Emit DW_AT_object_pointer once, on the declaration, for each function.

This effectively reverts r164326, but adds some comments and
justification and ensures we /don't/ emit the DW_AT_object_pointer on
the (abstract and concrete) definitions. (while still preserving it on
standalone definitions involving ObjC Blocks)

This does increase the size of member function declarations from 7 to 11
bytes, unfortunately, but still seems like the Right Thing to do so that
callers that see only the declaration still have the information about
the object pointer. That said, I don't know what, if any, DWARF
consumers don't have a heuristic to guess this in the case of normal
C++ member functions - perhaps we can remove it entirely.

llvm-svn: 207705

1 files changed, 9 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index ac4eea4a50b..d9ef6c04285 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -548,11 +548,16 @@ DIE *DwarfDebug::createScopeChildrenDIE(
 }
 
 void DwarfDebug::createAndAddScopeChildren(DwarfCompileUnit &TheCU,
-                                           LexicalScope *Scope, DIE &ScopeDIE) {
+                                           LexicalScope *Scope,
+                                           DISubprogram Sub, DIE &ScopeDIE) {
   // We create children when the scope DIE is not null.
   SmallVector<std::unique_ptr<DIE>, 8> Children;
   if (DIE *ObjectPointer = createScopeChildrenDIE(TheCU, Scope, Children))
-    TheCU.addDIEEntry(ScopeDIE, dwarf::DW_AT_object_pointer, *ObjectPointer);
+    // The declaration will have the object_pointer, otherwise put it on the
+    // definition. This happens with ObjC blocks that have object_pointer on
+    // non-member functions.
+    if (!Sub.getFunctionDeclaration())
+      TheCU.addDIEEntry(ScopeDIE, dwarf::DW_AT_object_pointer, *ObjectPointer);
 
   // Add children
   for (auto &I : Children)
@@ -571,7 +576,7 @@ void DwarfDebug::constructAbstractSubprogramScopeDIE(DwarfCompileUnit &TheCU,
 
   if (DIE *ScopeDIE = TheCU.getDIE(Sub)) {
     AbstractSPDies.insert(std::make_pair(Sub, ScopeDIE));
-    createAndAddScopeChildren(TheCU, Scope, *ScopeDIE);
+    createAndAddScopeChildren(TheCU, Scope, Sub, *ScopeDIE);
   }
 }
 
@@ -588,7 +593,7 @@ DIE &DwarfDebug::constructSubprogramScopeDIE(DwarfCompileUnit &TheCU,
 
   DIE &ScopeDIE = updateSubprogramScopeDIE(TheCU, Sub);
 
-  createAndAddScopeChildren(TheCU, Scope, ScopeDIE);
+  createAndAddScopeChildren(TheCU, Scope, Sub, ScopeDIE);
 
   return ScopeDIE;
 }