[llvm] [InstCombine] Optimize x * !x to 0 for vector #84608 (PR #84792)

[Yingwei Zheng via llvm-commits]

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@@ -198,6 +198,20 @@ Instruction *InstCombinerImpl::visitMul(BinaryOperator &I) {
   if (SimplifyAssociativeOrCommutative(I))
     return &I;
 
+  // mul (sext X)), Y -> select X, -Y, 0
+  // mul Y, (sext X)) -> select X, -Y, 0
+  Value *SExtOp;
+  if (match(Op0, m_SExt(m_Value(SExtOp))) &&
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dtcxzyw wrote:

Please add the one-use check.


https://github.com/llvm/llvm-project/pull/84792