Split address information for DWARF5 split dwarf proposal. This involves

using the DW_FORM_GNU_addr_index and a separate .debug_addr section which
stays in the executable and is fully linked.

Sneak in two other small changes:

a) Print out the debug_str_offsets.dwo section.
b) Change form we're expecting the entries in the debug_str_offsets.dwo
   section to take from ULEB128 to U32.

Add tests for all of this in the fission-cu.ll test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172578 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 65 insertions, 20 deletions

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 93106a0596..1813132f87 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -237,6 +237,15 @@ unsigned DwarfUnits::getStringPoolIndex(StringRef Str) {
   return Entry.second;
 }
 
+unsigned DwarfUnits::getAddrPoolIndex(MCSymbol *Sym) {
+  std::pair<MCSymbol*, unsigned> &Entry = AddressPool[Sym];
+  if (Entry.first) return Entry.second;
+
+  Entry.second = NextAddrPoolNumber++;
+  Entry.first = Sym;
+  return Entry.second;
+}
+
 // Define a unique number for the abbreviation.
 //
 void DwarfUnits::assignAbbrevNumber(DIEAbbrev &Abbrev) {
@@ -384,10 +393,12 @@ DIE *DwarfDebug::updateSubprogramScopeDIE(CompileUnit *SPCU,
     }
   }
 
-  SPCU->addLabel(SPDie, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr,
-                 Asm->GetTempSymbol("func_begin", Asm->getFunctionNumber()));
-  SPCU->addLabel(SPDie, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr,
-                 Asm->GetTempSymbol("func_end", Asm->getFunctionNumber()));
+  SPCU->addLabelAddress(SPDie, dwarf::DW_AT_low_pc,
+                        Asm->GetTempSymbol("func_begin",
+                                           Asm->getFunctionNumber()));
+  SPCU->addLabelAddress(SPDie, dwarf::DW_AT_high_pc,
+                        Asm->GetTempSymbol("func_end",
+                                           Asm->getFunctionNumber()));
   const TargetRegisterInfo *RI = Asm->TM.getRegisterInfo();
   MachineLocation Location(RI->getFrameRegister(*Asm->MF));
   SPCU->addAddress(SPDie, dwarf::DW_AT_frame_base, Location);
@@ -429,16 +440,16 @@ DIE *DwarfDebug::constructLexicalScopeDIE(CompileUnit *TheCU,
     return ScopeDIE;
   }
 
-  const MCSymbol *Start = getLabelBeforeInsn(RI->first);
-  const MCSymbol *End = getLabelAfterInsn(RI->second);
+  MCSymbol *Start = getLabelBeforeInsn(RI->first);
+  MCSymbol *End = getLabelAfterInsn(RI->second);
 
   if (End == 0) return 0;
 
   assert(Start->isDefined() && "Invalid starting label for an inlined scope!");
   assert(End->isDefined() && "Invalid end label for an inlined scope!");
 
-  TheCU->addLabel(ScopeDIE, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr, Start);
-  TheCU->addLabel(ScopeDIE, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr, End);
+  TheCU->addLabelAddress(ScopeDIE, dwarf::DW_AT_low_pc, Start);
+  TheCU->addLabelAddress(ScopeDIE, dwarf::DW_AT_high_pc, End);
 
   return ScopeDIE;
 }
@@ -462,8 +473,8 @@ DIE *DwarfDebug::constructInlinedScopeDIE(CompileUnit *TheCU,
   }
 
   SmallVector<InsnRange, 4>::const_iterator RI = Ranges.begin();
-  const MCSymbol *StartLabel = getLabelBeforeInsn(RI->first);
-  const MCSymbol *EndLabel = getLabelAfterInsn(RI->second);
+  MCSymbol *StartLabel = getLabelBeforeInsn(RI->first);
+  MCSymbol *EndLabel = getLabelAfterInsn(RI->second);
 
   if (StartLabel == 0 || EndLabel == 0) {
     llvm_unreachable("Unexpected Start and End labels for an inlined scope!");
@@ -492,10 +503,8 @@ DIE *DwarfDebug::constructInlinedScopeDIE(CompileUnit *TheCU,
     DebugRangeSymbols.push_back(NULL);
     DebugRangeSymbols.push_back(NULL);
   } else {
-    TheCU->addLabel(ScopeDIE, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr,
-                    StartLabel);
-    TheCU->addLabel(ScopeDIE, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr,
-                    EndLabel);
+    TheCU->addLabelAddress(ScopeDIE, dwarf::DW_AT_low_pc, StartLabel);
+    TheCU->addLabelAddress(ScopeDIE, dwarf::DW_AT_high_pc, EndLabel);
   }
 
