From 1e4782d6f95c065d06ed53eb96036737beb66bef Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Tue, 29 Jun 2010 20:17:53 +0000
Subject: [PATCH] Do not hardcode DW_AT_stmt_list value. Inspired by Artur
 Pietrek.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107202 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/AsmPrinter/DwarfDebug.cpp | 23 ++++++++++++++++-------
 lib/CodeGen/AsmPrinter/DwarfDebug.h   |  1 +
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 2a25cb91010..b983cf2baf5 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -321,6 +321,7 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   DwarfFrameSectionSym = DwarfInfoSectionSym = DwarfAbbrevSectionSym = 0;
   DwarfStrSectionSym = TextSectionSym = 0;
   DwarfDebugRangeSectionSym = DwarfDebugLocSectionSym = 0; 
+  DwarfDebugLineSectionSym = CurrentLineSectionSym = 0;
   FunctionBeginSym = FunctionEndSym = 0;
   {
     NamedRegionTimer T(DbgTimerName, DWARFGroupName, TimePassesIsEnabled);
@@ -1794,9 +1795,9 @@ void DwarfDebug::constructCompileUnit(const MDNode *N) {
   // simplifies debug range entries.
   addUInt(Die, dwarf::DW_AT_entry_pc, dwarf::DW_FORM_addr, 0);
   // DW_AT_stmt_list is a offset of line number information for this
-  // compile unit in debug_line section. It is always zero when only one
-  // compile unit is emitted in one object file.
-  addUInt(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4, 0);
+  // compile unit in debug_line section. This offset is calculated 
+  // during endMoudle().
+  addLabel(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4, 0);
 
   if (!Dir.empty())
     addString(Die, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string, Dir);
@@ -2081,15 +2082,15 @@ void DwarfDebug::endModule() {
   // Compute DIE offsets and sizes.
   computeSizeAndOffsets();
 
+  // Emit source line correspondence into a debug line section.
+  emitDebugLines();
+
   // Emit all the DIEs into a debug info section
   emitDebugInfo();
 
   // Corresponding abbreviations into a abbrev section.
   emitAbbreviations();
 
-  // Emit source line correspondence into a debug line section.
-  emitDebugLines();
-
   // Emit info into a debug pubnames section.
   emitDebugPubNames();
 
@@ -2992,7 +2993,8 @@ void DwarfDebug::EmitSectionLabels() {
   if (const MCSection *MacroInfo = TLOF.getDwarfMacroInfoSection())
     EmitSectionSym(Asm, MacroInfo);
 
-  EmitSectionSym(Asm, TLOF.getDwarfLineSection());
+  DwarfDebugLineSectionSym = 
+    EmitSectionSym(Asm, TLOF.getDwarfLineSection(), "section_line");
   EmitSectionSym(Asm, TLOF.getDwarfLocSection());
   EmitSectionSym(Asm, TLOF.getDwarfPubNamesSection());
   EmitSectionSym(Asm, TLOF.getDwarfPubTypesSection());
@@ -3055,6 +3057,11 @@ void DwarfDebug::emitDIE(DIE *Die) {
                                      4);
       break;
     }
+    case dwarf::DW_AT_stmt_list: {
+      Asm->EmitLabelDifference(CurrentLineSectionSym, 
+                               DwarfDebugLineSectionSym, 4);
+      break;
+    }
     case dwarf::DW_AT_location: {
       if (UseDotDebugLocEntry.count(Die) != 0) {
         DIELabel *L = cast<DIELabel>(Values[i]);
@@ -3200,6 +3207,8 @@ void DwarfDebug::emitDebugLines() {
                             Asm->getObjFileLowering().getDwarfLineSection());
 
   // Construct the section header.
+  CurrentLineSectionSym = Asm->GetTempSymbol("section_line_begin");
+  Asm->OutStreamer.EmitLabel(CurrentLineSectionSym);
   Asm->OutStreamer.AddComment("Length of Source Line Info");
   Asm->EmitLabelDifference(Asm->GetTempSymbol("line_end"),
                            Asm->GetTempSymbol("line_begin"), 4);
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 9b3427dcaf3..4ad3b23a70a 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -258,6 +258,7 @@ class DwarfDebug {
   MCSymbol *DwarfFrameSectionSym, *DwarfInfoSectionSym, *DwarfAbbrevSectionSym;
   MCSymbol *DwarfStrSectionSym, *TextSectionSym, *DwarfDebugRangeSectionSym;
   MCSymbol *DwarfDebugLocSectionSym;
+  MCSymbol *DwarfDebugLineSectionSym, *CurrentLineSectionSym;
   MCSymbol *FunctionBeginSym, *FunctionEndSym;
 private: