[PATCH] D86565: [Attributor][FIX] Do not deduce noundef for dead positions

[Shinji Okumura via Phabricator via llvm-commits]

okura created this revision.
Herald added subscribers: llvm-commits, kuter, uenoku, hiraditya.
Herald added a reviewer: uenoku.
Herald added a reviewer: jdoerfert.
Herald added a reviewer: homerdin.
Herald added a project: LLVM.
okura requested review of this revision.
Herald added a reviewer: sstefan1.
Herald added a reviewer: baziotis.
Herald added a subscriber: bbn.

https://reviews.llvm.org/D86565

Files:
  llvm/lib/Transforms/IPO/AttributorAttributes.cpp


Index: llvm/lib/Transforms/IPO/AttributorAttributes.cpp
===================================================================
--- llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -7743,6 +7743,16 @@
   const std::string getAsStr() const override {
     return getAssumed() ? "noundef" : "may-undef-or-poison";
   }
+
+  ChangeStatus manifest(Attributor &A) override {
+    // We don't manifest noundef attribute for dead positions because the
+    // associated values with dead positions would be replaced with undef
+    // values.
+    if (A.isAssumedDead(getIRPosition(), nullptr, nullptr,
+                        /* CheckBBLivenessOnly */ true))
+      return ChangeStatus::UNCHANGED;
+    return AANoUndef::manifest(A);
+  }
 };
 
 struct AANoUndefFloating : public AANoUndefImpl {


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