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[LifetimeSafety] Avoid adding already present items in sets/maps #159582

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Merged
merged 1 commit into from
Sep 19, 2025
+14 −9
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[LifetimeSafety] Avoid adding already present items in sets/maps #159582

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12 changes: 8 additions & 4 deletions clang/lib/Analysis/LifetimeSafety.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
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would the add() on line 918 also possibly do more allocation than desired (and cost more than checking if contains first), if E was already in A ?

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Added this check as well.

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;
}

Expand Down Expand Up @@ -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;
}
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11 changes: 6 additions & 5 deletions clang/test/Analysis/LifetimeSafety/benchmark.py
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Original file line number Diff line number Diff line change
Expand Up @@ -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 = {
Expand Down Expand Up @@ -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)
Expand Down Expand Up @@ -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],
},
]

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