if a 'with overflow' intrinsic just has the normal result used, simplify
it to a normal binop. Patch by Alastair Lynn, testcase by me.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86524 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 6e9324f..52b9b04 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -12452,6 +12452,47 @@
return ExtractValueInst::Create(IV->getInsertedValueOperand(),
exti, exte);
}
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Agg)) {
+ // We're extracting from an intrinsic, see if we're the only user, which
+ // allows us to simplify multiple result intrinsics to simpler things that
+ // just get one value..
+ if (II->hasOneUse()) {
+ // Check if we're grabbing the overflow bit or the result of a 'with
+ // overflow' intrinsic. If it's the latter we can remove the intrinsic
+ // and replace it with a traditional binary instruction.
+ switch (II->getIntrinsicID()) {
+ case Intrinsic::uadd_with_overflow:
+ case Intrinsic::sadd_with_overflow:
+ if (*EV.idx_begin() == 0) { // Normal result.
+ Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
+ II->replaceAllUsesWith(UndefValue::get(II->getType()));
+ EraseInstFromFunction(*II);
+ return BinaryOperator::CreateAdd(LHS, RHS);
+ }
+ break;
+ case Intrinsic::usub_with_overflow:
+ case Intrinsic::ssub_with_overflow:
+ if (*EV.idx_begin() == 0) { // Normal result.
+ Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
+ II->replaceAllUsesWith(UndefValue::get(II->getType()));
+ EraseInstFromFunction(*II);
+ return BinaryOperator::CreateSub(LHS, RHS);
+ }
+ break;
+ case Intrinsic::umul_with_overflow:
+ case Intrinsic::smul_with_overflow:
+ if (*EV.idx_begin() == 0) { // Normal result.
+ Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
+ II->replaceAllUsesWith(UndefValue::get(II->getType()));
+ EraseInstFromFunction(*II);
+ return BinaryOperator::CreateMul(LHS, RHS);
+ }
+ break;
+ default:
+ break;
+ }
+ }
+ }
// Can't simplify extracts from other values. Note that nested extracts are
// already simplified implicitely by the above (extract ( extract (insert) )
// will be translated into extract ( insert ( extract ) ) first and then just