[PATCH] D59471: [InstCombine] Fold add nuw + uadd.with.overflow

[Sanjay Patel via Phabricator via llvm-commits]

spatel accepted this revision.
spatel added a comment.

Logic looks fine, so I won't hold it up, but seems better to not duplicate code for sibling transforms?

  diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
  index 49524d7f42e..9de4e60c1b9 100644
  --- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
  +++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
  @@ -2046,6 +2046,7 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
         return &CI;
       break;
     }
  +  case Intrinsic::uadd_with_overflow:
     case Intrinsic::sadd_with_overflow: {
       if (Instruction *I = canonicalizeConstantArg0ToArg1(CI))
         return I;
  @@ -2053,25 +2054,28 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
         return I;
   
       // Given 2 constant operands whose sum does not overflow:
  +    // uaddo (X +nuw C0), C1 -> uaddo X, C0 + C1
       // saddo (X +nsw C0), C1 -> saddo X, C0 + C1
  +    bool IsUnsigned = II->getIntrinsicID() == Intrinsic::uadd_with_overflow;
       Value *X;
       const APInt *C0, *C1;
       Value *Arg0 = II->getArgOperand(0);
       Value *Arg1 = II->getArgOperand(1);
  -    if (match(Arg0, m_NSWAdd(m_Value(X), m_APInt(C0))) &&
  -        match(Arg1, m_APInt(C1))) {
  +    bool HasAdd = IsUnsigned ? match(Arg0, m_NUWAdd(m_Value(X), m_APInt(C0)))
  +                             : match(Arg0, m_NSWAdd(m_Value(X), m_APInt(C0)));
  +    if (HasAdd && match(Arg1, m_APInt(C1))) {
         bool Overflow;
  -      APInt NewC = C1->sadd_ov(*C0, Overflow);
  +      APInt NewC = IsUnsigned ? C1->uadd_ov(*C0, Overflow)
  +                              : C1->sadd_ov(*C0, Overflow);
         if (!Overflow)
           return replaceInstUsesWith(
               *II, Builder.CreateBinaryIntrinsic(
  -                     Intrinsic::sadd_with_overflow, X,
  +                     II->getIntrinsicID(), X,
                        ConstantInt::get(Arg1->getType(), NewC)));
       }
   
       break;
     }
  -  case Intrinsic::uadd_with_overflow:
     case Intrinsic::umul_with_overflow:
     case Intrinsic::smul_with_overflow:
       if (Instruction *I = canonicalizeConstantArg0ToArg1(CI))


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  https://reviews.llvm.org/D59471/new/

https://reviews.llvm.org/D59471