[llvm] [InstCombine] Fold (X * 0.0) * constant => X * 0.0 #85241 (PR #92512)

[Matt Arsenault via llvm-commits]

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@@ -905,6 +905,16 @@ Instruction *InstCombinerImpl::visitFMul(BinaryOperator &I) {
     }
   }
 
+  // (X * 0.0) * constant => X * 0.0
+  Constant *C1;
+  if (match(Op0, m_FMul(m_Value(X), m_Constant(C1))) &&
+      match(C1, m_AnyZeroFP()) && match(Op1, m_Constant(C))) {
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arsenm wrote:

It can't point at a specific constant in the non-splat case. You should be able to just match m_AnyZeroFP and cast<Constant>

https://github.com/llvm/llvm-project/pull/92512