[llvm] 8befd05 - [Attributor][FIX] Track change status for AAIsDead properly

[Johannes Doerfert via llvm-commits]

Author: Johannes Doerfert
Date: 2021-07-26T21:21:59-05:00
New Revision: 8befd05aad9f425937182ac137d3509ddd4d47b3

URL: https://github.com/llvm/llvm-project/commit/8befd05aad9f425937182ac137d3509ddd4d47b3
DIFF: https://github.com/llvm/llvm-project/commit/8befd05aad9f425937182ac137d3509ddd4d47b3.diff

LOG: [Attributor][FIX] Track change status for AAIsDead properly

If we add a new live edge we need to indicate a change or otherwise the
new live block is not shown to users. Similarly, new known dead ends and
a changed `ToBeExploredFrom` set need to cause us to return CHANGED.

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
index d1605ab7b93f..309c692d454d 100644
--- a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -3836,10 +3836,8 @@ ChangeStatus AAIsDeadFunction::updateImpl(Attributor &A) {
 
     // Fast forward for uninteresting instructions. We could look for UB here
     // though.
-    while (!I->isTerminator() && !isa<CallBase>(I)) {
-      Change = ChangeStatus::CHANGED;
+    while (!I->isTerminator() && !isa<CallBase>(I))
       I = I->getNextNode();
-    }
 
     AliveSuccessors.clear();
 
@@ -3872,11 +3870,11 @@ ChangeStatus AAIsDeadFunction::updateImpl(Attributor &A) {
 
     if (UsedAssumedInformation) {
       NewToBeExploredFrom.insert(I);
-    } else {
-      Change = ChangeStatus::CHANGED;
-      if (AliveSuccessors.empty() ||
-          (I->isTerminator() && AliveSuccessors.size() < I->getNumSuccessors()))
-        KnownDeadEnds.insert(I);
+    } else if (AliveSuccessors.empty() ||
+               (I->isTerminator() &&
+                AliveSuccessors.size() < I->getNumSuccessors())) {
+      if (KnownDeadEnds.insert(I))
+        Change = ChangeStatus::CHANGED;
     }
 
     LLVM_DEBUG(dbgs() << "[AAIsDead] #AliveSuccessors: "
@@ -3890,15 +3888,23 @@ ChangeStatus AAIsDeadFunction::updateImpl(Attributor &A) {
         Worklist.push_back(AliveSuccessor);
       } else {
         // record the assumed live edge
-        AssumedLiveEdges.insert(
-            std::make_pair(I->getParent(), AliveSuccessor->getParent()));
+        auto Edge = std::make_pair(I->getParent(), AliveSuccessor->getParent());
+        if (AssumedLiveEdges.insert(Edge).second)
+          Change = ChangeStatus::CHANGED;
         if (assumeLive(A, *AliveSuccessor->getParent()))
           Worklist.push_back(AliveSuccessor);
       }
     }
   }
 
-  ToBeExploredFrom = std::move(NewToBeExploredFrom);
+  // Check if the content of ToBeExploredFrom changed, ignore the order.
+  if (NewToBeExploredFrom.size() != ToBeExploredFrom.size() ||
+      llvm::any_of(NewToBeExploredFrom, [&](const Instruction *I) {
+        return !ToBeExploredFrom.count(I);
+      })) {
+    Change = ChangeStatus::CHANGED;
+    ToBeExploredFrom = std::move(NewToBeExploredFrom);
+  }
 
   // If we know everything is live there is no need to query for liveness.
   // Instead, indicating a pessimistic fixpoint will cause the state to be