Reapply r180982 with repaired logic and an additional testcase.

Un-break the gdb buildbot.
- Use the debug location of the return expression for the cleanup code
  if the return expression is trivially evaluatable, regardless of the
  number of stop points in the function.
- Ensure that any EH code in the cleanup still gets the line number of
  the closing } of the lexical scope.
- Added a testcase with EH in the cleanup.

rdar://problem/13442648

llvm-svn: 181056

clang/lib/CodeGen/CGCleanup.cpp

@@ -371,7 +371,8 @@ void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) {
 }
 
 /// Pops cleanup blocks until the given savepoint is reached.
-void CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old) {
+void CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old,
+                                       SourceLocation EHLoc) {
   assert(Old.isValid());
 
   while (EHStack.stable_begin() != Old) {
@@ -383,7 +384,7 @@ void CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old) {
     bool FallThroughIsBranchThrough =
       Old.strictlyEncloses(Scope.getEnclosingNormalCleanup());
 
-    PopCleanupBlock(FallThroughIsBranchThrough);
+    PopCleanupBlock(FallThroughIsBranchThrough, EHLoc);
   }
 }
 
@@ -532,7 +533,8 @@ static void destroyOptimisticNormalEntry(CodeGenFunction &CGF,
 /// Pops a cleanup block.  If the block includes a normal cleanup, the
 /// current insertion point is threaded through the cleanup, as are
 /// any branch fixups on the cleanup.
-void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
+void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough,
+                                      SourceLocation EHLoc) {
   assert(!EHStack.empty() && "cleanup stack is empty!");
   assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!");
   EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
@@ -833,6 +835,9 @@ void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
 
   // Emit the EH cleanup if required.
   if (RequiresEHCleanup) {
+    if (CGDebugInfo *DI = getDebugInfo())
+      DI->EmitLocation(Builder, EHLoc);
+
     CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
 
     EmitBlock(EHEntry);
@@ -840,6 +845,7 @@ void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
     // We only actually emit the cleanup code if the cleanup is either
     // active or was used before it was deactivated.
     if (EHActiveFlag || IsActive) {
+
       cleanupFlags.setIsForEHCleanup();
       EmitCleanup(*this, Fn, cleanupFlags, EHActiveFlag);
     }

clang/lib/CodeGen/CGStmt.cpp

@@ -38,8 +38,8 @@ void CodeGenFunction::EmitStopPoint(const Stmt *S) {
       Loc = S->getLocStart();
     DI->EmitLocation(Builder, Loc);
 
-    if (++NumStopPoints == 1)
-      FirstStopPoint = Loc;
+    //if (++NumStopPoints == 1)
+      LastStopPoint = Loc;
   }
 }
 
@@ -842,8 +842,9 @@ void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) {
     }
   }
 
+  NumReturnExprs += 1;
   if (RV == 0 || RV->isEvaluatable(getContext()))
-    ++NumSimpleReturnExprs;
+    NumSimpleReturnExprs += 1;
 
   cleanupScope.ForceCleanup();
   EmitBranchThroughCleanup(ReturnBlock);

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -44,7 +44,7 @@ CodeGenFunction::CodeGenFunction(CodeGenModule &cgm, bool suppressNewContext)
     DebugInfo(0), DisableDebugInfo(false), CalleeWithThisReturn(0),
     DidCallStackSave(false),
     IndirectBranch(0), SwitchInsn(0), CaseRangeBlock(0), UnreachableBlock(0),
-    NumStopPoints(0), NumSimpleReturnExprs(0),
+    NumReturnExprs(0), NumSimpleReturnExprs(0),
     CXXABIThisDecl(0), CXXABIThisValue(0), CXXThisValue(0),
     CXXDefaultInitExprThis(0),
     CXXStructorImplicitParamDecl(0), CXXStructorImplicitParamValue(0),
@@ -188,14 +188,16 @@ void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
   assert(BreakContinueStack.empty() &&
          "mismatched push/pop in break/continue stack!");
 
-  // If the function contains only a single, simple return statement,
-  // the cleanup code may become the first breakpoint in the
-  // function. To be safe set the debug location for it to the
-  // location of the return statement.  Otherwise point it to end of
-  // the function's lexical scope.
+  bool OnlySimpleReturnStmts = NumSimpleReturnExprs > 0
+    && NumSimpleReturnExprs == NumReturnExprs;
+  // If the function contains only a simple return statement, the
+  // cleanup code may become the first breakpoint in the function. To
+  // be safe, set the debug location for it to the location of the
+  // return statement.  Otherwise point it to end of the function's
+  // lexical scope.
   if (CGDebugInfo *DI = getDebugInfo()) {
-    if (NumSimpleReturnExprs == 1 && NumStopPoints == 1)
-      DI->EmitLocation(Builder, FirstStopPoint);
+    if (OnlySimpleReturnStmts)
+       DI->EmitLocation(Builder, LastStopPoint);
     else
       DI->EmitLocation(Builder, EndLoc);
   }
@@ -206,14 +208,14 @@ void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
   // edges will be *really* confused.
   bool EmitRetDbgLoc = true;
   if (EHStack.stable_begin() != PrologueCleanupDepth) {
-    PopCleanupBlocks(PrologueCleanupDepth);
+    PopCleanupBlocks(PrologueCleanupDepth, EndLoc);
 
