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Look for VECTOR_SHUFFLE that's identity operation on either LHS or RHS. This can happen before DAGCombiner catches it.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37636 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-06-19 00:02:56 +00:00
parent d2e8442a13
commit 49892af264
1 changed files with 19 additions and 2 deletions
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21
lib/Target/X86/X86ISelLowering.cpp
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@ -1954,6 +1954,16 @@ bool X86::isMOVSLDUPMask(SDNode *N) {
return HasHi;
}
/// isIdentityMask - Return true if the specified VECTOR_SHUFFLE operand
/// specifies a identity operation on the LHS or RHS.
static bool isIdentityMask(SDNode *N, bool RHS = false) {
unsigned NumElems = N->getNumOperands();
for (unsigned i = 0; i < NumElems; ++i)
if (!isUndefOrEqual(N->getOperand(i), i + (RHS ? NumElems : 0)))
return false;
return true;
}
/// isSplatMask - Return true if the specified VECTOR_SHUFFLE operand specifies
/// a splat of a single element.
static bool isSplatMask(SDNode *N) {
@ -2630,6 +2640,11 @@ X86TargetLowering::LowerVECTOR_SHUFFLE(SDOperand Op, SelectionDAG &DAG) {
if (isZeroShuffle(Op.Val))
return getZeroVector(VT, DAG);
if (isIdentityMask(PermMask.Val))
return V1;
else if (isIdentityMask(PermMask.Val, true))
return V2;
if (isSplatMask(PermMask.Val)) {
if (NumElems <= 4) return Op;
// Promote it to a v4i32 splat.
@ -4316,12 +4331,14 @@ X86TargetLowering::isShuffleMaskLegal(SDOperand Mask, MVT::ValueType VT) const {
// Only do shuffles on 128-bit vector types for now.
if (MVT::getSizeInBits(VT) == 64) return false;
return (Mask.Val->getNumOperands() <= 4 ||
isIdentityMask(Mask.Val) ||
isIdentityMask(Mask.Val, true) ||
isSplatMask(Mask.Val) ||
isPSHUFHW_PSHUFLWMask(Mask.Val) ||
X86::isUNPCKLMask(Mask.Val) ||
X86::isUNPCKHMask(Mask.Val) ||
X86::isUNPCKL_v_undef_Mask(Mask.Val) ||
X86::isUNPCKH_v_undef_Mask(Mask.Val) ||
X86::isUNPCKHMask(Mask.Val));
X86::isUNPCKH_v_undef_Mask(Mask.Val));
}
bool X86TargetLowering::isVectorClearMaskLegal(std::vector<SDOperand> &BVOps,