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Reorder shuffle and binary operation.

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This patch enables transformations:

    BinOp(shuffle(v1), shuffle(v2)) -> shuffle(BinOp(v1, v2))
    BinOp(shuffle(v1), const1) -> shuffle(BinOp, const2)

They allow to eliminate extra shuffles in some cases.

Differential Revision: http://reviews.llvm.org/D3525


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208488 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Serge Pavlov
2014-05-11 08:46:12 +00:00
parent 4ccf0ebb19
commit 86118b4532
9 changed files with 300 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+25 -10
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@@ -839,6 +839,20 @@ InstCombiner::EvaluateInDifferentElementOrder(Value *V, ArrayRef<int> Mask) {
llvm_unreachable("failed to reorder elements of vector instruction!");
}
static void RecognizeIdentityMask(const SmallVectorImpl<int> &Mask,
bool &isLHSID, bool &isRHSID) {
isLHSID = isRHSID = true;
for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
if (Mask[i] < 0) continue; // Ignore undef values.
// Is this an identity shuffle of the LHS value?
isLHSID &= (Mask[i] == (int)i);
// Is this an identity shuffle of the RHS value?
isRHSID &= (Mask[i]-e == i);
}
}
Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
Value *LHS = SVI.getOperand(0);
Value *RHS = SVI.getOperand(1);
@@ -902,16 +916,8 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
if (VWidth == LHSWidth) {
// Analyze the shuffle, are the LHS or RHS and identity shuffles?
bool isLHSID = true, isRHSID = true;
for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
if (Mask[i] < 0) continue; // Ignore undef values.
// Is this an identity shuffle of the LHS value?
isLHSID &= (Mask[i] == (int)i);
// Is this an identity shuffle of the RHS value?
isRHSID &= (Mask[i]-e == i);
}
bool isLHSID, isRHSID;
RecognizeIdentityMask(Mask, isLHSID, isRHSID);
// Eliminate identity shuffles.
if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
@@ -1106,5 +1112,14 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
return new ShuffleVectorInst(newLHS, newRHS, ConstantVector::get(Elts));
}
// If the result mask is an identity, replace uses of this instruction with
// corresponding argument.
if (VWidth == LHSWidth) {
bool isLHSID, isRHSID;
RecognizeIdentityMask(newMask, isLHSID, isRHSID);
if (isLHSID) return ReplaceInstUsesWith(SVI, newLHS);
if (isRHSID) return ReplaceInstUsesWith(SVI, newRHS);
}
return MadeChange ? &SVI : nullptr;
}