From f5938eeeb32128cb1f85b118cc929ff2ae1af71f Mon Sep 17 00:00:00 2001
From: Frederic Riss <friss@apple.com>
Date: Fri, 19 Sep 2014 15:12:03 +0000
Subject: [PATCH] Change DwarfCompileUnit::createGlobalVariable to
 getOrCreateGlobalVariable.

Summary:
This will allow to request the creation of a forward delacred variable
at is point of use (for imported declarations, this will be
DwarfDebug::constructImportedEntityDIE) rather than having to put the
forward decl in a retention list.

Note that getOrCreateGlobalVariable returns the actual definition DIE when the
routine creates a declaration and a definition DIE. If you agree this is the
right behavior, then I'll have a followup patch that registers the definition
in the DIE map instead of the declaration as it is today (this 'breaks' only
one test, where we test that the imported entity is the declaration). I'm
not sure what's best here, but it's easy enough for a consumer to follow the
DW_AT_specification link to get to the declaration, whereas it takes more
work to find the actual definition from a declaration DIE.

Reviewers: echristo, dblaikie, aprantl

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5381

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218126 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/AsmPrinter/DwarfDebug.cpp |  2 +-
 lib/CodeGen/AsmPrinter/DwarfUnit.cpp  | 19 ++++++++++---------
 lib/CodeGen/AsmPrinter/DwarfUnit.h    |  4 ++--
 3 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 845506fbfb2..742646b0555 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -783,7 +783,7 @@ void DwarfDebug::beginModule() {
               ScopesWithImportedEntities.end(), less_first());
     DIArray GVs = CUNode.getGlobalVariables();
     for (unsigned i = 0, e = GVs.getNumElements(); i != e; ++i)
-      CU.createGlobalVariableDIE(DIGlobalVariable(GVs.getElement(i)));
+      CU.getOrCreateGlobalVariableDIE(DIGlobalVariable(GVs.getElement(i)));
     DIArray SPs = CUNode.getSubprograms();
     for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i)
       SPMap.insert(std::make_pair(SPs.getElement(i), &CU));
diff --git a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index 47c8bd9f92b..4bf18db32ff 100644
--- a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -1596,11 +1596,11 @@ static const ConstantExpr *getMergedGlobalExpr(const Value *V) {
   return CE;
 }
 
-/// createGlobalVariableDIE - create global variable DIE.
-void DwarfCompileUnit::createGlobalVariableDIE(DIGlobalVariable GV) {
+/// getOrCreateGlobalVariableDIE - get or create global variable DIE.
+DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(DIGlobalVariable GV) {
   // Check for pre-existence.
-  if (getDIE(GV))
-    return;
+  if (DIE *Die = getDIE(GV))
+    return Die;
 
   assert(GV.isGlobalVariable());
 
@@ -1725,18 +1725,19 @@ void DwarfCompileUnit::createGlobalVariableDIE(DIGlobalVariable GV) {
     addBlock(*VariableDIE, dwarf::DW_AT_location, Loc);
   }
 
+  DIE *ResultDIE = VariableSpecDIE ? VariableSpecDIE : VariableDIE;
+
   if (addToAccelTable) {
-    DIE &AddrDIE = VariableSpecDIE ? *VariableSpecDIE : *VariableDIE;
-    DD->addAccelName(GV.getName(), AddrDIE);
+    DD->addAccelName(GV.getName(), *ResultDIE);
 
     // If the linkage name is different than the name, go ahead and output
     // that as well into the name table.
     if (GV.getLinkageName() != "" && GV.getName() != GV.getLinkageName())
-      DD->addAccelName(GV.getLinkageName(), AddrDIE);
+      DD->addAccelName(GV.getLinkageName(), *ResultDIE);
   }
 
-  addGlobalName(GV.getName(), VariableSpecDIE ? *VariableSpecDIE : *VariableDIE,
-                GV.getContext());
+  addGlobalName(GV.getName(), *ResultDIE, GV.getContext());
+  return ResultDIE;
 }
 
 /// constructSubrangeDIE - Construct subrange DIE from DISubrange.
diff --git a/lib/CodeGen/AsmPrinter/DwarfUnit.h b/lib/CodeGen/AsmPrinter/DwarfUnit.h
index 14ce9a32c5a..c2026cf0032 100644
--- a/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -536,8 +536,8 @@ public:
   /// Apply the DW_AT_stmt_list from this compile unit to the specified DIE.
   void applyStmtList(DIE &D);
 
-  /// createGlobalVariableDIE - create global variable DIE.
-  void createGlobalVariableDIE(DIGlobalVariable GV);
+  /// getOrCreateGlobalVariableDIE - get or create global variable DIE.
+  DIE *getOrCreateGlobalVariableDIE(DIGlobalVariable GV);
 
   /// addLabelAddress - Add a dwarf label attribute data and value using
   /// either DW_FORM_addr or DW_FORM_GNU_addr_index.
-- 
2.34.1