1 files changed, 70 insertions, 0 deletions
diff --git a/clang/lib/CodeGen/VarBypassDetector.h b/clang/lib/CodeGen/VarBypassDetector.h
new file mode 100644
index 00000000000..f50baf4bab9
--- /dev/null
+++ b/clang/lib/CodeGen/VarBypassDetector.h
@@ -0,0 +1,70 @@
+//===--- VarBypassDetector.cpp - Bypass jumps detector ------------*- C++ -*-=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains VarBypassDetector class, which is used to detect
+// local variable declarations which can be bypassed by jumps.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_CODEGEN_VARBYPASSDETECTOR_H
+#define LLVM_CLANG_LIB_CODEGEN_VARBYPASSDETECTOR_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/SmallVector.h"
+
+namespace clang {
+
+class Decl;
+class Stmt;
+class VarDecl;
+
+namespace CodeGen {
+
+/// The class detects jumps which bypass local variables declaration:
+///    goto L;
+///    int a;
+///  L:
+///
+/// This is simplified version of JumpScopeChecker. Primary differences:
+///  * Detects only jumps into the scope local variables.
+///  * Does not detect jumps out of the scope of local variables.
+///  * Not limited to variables with initializers, JumpScopeChecker is limited.
+class VarBypassDetector {
+  // Scope information. Contains a parent scope and related variable
+  // declaration.
+  llvm::SmallVector<std::pair<unsigned, const VarDecl *>, 48> Scopes;
+  // List of jumps with scopes.
+  llvm::SmallVector<std::pair<const Stmt *, unsigned>, 16> FromScopes;
+  // Lookup map to find scope for destinations.
+  llvm::DenseMap<const Stmt *, unsigned> ToScopes;
+  // Set of variables which were bypassed by some jump.
+  llvm::DenseSet<const VarDecl *> Bypasses;
+  // If true assume that all variables are being bypassed.
+  bool AlwaysBypassed = false;
+
+public:
+  void Init(const Stmt *Body);
+
+  /// Returns true if the variable declaration was by bypassed by any goto or
+  /// switch statement.
+  bool IsBypassed(const VarDecl *D) const {
+    return AlwaysBypassed || Bypasses.find(D) != Bypasses.end();
+  }
+
+private:
+  bool BuildScopeInformation(const Decl *D, unsigned &ParentScope);
+  bool BuildScopeInformation(const Stmt *S, unsigned &origParentScope);
+  void Detect();
+  void Detect(unsigned From, unsigned To);
+};
+}
+}
+
+#endif