This is the mail archive of the
mailing list for the GCC project.
Re: Fwd: [PATCH] Scheduling result adjustment to enable macro-fusion
- From: Wei Mi <wmi at google dot com>
- To: Jan Hubicka <hubicka at ucw dot cz>
- Cc: "H.J. Lu" <hjl dot tools at gmail dot com>, Alexander Monakov <amonakov at ispras dot ru>, Steven Bosscher <stevenb dot gcc at gmail dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, David Li <davidxl at google dot com>, Kirill Yukhin <kirill dot yukhin at gmail dot com>
- Date: Sun, 22 Sep 2013 12:59:35 -0700
- Subject: Re: Fwd: [PATCH] Scheduling result adjustment to enable macro-fusion
- Authentication-results: sourceware.org; auth=none
- References: <CAMe9rOo-dc7=ax8_pA21wuxnqphLBvf_Voi2n1OHJX7ZEab=ew at mail dot gmail dot com> <CA+4CFy4fqCRvM2Luw2_p6AEZOmucSV1KemntEO3_XU5TfzA-7A at mail dot gmail dot com> <CA+4CFy6gdxREYiJa2B70RBe2aUtLY3zQ9ShK9jGEy26Hdn9QOg at mail dot gmail dot com> <CAMe9rOp1R8XACsL=v-JZkvpPzTOFiZhZPMqQXWkmPgHW5cjC6w at mail dot gmail dot com> <CA+4CFy5nM2Dw7kv0G61N5PKHoAanmAaKm+45oS4pN22TKgSAFg at mail dot gmail dot com> <20130922095726 dot GA23006 at atrey dot karlin dot mff dot cuni dot cz> <20130922101916 dot GA31130 at atrey dot karlin dot mff dot cuni dot cz>
> You disable fusion for Budozer here sinze you did not add it into
Ok, will add it.
> Perhaps we can have TARGET_FUSE_CMP_AND_BRANCH_64 and TARGET_FUSE_CMP_AND_BRANCH_32
> plus an macro TARGET_FUSE_CMP_AND_BRANCH that chose corresponding variant based
> on TARGET_64BIT rather than having to wind down the test in every use.
Ok, will fix it.
>> +/* X86_TUNE_FUSE_CMP_AND_BRANCH_SOFLAGS: Fuse compare with a
>> + subsequent conditional jump instruction when the condition jump
>> + check sign flag (SF) or overflow flag (OF). */
>> +DEF_TUNE (X86_TUNE_FUSE_CMP_AND_BRANCH_SOFLAGS, "fuse_cmp_and_branch_soflags",
>> + m_COREI7 | m_COREI7_AVX | m_HASWELL)
> This flag is affecting only fuding of ALU and BRANCh or should it also affect
> X86_TUNE_FUSE_CMP_AND_BRANCH? In current implementation it seems to be the first
> and in that case it ought to be documented that way and probably
> called ALT_AND_BRANCH_SOFLAGS to avoid confussion.
X86_TUNE_FUSE_CMP_AND_BRANCH_SOFLAGS is not affecting fusing ALU and
BRANCH. It is added because m_CORE2 doesn't support fusing cmp and
> This is what Agner Fog says:
> A CMP or TEST instruction immediately followed by a conditional jump can be
> fused into a single macro-op. This applies to all versions of the CMP and TEST
> instructions and all conditional jumps except if the CMP or TEST has a
> rip-relative address or both a displacement and an immediate operand.
> So it is a bit more weird. Perhaps you can extend your predicate to look
> for IP relative addresses & displacements of CMP and TEST, too.
Thanks for checking it. Agner's guide also mentions this constraint
for sandybridge, ivybridge.... I missed it because Intel optimization
reference manual doesn't mention it. I did some experiment just now
and verified the constraint for sandybridge existed. Will add the