   InlinedSubprogramDIEs.insert(OriginDIE);
@@ -646,8 +655,8 @@ CompileUnit *DwarfDebug::constructCompileUnit(const MDNode *N) {
                  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.
-  NewCU->addUInt(Die, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr, 0);
+  // into an entity. We're using 0 (or a NULL label) for this.
+  NewCU->addLabelAddress(Die, dwarf::DW_AT_low_pc, NULL);
   // DW_AT_stmt_list is a offset of line number information for this
   // compile unit in debug_line section.
   if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
@@ -975,6 +984,9 @@ void DwarfDebug::endModule() {
     // Emit info into a debug macinfo section.
     emitDebugMacInfo();
 
+    // Emit DWO addresses.
+    InfoHolder.emitAddresses(Asm->getObjFileLowering().getDwarfAddrSection());
+
     // Emit inline info.
     // TODO: When we don't need the option anymore we
     // can remove all of the code that this section
@@ -1234,14 +1246,14 @@ DwarfDebug::collectVariableInfo(const MachineFunction *MF,
 }
 
 // Return Label preceding the instruction.
-const MCSymbol *DwarfDebug::getLabelBeforeInsn(const MachineInstr *MI) {
+MCSymbol *DwarfDebug::getLabelBeforeInsn(const MachineInstr *MI) {
   MCSymbol *Label = LabelsBeforeInsn.lookup(MI);
   assert(Label && "Didn't insert label before instruction");
   return Label;
 }
 
 // Return Label immediately following the instruction.
-const MCSymbol *DwarfDebug::getLabelAfterInsn(const MachineInstr *MI) {
+MCSymbol *DwarfDebug::getLabelAfterInsn(const MachineInstr *MI) {
   return LabelsAfterInsn.lookup(MI);
 }
 
@@ -2158,7 +2170,7 @@ void DwarfUnits::emitStrings(const MCSection *StrSection,
   if (OffsetSection) {
     Asm->OutStreamer.SwitchSection(OffsetSection);
     unsigned offset = 0;
-    unsigned size = 4;
+    unsigned size = 4; // FIXME: DWARF64 is 8.
     for (unsigned i = 0, e = Entries.size(); i != e; ++i) {
       Asm->OutStreamer.EmitIntValue(offset, size);
       offset += Entries[i].second->getKeyLength() + 1;
@@ -2166,6 +2178,38 @@ void DwarfUnits::emitStrings(const MCSection *StrSection,
   }
 }
 
+// Emit strings into a string section.
+void DwarfUnits::emitAddresses(const MCSection *AddrSection) {
+
+  if (AddressPool.empty()) return;
+
+  // Start the dwarf addr section.
+  Asm->OutStreamer.SwitchSection(AddrSection);
+
+  // Get all of the string pool entries and put them in an array by their ID so
+  // we can sort them.
+  SmallVector<std::pair<unsigned,
+                        std::pair<MCSymbol*, unsigned>* >, 64> Entries;
+
+  for (DenseMap<MCSymbol*, std::pair<MCSymbol*, unsigned> >::iterator
+         I = AddressPool.begin(), E = AddressPool.end();
+       I != E; ++I)
+    Entries.push_back(std::make_pair(I->second.second, &(I->second)));
+
+  array_pod_sort(Entries.begin(), Entries.end());
+
+  for (unsigned i = 0, e = Entries.size(); i != e; ++i) {
+    // Emit a label for reference from debug information entries.
+    MCSymbol *Sym = Entries[i].second->first;
+    if (Sym)
+      Asm->EmitLabelReference(Entries[i].second->first,
+                              Asm->getDataLayout().getPointerSize());
+    else
+      Asm->OutStreamer.EmitIntValue(0, Asm->getDataLayout().getPointerSize());
+  }
+
+}
+
 // Emit visible names into a debug str section.
 void DwarfDebug::emitDebugStr() {
   DwarfUnits &Holder = useSplitDwarf() ? SkeletonHolder : InfoHolder;
@@ -2402,8 +2446,9 @@ CompileUnit *DwarfDebug::constructSkeletonCU(const MDNode *N) {
   // FIXME: We also need DW_AT_addr_base and DW_AT_dwo_id.
 
   // 2.17.1 requires that we use DW_AT_low_pc for a single entry point
-  // into an entity.
+  // into an entity. We're using 0, or a NULL label for this.
   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.
   if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())