[codeview] omit debug locations for nested exprs unless column info enabled

Summary:
Microsoft Visual Studio expects debug locations to correspond to
statements. We used to emit locations for expressions nested inside statements.
This would confuse the debugger, causing it to stop multiple times on the
same line and breaking the "step into specific" feature. This change inhibits
the emission of debug locations for nested expressions when emitting CodeView
debug information, unless column information is enabled.

Fixes PR34312.

Reviewers: rnk, zturner

Reviewed By: rnk

Subscribers: majnemer, echristo, aprantl, cfe-commits

Differential Revision: https://reviews.llvm.org/D37529

llvm-svn: 312965

3 files changed, 11 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index befb704f39e..f4c84c5c630 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -97,6 +97,10 @@ void ApplyDebugLocation::init(SourceLocation TemporaryLocation,
   }
 
   OriginalLocation = CGF->Builder.getCurrentDebugLocation();
+
+  if (OriginalLocation && !DI->CGM.getExpressionLocationsEnabled())
+    return;
+
   if (TemporaryLocation.isValid()) {
     DI->EmitLocation(CGF->Builder, TemporaryLocation);
     return;
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index b0b5e7d387f..43607002544 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -3553,6 +3553,10 @@ CodeGenModule::GetAddrOfConstantCFString(const StringLiteral *Literal) {
   return ConstantAddress(GV, Alignment);
 }
 
+bool CodeGenModule::getExpressionLocationsEnabled() const {
+  return !CodeGenOpts.EmitCodeView || CodeGenOpts.DebugColumnInfo;
+}
+
 QualType CodeGenModule::getObjCFastEnumerationStateType() {
   if (ObjCFastEnumerationStateType.isNull()) {
     RecordDecl *D = Context.buildImplicitRecord("__objcFastEnumerationState");
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 235ef31bd7a..4bff296cb19 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -513,6 +513,9 @@ public:
   /// Finalize LLVM code generation.
   void Release();
 
+  /// Return true if we should emit location information for expressions.
+  bool getExpressionLocationsEnabled() const;
+
   /// Return a reference to the configured Objective-C runtime.
   CGObjCRuntime &getObjCRuntime() {
     if (!ObjCRuntime) createObjCRuntime();