From b6cdc96e7679f0344a36395a87c249930fac8a9f Mon Sep 17 00:00:00 2001
From: Adrian Prantl <aprantl@apple.com>
Date: Wed, 24 Jul 2013 20:34:39 +0000
Subject: [PATCH] Debug Info: Fix an oversight of r186553. Ensure that the
 function prologue of an artificial function gets an artificial location as
 well.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187074 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CGBlocks.cpp             | 10 ++++++----
 lib/CodeGen/CGDebugInfo.cpp          | 12 +++++++++---
 lib/CodeGen/CGDebugInfo.h            | 13 ++++++++++---
 test/CodeGenObjC/debug-info-blocks.m |  3 +++
 4 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/lib/CodeGen/CGBlocks.cpp b/lib/CodeGen/CGBlocks.cpp
index ec4af58fc3..f200ec96e7 100644
--- a/lib/CodeGen/CGBlocks.cpp
+++ b/lib/CodeGen/CGBlocks.cpp
@@ -1313,9 +1313,10 @@ CodeGenFunction::GenerateCopyHelperFunction(const CGBlockInfo &blockInfo) {
                                           SC_Static,
                                           false,
                                           false);
-  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
-  // Don't emit any line table entries for the body of this function.
+  // Create a scope with an artificial location for the body of this function.
   ArtificialLocation AL(*this, Builder);
+  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
+  AL.Emit();
 
   llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
 
@@ -1488,9 +1489,10 @@ CodeGenFunction::GenerateDestroyHelperFunction(const CGBlockInfo &blockInfo) {
                                           SourceLocation(), II, C.VoidTy, 0,
                                           SC_Static,
                                           false, false);
-  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
-  // Don't emit any line table entries for the body of this function.
+  // Create a scope with an artificial location for the body of this function.
   ArtificialLocation AL(*this, Builder);
+  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
+  AL.Emit();
 
   llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
 
diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index 4de21d2b39..4e77f87cc6 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -72,13 +72,19 @@ ArtificialLocation::ArtificialLocation(CodeGenFunction &CGF, CGBuilderTy &B)
   : DI(CGF.getDebugInfo()), Builder(B) {
   if (DI) {
     SavedLoc = DI->getLocation();
+    DI->CurLoc = SourceLocation();
+    Builder.SetCurrentDebugLocation(llvm::DebugLoc());
+  }
+}
+
+void ArtificialLocation::Emit() {
+  if (DI) {
     // Sync the Builder.
     DI->EmitLocation(Builder, SavedLoc);
     DI->CurLoc = SourceLocation();
     // Construct a location that has a valid scope, but no line info.
-    llvm::DIDescriptor Scope = DI->LexicalBlockStack.empty() ?
-      llvm::DIDescriptor(DI->TheCU) :
-      llvm::DIDescriptor(DI->LexicalBlockStack.back());
+    assert(!DI->LexicalBlockStack.empty());
+    llvm::DIDescriptor Scope(DI->LexicalBlockStack.back());
     Builder.SetCurrentDebugLocation(llvm::DebugLoc::get(0, 0, Scope));
   }
 }
diff --git a/lib/CodeGen/CGDebugInfo.h b/lib/CodeGen/CGDebugInfo.h
index 6eeb911d21..b090c4d3bf 100644
--- a/lib/CodeGen/CGDebugInfo.h
+++ b/lib/CodeGen/CGDebugInfo.h
@@ -407,9 +407,11 @@ public:
 /// an artificial debug location that has a valid scope, but no line
 /// information. This is useful when emitting compiler-generated
 /// helper functions that have no source location associated with
-/// them.
+/// them. The DWARF specification allows the compiler to use the
+/// special line number 0 to indicate code that can not be attributed
+/// to any source location.
 ///
-/// This is necessary because pasing an empty SourceLocation to
+/// This is necessary because passing an empty SourceLocation to
 /// CGDebugInfo::setLocation() will result in the last valid location
 /// being reused.
 class ArtificialLocation {
@@ -418,7 +420,12 @@ class ArtificialLocation {
   CGBuilderTy &Builder;
 public:
   ArtificialLocation(CodeGenFunction &CGF, CGBuilderTy &B);
-  /// ~BuildinLocation - Autorestore everything back to normal.
+
+  /// Set the current location to line 0, but within the current scope
+  /// (= the top of the LexicalScopeStack).
+  void Emit();
+
+  /// ~ArtificialLocation - Autorestore everything back to normal.
   ~ArtificialLocation();
 };
 
diff --git a/test/CodeGenObjC/debug-info-blocks.m b/test/CodeGenObjC/debug-info-blocks.m
index d9ac24edbb..63068a9ca9 100644
--- a/test/CodeGenObjC/debug-info-blocks.m
+++ b/test/CodeGenObjC/debug-info-blocks.m
@@ -15,11 +15,14 @@
 // Test that we do emit scope info for the helper functions.
 // CHECK: define {{.*}} @__copy_helper_block_{{.*}}(i8*, i8*)
 // CHECK-NOT: ret
+// CHECK: call {{.*}}, !dbg ![[DBG_LINE:[0-9]+]]
+// CHECK-NOT: ret
 // CHECK: load {{.*}}, !dbg ![[COPY_LINE:[0-9]+]]
 // CHECK: define {{.*}} @__destroy_helper_block_{{.*}}(i8*)
 // CHECK-NOT: ret
 // CHECK: load {{.*}}, !dbg ![[DESTROY_LINE:[0-9]+]]
 
+// CHECK-DAG: [[DBG_LINE]] = metadata !{i32 0, i32 0, metadata ![[COPY_SP:[0-9]+]], null}
 // CHECK-DAG: [[COPY_LINE]] = metadata !{i32 0, i32 0, metadata ![[COPY_SP:[0-9]+]], null}
 // CHECK-DAG: [[COPY_SP]] = {{.*}}[ DW_TAG_subprogram ]{{.*}}[__copy_helper_block_]
 // CHECK-DAG: [[DESTROY_LINE]] = metadata !{i32 0, i32 0, metadata ![[DESTROY_SP:[0-9]+]], null}
-- 
2.40.0