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Debug Info: Add basic support for external types references. 

This is a necessary prerequisite for bootstrapping the emission
of debug info inside modules.

- Adds a FlagExternalTypeRef to DICompositeType.
  External types must have a unique identifier.
- External type references are emitted using a forward declaration
  with a DW_AT_signature([DW_FORM_ref_sig8]) based on the UID.

http://reviews.llvm.org/D9612

llvm-svn: 242302
This commit is contained in:
Adrian Prantl 2015-07-15 17:01:41 +00:00
parent 5b4acbd6b6
commit ee5feafc0f
9 changed files with 100 additions and 3 deletions
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7
llvm/include/llvm/IR/DIBuilder.h
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@ -384,6 +384,13 @@ namespace llvm {
DITypeRefArray ParameterTypes,
unsigned Flags = 0);
/// Create an external type reference.
/// \param Tag Dwarf TAG.
/// \param File File in which the type is defined.
/// \param UniqueIdentifier A unique identifier for the type.
DICompositeType *createExternalTypeRef(unsigned Tag, DIFile *File,
StringRef UniqueIdentifier);
/// Create a new DIType* with "artificial" flag set.
DIType *createArtificialType(DIType *Ty);

1
llvm/include/llvm/IR/DebugInfoFlags.def
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@ -32,5 +32,6 @@ HANDLE_DI_FLAG((1 << 11), Vector)
HANDLE_DI_FLAG((1 << 12), StaticMember)
HANDLE_DI_FLAG((1 << 13), LValueReference)
HANDLE_DI_FLAG((1 << 14), RValueReference)
HANDLE_DI_FLAG((1 << 15), ExternalTypeRef)
#undef HANDLE_DI_FLAG

1
llvm/include/llvm/IR/DebugInfoMetadata.h
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@ -574,6 +574,7 @@ public:
bool isStaticMember() const { return getFlags() & FlagStaticMember; }
bool isLValueReference() const { return getFlags() & FlagLValueReference; }
bool isRValueReference() const { return getFlags() & FlagRValueReference; }
bool isExternalTypeRef() const { return getFlags() & FlagExternalTypeRef; }
DITypeRef getRef() const { return DITypeRef::get(this); }

7
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
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@ -467,7 +467,10 @@ void DwarfDebug::beginModule() {
for (auto *Ty : CUNode->getRetainedTypes()) {
// The retained types array by design contains pointers to
// MDNodes rather than DIRefs. Unique them here.
CU.getOrCreateTypeDIE(cast<DIType>(resolve(Ty->getRef())));
DIType *RT = cast<DIType>(resolve(Ty->getRef()));
if (!RT->isExternalTypeRef())
// There is no point in force-emitting a forward declaration.
CU.getOrCreateTypeDIE(RT);
}
// Emit imported_modules last so that the relevant context is already
// available.
@ -1884,7 +1887,7 @@ MCDwarfDwoLineTable *DwarfDebug::getDwoLineTable(const DwarfCompileUnit &CU) {
return &SplitTypeUnitFileTable;
}
static uint64_t makeTypeSignature(StringRef Identifier) {
uint64_t DwarfDebug::makeTypeSignature(StringRef Identifier) {
MD5 Hash;
Hash.update(Identifier);
// ... take the least significant 8 bytes and return those. Our MD5

3
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
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@ -544,6 +544,9 @@ public:
/// Process end of an instruction.
void endInstruction() override;
/// Perform an MD5 checksum of \p Identifier and return the lower 64 bits.
static uint64_t makeTypeSignature(StringRef Identifier);
/// Add a DIE to the set of types that we're going to pull into
/// type units.
void addDwarfTypeUnitType(DwarfCompileUnit &CU, StringRef Identifier,

17
llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
View File

@ -277,6 +277,13 @@ void DwarfUnit::addDIETypeSignature(DIE &Die, const DwarfTypeUnit &Type) {
dwarf::DW_FORM_ref_sig8, DIETypeSignature(Type));
}
void DwarfUnit::addDIETypeSignature(DIE &Die, dwarf::Attribute Attribute,
StringRef Identifier) {
uint64_t Signature = DD->makeTypeSignature(Identifier);
Die.addValue(DIEValueAllocator, Attribute, dwarf::DW_FORM_ref_sig8,
DIEInteger(Signature));
}
void DwarfUnit::addDIEEntry(DIE &Die, dwarf::Attribute Attribute,
DIEEntry Entry) {
const DIE *DieCU = Die.getUnitOrNull();
@ -700,7 +707,8 @@ DIE *DwarfUnit::createTypeDIE(const DICompositeType *Ty) {
constructTypeDIE(TyDIE, cast<DICompositeType>(Ty));
updateAcceleratorTables(Context, Ty, TyDIE);
if (!Ty->isExternalTypeRef())
updateAcceleratorTables(Context, Ty, TyDIE);
return &TyDIE;
}
@ -899,6 +907,13 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DISubroutineType *CTy) {
}
void DwarfUnit::constructTypeDIE(DIE &Buffer, const DICompositeType *CTy) {
if (CTy->isExternalTypeRef()) {
StringRef Identifier = CTy->getIdentifier();
assert(!Identifier.empty() && "external type ref without identifier");
addFlag(Buffer, dwarf::DW_AT_declaration);
return addDIETypeSignature(Buffer, dwarf::DW_AT_signature, Identifier);
}
// Add name if not anonymous or intermediate type.
StringRef Name = CTy->getName();

