[clang][bytecode] Add assert to ensure correct state restoration in CallBI function

[smanna12]

This commit adds an assert statement to the CallBI function to ensure that the interpreter state (S.Current) is correctly reset to the previous frame (FrameBefore) after InterpretBuiltin returns true. This helps catch any potential issues during development and debugging.

[llvmbot]

@llvm/pr-subscribers-clang

Author: None (smanna12)

Changes

This commit addresses two static analyzer issues in the CallBI function:

Resource Leak: Ensures that the NewFrame object is properly managed by releasing ownership when InterpretBuiltin returns true, preventing a resource leak.

Use-After-Free: Ensures that S.Current is correctly reset to the previous frame (FrameBefore) after InterpretBuiltin returns true, preventing a use-after-free error.

The changes ensure that the NewFrame object is not prematurely deleted and that the interpreter state is correctly restored in case of failure.

---

Full diff: https://github.com/llvm/llvm-project/pull/115496.diff

1 Files Affected:

• (modified) clang/lib/AST/ByteCode/Interp.cpp (+7-1)

diff --git a/clang/lib/AST/ByteCode/Interp.cpp b/clang/lib/AST/ByteCode/Interp.cpp
index 0e571624ae18d1..dd1236b6d6115d 100644
--- a/clang/lib/AST/ByteCode/Interp.cpp
+++ b/clang/lib/AST/ByteCode/Interp.cpp
@@ -1374,9 +1374,15 @@ bool CallBI(InterpState &S, CodePtr OpPC, const Function *Func,
   S.Current = NewFrame.get();
 
   if (InterpretBuiltin(S, OpPC, Func, CE, BuiltinID)) {
-    NewFrame.release();
+    // Release ownership of NewFrame to prevent it from being deleted.
+    NewFrame.release(); // Frame was deleted already.
+    // Ensure that S.Current is correctly reset to the previous frame.
+    assert(S.Current == FrameBefore);
     return true;
   }
+
+  // Interpreting the function failed somehow. Reset to
+  // previous state.
   S.Current = FrameBefore;
   return false;
 }

[tbaederr]

Please reword the title of the PR. It sounds like this commit is actually fixing anything but it just silences the static analyzer.

[smanna12]

Please reword the title of the PR. It sounds like this commit is actually fixing anything but it just silences the static analyzer.

Thanks @tbaederr for reviews! I have updated title and commit message.

[smanna12]

Thank you @tbaederr for reviews!