Emit declarations before definitions if they are available. This causes DW_AT_specification to

point back in the file in the included testcase. Fixes PR11300.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143726 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 83 insertions, 6 deletions

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 0f4ea051a2..b022c430ac 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -194,11 +194,7 @@ DIE *DwarfDebug::updateSubprogramScopeDIE(CompileUnit *SPCU,
   DISubprogram SP(SPNode);
 
   DISubprogram SPDecl = SP.getFunctionDeclaration();
-  if (SPDecl.isSubprogram())
-    // Refer function declaration directly.
-    SPCU->addDIEEntry(SPDie, dwarf::DW_AT_specification, dwarf::DW_FORM_ref4,
-                      SPCU->getOrCreateSubprogramDIE(SPDecl));
-  else {
+  if (!SPDecl.isSubprogram()) {
     // There is not any need to generate specification DIE for a function
     // defined at compile unit level. If a function is defined inside another
     // function then gdb prefers the definition at top level and but does not
@@ -512,14 +508,31 @@ CompileUnit *DwarfDebug::constructCompileUnit(const MDNode *N) {
 /// construct SubprogramDIE - Construct subprogram DIE.
 void DwarfDebug::constructSubprogramDIE(CompileUnit *TheCU, 
                                         const MDNode *N) {
+  CompileUnit *&CURef = SPMap[N];
+  if (CURef)
+    return;
+  CURef = TheCU;
+
   DISubprogram SP(N);
   if (!SP.isDefinition())
     // This is a method declaration which will be handled while constructing
     // class type.
     return;
 
+  DISubprogram SPDecl = SP.getFunctionDeclaration();
+  DIE *DeclDie = NULL;
+  if (SPDecl.isSubprogram()) {
+    DeclDie = TheCU->getOrCreateSubprogramDIE(SPDecl);
+  }
+
   DIE *SubprogramDie = TheCU->getOrCreateSubprogramDIE(SP);
 
+  if (DeclDie) {
+    // Refer function declaration directly.
+    TheCU->addDIEEntry(SubprogramDie, dwarf::DW_AT_specification,
+                       dwarf::DW_FORM_ref4, DeclDie);
+  }
+
   // Add to map.
   TheCU->insertDIE(N, SubprogramDie);
 
@@ -529,7 +542,6 @@ void DwarfDebug::constructSubprogramDIE(CompileUnit *TheCU,
   // Expose as global.
   TheCU->addGlobal(SP.getName(), SubprogramDie);
 
