[DWARF] Basic support for producing DWARFv5 .debug_addr section

This revision implements support for generating DWARFv5 .debug_addr section.
The implementation is pretty straight-forward: we just check the dwarf version
and emit section header if needed.

Reviewers: aprantl, dblaikie, probinson

Reviewed by: dblaikie

Differential Revision: https://reviews.llvm.org/D50005

llvm-svn: 338487

4 files changed, 31 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/AddressPool.cpp b/llvm/lib/CodeGen/AsmPrinter/AddressPool.cpp
index 4a226527cb5..c8305ad9c54 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AddressPool.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AddressPool.cpp
@@ -24,8 +24,26 @@ unsigned AddressPool::getIndex(const MCSymbol *Sym, bool TLS) {
   return IterBool.first->second.Number;
 }
 
+
+void AddressPool::emitHeader(AsmPrinter &Asm, MCSection *Section) {
+  static const uint8_t AddrSize = Asm.getDataLayout().getPointerSize();
+  Asm.OutStreamer->SwitchSection(Section);
+
+  uint64_t Length = sizeof(uint16_t) // version
+                  + sizeof(uint8_t)  // address_size
+                  + sizeof(uint8_t)  // segment_selector_size
+                  + AddrSize * Pool.size(); // entries
+  Asm.emitInt32(Length); // TODO: Support DWARF64 format.
+  Asm.emitInt16(Asm.getDwarfVersion());
+  Asm.emitInt8(AddrSize);
+  Asm.emitInt8(0); // TODO: Support non-zero segment_selector_size.
+}
+
 // Emit addresses into the section given.
 void AddressPool::emit(AsmPrinter &Asm, MCSection *AddrSection) {
+  if (Asm.getDwarfVersion() >= 5)
+    emitHeader(Asm, AddrSection);
+
   if (Pool.empty())
     return;
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/AddressPool.h b/llvm/lib/CodeGen/AsmPrinter/AddressPool.h
index 5350006bf74..d5008fab556 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AddressPool.h
+++ b/llvm/lib/CodeGen/AsmPrinter/AddressPool.h
@@ -50,6 +50,9 @@ public:
   bool hasBeenUsed() const { return HasBeenUsed; }
 
   void resetUsedFlag() { HasBeenUsed = false; }
+
+private:
+  void emitHeader(AsmPrinter &Asm, MCSection *Section);
 };
 
 } // end namespace llvm
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index e5a457e424b..0af408ae599 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -886,8 +886,7 @@ void DwarfDebug::endModule() {
     emitDebugInfoDWO();
     emitDebugAbbrevDWO();
     emitDebugLineDWO();
-    // Emit DWO addresses.
-    AddrPool.emit(*Asm, Asm->getObjFileLowering().getDwarfAddrSection());
+    emitDebugAddr();
   }
 
   // Emit info into the dwarf accelerator table sections.
@@ -2297,6 +2296,12 @@ void DwarfDebug::emitDebugStrDWO() {
                          OffSec, /* UseRelativeOffsets = */ false);
 }
 
+// Emit DWO addresses.
+void DwarfDebug::emitDebugAddr() {
+  assert(useSplitDwarf() && "No split dwarf?");
+  AddrPool.emit(*Asm, Asm->getObjFileLowering().getDwarfAddrSection());
+}
+
 MCDwarfDwoLineTable *DwarfDebug::getDwoLineTable(const DwarfCompileUnit &CU) {
   if (!useSplitDwarf())
     return nullptr;
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 0c7be5d27df..abf2e43b131 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -447,6 +447,9 @@ class DwarfDebug : public DebugHandlerBase {
   /// Emit the debug str dwo section.
   void emitDebugStrDWO();
 
+  /// Emit DWO addresses.
+  void emitDebugAddr();
+
   /// Flags to let the linker know we have emitted new style pubnames. Only
   /// emit it here if we don't have a skeleton CU for split dwarf.
   void addGnuPubAttributes(DwarfCompileUnit &U, DIE &D) const;