul 26, 2012 at 2:39 PM, Diego Biurrun <[email protected]> wrote:
> > On Thu, Jul 26, 2012 at 01:50:17PM -0700, Ronald S. Bultje wrote:
> >>
> >> discussion thread. We currently use HAVE_SSSE3 and related macros to
> >> indicate that we want to compile these and that our compiler tools are
> >> good enough to know what to do with it. As a result, we currently use
> >> HAVE_AVX around all avx code (yasm only - we don't have any avx inline
> >> asm), HAVE_SSSE3 around some yasm and all inline asm code that uses
> >> ssse3 instructions, and sometimes HAVE_SSE/2 around inline asm using
> >> xmm regs. There is no HAVE_SSE4. HAVE_MMX2 is almost never used but
> >> does exist.
> >
> > Do we need HAVE_SSE4?  It should be easy enough to add.
> >
> >> HAVE_MMX is something entirely different and is used as an
> >> alternative form of ARCH_X86.
> >
> > No, HAVE_MMX is just that.  True, it's abused in some places where
> > ARCH_X86 would be better (when invoking init functions), but that
> > is an issue that needs to be addressed at some point.
> >
> >> In addition to that, we're using inline asm checks to test whether to
> >> enable HAVE_SSSE3 and HAVE_SSE2 (line 2850 of configure).
> >>
> >> Can we split these macros in something for yasm vs something for
> >> inline asm? This means e.g. that we can use ssse3 if yasm (but not
> >> inline asm) supports it, if inline asm is lacking, etc.
> >
> > What is your goal?  Do you want to write something like
> >
> >   #if HAVE_INLINE_SSSE3
> >
> > instead of
> >
> >   #if HAVE_SSSE3 && HAVE_INLINE_ASM
> >
> > ?
> 
> Right now, in practice:
> 
> HAVE_SSSE3 means "we support inline ssse3"
> HAVE_SSE2 means "we support inline sse2"
> HAVE_AVX means "we support yasm avx" but depends on HAVE_SSSE3
> 
> I wonder whether it makes sense to have a "generic" HAVE_SSSE3 anyway
> - when would we use it, what would it mean? I think in practice, we
> probably want a HAVE_INLINE_SSSE3, as you said, because yes, there's
> compilers that don't support this, but do support HAVE_INLINE_ASM in
> general. Likewise, HAVE_AVX could be renamed HAVE_YASM_AVX or so.
> Having HAVE_YASM_SSSE3 seems pointless, I don't think we support any
> yasm/nasm version that doesn't understand ssse3, so it'd always be 1.
> However, this would make it clear that HAVE_SSSE3 and HAVE_AVX don't
> and shouldn't depend on each other.

Try dropping the line

  avx_deps="ssse3"

from configure and see if that works out the way you want it to.

Diego
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