Reapply r198196 with a fix to zero initialize the skeleton pointer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198199 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -773,12 +773,6 @@ DwarfCompileUnit *DwarfDebug::constructDwarfCompileUnit(DICompileUnit DIUnit) {
                  DIUnit.getLanguage());
   NewCU->addString(Die, dwarf::DW_AT_name, FN);
 
-  // 2.17.1 requires that we use DW_AT_low_pc for a single entry point
-  // into an entity. We're using 0 (or a NULL label) for this. For
-  // split dwarf it's in the skeleton CU so omit it here.
-  if (!useSplitDwarf())
-    NewCU->addLabelAddress(Die, dwarf::DW_AT_low_pc, NULL);
-
   // Define start line table label for each Compile Unit.
   MCSymbol *LineTableStartSym =
       Asm->GetTempSymbol("line_table_start", NewCU->getUniqueID());
@@ -837,6 +831,10 @@ DwarfCompileUnit *DwarfDebug::constructDwarfCompileUnit(DICompileUnit DIUnit) {
       // skeleton units, not full units, if it's going to reference skeletons
       DwarfInfoSectionSym);
 
+  // If we're splitting the dwarf then construct the skeleton CU now.
+  if (useSplitDwarf())
+    NewCU->setSkeleton(constructSkeletonCU(NewCU));
+
   CUMap.insert(std::make_pair(DIUnit, NewCU));
   CUDieMap.insert(std::make_pair(Die, NewCU));
   return NewCU;
@@ -1082,7 +1080,9 @@ void DwarfDebug::finalizeModuleInfo() {
     // Add CU specific attributes if we need to add any.
     if (TheU->getUnitDie()->getTag() == dwarf::DW_TAG_compile_unit) {
       // If we're splitting the dwarf out now that we've got the entire
-      // CU then construct a skeleton CU based upon it.
+      // CU then add the dwo id to it.
+      DwarfCompileUnit *SkCU =
+          static_cast<DwarfCompileUnit *>(TheU->getSkeleton());
       if (useSplitDwarf()) {
         // This should be a unique identifier when we want to build .dwp files.
         uint64_t ID = 0;
@@ -1092,19 +1092,22 @@ void DwarfDebug::finalizeModuleInfo() {
         }
         TheU->addUInt(TheU->getUnitDie(), dwarf::DW_AT_GNU_dwo_id,
                       dwarf::DW_FORM_data8, ID);
-        // Now construct the skeleton CU associated.
-        DwarfCompileUnit *SkCU =
-            constructSkeletonCU(static_cast<DwarfCompileUnit *>(TheU));
         SkCU->addUInt(SkCU->getUnitDie(), dwarf::DW_AT_GNU_dwo_id,
                       dwarf::DW_FORM_data8, ID);
-      } else {
-        // Attribute if we've emitted a range list for the compile unit, this
-        // will get constructed for the skeleton CU separately if we have one.
-        if (DwarfCURanges && TheU->getRanges().size())
-          addSectionLabel(Asm, TheU, TheU->getUnitDie(), dwarf::DW_AT_ranges,
-                          Asm->GetTempSymbol("cu_ranges", TheU->getUniqueID()),
-                          DwarfDebugRangeSectionSym);
       }
+
+      // If we've requested ranges and have them emit a DW_AT_ranges attribute
+      // on the unit that will remain in the .o file, otherwise add a DW_AT_low_pc.
+      // FIXME: Also add a high pc if we can.
+      // FIXME: We should use ranges if we have multiple compile units.
+      DwarfCompileUnit *U = SkCU ? SkCU : static_cast<DwarfCompileUnit *>(TheU);
+      if (DwarfCURanges && TheU->getRanges().size())
+        addSectionLabel(Asm, U, U->getUnitDie(), dwarf::DW_AT_ranges,
+                        Asm->GetTempSymbol("cu_ranges", U->getUniqueID()),
+                        DwarfDebugRangeSectionSym);
+      else
+        U->addLocalLabelAddress(U->getUnitDie(), dwarf::DW_AT_low_pc,
+                                TextSectionSym);
     }
   }
 
