DebugInfo: Add ability to not emit DW_AT_vtable_elem_location for vir…

…tual functions. A virtual index of -1u indicates that the subprogram's virtual index is unrepresentable (for example, when using the relative vtable ABI), so do not emit a DW_AT_vtable_elem_location attribute for it. Differential Revision: http://reviews.llvm.org/D18236 llvm-svn: 263765
llvm · Mar 17, 2016 · a1f8625 · a1f8625
1 parent 64e936f
commit a1f8625
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Showing 6 changed files with 105 additions and 11 deletions.
diff --git a/llvm/include/llvm/IR/DIBuilder.h b/llvm/include/llvm/IR/DIBuilder.h
@@ -558,7 +558,8 @@ namespace llvm {
     /// \param isDefinition  True if this is a function definition.
     /// \param Virtuality    Attributes describing virtualness. e.g. pure
     ///                      virtual function.
-    /// \param VTableIndex   Index no of this method in virtual table.
+    /// \param VTableIndex   Index no of this method in virtual table, or -1u if
+    ///                      unrepresentable.
     /// \param VTableHolder  Type that holds vtable.
     /// \param Flags         e.g. is this function prototyped or not.
     ///                      This flags are used to emit dwarf attributes.

diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
@@ -3353,7 +3353,7 @@ bool LLParser::ParseMDField(LocTy Loc, StringRef Name,
     return TokError("expected DWARF virtuality code");
 
   unsigned Virtuality = dwarf::getVirtuality(Lex.getStrVal());
-  if (!Virtuality)
+  if (Virtuality == dwarf::DW_VIRTUALITY_invalid)
     return TokError("invalid DWARF virtuality code" + Twine(" '") +
                     Lex.getStrVal() + "'");
   assert(Virtuality <= Result.Max && "Expected valid DWARF virtuality code");

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -1218,10 +1218,12 @@ void DwarfUnit::applySubprogramAttributes(const DISubprogram *SP, DIE &SPDie,
   unsigned VK = SP->getVirtuality();
   if (VK) {
     addUInt(SPDie, dwarf::DW_AT_virtuality, dwarf::DW_FORM_data1, VK);
-    DIELoc *Block = getDIELoc();
-    addUInt(*Block, dwarf::DW_FORM_data1, dwarf::DW_OP_constu);
-    addUInt(*Block, dwarf::DW_FORM_udata, SP->getVirtualIndex());
-    addBlock(SPDie, dwarf::DW_AT_vtable_elem_location, Block);
+    if (SP->getVirtualIndex() != -1u) {
+      DIELoc *Block = getDIELoc();
+      addUInt(*Block, dwarf::DW_FORM_data1, dwarf::DW_OP_constu);
+      addUInt(*Block, dwarf::DW_FORM_udata, SP->getVirtualIndex());
+      addBlock(SPDie, dwarf::DW_AT_vtable_elem_location, Block);
+    }
     ContainingTypeMap.insert(
         std::make_pair(&SPDie, resolve(SP->getContainingType())));
   }

diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
@@ -1669,7 +1669,9 @@ static void writeDISubprogram(raw_ostream &Out, const DISubprogram *N,
   Printer.printMetadata("containingType", N->getRawContainingType());
   Printer.printDwarfEnum("virtuality", N->getVirtuality(),
                          dwarf::VirtualityString);
-  Printer.printInt("virtualIndex", N->getVirtualIndex());
+  if (N->getVirtuality() != dwarf::DW_VIRTUALITY_none ||
+      N->getVirtualIndex() != 0)
+    Printer.printInt("virtualIndex", N->getVirtualIndex(), false);
   Printer.printDIFlags("flags", N->getFlags());
   Printer.printBool("isOptimized", N->isOptimized());
   Printer.printMetadata("templateParams", N->getRawTemplateParams());

diff --git a/llvm/test/Assembler/disubprogram.ll b/llvm/test/Assembler/disubprogram.ll
@@ -6,8 +6,8 @@ define void @_Z3foov() !dbg !9 {
   ret void
 }
 
-; CHECK: !named = !{!0, !1, !2, !3, !4, !5, !6, !7, !8, !9}
-!named = !{!0, !1, !2, !3, !4, !5, !6, !7, !8, !9}
+; CHECK: !named = !{!0, !1, !2, !3, !4, !5, !6, !7, !8, !9, !10, !11}
+!named = !{!0, !1, !2, !3, !4, !5, !6, !7, !8, !9, !10, !11}
 
 !0 = !{null}
 !1 = distinct !DICompositeType(tag: DW_TAG_structure_type)
@@ -31,5 +31,23 @@ define void @_Z3foov() !dbg !9 {
                             flags: DIFlagPrototyped, isOptimized: true,
                             templateParams: !5, declaration: !8, variables: !6)
 
