diff options
author | Bruno Cardoso Lopes <bruno.cardoso@gmail.com> | 2015-08-19 14:34:41 +0000 |
---|---|---|
committer | Bruno Cardoso Lopes <bruno.cardoso@gmail.com> | 2015-08-19 14:34:41 +0000 |
commit | e94e9970af2df2deebaf9d24a2b4b49937c16221 (patch) | |
tree | 55237be51841bc7d3ba917afe3b51263c83dd048 /llvm/lib/Target/X86/X86InstrMMX.td | |
parent | a0e0cfcfc885657cd7c777aba85f69543879f0e9 (diff) |
[PeepholeOptimizer] Look through PHIs to find additional register sources
Reapply r243486.
- Teaches the ValueTracker in the PeepholeOptimizer to look through PHI
instructions.
- Add findNextSourceAndRewritePHI method to lookup into multiple sources
returnted by the ValueTracker and rewrite PHIs with new sources.
With these changes we can find more register sources and rewrite more
copies to allow coaslescing of bitcast instructions. Hence, we eliminate
unnecessary VR64 <-> GR64 copies in x86, but it could be extended to
other archs by marking "isBitcast" on target specific instructions. The
x86 example follows:
A:
psllq %mm1, %mm0
movd %mm0, %r9
jmp C
B:
por %mm1, %mm0
movd %mm0, %r9
jmp C
C:
movd %r9, %mm0
pshufw $238, %mm0, %mm0
Becomes:
A:
psllq %mm1, %mm0
jmp C
B:
por %mm1, %mm0
jmp C
C:
pshufw $238, %mm0, %mm0
Differential Revision: http://reviews.llvm.org/D11197
rdar://problem/20404526
Diffstat (limited to 'llvm/lib/Target/X86/X86InstrMMX.td')
-rw-r--r-- | llvm/lib/Target/X86/X86InstrMMX.td | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/llvm/lib/Target/X86/X86InstrMMX.td b/llvm/lib/Target/X86/X86InstrMMX.td index eaa7894004c..ab301adca48 100644 --- a/llvm/lib/Target/X86/X86InstrMMX.td +++ b/llvm/lib/Target/X86/X86InstrMMX.td @@ -249,6 +249,7 @@ def MMX_MOVD64grr : MMXI<0x7E, MRMDestReg, (outs GR32:$dst), (ins VR64:$src), (MMX_X86movd2w (x86mmx VR64:$src)))], IIC_MMX_MOV_REG_MM>, Sched<[WriteMove]>; +let isBitcast = 1 in def MMX_MOVD64to64rr : MMXRI<0x6E, MRMSrcReg, (outs VR64:$dst), (ins GR64:$src), "movd\t{$src, $dst|$dst, $src}", [(set VR64:$dst, (bitconvert GR64:$src))], @@ -262,7 +263,7 @@ def MMX_MOVD64to64rm : MMXRI<0x6E, MRMSrcMem, (outs VR64:$dst), // These are 64 bit moves, but since the OS X assembler doesn't // recognize a register-register movq, we write them as // movd. -let SchedRW = [WriteMove] in { +let SchedRW = [WriteMove], isBitcast = 1 in { def MMX_MOVD64from64rr : MMXRI<0x7E, MRMDestReg, (outs GR64:$dst), (ins VR64:$src), "movd\t{$src, $dst|$dst, $src}", |