     // Make sure the line table doesn't jump back into the body for
     // the ret after it's been at EndLoc.
     EmitRetDbgLoc = false;
 
     if (CGDebugInfo *DI = getDebugInfo())
-      if (NumSimpleReturnExprs == 1 && NumStopPoints == 1)
+      if (OnlySimpleReturnStmts)
         DI->EmitLocation(Builder, EndLoc);
   }
 

clang/lib/CodeGen/CodeGenFunction.h

@@ -784,7 +784,9 @@ public:
 
   /// PopCleanupBlock - Will pop the cleanup entry on the stack and
   /// process all branch fixups.
-  void PopCleanupBlock(bool FallThroughIsBranchThrough = false);
+  /// \param EHLoc - Optional debug location for EH code.
+  void PopCleanupBlock(bool FallThroughIsBranchThrough = false,
+                       SourceLocation EHLoc=SourceLocation());
 
   /// DeactivateCleanupBlock - Deactivates the given cleanup block.
   /// The block cannot be reactivated.  Pops it if it's the top of the
@@ -905,7 +907,9 @@ public:
 
   /// PopCleanupBlocks - Takes the old cleanup stack size and emits
   /// the cleanup blocks that have been added.
-  void PopCleanupBlocks(EHScopeStack::stable_iterator OldCleanupStackSize);
+  /// \param EHLoc - Optional debug location for EH code.
+  void PopCleanupBlocks(EHScopeStack::stable_iterator OldCleanupStackSize,
+                        SourceLocation EHLoc=SourceLocation());
 
   void ResolveBranchFixups(llvm::BasicBlock *Target);
 
@@ -1206,14 +1210,14 @@ private:
   /// lazily by getUnreachableBlock().
   llvm::BasicBlock *UnreachableBlock;
 
-  /// Counts of the number of distinct breakpoint locations in this function.
-  unsigned NumStopPoints;
+  /// Counts of the number return expressions in the function.
+  unsigned NumReturnExprs;
 
   /// Count the number of simple (constant) return expressions in the function.
   unsigned NumSimpleReturnExprs;
 
-  /// The first debug location (breakpoint) in the function.
-  SourceLocation FirstStopPoint;
+  /// The last regular (non-return) debug location (breakpoint) in the function.
+  SourceLocation LastStopPoint;
 
 public:
   /// A scope within which we are constructing the fields of an object which

clang/test/CodeGen/linetable-endscope.c

@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -emit-llvm -g -triple x86_64-apple-darwin10 %s -o - | FileCheck %s
+
+// Check the line numbers for the ret instruction. We expect it to be
+// at the closing of the lexical scope in this case. See the comments in
+// CodeGenFunction::FinishFunction() for more details.
+
+// CHECK: define {{.*}}foo
+// CHECK: store {{.*}}, !dbg ![[CONV:[0-9]+]]
+// CHECK: ret {{.*}}, !dbg ![[RET:[0-9]+]]
+
+void foo(char c)
+{
+  int i;
+  // CHECK: ![[CONV]] = metadata !{i32 [[@LINE+1]], i32 0, metadata !{{.*}}, null}
+  i = c;
+  // CHECK: ![[RET]] = metadata !{i32 [[@LINE+1]], i32 0, metadata !{{.*}}, null}
+}

clang/test/CodeGenCXX/linetable-cleanup.cpp

@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -emit-llvm -g -triple x86_64-apple-darwin10 %s -o - | FileCheck %s
+
+// Check the line numbers for cleanup code with EH in combinatin with
+// simple return expressions.
+
+// CHECK: define {{.*}}foo
+// CHECK: call void @_ZN1CD1Ev(%class.C* {{.*}}), !dbg ![[CLEANUP:[0-9]+]]
+// CHECK: ret i32 0, !dbg ![[RET:[0-9]+]]
+
+class C {
+public:
+  ~C() {}
+  int i;
+};
+
+int foo()
+{
+  C c;
+  c.i = 42;
+  // This breakpoint should be at/before the cleanup code.
+  // CHECK: ![[CLEANUP]] = metadata !{i32 [[@LINE+1]], i32 0, metadata !{{.*}}, null}
+  return 0;
+  // CHECK: ![[RET]] = metadata !{i32 [[@LINE+1]], i32 0, metadata !{{.*}}, null}
+}