@@ -2997,15 +3000,6 @@ DwarfCompileUnit *DwarfDebug::constructSkeletonCU(const DwarfCompileUnit *CU) {
   else
     NewCU->addSectionOffset(Die, dwarf::DW_AT_GNU_addr_base, 0);
 
-  // Attribute if we've emitted a range list for the compile unit, this
-  // will get constructed for the skeleton CU separately if we have one.
-  if (DwarfCURanges && CU->getRanges().size())
-    addSectionLabel(Asm, NewCU, Die, dwarf::DW_AT_ranges,
-                    Asm->GetTempSymbol("cu_ranges", CU->getUniqueID()),
-                    DwarfDebugRangeSectionSym);
-  else
-    NewCU->addUInt(Die, dwarf::DW_AT_low_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.
   // FIXME: Should handle multiple compile units.

lib/CodeGen/AsmPrinter/DwarfUnit.cpp

@@ -43,7 +43,7 @@ GenerateDwarfTypeUnits("generate-type-units", cl::Hidden,
 DwarfUnit::DwarfUnit(unsigned UID, DIE *D, DICompileUnit Node, AsmPrinter *A,
                      DwarfDebug *DW, DwarfFile *DWU)
     : UniqueID(UID), Node(Node), UnitDie(D), DebugInfoOffset(0), Asm(A), DD(DW),
-      DU(DWU), IndexTyDie(0), Section(0) {
+      DU(DWU), IndexTyDie(0), Section(0), Skeleton(0) {
   DIEIntegerOne = new (DIEValueAllocator) DIEInteger(1);
 }
 
@@ -293,6 +293,23 @@ void DwarfCompileUnit::addLabelAddress(DIE *Die, dwarf::Attribute Attribute,
   }
 }
 
+/// addLocalLabelAddress - Add a dwarf label attribute data and value using
+/// DW_FORM_addr.
+void DwarfCompileUnit::addLocalLabelAddress(DIE *Die,
+                                            dwarf::Attribute Attribute,
+                                            MCSymbol *Label) {
+  if (Label)
+    DD->addArangeLabel(SymbolCU(this, Label));
+
+  if (Label != NULL) {
+    DIEValue *Value = new (DIEValueAllocator) DIELabel(Label);
+    Die->addValue(Attribute, dwarf::DW_FORM_addr, Value);
+  } else {
+    DIEValue *Value = new (DIEValueAllocator) DIEInteger(0);
+    Die->addValue(Attribute, dwarf::DW_FORM_addr, Value);
+  }
+}
+
 /// addOpAddress - Add a dwarf op address data and value using the
 /// form given and an op of either DW_FORM_addr or DW_FORM_GNU_addr_index.
 ///

lib/CodeGen/AsmPrinter/DwarfUnit.h

@@ -146,12 +146,21 @@ class DwarfUnit {
   /// The label for the start of the range sets for the elements of this unit.
   MCSymbol *LabelRange;
 
+  /// Skeleton unit associated with this unit.
+  DwarfUnit *Skeleton;
+
   DwarfUnit(unsigned UID, DIE *D, DICompileUnit CU, AsmPrinter *A,
             DwarfDebug *DW, DwarfFile *DWU);
 
 public:
   virtual ~DwarfUnit();
 
+  /// Set the skeleton unit associated with this unit.
+  void setSkeleton(DwarfUnit *Skel) { Skeleton = Skel; }
+
+  /// Get the skeleton unit associated with this unit.
+  DwarfUnit *getSkeleton() const { return Skeleton; }
+
   /// Pass in the SectionSym even though we could recreate it in every compile
   /// unit (type units will have actually distinct symbols once they're in
   /// comdat sections).
@@ -521,6 +530,11 @@ class DwarfCompileUnit : public DwarfUnit {
   /// either DW_FORM_addr or DW_FORM_GNU_addr_index.
   void addLabelAddress(DIE *Die, dwarf::Attribute Attribute, MCSymbol *Label);
 
