diff options
Diffstat (limited to 'llvm/lib/Transforms/InstCombine/InstructionCombining.cpp')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstructionCombining.cpp | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index c25199d..c0fb365 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -2185,17 +2185,15 @@ Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) { unsigned NewWidth = BitWidth - std::max(LeadingKnownZeros, LeadingKnownOnes); - // Truncate the condition operand if the new type is equal to or larger than - // the largest legal integer type. We need to be conservative here since - // x86 generates redundant zero-extension instructions if the operand is - // truncated to i8 or i16. + // Shrink the condition operand if the new type is smaller than the old type. + // This may produce a non-standard type for the switch, but that's ok because + // the backend should extend back to a legal type for the target. bool TruncCond = false; - if (NewWidth > 0 && BitWidth > NewWidth && - NewWidth >= DL.getLargestLegalIntTypeSizeInBits()) { + if (NewWidth > 0 && NewWidth < BitWidth) { TruncCond = true; IntegerType *Ty = IntegerType::get(SI.getContext(), NewWidth); Builder->SetInsertPoint(&SI); - Value *NewCond = Builder->CreateTrunc(SI.getCondition(), Ty, "trunc"); + Value *NewCond = Builder->CreateTrunc(Cond, Ty, "trunc"); SI.setCondition(NewCond); for (auto &C : SI.cases()) |