[PATCH] D137027: [llvm] Improve performance of programUndefinedIfUndefOrPoison

[Geza Lore via Phabricator via llvm-commits]

gezalore updated this revision to Diff 471792.
gezalore edited the summary of this revision.
gezalore added a comment.

Simplify according to feedback


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D137027/new/

https://reviews.llvm.org/D137027

Files:
  llvm/lib/Analysis/ValueTracking.cpp


Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -5729,11 +5729,6 @@
   SmallSet<const BasicBlock *, 4> Visited;
 
   YieldsPoison.insert(V);
-  auto Propagate = [&](const User *User) {
-    if (propagatesPoison(cast<Operator>(User)))
-      YieldsPoison.insert(User);
-  };
-  for_each(V->users(), Propagate);
   Visited.insert(BB);
 
   while (true) {
@@ -5747,9 +5742,16 @@
       if (!isGuaranteedToTransferExecutionToSuccessor(&I))
         return false;
 
-      // Mark poison that propagates from I through uses of I.
-      if (YieldsPoison.count(&I))
-        for_each(I.users(), Propagate);
+      // If this instruction propagates poison, mark it as poison if any of
+      // its operands are poison
+      if (propagatesPoison(cast<Operator>(&I))) {
+        for (const Use &U : I.operands()) {
+          if (YieldsPoison.count(U.get())) {
+            YieldsPoison.insert(&I);
+            break;
+          }
+        }
+      }
     }
 
     BB = BB->getSingleSuccessor();


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