-!10 = !{i32 1, !"Debug Info Version", i32 3}
-!llvm.module.flags = !{!10}
+; CHECK: !10 = distinct !DISubprogram
+; CHECK-SAME: virtualIndex: 0,
+!10 = distinct !DISubprogram(name: "foo", linkageName: "_Zfoov", scope: !1,
+                            file: !2, line: 7, type: !3, isLocal: true,
+                            isDefinition: true, scopeLine: 8, containingType: !4,
+                            virtuality: DW_VIRTUALITY_pure_virtual, virtualIndex: 0,
+                            flags: DIFlagPrototyped, isOptimized: true,
+                            templateParams: !5, declaration: !8, variables: !6)
+
+; CHECK: !11 = distinct !DISubprogram
+; CHECK-NOT: virtualIndex
+!11 = distinct !DISubprogram(name: "foo", linkageName: "_Zfoov", scope: !1,
+                            file: !2, line: 7, type: !3, isLocal: true,
+                            isDefinition: true, scopeLine: 8, containingType: !4,
+                            virtuality: DW_VIRTUALITY_none,
+                            flags: DIFlagPrototyped, isOptimized: true,
+                            templateParams: !5, declaration: !8, variables: !6)
+
+!12 = !{i32 1, !"Debug Info Version", i32 3}
+!llvm.module.flags = !{!12}
diff --git a/llvm/test/DebugInfo/Generic/virtual-index.ll b/llvm/test/DebugInfo/Generic/virtual-index.ll
@@ -0,0 +1,71 @@
+; REQUIRES: object-emission
+
+; RUN: %llc_dwarf -O0 -filetype=obj < %s > %t
+; RUN: llvm-dwarfdump %t | FileCheck %s
+
+; Generated from the following C++ source code:
+;
+; struct A {
+;   virtual void f();
+;   virtual void g();
+; };
+;
+; void A::f() {}
+; void A::g() {}
+;
+; and manually edited to set virtualIndex attribute on the A::g subprogram to
+; 4294967295.
+
+; CHECK: DW_TAG_subprogram [
+; CHECK: DW_AT_vtable_elem_location [DW_FORM_exprloc]  (<0x2> 10 00 )
+
+; CHECK: DW_TAG_subprogram [
+; CHECK-NOT: DW_AT_vtable_elem_location
+
+%struct.A = type { i32 (...)** }
+
+@_ZTV1A = unnamed_addr constant [4 x i8*] [i8* null, i8* null, i8* bitcast (void (%struct.A*)* @_ZN1A1fEv to i8*), i8* bitcast (void (%struct.A*)* @_ZN1A1gEv to i8*)], align 8
+
+define void @_ZN1A1fEv(%struct.A* %this) unnamed_addr !dbg !18 {
+  ret void
+}
+
+define void @_ZN1A1gEv(%struct.A* %this) unnamed_addr !dbg !19 {
+  ret void
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!20, !21}
+!llvm.ident = !{!22}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, retainedTypes: !3, subprograms: !17)
+!1 = !DIFile(filename: "x", directory: "x")
+!2 = !{}
+!3 = !{!4}
+!4 = !DICompositeType(tag: DW_TAG_structure_type, name: "A", file: !1, line: 1, size: 64, align: 64, elements: !5, vtableHolder: !"_ZTS1A", identifier: "_ZTS1A")
+!5 = !{!6, !12, !16}
+!6 = !DIDerivedType(tag: DW_TAG_member, name: "_vptr$A", scope: !1, file: !1, baseType: !7, size: 64, flags: DIFlagArtificial)
+!7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !8, size: 64)
+!8 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "__vtbl_ptr_type", baseType: !9, size: 64)
+!9 = !DISubroutineType(types: !10)
+!10 = !{!11}
+!11 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!12 = !DISubprogram(name: "f", linkageName: "_ZN1A1fEv", scope: !"_ZTS1A", file: !1, line: 2, type: !13, isLocal: false, isDefinition: false, scopeLine: 2, containingType: !"_ZTS1A", virtuality: DW_VIRTUALITY_virtual, virtualIndex: 0, flags: DIFlagPrototyped, isOptimized: false)
+!13 = !DISubroutineType(types: !14)
+!14 = !{null, !15}
+!15 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !"_ZTS1A", size: 64, align: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!16 = !DISubprogram(name: "g", linkageName: "_ZN1A1gEv", scope: !"_ZTS1A", file: !1, line: 3, type: !13, isLocal: false, isDefinition: false, scopeLine: 3, containingType: !"_ZTS1A", virtuality: DW_VIRTUALITY_virtual, virtualIndex: 4294967295, flags: DIFlagPrototyped, isOptimized: false)
+!17 = !{!18, !19}
+!18 = distinct !DISubprogram(name: "f", linkageName: "_ZN1A1fEv", scope: !"_ZTS1A", file: !1, line: 6, type: !13, isLocal: false, isDefinition: true, scopeLine: 6, flags: DIFlagPrototyped, isOptimized: false, declaration: !12, variables: !2)
+!19 = distinct !DISubprogram(name: "g", linkageName: "_ZN1A1gEv", scope: !"_ZTS1A", file: !1, line: 7, type: !13, isLocal: false, isDefinition: true, scopeLine: 7, flags: DIFlagPrototyped, isOptimized: false, declaration: !16, variables: !2)
+!20 = !{i32 2, !"Dwarf Version", i32 4}
+!21 = !{i32 2, !"Debug Info Version", i32 3}
+!22 = !{!"clang version 3.9.0 (trunk 263469) (llvm/trunk 263156)"}
+!23 = !DILocalVariable(name: "this", arg: 1, scope: !18, type: !24, flags: DIFlagArtificial | DIFlagObjectPointer)
+!24 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !"_ZTS1A", size: 64, align: 64)
+!25 = !DIExpression()
+!26 = !DILocation(line: 0, scope: !18)
+!27 = !DILocation(line: 6, column: 14, scope: !18)
+!28 = !DILocalVariable(name: "this", arg: 1, scope: !19, type: !24, flags: DIFlagArtificial | DIFlagObjectPointer)
+!29 = !DILocation(line: 0, scope: !19)
+!30 = !DILocation(line: 7, column: 14, scope: !19)