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[SLP] Refactoring of horizontal reduction analysis, NFC.

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Some checks in SLP horizontal reduction analysis function are performed
several times, though it is enough to perform these checks only once
during an initial attempt at adding candidate for the reduction
instruction/reduced value.

Differential Revision: https://reviews.llvm.org/D29175

llvm-svn: 293274
This commit is contained in:
Alexey Bataev
2017-01-27 10:54:04 +00:00
parent fd2d7c72fc
commit 4015bf8372
1 changed files with 25 additions and 24 deletions
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49
llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
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@@ -4176,8 +4176,9 @@ public:
ReductionPHI = Phi;
// We currently only support adds.
if (ReductionOpcode != Instruction::Add &&
ReductionOpcode != Instruction::FAdd)
if ((ReductionOpcode != Instruction::Add &&
ReductionOpcode != Instruction::FAdd) ||
!B->isAssociative())
return false;
// Post order traverse the reduction tree starting at B. We only handle true
@@ -4189,31 +4190,12 @@ public:
unsigned EdgeToVist = Stack.back().second++;
bool IsReducedValue = TreeN->getOpcode() != ReductionOpcode;
// Only handle trees in the current basic block.
if (TreeN->getParent() != B->getParent())
return false;
// Each tree node needs to have one user except for the ultimate
// reduction.
if (!TreeN->hasOneUse() && TreeN != B)
return false;
// Postorder vist.
if (EdgeToVist == 2 || IsReducedValue) {
if (IsReducedValue) {
// Make sure that the opcodes of the operations that we are going to
// reduce match.
if (!ReducedValueOpcode)
ReducedValueOpcode = TreeN->getOpcode();
else if (ReducedValueOpcode != TreeN->getOpcode())
return false;
if (IsReducedValue)
ReducedVals.push_back(TreeN);
} else {
// We need to be able to reassociate the adds.
if (!TreeN->isAssociative())
return false;
else
ReductionOps.push_back(TreeN);
}
// Retract.
Stack.pop_back();
continue;
@@ -4229,8 +4211,27 @@ public:
// reduced value class.
if (I && (!ReducedValueOpcode || I->getOpcode() == ReducedValueOpcode ||
I->getOpcode() == ReductionOpcode)) {
if (!ReducedValueOpcode && I->getOpcode() != ReductionOpcode)
// Only handle trees in the current basic block.
if (I->getParent() != B->getParent())
return false;
// Each tree node needs to have one user except for the ultimate
// reduction.
if (!I->hasOneUse() && I != B)
return false;
if (I->getOpcode() == ReductionOpcode) {
// We need to be able to reassociate the reduction operations.
if (!I->isAssociative())
return false;
} else if (ReducedValueOpcode &&
ReducedValueOpcode != I->getOpcode()) {
// Make sure that the opcodes of the operations that we are going to
// reduce match.
return false;
} else if (!ReducedValueOpcode)
ReducedValueOpcode = I->getOpcode();
Stack.push_back(std::make_pair(I, 0));
continue;
}