[analyzer] Sort path diagnostics with array_pod_sort.

They're expensive to compare and we won't sort many of them so std::sort
doesn't give any benefits and causes code bloat. Func fact: clang -O3 didn't
even bother to inline libc++'s std::sort here.

While there validate the predicate a bit harder, the sort is unstable and we
don't want to introduce any non-determinism. I had to spell out the function
pointer type because GCC 4.7 still fails to convert the lambda to a function
pointer :(

No intended functionality change.

llvm-svn: 232263

diff --git a/clang/lib/StaticAnalyzer/Core/PathDiagnostic.cpp b/clang/lib/StaticAnalyzer/Core/PathDiagnostic.cpp
index b971fff..e2102fb 100644 (file)
--- a/clang/lib/StaticAnalyzer/Core/PathDiagnostic.cpp
+++ b/clang/lib/StaticAnalyzer/Core/PathDiagnostic.cpp
@@ -432,11 +432,15 @@ void PathDiagnosticConsumer::FlushDiagnostics(
 
   // Sort the diagnostics so that they are always emitted in a deterministic
   // order.
-  if (!BatchDiags.empty())
-    std::sort(BatchDiags.begin(), BatchDiags.end(),
-              [](const PathDiagnostic *X, const PathDiagnostic *Y) {
-      return X != Y && compare(*X, *Y);
-    });
+  int (*Comp)(const PathDiagnostic *const *, const PathDiagnostic *const *) =
+      [](const PathDiagnostic *const *X, const PathDiagnostic *const *Y) {
+        assert(*X != *Y && "PathDiagnostics not uniqued!");
+        if (compare(**X, **Y))
+          return -1;
+        assert(compare(**Y, **X) && "Not a total order!");
+        return 1;
+      };
+  array_pod_sort(BatchDiags.begin(), BatchDiags.end(), Comp);
 
   FlushDiagnosticsImpl(BatchDiags, Files);