+  /// addLocalLabelAddress - Add a dwarf label attribute data and value using
+  /// DW_FORM_addr.
+  void addLocalLabelAddress(DIE *Die, dwarf::Attribute Attribute,
+                            MCSymbol *Label);
+
   uint16_t getLanguage() const LLVM_OVERRIDE { return getNode().getLanguage(); }
 };
 

test/DebugInfo/X86/fission-cu.ll

@@ -25,19 +25,19 @@
 ; CHECK: [1] DW_TAG_compile_unit DW_CHILDREN_no
 ; CHECK: DW_AT_GNU_dwo_name      DW_FORM_strp
 ; CHECK: DW_AT_GNU_addr_base     DW_FORM_sec_offset
-; CHECK: DW_AT_low_pc    DW_FORM_addr
 ; CHECK: DW_AT_stmt_list DW_FORM_sec_offset
 ; CHECK: DW_AT_comp_dir  DW_FORM_strp
 ; CHECK: DW_AT_GNU_dwo_id        DW_FORM_data8
+; CHECK: DW_AT_low_pc    DW_FORM_addr
 
 ; CHECK: .debug_info contents:
 ; CHECK: DW_TAG_compile_unit
 ; CHECK: DW_AT_GNU_dwo_name [DW_FORM_strp] ( .debug_str[0x00000000] = "baz.dwo")
 ; CHECK: DW_AT_GNU_addr_base [DW_FORM_sec_offset]                   (0x00000000)
-; CHECK: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
 ; CHECK: DW_AT_stmt_list [DW_FORM_sec_offset]   (0x00000000)
 ; CHECK: DW_AT_comp_dir [DW_FORM_strp]     ( .debug_str[0x00000008] = "/usr/local/google/home/echristo/tmp")
 ; CHECK: DW_AT_GNU_dwo_id [DW_FORM_data8]  (0x0000000000000000)
+; CHECK: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
 
 ; CHECK: .debug_str contents:
 ; CHECK: 0x00000000: "baz.dwo"
@@ -110,5 +110,6 @@
 ; OBJ-NEXT: R_X86_64_32 .debug_addr
 ; OBJ-NEXT: R_X86_64_32 .debug_line
 ; OBJ-NEXT: R_X86_64_32 .debug_str
+; OBJ-NEXT: R_X86_64_64 .text 0x0
 ; OBJ-NEXT: }
 !9 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}

test/DebugInfo/X86/stmt-list-multiple-compile-units.ll

@@ -7,12 +7,12 @@
 ; rdar://13067005
 ; CHECK: .debug_info contents:
 ; CHECK: DW_TAG_compile_unit
-; CHECK: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
 ; CHECK: DW_AT_stmt_list [DW_FORM_sec_offset]   (0x00000000)
+; CHECK: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
 
 ; CHECK: DW_TAG_compile_unit
-; CHECK: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
 ; CHECK: DW_AT_stmt_list [DW_FORM_sec_offset]   (0x0000003c)
+; CHECK: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
 
 ; CHECK: .debug_line contents:
 ; CHECK-NEXT: Line table prologue:
@@ -25,12 +25,12 @@
 
 ; DWARF3: .debug_info contents:
 ; DWARF3: DW_TAG_compile_unit
-; DWARF3: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
 ; DWARF3: DW_AT_stmt_list [DW_FORM_data4]   (0x00000000)
+; DWARF3: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
 
 ; DWARF3: DW_TAG_compile_unit
-; DWARF3: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
 ; DWARF3: DW_AT_stmt_list [DW_FORM_data4]   (0x0000003c)
+; DWARF3: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
 
 ; DWARF3: .debug_line contents:
 ; DWARF3-NEXT: Line table prologue: