From 0c5e3132aa3a6a382368b1a87aa49aa487e79d03 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sat, 21 Mar 2009 07:48:31 +0000
Subject: [PATCH] simplify and comment some code better.  Make
 BindRuntimeGlobals more optimistic that it will work (optimizing for the
 common case).

llvm-svn: 67438
---
 clang/lib/CodeGen/CGExpr.cpp        |  1 +
 clang/lib/CodeGen/CodeGenModule.cpp | 53 ++++++++++++++++-------------
 clang/lib/CodeGen/CodeGenModule.h   |  5 ++-
 3 files changed, 34 insertions(+), 25 deletions(-)

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 95cb53c1f70d..d34b0f5ea38b 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -29,6 +29,7 @@ using namespace CodeGen;
 /// block.
 llvm::AllocaInst *CodeGenFunction::CreateTempAlloca(const llvm::Type *Ty,
                                                     const char *Name) {
+  // FIXME: Should not pass name if names are disabled in IRBuilder.
   return new llvm::AllocaInst(Ty, 0, Name, AllocaInsertPt);
 }
 
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 6f70524d6d67..91ab2b7b03e9 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -81,32 +81,37 @@ void CodeGenModule::BindRuntimeGlobals() {
       continue;
     }
       
-    // See if there is a conflict against a function.
+    // See if there is a conflict against a function by setting the name and
+    // seeing if we got the desired name.
+    GV->setName(Name);
+    if (GV->isName(Name.c_str()))
+      continue;  // Yep, it worked!
+    
+    GV->setName(""); // Zap the bogus name until we work out the conflict.
     llvm::GlobalValue *Conflict = TheModule.getNamedValue(Name);
-    if (Conflict) {
-      // Decide which version to take. If the conflict is a definition
-      // we are forced to take that, otherwise assume the runtime
-      // knows best.
+    assert(Conflict && "Must have conflicted!");
+    
+    // Decide which version to take. If the conflict is a definition
+    // we are forced to take that, otherwise assume the runtime
+    // knows best.
 
-      // FIXME: This will fail phenomenally when the conflict is the
-      // wrong type of value. Just bail on it for now. This should
-      // really reuse something inside the LLVM Linker code.
-      assert(GV->getValueID() == Conflict->getValueID() &&
-             "Unable to resolve conflict between globals of different types.");
-      if (!Conflict->isDeclaration()) {
-        llvm::Value *Casted = 
-          llvm::ConstantExpr::getBitCast(Conflict, GV->getType());
-        GV->replaceAllUsesWith(Casted);
-        GV->eraseFromParent();
-      } else {
-        GV->takeName(Conflict);
-        llvm::Value *Casted = 
-          llvm::ConstantExpr::getBitCast(GV, Conflict->getType());
-        Conflict->replaceAllUsesWith(Casted);
-        Conflict->eraseFromParent();
-      }
-    } else
-      GV->setName(Name);
+    // FIXME: This will fail phenomenally when the conflict is the
+    // wrong type of value. Just bail on it for now. This should
+    // really reuse something inside the LLVM Linker code.
+    assert(GV->getValueID() == Conflict->getValueID() &&
+           "Unable to resolve conflict between globals of different types.");
+    if (!Conflict->isDeclaration()) {
+      llvm::Value *Casted = 
+        llvm::ConstantExpr::getBitCast(Conflict, GV->getType());
+      GV->replaceAllUsesWith(Casted);
+      GV->eraseFromParent();
+    } else {
+      GV->takeName(Conflict);
+      llvm::Value *Casted = 
+        llvm::ConstantExpr::getBitCast(GV, Conflict->getType());
+      Conflict->replaceAllUsesWith(Casted);
+      Conflict->eraseFromParent();
+    }
   }
 }
 
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 12c103ba62c3..a2cb442a8420 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -94,7 +94,7 @@ class CodeGenModule : public BlockModule {
   /// emitted. Note that the entries in this map are the actual
   /// globals and therefore may not be of the same type as the decl,
   /// they should be bitcasted on retrieval. Also note that the
-  /// globals are keyed on their source name, not the global name
+  /// globals are keyed on their source mangled name, not the global name
   /// (which may change with attributes such as asm-labels).  This key
   /// to this map should be generated using getMangledName().
   llvm::DenseMap<const char*, llvm::GlobalValue*> GlobalDeclMap;
@@ -141,6 +141,9 @@ class CodeGenModule : public BlockModule {
   /// strings. This value has type int * but is actually an Obj-C class pointer.
   llvm::Constant *CFConstantStringClassRef;
 
+  /// BuiltinFunctions - This is the cached set of Function*'s that have been
+  /// created for each builtin, indexed by the Builtin ID.  This is null if the
+  /// Function* has not yet been created.
   std::vector<llvm::Value *> BuiltinFunctions;
 public:
   CodeGenModule(ASTContext &C, const LangOptions &Features, llvm::Module &M,