On Tue, May 24, 2016 at 08:35:12PM +0200, Uros Bizjak wrote:
> On Tue, May 24, 2016 at 6:55 PM, Jakub Jelinek <[email protected]> wrote:
> > Hi!
> >
> > The Yr constraint contrary to what has been said when it has been submitted
> > actually is always NO_REX_SSE_REGS or NO_REGS, never ALL_SSE_REGS, so
> > the RA restriction to only the first 8 regs is done no matter what we tune
> > for.
> >
> > This is because we test X86_TUNE_AVOID_4BYTE_PREFIXES, which is an enum
> > value (59), rather than actually checking if the tune flag.
> >
> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> >
> > 2016-05-24 Jakub Jelinek <[email protected]>
> >
> > * config/i386/i386.h (TARGET_AVOID_4BYTE_PREFIXES): Define.
> > * config/i386/constraints.md (Yr): Test TARGET_AVOID_4BYTE_PREFIXES
> > rather than X86_TUNE_AVOID_4BYTE_PREFIXES.
>
> Uh, another brown-paper bag bug...
>
> OK everywhere.
I fear it might be too dangerous for -mavx512* for the branches; I went
through all the Yr uses on the trunk, but not on the branches.
Would you be ok with using
"TARGET_SSE ? (TARGET_AVOID_4BYTE_PREFIXES ? NO_REX_SSE_REGS : SSE_REGS) :
NO_REGS"
on the branches instead?
Or I guess we could use it on the trunk too, it should make no difference there
(because on the trunk it is only used when !TARGET_AVX).
Or maybe even
"TARGET_SSE ? ((TARGET_AVOID_4BYTE_PREFIXES && !TARGET_AVX) ? NO_REX_SSE_REGS :
SSE_REGS) : NO_REGS"
(again, should make zero difference on the trunk, but might be better for
the branches).
> > --- gcc/config/i386/i386.h.jj 2016-05-24 10:56:02.000000000 +0200
> > +++ gcc/config/i386/i386.h 2016-05-24 15:13:05.715906018 +0200
> > @@ -465,6 +465,8 @@ extern unsigned char ix86_tune_features[
> > ix86_tune_features[X86_TUNE_SLOW_PSHUFB]
> > #define TARGET_VECTOR_PARALLEL_EXECUTION \
> > ix86_tune_features[X86_TUNE_VECTOR_PARALLEL_EXECUTION]
> > +#define TARGET_AVOID_4BYTE_PREFIXES \
> > + ix86_tune_features[X86_TUNE_AVOID_4BYTE_PREFIXES]
> > #define TARGET_FUSE_CMP_AND_BRANCH_32 \
> > ix86_tune_features[X86_TUNE_FUSE_CMP_AND_BRANCH_32]
> > #define TARGET_FUSE_CMP_AND_BRANCH_64 \
> > --- gcc/config/i386/constraints.md.jj 2016-05-12 10:29:41.000000000 +0200
> > +++ gcc/config/i386/constraints.md 2016-05-24 15:14:21.647914550 +0200
> > @@ -142,7 +142,7 @@ (define_register_constraint "Yf"
> > "@internal Any x87 register when 80387 FP arithmetic is enabled.")
> >
> > (define_register_constraint "Yr"
> > - "TARGET_SSE ? (X86_TUNE_AVOID_4BYTE_PREFIXES ? NO_REX_SSE_REGS :
> > ALL_SSE_REGS) : NO_REGS"
> > + "TARGET_SSE ? (TARGET_AVOID_4BYTE_PREFIXES ? NO_REX_SSE_REGS :
> > ALL_SSE_REGS) : NO_REGS"
> > "@internal Lower SSE register when avoiding REX prefix and all SSE
> > registers otherwise.")
> >
> > (define_register_constraint "Yv"
Jakub
