From 48f17ba2a611d197082d4de730b646a4ecf68df4 Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Tue, 7 Dec 2010 23:58:00 +0000
Subject: [PATCH] Add support to create local variable's debug info.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121211 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Analysis/DIBuilder.h | 19 ++++++++++++++++++
 lib/Analysis/DIBuilder.cpp        | 33 +++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/include/llvm/Analysis/DIBuilder.h b/include/llvm/Analysis/DIBuilder.h
index 532fe514dd9..62f2294c1bb 100644
--- a/include/llvm/Analysis/DIBuilder.h
+++ b/include/llvm/Analysis/DIBuilder.h
@@ -188,6 +188,25 @@ namespace llvm {
                          DIType Ty, bool isLocalToUnit, llvm::Value *Val);
 
 
+    /// CreateLocalVariable - Create a new descriptor for the specified 
+    /// local variable.
+    /// @param Tag         Dwarf TAG. Usually DW_TAG_auto_variable or
+    ///                    DW_TAG_arg_variable.
+    /// @param Scope       Variable scope.
+    /// @param Name        Variable name.
+    /// @param File        File where this variable is defined.
+    /// @param LineNo      Line number.
+    /// @param Ty          Variable Type
+    /// @param AlwaysPreserve Boolean. Set to true if debug info for this
+    ///                       variable should be preserved in optimized build.
+    /// @param Flags          Flags, e.g. artificial variable.
+    DIVariable CreateLocalVariable(unsigned Tag, DIDescriptor Scope,
+                                   StringRef Name,
+                                   DIFile File, unsigned LineNo,
+                                   DIType Ty, bool AlwaysPreserve = false,
+                                   unsigned Flags = 0);
+
+
     /// CreateComplexVariable - Create a new descriptor for the specified
     /// variable which has a complex address expression for its address.
     /// @param Tag         Dwarf TAG. Usually DW_TAG_auto_variable or
diff --git a/lib/Analysis/DIBuilder.cpp b/lib/Analysis/DIBuilder.cpp
index 6d32afea979..4b1988cd9ec 100644
--- a/lib/Analysis/DIBuilder.cpp
+++ b/lib/Analysis/DIBuilder.cpp
@@ -27,6 +27,7 @@ static Constant *GetTagConstant(LLVMContext &VMContext, unsigned Tag) {
          "Tag too large for debug encoding!");
   return ConstantInt::get(Type::getInt32Ty(VMContext), Tag | LLVMDebugVersion);
 }
+
 DIBuilder::DIBuilder(Module &m)
   : M(m), VMContext(M.getContext()), TheCU(0), DeclareFn(0), ValueFn(0) {}
 
@@ -368,6 +369,38 @@ CreateStaticVariable(DIDescriptor Context, StringRef Name,
   return DIGlobalVariable(Node);
 }
 
+/// CreateVariable - Create a new descriptor for the specified variable.
+DIVariable DIBuilder::CreateLocalVariable(unsigned Tag, DIDescriptor Scope,
+                                          StringRef Name, DIFile File,
+                                          unsigned LineNo, DIType Ty, 
+                                          bool AlwaysPreserve, unsigned Flags) {
+  Value *Elts[] = {
+    GetTagConstant(VMContext, Tag),
+    Scope,
+    MDString::get(VMContext, Name),
+    File,
+    ConstantInt::get(Type::getInt32Ty(VMContext), LineNo),
+    Ty,
+    ConstantInt::get(Type::getInt32Ty(VMContext), Flags)
+  };
+  MDNode *Node = MDNode::get(VMContext, &Elts[0], array_lengthof(Elts));
+  if (AlwaysPreserve) {
+    // The optimizer may remove local variable. If there is an interest
+    // to preserve variable info in such situation then stash it in a
+    // named mdnode.
+    DISubprogram Fn(getDISubprogram(Scope));
+    StringRef FName = "fn";
+    if (Fn.getFunction())
+      FName = Fn.getFunction()->getName();
+    char One = '\1';
+    if (FName.startswith(StringRef(&One, 1)))
+      FName = FName.substr(1);
+    NamedMDNode *FnLocals = getOrInsertFnSpecificMDNode(M, FName);
+    FnLocals->addOperand(Node);
+  }
+  return DIVariable(Node);
+}
+
 /// CreateComplexVariable - Create a new descriptor for the specified variable
 /// which has a complex address expression for its address.
 DIVariable DIBuilder::CreateComplexVariable(unsigned Tag, DIDescriptor Scope,