Add a line number for the scope of the function (starting at the first

brace) so that we get more accurate line number information about the
declaration of a given function and the line where the function
first starts.

Part of rdar://11026482

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153916 91177308-0d34-0410-b5e6-96231b3b80d8

docs/SourceLevelDebugging.html

@@ -452,6 +452,7 @@ global variables are collected inside the named metadata
   metadata, ;; Reference to type descriptor
   i1,       ;; True if the global is local to compile unit (static)
   i1,       ;; True if the global is defined in the compile unit (not extern)
+  i32,      ;; Line number where the scope of the subprogram begins
   i32,      ;; Virtuality, e.g. dwarf::DW_VIRTUALITY__virtual
   i32,      ;; Index into a virtual function
   metadata, ;; indicates which base type contains the vtable pointer for the

include/llvm/Analysis/DIBuilder.h

@@ -445,6 +445,7 @@ namespace llvm {
     /// @param Ty            Function type.
     /// @param isLocalToUnit True if this function is not externally visible..
     /// @param isDefinition  True if this is a function definition.
+    /// @param ScopeLine     Set to the beginning of the scope this starts
     /// @param Flags         e.g. is this function prototyped or not.
     ///                      This flags are used to emit dwarf attributes.
     /// @param isOptimized   True if optimization is ON.
@@ -455,6 +456,7 @@ namespace llvm {
                                 DIFile File, unsigned LineNo,
                                 DIType Ty, bool isLocalToUnit,
                                 bool isDefinition,
+                                unsigned ScopeLine,
                                 unsigned Flags = 0,
                                 bool isOptimized = false,
                                 Function *Fn = 0,

include/llvm/Analysis/DebugInfo.h

@@ -519,6 +519,7 @@ namespace llvm {
     DICompositeType getContainingType() const {
       return getFieldAs<DICompositeType>(13);
     }
+
     unsigned isArtificial() const    { 
       if (getVersion() <= llvm::LLVMDebugVersion8)
         return getUnsignedField(14); 
@@ -567,6 +568,11 @@ namespace llvm {
       return getFieldAs<DIFile>(6).getDirectory(); 
     }
 
+    /// getScopeLineNumber - Get the beginning of the scope of the
+    /// function, not necessarily where the name of the program
+    /// starts.
+    unsigned getScopeLineNumber() const { return getUnsignedField(20); }
+
     /// Verify - Verify that a subprogram descriptor is well formed.
     bool Verify() const;
 

lib/Analysis/DIBuilder.cpp

@@ -17,6 +17,7 @@
 #include "llvm/IntrinsicInst.h"
 #include "llvm/Module.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/Debug.h"
 #include "llvm/Support/Dwarf.h"
 
 using namespace llvm;
@@ -825,6 +826,7 @@ DISubprogram DIBuilder::createFunction(DIDescriptor Context,
                                        DIFile File, unsigned LineNo,
                                        DIType Ty,
                                        bool isLocalToUnit, bool isDefinition,
+                                       unsigned ScopeLine,
                                        unsigned Flags, bool isOptimized,
                                        Function *Fn,
                                        MDNode *TParams,
@@ -854,7 +856,8 @@ DISubprogram DIBuilder::createFunction(DIDescriptor Context,
     Fn,
     TParams,
     Decl,
-    THolder
+    THolder,
+    ConstantInt::get(Type::getInt32Ty(VMContext), ScopeLine)
   };
   MDNode *Node = MDNode::get(VMContext, Elts);
 
@@ -902,7 +905,9 @@ DISubprogram DIBuilder::createMethod(DIDescriptor Context,
     Fn,
     TParam,
     llvm::Constant::getNullValue(Type::getInt32Ty(VMContext)),
-    THolder
+    THolder,
+    // FIXME: Do we want to use a different scope lines?
+    ConstantInt::get(Type::getInt32Ty(VMContext), LineNo)
   };
   MDNode *Node = MDNode::get(VMContext, Elts);
   return DISubprogram(Node);

lib/Analysis/DebugInfo.cpp

@@ -787,6 +787,9 @@ void DISubprogram::print(raw_ostream &OS) const {
   if (isDefinition())
     OS << " [def] ";
 
+  if (getScopeLineNumber() != getLineNumber())
+    OS << " [Scope: " << getScopeLineNumber() << "] ";
+
   OS << "\n";
 }
 

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1193,12 +1193,19 @@ static MDNode *getScopeNode(DebugLoc DL, const LLVMContext &Ctx) {
 }
 
 /// getFnDebugLoc - Walk up the scope chain of given debug loc and find
-/// line number  info for the function.
+/// line number info for the function.
 static DebugLoc getFnDebugLoc(DebugLoc DL, const LLVMContext &Ctx) {
   const MDNode *Scope = getScopeNode(DL, Ctx);
   DISubprogram SP = getDISubprogram(Scope);
-  if (SP.Verify()) 
-    return DebugLoc::get(SP.getLineNumber(), 0, SP);
+  if (SP.Verify()) {
+    // Check for number of operands since the compatibility is
+    // cheap here.
+    if (Scope->getNumOperands() > 19)
+      return DebugLoc::get(SP.getScopeLineNumber(), 0, SP);
+    else
+      return DebugLoc::get(SP.getLineNumber(), 0, SP);
+  }
+
   return DebugLoc();
 }