//
Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
AddUsersToWorkList(I); // Add all modified instrs to worklist
- I.replaceAllUsesWith(V);
- return &I;
+ if (&I != V) {
+ I.replaceAllUsesWith(V);
+ return &I;
+ } else {
+ // If we are replacing the instruction with itself, this must be in a
+ // segment of unreachable code, so just clobber the instruction.
+ I.replaceAllUsesWith(Constant::getNullValue(I.getType()));
+ return &I;
+ }
}
// EraseInstFromFunction - When dealing with an instruction that has side
// Make what used to be the LHS of the root be the user of the root...
Value *ExtraOperand = TmpLHSI->getOperand(1);
- Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
+ if (&Root != TmpLHSI)
+ Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
+ else {
+ Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
+ return 0;
+ }
TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
BB->getInstList().remove(&Root); // Remove root from the BB
BB->getInstList().insert(TmpLHSI, &Root); // Insert root before TmpLHSI