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If a shuffle is a splat, check if the argument is a build_vector with all elements being the same. If so, return the argument.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@29242 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2006-07-21 08:25:53 +00:00
parent 49717a4ee5
commit 917ec983df
1 changed files with 90 additions and 8 deletions
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98
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -2601,16 +2601,23 @@ SDOperand DAGCombiner::visitVECTOR_SHUFFLE(SDNode *N) {
// Check if the shuffle is a unary shuffle, i.e. one of the vectors is not
// needed at all.
bool isUnary = true;
bool isSplat = true;
int VecNum = -1;
unsigned BaseIdx;
for (unsigned i = 0; i != NumElts; ++i)
if (ShufMask.getOperand(i).getOpcode() != ISD::UNDEF) {
unsigned Idx = cast<ConstantSDNode>(ShufMask.getOperand(i))->getValue();
int V = (Idx < NumElts) ? 0 : 1;
if (VecNum == -1)
if (VecNum == -1) {
VecNum = V;
else if (VecNum != V) {
isUnary = false;
break;
BaseIdx = Idx;
} else {
if (BaseIdx != Idx)
isSplat = false;
if (VecNum != V) {
isUnary = false;
break;
}
}
}
@ -2620,6 +2627,40 @@ SDOperand DAGCombiner::visitVECTOR_SHUFFLE(SDNode *N) {
if (isUnary && VecNum == 1)
std::swap(N0, N1);
// If it is a splat, check if the argument vector is a build_vector with
// all scalar elements the same.
if (isSplat) {
SDNode *V = N0.Val;
if (V->getOpcode() == ISD::BIT_CONVERT)
V = V->getOperand(0).Val;
if (V->getOpcode() == ISD::BUILD_VECTOR) {
unsigned NumElems = V->getNumOperands()-2;
if (NumElems > BaseIdx) {
SDOperand Base;
bool AllSame = true;
for (unsigned i = 0; i != NumElems; ++i) {
if (V->getOperand(i).getOpcode() != ISD::UNDEF) {
Base = V->getOperand(i);
break;
}
}
// Splat of <u, u, u, u>, return <u, u, u, u>
if (!Base.Val)
return N0;
for (unsigned i = 0; i != NumElems; ++i) {
if (V->getOperand(i).getOpcode() != ISD::UNDEF &&
V->getOperand(i) != Base) {
AllSame = false;
break;
}
}
// Splat of <x, x, x, x>, return <x, x, x, x>
if (AllSame)
return N0;
}
}
}
// If it is a unary or the LHS and the RHS are the same node, turn the RHS
// into an undef.
if (isUnary || N0 == N1) {
@ -2679,16 +2720,23 @@ SDOperand DAGCombiner::visitVVECTOR_SHUFFLE(SDNode *N) {
// Check if the shuffle is a unary shuffle, i.e. one of the vectors is not
// needed at all.
bool isUnary = true;
bool isSplat = true;
int VecNum = -1;
unsigned BaseIdx;
for (unsigned i = 0; i != NumElts; ++i)
if (ShufMask.getOperand(i).getOpcode() != ISD::UNDEF) {
unsigned Idx = cast<ConstantSDNode>(ShufMask.getOperand(i))->getValue();
int V = (Idx < NumElts) ? 0 : 1;
if (VecNum == -1)
if (VecNum == -1) {
VecNum = V;
else if (VecNum != V) {
isUnary = false;
break;
BaseIdx = Idx;
} else {
if (BaseIdx != Idx)
isSplat = false;
if (VecNum != V) {
isUnary = false;
break;
}
}
}
@ -2698,6 +2746,40 @@ SDOperand DAGCombiner::visitVVECTOR_SHUFFLE(SDNode *N) {
if (isUnary && VecNum == 1)
std::swap(N0, N1);
// If it is a splat, check if the argument vector is a build_vector with
// all scalar elements the same.
if (isSplat) {
SDNode *V = N0.Val;
if (V->getOpcode() == ISD::VBIT_CONVERT)
V = V->getOperand(0).Val;
if (V->getOpcode() == ISD::VBUILD_VECTOR) {
unsigned NumElems = V->getNumOperands()-2;
if (NumElems > BaseIdx) {
SDOperand Base;
bool AllSame = true;
for (unsigned i = 0; i != NumElems; ++i) {
if (V->getOperand(i).getOpcode() != ISD::UNDEF) {
Base = V->getOperand(i);
break;
}
}
// Splat of <u, u, u, u>, return <u, u, u, u>
if (!Base.Val)
return N0;
for (unsigned i = 0; i != NumElems; ++i) {
if (V->getOperand(i).getOpcode() != ISD::UNDEF &&
V->getOperand(i) != Base) {
AllSame = false;
break;
}
}
// Splat of <x, x, x, x>, return <x, x, x, x>
if (AllSame)
return N0;
}
}
}
// If it is a unary or the LHS and the RHS are the same node, turn the RHS
// into an undef.
if (isUnary || N0 == N1) {