4
llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
View File

@ -228,7 +228,11 @@ public:
/// Add a DIE attribute data and value.
void addDIEEntry(DIE &Die, dwarf::Attribute Attribute, DIEEntry Entry);
/// Add a type's DW_AT_signature and set the declaration flag.
void addDIETypeSignature(DIE &Die, const DwarfTypeUnit &Type);
/// Add an attribute containing the type signature for a unique identifier.
void addDIETypeSignature(DIE &Die, dwarf::Attribute Attribute,
StringRef Identifier);
/// Add block data.
void addBlock(DIE &Die, dwarf::Attribute Attribute, DIELoc *Block);

12
llvm/lib/IR/DIBuilder.cpp
View File

@ -435,6 +435,18 @@ DISubroutineType *DIBuilder::createSubroutineType(DIFile *File,
return DISubroutineType::get(VMContext, Flags, ParameterTypes);
}
DICompositeType *DIBuilder::createExternalTypeRef(unsigned Tag, DIFile *File,
StringRef UniqueIdentifier) {
assert(!UniqueIdentifier.empty() && "external type ref without uid");
auto *CTy =
DICompositeType::get(VMContext, Tag, "", nullptr, 0, nullptr, nullptr, 0,
0, 0, DINode::FlagExternalTypeRef, nullptr, 0,
nullptr, nullptr, UniqueIdentifier);
// Types with unique IDs need to be in the type map.
retainType(CTy);
return CTy;
}
DICompositeType *DIBuilder::createEnumerationType(
DIScope *Scope, StringRef Name, DIFile *File, unsigned LineNumber,
uint64_t SizeInBits, uint64_t AlignInBits, DINodeArray Elements,

51
llvm/test/DebugInfo/X86/externaltyperef.ll Normal file
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@ -0,0 +1,51 @@
; REQUIRES: object-emission
; RUN: %llc_dwarf -filetype=obj -O0 < %s | llvm-dwarfdump -debug-dump=info - | FileCheck %s
; Manually derived by externalizing the composite types from:
;
; namespace N { class B; }
; using N::B;
; class A;
; A *a;
;
; Test the direct use of an external type.
; CHECK: DW_TAG_variable
; CHECK: DW_AT_type [DW_FORM_ref4] {{.*}}{[[PTR:.*]]}
; CHECK: [[PTR]]: DW_TAG_pointer_type
; CHECK: DW_AT_type [DW_FORM_ref4] {{.*}}{[[A:.*]]}
; CHECK: [[A]]: DW_TAG_class_type
; CHECK: DW_AT_declaration [DW_FORM_flag] (0x01)
; CHECK: DW_AT_signature [DW_FORM_ref_sig8] (0x4e834ea939695c24)
; CHECK: [[B:.*]]: DW_TAG_class_type
; CHECK: DW_AT_declaration [DW_FORM_flag] (0x01)
; CHECK: DW_AT_signature [DW_FORM_ref_sig8] (0x942e51c7addda5f7)
; CHECK: DW_TAG_imported_declaration
; CHECK: DW_AT_import [DW_FORM_ref4] {{.*}}[[B]]
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.10.0"
%class.A = type opaque
@a = global %class.A* null, align 8
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!13, !14, !15}
!llvm.ident = !{!16}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.7.0 (trunk 242039) (llvm/trunk 242046)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, retainedTypes: !3, globals: !5, imports: !11)
!1 = !DIFile(filename: "test.cpp", directory: "/")
!2 = !{}
!3 = !{!4, !9}
!4 = !DICompositeType(tag: DW_TAG_class_type, name: "A", file: !1, flags: DIFlagExternalTypeRef, identifier: "_ZTS1A")
!5 = !{!6}
!6 = !DIGlobalVariable(name: "a", scope: !0, file: !1, line: 2, type: !7, isLocal: false, isDefinition: true, variable: %class.A** @a)
!7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !"_ZTS1A", size: 64, align: 64)
!8 = !DICompositeType(tag: DW_TAG_class_type, name: "B", file: !1, flags: DIFlagExternalTypeRef, identifier: "_ZTS1B")
!9 = !DICompositeType(tag: DW_TAG_class_type, name: "A", file: !1, flags: DIFlagExternalTypeRef, identifier: "_ZTSN1N1BE")
!10 = !DINamespace(name: "N", scope: null, file: !1, line: 1)
!11 = !{!12}
!12 = !DIImportedEntity(tag: DW_TAG_imported_declaration, scope: !0, entity: !"_ZTSN1N1BE", line: 4)
!13 = !{i32 2, !"Dwarf Version", i32 2}
!14 = !{i32 2, !"Debug Info Version", i32 3}
!15 = !{i32 1, !"PIC Level", i32 2}
!16 = !{!"clang version 3.7.0 (trunk 242039) (llvm/trunk 242046)"}