[clang] fix-pruned-edges (PR #150670)

[Utkarsh Saxena via cfe-commits]

https://github.com/usx95 created https://github.com/llvm/llvm-project/pull/150670

None

>From e0d060af9a0a85424c6ea776465efeeddf5d213b Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Fri, 25 Jul 2025 18:11:45 +0000
Subject: [PATCH] fix-pruned-edges

---
 clang/lib/Analysis/LifetimeSafety.cpp         |  2 ++
 .../unittests/Analysis/LifetimeSafetyTest.cpp | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/clang/lib/Analysis/LifetimeSafety.cpp b/clang/lib/Analysis/LifetimeSafety.cpp
index 94b8197bbf6f3..f39998cca56fe 100644
--- a/clang/lib/Analysis/LifetimeSafety.cpp
+++ b/clang/lib/Analysis/LifetimeSafety.cpp
@@ -603,6 +603,8 @@ class DataflowAnalysis {
       OutStates[B] = StateOut;
       Visited.set(B->getBlockID());
       for (const CFGBlock *AdjacentB : isForward() ? B->succs() : B->preds()) {
+        if (!AdjacentB)
+          continue;
         Lattice OldInState = getInState(AdjacentB);
         Lattice NewInState = D.join(OldInState, StateOut);
         // Enqueue the adjacent block if its in-state has changed or if we have
diff --git a/clang/unittests/Analysis/LifetimeSafetyTest.cpp b/clang/unittests/Analysis/LifetimeSafetyTest.cpp
index a48dc45e4f806..7cd679e184f6c 100644
--- a/clang/unittests/Analysis/LifetimeSafetyTest.cpp
+++ b/clang/unittests/Analysis/LifetimeSafetyTest.cpp
@@ -512,6 +512,25 @@ TEST_F(LifetimeAnalysisTest, PointersAndExpirationInACycle) {
   EXPECT_THAT(LoansTo({"temp"}), AreExpiredAt("after_loop"));
 }
 
+TEST_F(LifetimeAnalysisTest, InfiniteLoopPrunesEdges) {
+  SetupTest(R"(
+    void target(MyObj out) {
+      MyObj *p = &out;
+      POINT(before_loop);
+
+      for (;;) {
+        POINT(begin);
+        MyObj in;
+        p = ∈
+        POINT(end);
+      }
+    }
+  )");
+  EXPECT_THAT(Origin("p"), HasLoansTo({"out"}, "before_loop"));
+  EXPECT_THAT(Origin("p"), HasLoansTo({"in", "out"}, "begin"));
+  EXPECT_THAT(Origin("p"), HasLoansTo({"in"}, "end"));
+}
+
 TEST_F(LifetimeAnalysisTest, NestedScopes) {
   SetupTest(R"(
     void target() {