[GISel][SDAG] Avoid push_back in loops for some shuffle mask handling. #119434
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Each call to push_back contains a check to see if the vector needs to grow. Using resize or the giving the size to the constructor can reduce the number of checks for growing.
Member
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@llvm/pr-subscribers-llvm-globalisel Author: Craig Topper (topperc) ChangesEach call to push_back contains a check to see if the vector needs to grow. Using resize or the giving the size to the constructor can reduce the number of checks for growing. Full diff: https://github.com/llvm/llvm-project/pull/119434.diff 2 Files Affected:
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 2544f2479ddc68..6676cee8f618a8 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -6173,8 +6173,7 @@ LegalizerHelper::equalizeVectorShuffleLengths(MachineInstr &MI) {
// Extend mask to match new destination vector size with
// undef values.
SmallVector<int, 16> NewMask(Mask);
- for (unsigned I = MaskNumElts; I < SrcNumElts; ++I)
- NewMask.push_back(-1);
+ NewMask.resize(SrcNumElts, -1);
moreElementsVectorDst(MI, SrcTy, 0);
MIRBuilder.setInstrAndDebugLoc(MI);
@@ -6254,16 +6253,14 @@ LegalizerHelper::moreElementsVectorShuffle(MachineInstr &MI,
moreElementsVectorSrc(MI, MoreTy, 2);
// Adjust mask based on new input vector length.
- SmallVector<int, 16> NewMask;
+ SmallVector<int, 16> NewMask(WidenNumElts, -1);
for (unsigned I = 0; I != NumElts; ++I) {
int Idx = Mask[I];
if (Idx < static_cast<int>(NumElts))
- NewMask.push_back(Idx);
+ NewMask[I] = Idx;
else
- NewMask.push_back(Idx - NumElts + WidenNumElts);
+ NewMask[I] = Idx - NumElts + WidenNumElts;
}
- for (unsigned I = NumElts; I != WidenNumElts; ++I)
- NewMask.push_back(-1);
moreElementsVectorDst(MI, MoreTy, 0);
MIRBuilder.setInstrAndDebugLoc(MI);
MIRBuilder.buildShuffleVector(MI.getOperand(0).getReg(),
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index 465128099f4447..205ad899e4c278 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -6421,16 +6421,14 @@ SDValue DAGTypeLegalizer::WidenVecRes_VECTOR_SHUFFLE(ShuffleVectorSDNode *N) {
SDValue InOp2 = GetWidenedVector(N->getOperand(1));
// Adjust mask based on new input vector length.
- SmallVector<int, 16> NewMask;
+ SmallVector<int, 16> NewMask(WidenNumElts, -1);
for (unsigned i = 0; i != NumElts; ++i) {
int Idx = N->getMaskElt(i);
if (Idx < (int)NumElts)
- NewMask.push_back(Idx);
+ NewMask[i] = Idx;
else
- NewMask.push_back(Idx - NumElts + WidenNumElts);
+ NewMask[i] = Idx - NumElts + WidenNumElts;
}
- for (unsigned i = NumElts; i != WidenNumElts; ++i)
- NewMask.push_back(-1);
return DAG.getVectorShuffle(WidenVT, dl, InOp1, InOp2, NewMask);
}
@@ -6478,12 +6476,9 @@ SDValue DAGTypeLegalizer::WidenVecRes_VECTOR_REVERSE(SDNode *N) {
// Use VECTOR_SHUFFLE to combine new vector from 'ReverseVal' for
// fixed-vectors.
- SmallVector<int, 16> Mask;
- for (unsigned i = 0; i != VTNumElts; ++i) {
- Mask.push_back(IdxVal + i);
- }
- for (unsigned i = VTNumElts; i != WidenNumElts; ++i)
- Mask.push_back(-1);
+ SmallVector<int, 16> Mask(VTNumElts, -1);
+ for (unsigned i = 0; i != VTNumElts; ++i)
+ Mask[i] = IdxVal + i;
return DAG.getVectorShuffle(WidenVT, dl, ReverseVal, DAG.getUNDEF(WidenVT),
Mask);
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Member
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@llvm/pr-subscribers-llvm-selectiondag Author: Craig Topper (topperc) ChangesEach call to push_back contains a check to see if the vector needs to grow. Using resize or the giving the size to the constructor can reduce the number of checks for growing. Full diff: https://github.com/llvm/llvm-project/pull/119434.diff 2 Files Affected:
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 2544f2479ddc68..6676cee8f618a8 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -6173,8 +6173,7 @@ LegalizerHelper::equalizeVectorShuffleLengths(MachineInstr &MI) {
// Extend mask to match new destination vector size with
// undef values.
