Clean up uses of switch instructions so they are not dependent on the operand ordering. Patch by Stepan Dyatkovskiy.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140803 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index f64990f..af2a5d2 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1237,11 +1237,17 @@
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'
- for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
- SI.setOperand(i,
- ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
- AddRHS));
- SI.setOperand(0, I->getOperand(0));
+ unsigned NumCases = SI.getNumCases();
+ // Skip the first item since that's the default case.
+ for (unsigned i = 1; i < NumCases; ++i) {
+ ConstantInt* CaseVal = SI.getCaseValue(i);
+ Constant* NewCaseVal = ConstantExpr::getSub(cast<Constant>(CaseVal),
+ AddRHS);
+ assert(isa<ConstantInt>(NewCaseVal) &&
+ "Result of expression should be constant");
+ SI.setSuccessorValue(i, cast<ConstantInt>(NewCaseVal));
+ }
+ SI.setCondition(I->getOperand(0));
Worklist.Add(I);
return &SI;
}