diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstructionCombining.cpp | 40 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/narrow-switch.ll | 9 |
2 files changed, 20 insertions, 29 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index f96766db6df..0d29c1dceea 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -2232,6 +2232,20 @@ Instruction *InstCombiner::visitBranchInst(BranchInst &BI) { Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) { Value *Cond = SI.getCondition(); + Value *Op0; + ConstantInt *AddRHS; + if (match(Cond, m_Add(m_Value(Op0), m_ConstantInt(AddRHS)))) { + // Change 'switch (X+4) case 1:' into 'switch (X) case -3'. + for (SwitchInst::CaseIt CaseIter : SI.cases()) { + Constant *NewCase = ConstantExpr::getSub(CaseIter.getCaseValue(), AddRHS); + assert(isa<ConstantInt>(NewCase) && + "Result of expression should be constant"); + CaseIter.setValue(cast<ConstantInt>(NewCase)); + } + SI.setCondition(Op0); + return &SI; + } + unsigned BitWidth = cast<IntegerType>(Cond->getType())->getBitWidth(); APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); computeKnownBits(Cond, KnownZero, KnownOne, 0, &SI); @@ -2252,9 +2266,7 @@ Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) { // 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 && NewWidth < BitWidth) { - TruncCond = true; IntegerType *Ty = IntegerType::get(SI.getContext(), NewWidth); Builder->SetInsertPoint(&SI); Value *NewCond = Builder->CreateTrunc(Cond, Ty, "trunc"); @@ -2264,32 +2276,10 @@ Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) { APInt TruncatedCase = CaseIter.getCaseValue()->getValue().trunc(NewWidth); CaseIter.setValue(ConstantInt::get(SI.getContext(), TruncatedCase)); } - } - - Value *Op0 = nullptr; - ConstantInt *AddRHS = nullptr; - if (match(Cond, m_Add(m_Value(Op0), m_ConstantInt(AddRHS)))) { - // Change 'switch (X+4) case 1:' into 'switch (X) case -3'. - for (SwitchInst::CaseIt CaseIter : SI.cases()) { - ConstantInt *CaseVal = CaseIter.getCaseValue(); - Constant *LHS = CaseVal; - if (TruncCond) { - LHS = LeadingKnownZeros - ? ConstantExpr::getZExt(CaseVal, Cond->getType()) - : ConstantExpr::getSExt(CaseVal, Cond->getType()); - } - Constant *NewCaseVal = ConstantExpr::getSub(LHS, AddRHS); - assert(isa<ConstantInt>(NewCaseVal) && - "Result of expression should be constant"); - CaseIter.setValue(cast<ConstantInt>(NewCaseVal)); - } - SI.setCondition(Op0); - if (auto *CondI = dyn_cast<Instruction>(Cond)) - Worklist.Add(CondI); return &SI; } - return TruncCond ? &SI : nullptr; + return nullptr; } Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) { diff --git a/llvm/test/Transforms/InstCombine/narrow-switch.ll b/llvm/test/Transforms/InstCombine/narrow-switch.ll index e58b4956568..8f4c24b9deb 100644 --- a/llvm/test/Transforms/InstCombine/narrow-switch.ll +++ b/llvm/test/Transforms/InstCombine/narrow-switch.ll @@ -135,10 +135,11 @@ sw.default: define i8 @PR31260(i8 %x) { ; ALL-LABEL: @PR31260( ; ALL-NEXT: entry: -; ALL-NEXT: [[T4:%.*]] = and i8 %x, 2 -; ALL-NEXT: switch i8 [[T4]], label %exit [ -; ALL-NEXT: i8 -128, label %case126 -; ALL-NEXT: i8 -126, label %case124 +; ALL-NEXT: [[TMP0:%.*]] = trunc i8 %x to i2 +; ALL-NEXT: [[TRUNC:%.*]] = and i2 [[TMP0]], -2 +; ALL-NEXT: switch i2 [[TRUNC]], label %exit [ +; ALL-NEXT: i2 0, label %case126 +; ALL-NEXT: i2 -2, label %case124 ; ALL-NEXT: ] ; ALL: exit: ; ALL-NEXT: ret i8 1 |
