diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Analysis/VectorUtils.cpp | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/llvm/lib/Analysis/VectorUtils.cpp b/llvm/lib/Analysis/VectorUtils.cpp index 23a0de856bc..2c03f1a05ce 100644 --- a/llvm/lib/Analysis/VectorUtils.cpp +++ b/llvm/lib/Analysis/VectorUtils.cpp @@ -320,6 +320,9 @@ llvm::computeMinimumValueSizes(ArrayRef<BasicBlock *> Blocks, DemandedBits &DB, SmallPtrSet<Instruction *, 4> InstructionSet; MapVector<Instruction *, uint64_t> MinBWs; + assert(Blocks.size() > 0 && "Must have at least one block!"); + const DataLayout &DL = Blocks[0]->getModule()->getDataLayout(); + // Determine the roots. We work bottom-up, from truncs or icmps. bool SeenExtFromIllegalType = false; for (auto *BB : Blocks) @@ -363,12 +366,19 @@ llvm::computeMinimumValueSizes(ArrayRef<BasicBlock *> Blocks, DemandedBits &DB, // 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) + APInt NeededBits = DB.getDemandedBits(I); + unsigned BW = NeededBits.getBitWidth(); + if (BW > 64) return MapVector<Instruction *, uint64_t>(); - uint64_t V = DB.getDemandedBits(I).getZExtValue(); - DBits[Leader] |= V; - DBits[I] = V; + auto NSB = ComputeNumSignBits(I, DL); + + // Query demanded bits for the bits required by the instruction. Remove + // any bits that are equal to the sign bit, because we can truncate the + // instruction without changing their value. + NeededBits &= APInt::getLowBitsSet(BW, BW - NSB); + DBits[Leader] |= NeededBits.getZExtValue(); + DBits[I] |= NeededBits.getZExtValue(); // Casts, loads and instructions outside of our range terminate a chain // successfully. |
