Instruction *visitFreeInst(FreeInst &FI);
Instruction *visitLoadInst(LoadInst &LI);
Instruction *visitBranchInst(BranchInst &BI);
+ Instruction *visitSwitchInst(SwitchInst &SI);
// visitInstruction - Specify what to return for unhandled instructions...
Instruction *visitInstruction(Instruction &I) { return 0; }
return 0;
}
+Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
+ Value *Cond = SI.getCondition();
+ 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'
+ 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));
+ WorkList.push_back(I);
+ return &SI;
+ }
+ }
+ return 0;
+}
+
void InstCombiner::removeFromWorkList(Instruction *I) {
WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),