Fix a couple of bugs, add some new cool stuff.

1. Fix a todo in Parser::ParseTag, to recover better.  On code like
   that in test/Sema/decl-invalid.c it causes us to return a single
   error instead of multiple.
2. Fix an error in Sema::ParseDeclarator, where it would crash if the
   declarator didn't have an identifier.  Instead, diagnose the problem.
3. Start adding infrastructure to track the range of locations covered
   by a declspec or declarator.  This is mostly implemented for declspec,
   but could be improved, it is missing for declarator.

Thanks to Neil for pointing out this crash.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@40482 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CodeGen/CGDecl.cpp b/CodeGen/CGDecl.cpp
new file mode 100644
index 0000000..63b9d6f
--- /dev/null
+++ b/CodeGen/CGDecl.cpp
@@ -0,0 +1,120 @@
+//===--- CGDecl.cpp - Emit LLVM Code for declarations ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This contains code to emit Decl nodes as LLVM code.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CodeGenFunction.h"
+#include "clang/AST/AST.h"
+#include "llvm/Type.h"
+using namespace clang;
+using namespace CodeGen;
+
+
+void CodeGenFunction::EmitDecl(const Decl &D) {
+  switch (D.getKind()) {
+  default: assert(0 && "Unknown decl kind!");
+  case Decl::FileVariable:
+    assert(0 && "Should not see file-scope variables inside a function!");
+  case Decl::ParmVariable:
+    assert(0 && "Parmdecls should not be in declstmts!");
+  case Decl::Typedef:   // typedef int X;
+  case Decl::Function:  // void X();
+  case Decl::Struct:    // struct X;
+  case Decl::Union:     // union X;
+  case Decl::Class:     // class X;
+  case Decl::Enum:      // enum X;
+    // None of these decls require codegen support.
+    return;
+    
+  case Decl::BlockVariable:
+    return EmitBlockVarDecl(cast<BlockVarDecl>(D));
+  case Decl::EnumConstant:
+    return EmitEnumConstantDecl(cast<EnumConstantDecl>(D));
+  }
+}
+
+void CodeGenFunction::EmitEnumConstantDecl(const EnumConstantDecl &D) {
+  assert(0 && "FIXME: Enum constant decls not implemented yet!");  
+}
+
+/// EmitBlockVarDecl - This method handles emission of any variable declaration
+/// inside a function, including static vars etc.
+void CodeGenFunction::EmitBlockVarDecl(const BlockVarDecl &D) {
+  switch (D.getStorageClass()) {
+  case VarDecl::Static:
+    assert(0 && "FIXME: local static vars not implemented yet");
+  case VarDecl::Extern:
+    assert(0 && "FIXME: should call up to codegenmodule");
+  default:
+    assert((D.getStorageClass() == VarDecl::None ||
+            D.getStorageClass() == VarDecl::Auto ||
+            D.getStorageClass() == VarDecl::Register) &&
+           "Unknown storage class");
+    return EmitLocalBlockVarDecl(D);
+  }
+}
+
+/// EmitLocalBlockVarDecl - Emit code and set up an entry in LocalDeclMap for a
+/// variable declaration with auto, register, or no storage class specifier.
+/// These turn into simple stack objects.
+void CodeGenFunction::EmitLocalBlockVarDecl(const BlockVarDecl &D) {
+  QualType Ty = D.getCanonicalType();
+
+  llvm::Value *DeclPtr;
+  if (Ty->isConstantSizeType(getContext())) {
+    // A normal fixed sized variable becomes an alloca in the entry block.
+    const llvm::Type *LTy = ConvertType(Ty);
+    // TODO: Alignment
+    DeclPtr = CreateTempAlloca(LTy, D.getName());
+  } else {
+    // TODO: Create a dynamic alloca.
+    assert(0 && "FIXME: Local VLAs not implemented yet");
+  }
+  
+  llvm::Value *&DMEntry = LocalDeclMap[&D];
+  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
+  DMEntry = DeclPtr;
+  
+  // If this local has an initializer, emit it now.
+  if (const Expr *Init = D.getInit())
+    EmitStoreThroughLValue(EmitExpr(Init), LValue::MakeAddr(DeclPtr), Ty);
+}
+
+/// Emit an alloca for the specified parameter and set up LocalDeclMap.
+void CodeGenFunction::EmitParmDecl(const ParmVarDecl &D, llvm::Value *Arg) {
+  QualType Ty = D.getCanonicalType();
+  
+  llvm::Value *DeclPtr;
+  if (!Ty->isConstantSizeType(getContext())) {
+    // Variable sized values always are passed by-reference.
+    DeclPtr = Arg;
+  } else {
+    // A fixed sized first class variable becomes an alloca in the entry block.
+    const llvm::Type *LTy = ConvertType(Ty);
+    if (LTy->isFirstClassType()) {
+      // TODO: Alignment
+      DeclPtr = new llvm::AllocaInst(LTy, 0, std::string(D.getName())+".addr",
+                                     AllocaInsertPt);
+      
+      // Store the initial value into the alloca.
+      Builder.CreateStore(Arg, DeclPtr);
+    } else {
+      // Otherwise, if this is an aggregate, just use the input pointer.
+      DeclPtr = Arg;
+    }
+    Arg->setName(D.getName());
+  }
+
+  llvm::Value *&DMEntry = LocalDeclMap[&D];
+  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
+  DMEntry = DeclPtr;
+}
+