[clang] Add time trace scopes to addToCallGraph & getCFG (PR #174717)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-analysis

Author: Kashika Akhouri (kashika0112)

<details>
<summary>Changes</summary>

his PR adds performance instrumentation to `clang::CallGraph` and `clang::AnalysisDeclContext` to aid in benchmarking the overhead of call graph construction and CFG rebuilding.

Changes
- `clang/include/clang/Analysis/CallGraph.h`: Added a TimeTraceScope labeled `AddToCallGraph` to instrument the discovery of function nodes and call edges across the Translation Unit.
- `clang/lib/Analysis/AnalysisDeclContext.cpp`: Added a TimeTraceScope labeled `BuildCFG` inside `getCFG()`. The scope is placed within the `!builtCFG` block to measure the actual construction time.

This aims to facilitate benchmarking on large codebases like LLVM to ensure that the performance impact of new analysis-based warnings remains within acceptable regressions.

---
Full diff: https://github.com/llvm/llvm-project/pull/174717.diff


2 Files Affected:

- (modified) clang/include/clang/Analysis/CallGraph.h (+2) 
- (modified) clang/lib/Analysis/AnalysisDeclContext.cpp (+2) 


``````````diff
diff --git a/clang/include/clang/Analysis/CallGraph.h b/clang/include/clang/Analysis/CallGraph.h
index c11d163f8fe20..f1c0d7a88643a 100644
--- a/clang/include/clang/Analysis/CallGraph.h
+++ b/clang/include/clang/Analysis/CallGraph.h
@@ -26,6 +26,7 @@
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/iterator_range.h"
+#include "llvm/Support/TimeProfiler.h"
 #include <memory>
 
 namespace clang {
@@ -61,6 +62,7 @@ class CallGraph : public DynamicRecursiveASTVisitor {
   ///
   /// Recursively walks the declaration to find all the dependent Decls as well.
   void addToCallGraph(Decl *D) {
+    llvm::TimeTraceScope TimeProfile("AddToCallGraph");
     TraverseDecl(D);
   }
 
diff --git a/clang/lib/Analysis/AnalysisDeclContext.cpp b/clang/lib/Analysis/AnalysisDeclContext.cpp
index 6f153e7e65255..2985a6e57dc18 100644
--- a/clang/lib/Analysis/AnalysisDeclContext.cpp
+++ b/clang/lib/Analysis/AnalysisDeclContext.cpp
@@ -42,6 +42,7 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/SaveAndRestore.h"
+#include "llvm/Support/TimeProfiler.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
 #include <memory>
@@ -218,6 +219,7 @@ CFG *AnalysisDeclContext::getCFG() {
     return getUnoptimizedCFG();
 
   if (!builtCFG) {
+    llvm::TimeTraceScope TimeProfile("BuildCFG");
     cfg = CFG::buildCFG(D, getBody(), &D->getASTContext(), cfgBuildOptions);
     // Even when the cfg is not successfully built, we don't
     // want to try building it again.

``````````

</details>


https://github.com/llvm/llvm-project/pull/174717