[llvm] [LoopUnroll] Skip called function in constant-op reduction filter (PR #200868)

[Florian Hahn via llvm-commits]

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@@ -1727,10 +1727,16 @@ llvm::canParallelizeReductionWhenUnrolling(PHINode &Phi, Loop *L,
     return std::nullopt;
 
   // Don't unroll reductions with constant ops; those can be folded to a
-  // single induction update.
-  if (any_of(cast<Instruction>(Phi.getIncomingValueForBlock(L->getLoopLatch()))
-                 ->operands(),
-             IsaPred<Constant>))
+  // single induction update. For calls (e.g. fmuladd or min/max
+  // intrinsics), the called function is itself a Constant operand and is
+  // not a reduction operand, so restrict the check to the argument list.
+  Instruction *LatchInst =
+      cast<Instruction>(Phi.getIncomingValueForBlock(L->getLoopLatch()));
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fhahn wrote:

can re-use LatchInst below?

https://github.com/llvm/llvm-project/pull/200868