[PATCH] D112389: [SCEV] Move SCEVLostPoisonFlags() check into SCEVExpander

[Nikita Popov via Phabricator via llvm-commits]

nikic updated this revision to Diff 381969.
nikic added a comment.

Rebase


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D112389/new/

https://reviews.llvm.org/D112389

Files:
  llvm/lib/Analysis/ScalarEvolution.cpp
  llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp


Index: llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
===================================================================
--- llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -1835,6 +1835,22 @@
   return V;
 }
 
+/// Check whether value has nuw/nsw/exact set but SCEV does not.
+/// TODO: In reality it is better to check the poison recursively
+/// but this is better than nothing.
+static bool SCEVLostPoisonFlags(const SCEV *S, const Instruction *I) {
+  if (isa<OverflowingBinaryOperator>(I)) {
+    if (auto *NS = dyn_cast<SCEVNAryExpr>(S)) {
+      if (I->hasNoSignedWrap() && !NS->hasNoSignedWrap())
+        return true;
+      if (I->hasNoUnsignedWrap() && !NS->hasNoUnsignedWrap())
+        return true;
+    }
+  } else if (isa<PossiblyExactOperator>(I) && I->isExact())
+    return true;
+  return false;
+}
+
 ScalarEvolution::ValueOffsetPair
 SCEVExpander::FindValueInExprValueMap(const SCEV *S,
                                       const Instruction *InsertPt) {
@@ -1858,7 +1874,8 @@
         if (S->getType() == V->getType() &&
             SE.DT.dominates(EntInst, InsertPt) &&
             (SE.LI.getLoopFor(EntInst->getParent()) == nullptr ||
-             SE.LI.getLoopFor(EntInst->getParent())->contains(InsertPt)))
+             SE.LI.getLoopFor(EntInst->getParent())->contains(InsertPt)) &&
+            !SCEVLostPoisonFlags(S, EntInst))
           return {V, Offset};
       }
     }
Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -4077,24 +4077,6 @@
   }
 }
 
-/// Check whether value has nuw/nsw/exact set but SCEV does not.
-/// TODO: In reality it is better to check the poison recursively
-/// but this is better than nothing.
-static bool SCEVLostPoisonFlags(const SCEV *S, const Value *V) {
-  if (auto *I = dyn_cast<Instruction>(V)) {
-    if (isa<OverflowingBinaryOperator>(I)) {
-      if (auto *NS = dyn_cast<SCEVNAryExpr>(S)) {
-        if (I->hasNoSignedWrap() && !NS->hasNoSignedWrap())
-          return true;
-        if (I->hasNoUnsignedWrap() && !NS->hasNoUnsignedWrap())
-          return true;
-      }
-    } else if (isa<PossiblyExactOperator>(I) && I->isExact())
-      return true;
-  }
-  return false;
-}
-
 /// Return an existing SCEV if it exists, otherwise analyze the expression and
 /// create a new one.
 const SCEV *ScalarEvolution::getSCEV(Value *V) {
@@ -4108,7 +4090,7 @@
     // ValueExprMap before insert S->{V, 0} into ExprValueMap.
     std::pair<ValueExprMapType::iterator, bool> Pair =
         ValueExprMap.insert({SCEVCallbackVH(V, this), S});
-    if (Pair.second && !SCEVLostPoisonFlags(S, V)) {
+    if (Pair.second) {
       ExprValueMap[S].insert({V, nullptr});
 
       // If S == Stripped + Offset, add Stripped -> {V, Offset} into


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