diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstructionCombining.cpp | 41 |
1 files changed, 20 insertions, 21 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index cc3d168677d..7a5964519a7 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -2213,28 +2213,27 @@ Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) { SI.getContext(), C.getCaseValue()->getValue().trunc(NewWidth))); } - if (Instruction *I = dyn_cast<Instruction>(Cond)) { - if (I->getOpcode() == Instruction::Add) - if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) { - // change 'switch (X+4) case 1:' into 'switch (X) case -3' - // Skip the first item since that's the default case. - for (SwitchInst::CaseIt i = SI.case_begin(), e = SI.case_end(); - i != e; ++i) { - ConstantInt* CaseVal = i.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"); - i.setValue(cast<ConstantInt>(NewCaseVal)); - } - SI.setCondition(I->getOperand(0)); - Worklist.Add(I); - return &SI; + ConstantInt *AddRHS = nullptr; + if (match(Cond, m_Add(m_Value(), m_ConstantInt(AddRHS)))) { + Instruction *I = cast<Instruction>(Cond); + // Change 'switch (X+4) case 1:' into 'switch (X) case -3'. + for (SwitchInst::CaseIt i = SI.case_begin(), e = SI.case_end(); i != e; + ++i) { + ConstantInt *CaseVal = i.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"); + i.setValue(cast<ConstantInt>(NewCaseVal)); + } + SI.setCondition(I->getOperand(0)); + Worklist.Add(I); + return &SI; } return TruncCond ? &SI : nullptr; |
