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

[Yingwei Zheng via llvm-commits]

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@@ -1432,6 +1432,36 @@ define <2 x i8> @sdiv_sdiv_mul_nsw(<2 x i8> %x, <2 x i8> %y, <2 x i8> %z) {
   ret <2 x i8> %r
 }
 
+; -(X * Y) / (X * Y) --> -1
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dtcxzyw wrote:

Please add some negative tests (e.g., `sub` w/o `nsw` flags)

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