From 4fe345729285ae634c657ab854057464d03220f7 Mon Sep 17 00:00:00 2001
From: Eric Christopher <echristo@apple.com>
Date: Wed, 8 Feb 2012 00:22:26 +0000
Subject: [PATCH] Add support for a temporary forward decl type. We want this
 so we can rauw forward declarations if we decide to emit the full type.

Part of rdar://10809898

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150024 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Analysis/DIBuilder.h |  4 ++++
 lib/Analysis/DIBuilder.cpp        | 22 ++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/include/llvm/Analysis/DIBuilder.h b/include/llvm/Analysis/DIBuilder.h
index 666ca5802ff..3785fa8c38f 100644
--- a/include/llvm/Analysis/DIBuilder.h
+++ b/include/llvm/Analysis/DIBuilder.h
@@ -341,6 +341,10 @@ namespace llvm {
     DIType createTemporaryType();
     DIType createTemporaryType(DIFile F);
 
+    /// createForwardDecl - Create a temporary forward-declared type.
+    DIType createForwardDecl(unsigned Tag, StringRef Name, DIFile F,
+                             unsigned Line);
+
     /// retainType - Retain DIType in a module even if it is not referenced 
     /// through debug info anchors.
     void retainType(DIType T);
diff --git a/lib/Analysis/DIBuilder.cpp b/lib/Analysis/DIBuilder.cpp
index 45603711afd..53a293af912 100644
--- a/lib/Analysis/DIBuilder.cpp
+++ b/lib/Analysis/DIBuilder.cpp
@@ -669,6 +669,28 @@ DIType DIBuilder::createTemporaryType(DIFile F) {
   return DIType(Node);
 }
 
+/// createForwardDecl - Create a temporary forward-declared type that
+/// can be RAUW'd if the full type is seen.
+DIType DIBuilder::createForwardDecl(unsigned Tag, StringRef Name, DIFile F,
+                                    unsigned Line) {
+  // Create a temporary MDNode.
+  Value *Elts[] = {
+    GetTagConstant(VMContext, Tag),
+    NULL, // TheCU
+    MDString::get(VMContext, Name),
+    F,
+    ConstantInt::get(Type::getInt32Ty(VMContext), Line),
+    // To ease transition include sizes etc of 0.
+    ConstantInt::get(Type::getInt32Ty(VMContext), 0),
+    ConstantInt::get(Type::getInt32Ty(VMContext), 0),
+    ConstantInt::get(Type::getInt32Ty(VMContext), 0),
+    ConstantInt::get(Type::getInt32Ty(VMContext),
+                     DIDescriptor::FlagFwdDecl)
+  };
+  MDNode *Node = MDNode::getTemporary(VMContext, Elts);
+  return DIType(Node);
+}
+
 /// getOrCreateArray - Get a DIArray, create one if required.
 DIArray DIBuilder::getOrCreateArray(ArrayRef<Value *> Elements) {
   if (Elements.empty()) {
-- 
2.34.1