-  SPMap[N] = TheCU;
   return;
 }
 
diff --git a/test/DebugInfo/pr11300.ll b/test/DebugInfo/pr11300.ll
new file mode 100644
index 0000000000..ed8be6bd13
--- /dev/null
+++ b/test/DebugInfo/pr11300.ll
@@ -0,0 +1,65 @@
+; RUN: llc %s -o %t -filetype=obj
+; RUN: llvm-dwarfdump %t | FileCheck %s
+
+; test that the DW_AT_specification is a back edge in the file.
+
+; CHECK: 0x00000063:     DW_TAG_subprogram [5]
+; CHECK: 0x00000089:     DW_AT_specification [DW_FORM_ref4]      (cu + 0x0063 => {0x00000063})
+
+%struct.foo = type { i8 }
+
+define void @_Z3zedP3foo(%struct.foo* %x) uwtable {
+entry:
+  %x.addr = alloca %struct.foo*, align 8
+  store %struct.foo* %x, %struct.foo** %x.addr, align 8
+  call void @llvm.dbg.declare(metadata !{%struct.foo** %x.addr}, metadata !23), !dbg !24
+  %0 = load %struct.foo** %x.addr, align 8, !dbg !25
+  call void @_ZN3foo3barEv(%struct.foo* %0), !dbg !25
+  ret void, !dbg !27
+}
+
+declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
+
+define linkonce_odr void @_ZN3foo3barEv(%struct.foo* %this) nounwind uwtable align 2 {
+entry:
+  %this.addr = alloca %struct.foo*, align 8
+  store %struct.foo* %this, %struct.foo** %this.addr, align 8
+  call void @llvm.dbg.declare(metadata !{%struct.foo** %this.addr}, metadata !28), !dbg !29
+  %this1 = load %struct.foo** %this.addr
+  ret void, !dbg !30
+}
+
+!llvm.dbg.cu = !{!0}
+
+!0 = metadata !{i32 720913, i32 0, i32 4, metadata !"/home/espindola/llvm/test.cc", metadata !"/home/espindola/tmpfs/build", metadata !"clang version 3.0 ()", i1 true, i1 false, metadata !"", i32 0, metadata !1, metadata !1, metadata !3, metadata !1} ; [ DW_TAG_compile_unit ]
+!1 = metadata !{metadata !2}
+!2 = metadata !{i32 0}
+!3 = metadata !{metadata !4}
+!4 = metadata !{metadata !5, metadata !20}
+!5 = metadata !{i32 720942, i32 0, metadata !6, metadata !"zed", metadata !"zed", metadata !"_Z3zedP3foo", metadata !6, i32 4, metadata !7, i1 false, i1 true, i32 0, i32 0, i32 0, i32 256, i1 false, void (%struct.foo*)* @_Z3zedP3foo, null, null, metadata !18} ; [ DW_TAG_subprogram ]
+!6 = metadata !{i32 720937, metadata !"/home/espindola/llvm/test.cc", metadata !"/home/espindola/tmpfs/build", null} ; [ DW_TAG_file_type ]
+!7 = metadata !{i32 720917, i32 0, metadata !"", i32 0, i32 0, i64 0, i64 0, i32 0, i32 0, i32 0, metadata !8, i32 0, i32 0} ; [ DW_TAG_subroutine_type ]
+!8 = metadata !{null, metadata !9}
+!9 = metadata !{i32 720911, null, metadata !"", null, i32 0, i64 64, i64 64, i64 0, i32 0, metadata !10} ; [ DW_TAG_pointer_type ]
+!10 = metadata !{i32 720898, null, metadata !"foo", metadata !6, i32 1, i64 8, i64 8, i32 0, i32 0, null, metadata !11, i32 0, null, null} ; [ DW_TAG_class_type ]
+!11 = metadata !{metadata !12}
+!12 = metadata !{i32 720942, i32 0, metadata !10, metadata !"bar", metadata !"bar", metadata !"_ZN3foo3barEv", metadata !6, i32 2, metadata !13, i1 false, i1 false, i32 0, i32 0, null, i32 256, i1 false, null, null, i32 0, metadata !16} ; [ DW_TAG_subprogram ]
+!13 = metadata !{i32 720917, i32 0, metadata !"", i32 0, i32 0, i64 0, i64 0, i32 0, i32 0, i32 0, metadata !14, i32 0, i32 0} ; [ DW_TAG_subroutine_type ]
+!14 = metadata !{null, metadata !15}
+!15 = metadata !{i32 720911, i32 0, metadata !"", i32 0, i32 0, i64 64, i64 64, i64 0, i32 64, metadata !10} ; [ DW_TAG_pointer_type ]
+!16 = metadata !{metadata !17}
+!17 = metadata !{i32 720932}                      ; [ DW_TAG_base_type ]
+!18 = metadata !{metadata !19}
+!19 = metadata !{i32 720932}                      ; [ DW_TAG_base_type ]
+!20 = metadata !{i32 720942, i32 0, null, metadata !"bar", metadata !"bar", metadata !"_ZN3foo3barEv", metadata !6, i32 2, metadata !13, i1 false, i1 true, i32 0, i32 0, i32 0, i32 256, i1 false, void (%struct.foo*)* @_ZN3foo3barEv, null, metadata !12, metadata !21} ; [ DW_TAG_subprogram ]
+!21 = metadata !{metadata !22}
+!22 = metadata !{i32 720932}                      ; [ DW_TAG_base_type ]
+!23 = metadata !{i32 721153, metadata !5, metadata !"x", metadata !6, i32 16777220, metadata !9, i32 0, i32 0} ; [ DW_TAG_arg_variable ]
+!24 = metadata !{i32 4, i32 15, metadata !5, null}
+!25 = metadata !{i32 4, i32 20, metadata !26, null}
+!26 = metadata !{i32 720907, metadata !5, i32 4, i32 18, metadata !6, i32 0} ; [ DW_TAG_lexical_block ]
+!27 = metadata !{i32 4, i32 30, metadata !26, null}
+!28 = metadata !{i32 721153, metadata !20, metadata !"this", metadata !6, i32 16777218, metadata !15, i32 64, i32 0} ; [ DW_TAG_arg_variable ]
+!29 = metadata !{i32 2, i32 8, metadata !20, null}
+!30 = metadata !{i32 2, i32 15, metadata !31, null}
+!31 = metadata !{i32 720907, metadata !20, i32 2, i32 14, metadata !6, i32 1} ; [ DW_TAG_lexical_block ]