[llvm] [mlir] [clang-tools-extra] [libcxx] [clang] [flang] [LV] Improve AnyOf reduction codegen. (PR #78304)

[via cfe-commits]

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@@ -1079,16 +1070,13 @@ Value *llvm::createAnyOfTargetReduction(IRBuilderBase &Builder, Value *Src,
     NewVal = SI->getTrueValue();
   }
 
-  // Create a splat vector with the new value and compare this to the vector
-  // we want to reduce.
-  ElementCount EC = cast<VectorType>(Src->getType())->getElementCount();
-  Value *Right = Builder.CreateVectorSplat(EC, InitVal);
-  Value *Cmp =
-      Builder.CreateCmp(CmpInst::ICMP_NE, Src, Right, "rdx.select.cmp");
-
   // If any predicate is true it means that we want to select the new value.
-  Cmp = Builder.CreateOrReduce(Cmp);
-  return Builder.CreateSelect(Cmp, NewVal, InitVal, "rdx.select");
+  Value *AnyOf =
+      Src->getType()->isVectorTy() ? Builder.CreateOrReduce(Src) : Src;
+  // The compares in the loop may yield poison, which propagates through the
+  // bitwise ORs. Freeze it here before the condition is used.
+  AnyOf = Builder.CreateFreeze(AnyOf);
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ayalz wrote:

Further refactoring thought: the AnyOf boolean reduction completes with the CreateOrReduce(), and freezing it. Similar to a plain "result |= value[i]" OR reduction, on i1 values, where freezing may also be needed? The subsequent select deserves a separate recipe, which post-processes the result of the AnyOf reduction and also depends on the "IfAny" and "Else" (or "Start" and "Other") Live-In VP/Values directly, rather than looking for them here and now.

https://github.com/llvm/llvm-project/pull/78304