[LV] Improve AnyOf reduction codegen. (#78304)

Update AnyOf reduction code generation to only keep track of the AnyOf
property in a boolean vector in the loop, only selecting either the new
or start value in the middle block.

The patch incorporates feedback from https://reviews.llvm.org/D153697.

This fixes the #62565, as now there aren't multiple uses of the
start/new values.

Fixes https://github.com/llvm/llvm-project/issues/62565

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

1 files changed, 6 insertions, 18 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
index 05b02a4..11b7665 100644
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -1034,15 +1034,6 @@ CmpInst::Predicate llvm::getMinMaxReductionPredicate(RecurKind RK) {
   }
 }
 
-Value *llvm::createAnyOfOp(IRBuilderBase &Builder, Value *StartVal,
-                           RecurKind RK, Value *Left, Value *Right) {
-  if (auto VTy = dyn_cast<VectorType>(Left->getType()))
-    StartVal = Builder.CreateVectorSplat(VTy->getElementCount(), StartVal);
-  Value *Cmp =
-      Builder.CreateCmp(CmpInst::ICMP_NE, Left, StartVal, "rdx.select.cmp");
-  return Builder.CreateSelect(Cmp, Left, Right, "rdx.select");
-}
-
 Value *llvm::createMinMaxOp(IRBuilderBase &Builder, RecurKind RK, Value *Left,
                             Value *Right) {
   Type *Ty = Left->getType();
@@ -1151,16 +1142,13 @@ 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);
+  return Builder.CreateSelect(AnyOf, NewVal, InitVal, "rdx.select");
 }
 
 Value *llvm::createSimpleTargetReduction(IRBuilderBase &Builder, Value *Src,