SmallVector<int, 16> NewMask(Mask);
- for (unsigned I = MaskNumElts; I < SrcNumElts; ++I)
- NewMask.push_back(-1);
+ NewMask.resize(SrcNumElts, -1);
moreElementsVectorDst(MI, SrcTy, 0);
MIRBuilder.setInstrAndDebugLoc(MI);
@@ -6254,16 +6253,14 @@ LegalizerHelper::moreElementsVectorShuffle(MachineInstr &MI,
moreElementsVectorSrc(MI, MoreTy, 2);
// Adjust mask based on new input vector length.
- SmallVector<int, 16> NewMask;
+ SmallVector<int, 16> NewMask(WidenNumElts, -1);
for (unsigned I = 0; I != NumElts; ++I) {
int Idx = Mask[I];
if (Idx < static_cast<int>(NumElts))
- NewMask.push_back(Idx);
+ NewMask[I] = Idx;
else
- NewMask.push_back(Idx - NumElts + WidenNumElts);
+ NewMask[I] = Idx - NumElts + WidenNumElts;
}
- for (unsigned I = NumElts; I != WidenNumElts; ++I)
- NewMask.push_back(-1);
moreElementsVectorDst(MI, MoreTy, 0);
MIRBuilder.setInstrAndDebugLoc(MI);
MIRBuilder.buildShuffleVector(MI.getOperand(0).getReg(),
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index 465128099f4447..205ad899e4c278 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -6421,16 +6421,14 @@ SDValue DAGTypeLegalizer::WidenVecRes_VECTOR_SHUFFLE(ShuffleVectorSDNode *N) {
SDValue InOp2 = GetWidenedVector(N->getOperand(1));
// Adjust mask based on new input vector length.
- SmallVector<int, 16> NewMask;
+ SmallVector<int, 16> NewMask(WidenNumElts, -1);
for (unsigned i = 0; i != NumElts; ++i) {
int Idx = N->getMaskElt(i);
if (Idx < (int)NumElts)
- NewMask.push_back(Idx);
+ NewMask[i] = Idx;
else
- NewMask.push_back(Idx - NumElts + WidenNumElts);
+ NewMask[i] = Idx - NumElts + WidenNumElts;
}
- for (unsigned i = NumElts; i != WidenNumElts; ++i)
- NewMask.push_back(-1);
return DAG.getVectorShuffle(WidenVT, dl, InOp1, InOp2, NewMask);
}
@@ -6478,12 +6476,9 @@ SDValue DAGTypeLegalizer::WidenVecRes_VECTOR_REVERSE(SDNode *N) {
// Use VECTOR_SHUFFLE to combine new vector from 'ReverseVal' for
// fixed-vectors.
- SmallVector<int, 16> Mask;
- for (unsigned i = 0; i != VTNumElts; ++i) {
- Mask.push_back(IdxVal + i);
- }
- for (unsigned i = VTNumElts; i != WidenNumElts; ++i)
- Mask.push_back(-1);
+ SmallVector<int, 16> Mask(VTNumElts, -1);
+ for (unsigned i = 0; i != VTNumElts; ++i)
+ Mask[i] = IdxVal + i;
return DAG.getVectorShuffle(WidenVT, dl, ReverseVal, DAG.getUNDEF(WidenVT),
Mask);
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aemerson
reviewed
Dec 10, 2024
| SmallVector<int, 16> NewMask(Mask); | ||
| for (unsigned I = MaskNumElts; I < SrcNumElts; ++I) | ||
| NewMask.push_back(-1); | ||
| NewMask.resize(SrcNumElts, -1); |
Contributor
There was a problem hiding this comment.
Use the constructor variant as you did in moreElementsVectorShuffle()?
Collaborator
Author
There was a problem hiding this comment.
We're already using the constructor to copy the first part of the Mask. We could do
SmallVector<int, 16> NewMask(SrcNumElts, -1);
std::copy(NewMask.begin(), Mask.begin(), Mask.end())
Then we'd have the correct size at the start.
RKSimon
reviewed
Dec 10, 2024
| for (unsigned i = VTNumElts; i != WidenNumElts; ++i) | ||
| Mask.push_back(-1); | ||
| SmallVector<int, 16> Mask(VTNumElts, -1); | ||
| for (unsigned i = 0; i != VTNumElts; ++i) |
Collaborator
Author
There was a problem hiding this comment.
Thanks.
I messed up the size here. I should have used WidenNumElts in the constructor. Need to see why nothing failed.
topperc
commented
Dec 10, 2024
| } | ||
| for (unsigned i = VTNumElts; i != WidenNumElts; ++i) | ||
| Mask.push_back(-1); | ||
| SmallVector<int, 16> Mask(WidenNumElts, -1); |
Collaborator
Author
There was a problem hiding this comment.
This code isn't tested because VECTOR_REVERSE is converted to a generic VECTOR_SHUFFLE for fixed vectors.
arsenm
approved these changes
Dec 11, 2024
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Each call to push_back contains a check to see if the vector needs to grow. Using resize or the giving the size to the constructor can reduce the number of checks for growing.