Add some helper methods that will be used in my next patch.

llvm-svn: 126596

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -387,6 +387,9 @@ bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) {
 
   // If this is a label, we have to emit the code, consider something like:
   // if (0) {  ...  foo:  bar(); }  goto foo;
+  //
+  // TODO: If anyone cared, we could track __label__'s, since we know that you
+  // can't jump to one from outside their declared region.
   if (isa<LabelStmt>(S))
     return true;
   
@@ -407,12 +410,46 @@ bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) {
   return false;
 }
 
+/// containsBreak - Return true if the statement contains a break out of it.
+/// If the statement (recursively) contains a switch or loop with a break
+/// inside of it, this is fine.
+bool CodeGenFunction::containsBreak(const Stmt *S) {
+  // Null statement, not a label!
+  if (S == 0) return false;
+
+  // If this is a switch or loop that defines its own break scope, then we can
+  // include it and anything inside of it.
+  if (isa<SwitchStmt>(S) || isa<WhileStmt>(S) || isa<DoStmt>(S) ||
+      isa<ForStmt>(S))
+    return true;
+  
+  // Scan subexpressions for verboten breaks.
+  for (Stmt::const_child_range I = S->children(); I; ++I)
+    if (containsBreak(*I))
+      return true;
+  
+  return false;
+}
+
 
 /// ConstantFoldsToSimpleInteger - If the specified expression does not fold
 /// to a constant, or if it does but contains a label, return false.  If it
 /// constant folds return true and set the boolean result in Result.
 bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond,
                                                    bool &ResultBool) {
+  llvm::APInt ResultInt;
+  if (!ConstantFoldsToSimpleInteger(Cond, ResultInt))
+    return false;
+  
+  ResultBool = ResultInt.getBoolValue();
+  return true;
+}
+
+/// ConstantFoldsToSimpleInteger - If the specified expression does not fold
+/// to a constant, or if it does but contains a label, return false.  If it
+/// constant folds return true and set the folded value.
+bool CodeGenFunction::
+ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APInt &ResultInt) {
   // FIXME: Rename and handle conversion of other evaluatable things
   // to bool.
   Expr::EvalResult Result;
@@ -423,11 +460,12 @@ bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond,
   if (CodeGenFunction::ContainsLabel(Cond))
     return false;  // Contains a label.
   
-  ResultBool = Result.Val.getInt().getBoolValue();
+  ResultInt = Result.Val.getInt();
   return true;
 }
 
 
+
 /// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if
 /// statement) to the specified blocks.  Based on the condition, this might try
 /// to simplify the codegen of the conditional based on the branch.

clang/lib/CodeGen/CodeGenFunction.h

@@ -2044,11 +2044,21 @@ public:
   /// that we can just remove the code.
   static bool ContainsLabel(const Stmt *S, bool IgnoreCaseStmts = false);
 
+  /// containsBreak - Return true if the statement contains a break out of it.
+  /// If the statement (recursively) contains a switch or loop with a break
+  /// inside of it, this is fine.
+  static bool containsBreak(const Stmt *S);
+  
   /// ConstantFoldsToSimpleInteger - If the specified expression does not fold
   /// to a constant, or if it does but contains a label, return false.  If it
   /// constant folds return true and set the boolean result in Result.
   bool ConstantFoldsToSimpleInteger(const Expr *Cond, bool &Result);
 
+  /// ConstantFoldsToSimpleInteger - If the specified expression does not fold
+  /// to a constant, or if it does but contains a label, return false.  If it
+  /// constant folds return true and set the folded value.
+  bool ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APInt &Result);
+  
   /// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an
   /// if statement) to the specified blocks.  Based on the condition, this might
   /// try to simplify the codegen of the conditional based on the branch.