DwarfDebug: Emit dwo_id+dwo_name for DICompileUnits that provide a dwoId.

For module debugging clang emits prefabricated skeleton compile units
that can be recognized by a nonzero dwoId.

llvm-svn: 247626

2 files changed, 23 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 4a673d49ced..31d73a9035f 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -459,6 +459,14 @@ DwarfDebug::constructDwarfCompileUnit(const DICompileUnit *DIUnit) {
   else
     NewCU.initSection(Asm->getObjFileLowering().getDwarfInfoSection());
 
+  // Module debugging: This is a prefabricated skeleton CU.
+  if (DIUnit->getDWOId()) {
+    NewCU.addUInt(Die, dwarf::DW_AT_GNU_dwo_id, dwarf::DW_FORM_data8,
+                  DIUnit->getDWOId());
+    NewCU.addString(Die, dwarf::DW_AT_GNU_dwo_name,
+                    DIUnit->getSplitDebugFilename());
+  }
+
   CUMap.insert(std::make_pair(DIUnit, &NewCU));
   CUDieMap.insert(std::make_pair(&Die, &NewCU));
   return NewCU;
diff --git a/llvm/test/DebugInfo/skeletoncu.ll b/llvm/test/DebugInfo/skeletoncu.ll
new file mode 100644
index 00000000000..74ffec4519e
--- /dev/null
+++ b/llvm/test/DebugInfo/skeletoncu.ll
@@ -0,0 +1,15 @@
+; RUN: %llc_dwarf %s -filetype=obj -o %t
+; RUN: llvm-dwarfdump -debug-dump=info %t | FileCheck %s
+; CHECK: DW_TAG_compile_unit
+; CHECK: DW_AT_GNU_dwo_id {{.*}}abcd
+; CHECK: DW_AT_GNU_dwo_name {{.*}}"my.dwo"
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "LLVM", isOptimized: false, runtimeVersion: 2, splitDebugFilename: "my.dwo", emissionKind: 1, enums: !2, retainedTypes: !2, subprograms: !2, globals: !2, imports: !2, dwoId: 43981)
+!1 = !DIFile(filename: "<stdin>", directory: "/")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+