[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

1 files changed, 18 insertions, 0 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;