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X86 MMX: optimize transfer from mmx to i32

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We used to generate a store (movq) + a load.
Now we use movd.

rdar://9946746

llvm-svn: 167056
This commit is contained in:
Manman Ren 2012-10-30 22:15:38 +00:00
parent e06ea2d50f
commit 584c3daf8d
4 changed files with 34 additions and 2 deletions
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8
lib/Target/X86/X86ISelLowering.cpp
View File

@ -14399,6 +14399,14 @@ static SDValue PerformEXTRACT_VECTOR_ELTCombine(SDNode *N, SelectionDAG &DAG,
return NewOp;
SDValue InputVector = N->getOperand(0);
// Detect whether we are trying to convert from mmx to i32 and the bitcast
// from mmx to v2i32 has a single usage.
if (InputVector.getNode()->getOpcode() == llvm::ISD::BITCAST &&
InputVector.getNode()->getOperand(0).getValueType() == MVT::x86mmx &&
InputVector.hasOneUse() && N->getValueType(0) == MVT::i32)
return DAG.getNode(X86ISD::MMX_MOVD2W, InputVector.getDebugLoc(),
N->getValueType(0),
InputVector.getNode()->getOperand(0));
// Only operate on vectors of 4 elements, where the alternative shuffling
// gets to be more expensive.

4
lib/Target/X86/X86ISelLowering.h
View File

@ -142,6 +142,10 @@ namespace llvm {
/// mnemonic, so do I; blame Intel.
MOVDQ2Q,
/// MMX_MOVD2W - Copies a 32-bit value from the low word of a MMX
/// vector to a GPR.
MMX_MOVD2W,
/// PEXTRB - Extract an 8-bit value from a vector and zero extend it to
/// i32, corresponds to X86::PEXTRB.
PEXTRB,

10
lib/Target/X86/X86InstrMMX.td
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@ -207,8 +207,14 @@ def MMX_MOVD64rm : MMXI<0x6E, MRMSrcMem, (outs VR64:$dst), (ins i32mem:$src),
let mayStore = 1 in
def MMX_MOVD64mr : MMXI<0x7E, MRMDestMem, (outs), (ins i32mem:$dst, VR64:$src),
"movd\t{$src, $dst|$dst, $src}", [], IIC_MMX_MOV_MM_RM>;
def MMX_MOVD64grr : MMXI<0x7E, MRMDestReg, (outs), (ins GR32:$dst, VR64:$src),
"movd\t{$src, $dst|$dst, $src}", [], IIC_MMX_MOV_REG_MM>;
// Low word of MMX to GPR.
def MMX_X86movd2w : SDNode<"X86ISD::MMX_MOVD2W", SDTypeProfile<1, 1,
[SDTCisVT<0, i32>, SDTCisVT<1, x86mmx>]>>;
def MMX_MOVD64grr : MMXI<0x7E, MRMDestReg, (outs GR32:$dst), (ins VR64:$src),
"movd\t{$src, $dst|$dst, $src}",
[(set GR32:$dst,
(MMX_X86movd2w (x86mmx VR64:$src)))], IIC_MMX_MOV_REG_MM>;
let neverHasSideEffects = 1 in
def MMX_MOVD64to64rr : MMXRI<0x6E, MRMSrcReg, (outs VR64:$dst), (ins GR64:$src),

14
test/CodeGen/X86/mmx-builtins.ll
View File

@ -1043,6 +1043,20 @@ entry:
ret i64 %5
}
define i32 @test21_2(<1 x i64> %a) nounwind readnone optsize ssp {
; CHECK: test21_2
; CHECK: pshufw
; CHECK: movd
entry:
%0 = bitcast <1 x i64> %a to <4 x i16>
%1 = bitcast <4 x i16> %0 to x86_mmx
%2 = tail call x86_mmx @llvm.x86.sse.pshuf.w(x86_mmx %1, i8 3) nounwind readnone
%3 = bitcast x86_mmx %2 to <4 x i16>
%4 = bitcast <4 x i16> %3 to <2 x i32>
%5 = extractelement <2 x i32> %4, i32 0
ret i32 %5
}
declare x86_mmx @llvm.x86.mmx.pmulu.dq(x86_mmx, x86_mmx) nounwind readnone
define i64 @test20(<1 x i64> %a, <1 x i64> %b) nounwind readnone optsize ssp {