[clang] [LifetimeSafety] Avoid adding already present items in sets/maps (PR #159582)

[Utkarsh Saxena via cfe-commits]

https://github.com/usx95 updated https://github.com/llvm/llvm-project/pull/159582

>From 215d59c655c6117dc5774dfb8163156aad152044 Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Thu, 18 Sep 2025 12:52:29 +0000
Subject: [PATCH] [LifetimeSafety] Avoid adding already present items in
 sets/maps

---
 clang/lib/Analysis/LifetimeSafety.cpp           | 12 ++++++++----
 clang/test/Analysis/LifetimeSafety/benchmark.py | 11 ++++++-----
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/clang/lib/Analysis/LifetimeSafety.cpp b/clang/lib/Analysis/LifetimeSafety.cpp
index 0dd5716d93fb6..d016c6f12e82e 100644
--- a/clang/lib/Analysis/LifetimeSafety.cpp
+++ b/clang/lib/Analysis/LifetimeSafety.cpp
@@ -910,10 +910,13 @@ template <typename T>
 static llvm::ImmutableSet<T> join(llvm::ImmutableSet<T> A,
                                   llvm::ImmutableSet<T> B,
                                   typename llvm::ImmutableSet<T>::Factory &F) {
+  if (A == B)
+    return A;
   if (A.getHeight() < B.getHeight())
     std::swap(A, B);
   for (const T &E : B)
-    A = F.add(A, E);
+    if (!A.contains(E))
+      A = F.add(A, E);
   return A;
 }
 
@@ -947,10 +950,11 @@ join(llvm::ImmutableMap<K, V> A, llvm::ImmutableMap<K, V> B,
   for (const auto &Entry : B) {
     const K &Key = Entry.first;
     const V &ValB = Entry.second;
-    if (const V *ValA = A.lookup(Key))
-      A = F.add(A, Key, JoinValues(*ValA, ValB));
-    else
+    const V *ValA = A.lookup(Key);
+    if (!ValA)
       A = F.add(A, Key, ValB);
+    else if (*ValA != ValB)
+      A = F.add(A, Key, JoinValues(*ValA, ValB));
   }
   return A;
 }
diff --git a/clang/test/Analysis/LifetimeSafety/benchmark.py b/clang/test/Analysis/LifetimeSafety/benchmark.py
index 4421fe9a81e21..2373f9984eecd 100644
--- a/clang/test/Analysis/LifetimeSafety/benchmark.py
+++ b/clang/test/Analysis/LifetimeSafety/benchmark.py
@@ -252,7 +252,7 @@ def generate_markdown_report(results: dict) -> str:
             report.append(" ".join(row))
 
         report.append("\n**Complexity Analysis:**\n")
-        report.append("| Analysis Phase    | Complexity O(n<sup>k</sup>) |")
+        report.append("| Analysis Phase    | Complexity O(n<sup>k</sup>) | ")
         report.append("|:------------------|:--------------------------|")
 
         analysis_phases = {
@@ -302,7 +302,7 @@ def run_single_test(
         source_file,
     ]
 
-    result = subprocess.run(clang_command, capture_output=True, text=True)
+    result = subprocess.run(clang_command, capture_output=True, text=True, timeout=60)
 
     if result.returncode != 0:
         print(f"Compilation failed for N={n}!", file=sys.stderr)
@@ -334,24 +334,25 @@ def run_single_test(
     os.makedirs(args.output_dir, exist_ok=True)
     print(f"Benchmark files will be saved in: {os.path.abspath(args.output_dir)}\n")
 
+    # Maximize 'n' values while keeping execution time under 10s.
     test_configurations = [
         {
             "name": "cycle",
             "title": "Pointer Cycle in Loop",
             "generator_func": generate_cpp_cycle_test,
-            "n_values": [10, 25, 50, 75, 100, 150],
+            "n_values": [25, 50, 75, 100],
         },
         {
             "name": "merge",
             "title": "CFG Merges",
             "generator_func": generate_cpp_merge_test,
-            "n_values": [10, 50, 100, 200, 400, 800],
+            "n_values": [400, 1000, 2000, 5000],
         },
         {
             "name": "nested_loops",
             "title": "Deeply Nested Loops",
             "generator_func": generate_cpp_nested_loop_test,
-            "n_values": [10, 50, 100, 200, 400, 800],
+            "n_values": [50, 100, 150, 200],
         },
     ]