Move the calling of emitTargetMD() later.

[robertlytton]

Summary

Because a global created by GetOrCreateLLVMGlobal() is not finalised until later viz:

extern char a[];
char f(){ return a[5];}
char a[10];

multiple & wrong Metadata was being outputted.

Change MangledDeclNames to use a MapVector rather than a DenseMap so that the Metadata
is output in order of original declaration. This is to improve human readability.

[robertlytton]

Use 'auto' in the for-loops

[robertlytton]

use 'auto' in for-loops

[• rafael]

Alp Toker changed how we handled mangled names last, he is probably the correct person to review this.

lib/CodeGen/CodeGenModule.cpp

3250 ↗

(On Diff #10533)

Can this use a range loop. If so, please commit that as a first independent improvement.

[rnk]

I just want to point out that this is a correctness fix too: clang's output should be deterministic, including the order in which we output metadata, which affects -emit-llvm.

[robertlytton]

change to use range loops
(should I be using 'auto &I' or plain 'auto I'?)

[robertlytton]

Closed by commit rL212262 (authored by rlytton).

cfe/trunk/lib/CodeGen/CodeGenModule.cpp

 ///
 /// Since there's currently no way to associate an MDNode directly
 /// with an llvm::GlobalValue, we create a global named metadata
 /// with the name 'clang.global.decl.ptrs'.
 void CodeGenModule::EmitDeclMetadata() {
   llvm::NamedMDNode *GlobalMetadata = nullptr;
 
   // StaticLocalDeclMap
-  for (llvm::DenseMap<GlobalDecl,StringRef>::iterator
-         I = MangledDeclNames.begin(), E = MangledDeclNames.end();
-       I != E; ++I) {
-    llvm::GlobalValue *Addr = getModule().getNamedValue(I->second);
-    EmitGlobalDeclMetadata(*this, GlobalMetadata, I->first, Addr);
+  for (auto &I : MangledDeclNames) {
+    llvm::GlobalValue *Addr = getModule().getNamedValue(I.second);
+    EmitGlobalDeclMetadata(*this, GlobalMetadata, I.first, Addr);
   }
 }
 
 /// Emits metadata nodes for all the local variables in the current
 /// function.
 void CodeGenFunction::EmitDeclMetadata() {
   if (LocalDeclMap.empty()) return;
 
   llvm::LLVMContext &Context = getLLVMContext();
 
   // Find the unique metadata ID for this name.
   unsigned DeclPtrKind = Context.getMDKindID("clang.decl.ptr");
 
   llvm::NamedMDNode *GlobalMetadata = nullptr;
 
-  for (llvm::DenseMap<const Decl*, llvm::Value*>::iterator
-         I = LocalDeclMap.begin(), E = LocalDeclMap.end(); I != E; ++I) {
-    const Decl *D = I->first;
-    llvm::Value *Addr = I->second;
-
+  for (auto &I : LocalDeclMap) {
+    const Decl *D = I.first;
+    llvm::Value *Addr = I.second;
     if (auto *Alloca = dyn_cast<llvm::AllocaInst>(Addr)) {
       llvm::Value *DAddr = GetPointerConstant(getLLVMContext(), D);
       Alloca->setMetadata(DeclPtrKind, llvm::MDNode::get(Context, DAddr));
     } else if (auto *GV = dyn_cast<llvm::GlobalValue>(Addr)) {
       GlobalDecl GD = GlobalDecl(cast<VarDecl>(D));
       EmitGlobalDeclMetadata(CGM, GlobalMetadata, GD, GV);
     }
   }