Do not unnecessarily use AT_specification DIE because it does not add any value.

Few weeks ago, llvm completely inverted the debug info graph. Earlier each debug info node used to keep track of its compile unit, now compile unit keeps track of important nodes. One impact of this change is that the global variable's do not have any context, which should be checked before deciding to use AT_specification DIE.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140282 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 33a065d5843044a3925af7d37435fa486420fba2..1e1ddca21c86986205a9d9853bc75a6f6920ca6b 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -1081,7 +1081,7 @@ void CompileUnit::createGlobalVariableDIE(const MDNode *N) {
              Asm->Mang->getSymbol(GV.getGlobal()));
     // Do not create specification DIE if context is either compile unit
     // or a subprogram.
-    if (GV.isDefinition() && !GVContext.isCompileUnit() &&
+    if (GVContext && GV.isDefinition() && !GVContext.isCompileUnit() &&
         !GVContext.isFile() && !isSubprogramContext(GVContext)) {
       // Create specification DIE.
       DIE *VariableSpecDIE = new DIE(dwarf::DW_TAG_variable);

diff --git a/test/CodeGen/X86/dbg-at-specficiation.ll b/test/CodeGen/X86/dbg-at-specficiation.ll
new file mode 100644 (file)
index 0000000..aa5e6ef
--- /dev/null
+++ b/test/CodeGen/X86/dbg-at-specficiation.ll
@@ -0,0 +1,20 @@
+; RUN: llc  < %s | FileCheck %s
+; Radar 10147769
+; Do not unnecessarily use AT_specification DIE.
+; CHECK-NOT: AT_specification
+
+@a = common global [10 x i32] zeroinitializer, align 16
+
+!llvm.dbg.cu = !{!0}
+
+!0 = metadata !{i32 720913, i32 0, i32 12, metadata !"x.c", metadata !"/private/tmp", metadata !"clang version 3.0 (trunk 140253)", i1 true, i1 false, metadata !"", i32 0, metadata !1, metadata !1, metadata !1, metadata !3} ; [ DW_TAG_compile_unit ]
+!1 = metadata !{metadata !2}
+!2 = metadata !{i32 0}
+!3 = metadata !{metadata !4}
+!4 = metadata !{metadata !5}
+!5 = metadata !{i32 720948, i32 0, null, metadata !"a", metadata !"a", metadata !"", metadata !6, i32 1, metadata !7, i32 0, i32 1, [10 x i32]* @a} ; [ DW_TAG_variable ]
+!6 = metadata !{i32 720937, metadata !"x.c", metadata !"/private/tmp", null} ; [ DW_TAG_file_type ]
+!7 = metadata !{i32 720897, null, metadata !"", null, i32 0, i64 320, i64 32, i32 0, i32 0, metadata !8, metadata !9, i32 0, i32 0} ; [ DW_TAG_array_type ]
+!8 = metadata !{i32 720932, null, metadata !"int", null, i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
+!9 = metadata !{metadata !10}
+!10 = metadata !{i32 720929, i64 0, i64 9}        ; [ DW_TAG_subrange_type ]