[llvm] [InstCombine] Simplification for (-a * b) / (a * b). (PR #71768)

[Yingwei Zheng via llvm-commits]

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@@ -1230,6 +1230,10 @@ static Value *simplifySDivInst(Value *Op0, Value *Op1, bool IsExact,
   // If two operands are negated and no signed overflow, return -1.
   if (isKnownNegation(Op0, Op1, /*NeedNSW=*/true))
     return Constant::getAllOnesValue(Op0->getType());
+  Value *X, *Y;
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dtcxzyw wrote:

Clang failed to fold `(-a + b) / (a - b)` into `-1` due to the lack of `nsw` flag.
Alive2: https://alive2.llvm.org/ce/z/tPAt3K

You can create a separate patch to address this :)


https://github.com/llvm/llvm-project/pull/71768