[LoopVectorize] Use MapVector rather than DenseMap for MinBWs.
The order in which instructions are truncated in truncateToMinimalBitwidths
effects code generation. Switch to a map with a determinisic order, since the
iteration order over a DenseMap is not defined.
This code is not hot, so the difference in container performance isn't
interesting.
Many thanks to David Blaikie for making me aware of MapVector!
Fixes PR25490.
Differential Revision: http://reviews.llvm.org/D14981
llvm-svn: 254179
diff --git a/llvm/lib/Analysis/VectorUtils.cpp b/llvm/lib/Analysis/VectorUtils.cpp
index 6f25687..fbf387b 100644
--- a/llvm/lib/Analysis/VectorUtils.cpp
+++ b/llvm/lib/Analysis/VectorUtils.cpp
@@ -438,7 +438,7 @@
return InsertEltInst->getOperand(1);
}
-DenseMap<Instruction *, uint64_t>
+MapVector<Instruction *, uint64_t>
llvm::computeMinimumValueSizes(ArrayRef<BasicBlock *> Blocks, DemandedBits &DB,
const TargetTransformInfo *TTI) {
@@ -451,7 +451,7 @@
SmallPtrSet<Value *, 16> Visited;
DenseMap<Value *, uint64_t> DBits;
SmallPtrSet<Instruction *, 4> InstructionSet;
- DenseMap<Instruction *, uint64_t> MinBWs;
+ MapVector<Instruction *, uint64_t> MinBWs;
// Determine the roots. We work bottom-up, from truncs or icmps.
bool SeenExtFromIllegalType = false;
@@ -497,7 +497,7 @@
// If we encounter a type that is larger than 64 bits, we can't represent
// it so bail out.
if (DB.getDemandedBits(I).getBitWidth() > 64)
- return DenseMap<Instruction *, uint64_t>();
+ return MapVector<Instruction *, uint64_t>();
uint64_t V = DB.getDemandedBits(I).getZExtValue();
DBits[Leader] |= V;