[DebugInfo] Add a specification attribute to LLVM DebugInfo #115362
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@llvm/pr-subscribers-debuginfo @llvm/pr-subscribers-llvm-ir Author: Augusto Noronha (augusto2112) ChangesAdd a specification_of attribute to LLVM DebugInfo, which is analogous to DWARF's DW_AT_specification. According to the DWARF spec: "A debugging information entry that represents a declaration that completes another (earlier) non-defining declaration may have a DW_AT_specification attribute whose value is a reference to the debugging information entry representing the non-defining declaration." This patch allows types to be specifications of other types. For example, a templated type where the template parameters are substituted in could be a specification of the non-substituted template type. Patch is 36.01 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/115362.diff 13 Files Affected:
diff --git a/llvm/include/llvm/IR/DIBuilder.h b/llvm/include/llvm/IR/DIBuilder.h
index 046890d0c7e1f1..bd0cfbed874a42 100644
--- a/llvm/include/llvm/IR/DIBuilder.h
+++ b/llvm/include/llvm/IR/DIBuilder.h
@@ -488,6 +488,9 @@ namespace llvm {
/// \param Elements Struct elements.
/// \param RunTimeLang Optional parameter, Objective-C runtime version.
/// \param UniqueIdentifier A unique identifier for the struct.
+ /// \param SpecificationOf The type that this type completes (is a
+ /// specification of). For example, this could be a templated type whose
+ /// template parameters have been substituted in.
/// \param NumExtraInhabitants The number of extra inhabitants of the type.
/// An extra inhabitant is a bit pattern that does not represent a valid
/// value for instances of a given type. This is used by the Swift language.
@@ -496,7 +499,7 @@ namespace llvm {
uint64_t SizeInBits, uint32_t AlignInBits, DINode::DIFlags Flags,
DIType *DerivedFrom, DINodeArray Elements, unsigned RunTimeLang = 0,
DIType *VTableHolder = nullptr, StringRef UniqueIdentifier = "",
- uint32_t NumExtraInhabitants = 0);
+ DIType *SpecificationOf = nullptr, uint32_t NumExtraInhabitants = 0);
/// Create debugging information entry for an union.
/// \param Scope Scope in which this union is defined.
diff --git a/llvm/include/llvm/IR/DebugInfoMetadata.h b/llvm/include/llvm/IR/DebugInfoMetadata.h
index 5c8394e45c9d7f..643f242c040829 100644
--- a/llvm/include/llvm/IR/DebugInfoMetadata.h
+++ b/llvm/include/llvm/IR/DebugInfoMetadata.h
@@ -1201,7 +1201,7 @@ class DICompositeType : public DIType {
static DICompositeType *
getImpl(LLVMContext &Context, unsigned Tag, StringRef Name, Metadata *File,
unsigned Line, DIScope *Scope, DIType *BaseType, uint64_t SizeInBits,
- uint32_t AlignInBits, uint64_t OffsetInBits,
+ uint32_t AlignInBits, uint64_t OffsetInBits, DIType *SpecificationOf,
uint32_t NumExtraInhabitants, DIFlags Flags, DINodeArray Elements,
unsigned RuntimeLang, DIType *VTableHolder,
DITemplateParameterArray TemplateParams, StringRef Identifier,
@@ -1215,7 +1215,7 @@ class DICompositeType : public DIType {
TemplateParams.get(),
getCanonicalMDString(Context, Identifier), Discriminator,
DataLocation, Associated, Allocated, Rank, Annotations.get(),
- NumExtraInhabitants, Storage, ShouldCreate);
+ SpecificationOf, NumExtraInhabitants, Storage, ShouldCreate);
}
static DICompositeType *
getImpl(LLVMContext &Context, unsigned Tag, MDString *Name, Metadata *File,
@@ -1225,8 +1225,9 @@ class DICompositeType : public DIType {
Metadata *VTableHolder, Metadata *TemplateParams,
MDString *Identifier, Metadata *Discriminator, Metadata *DataLocation,
Metadata *Associated, Metadata *Allocated, Metadata *Rank,
- Metadata *Annotations, uint32_t NumExtraInhabitants,
- StorageType Storage, bool ShouldCreate = true);
+ Metadata *Annotations, Metadata *SpecificationOf,
+ uint32_t NumExtraInhabitants, StorageType Storage,
+ bool ShouldCreate = true);
TempDICompositeType cloneImpl() const {
return getTemporary(
@@ -1235,7 +1236,8 @@ class DICompositeType : public DIType {
getFlags(), getElements(), getRuntimeLang(), getVTableHolder(),
getTemplateParams(), getIdentifier(), getDiscriminator(),
getRawDataLocation(), getRawAssociated(), getRawAllocated(),
- getRawRank(), getAnnotations(), getNumExtraInhabitants());
+ getRawRank(), getAnnotations(), getSpecificationOf(),
+ getNumExtraInhabitants());
}
public:
@@ -1249,11 +1251,12 @@ class DICompositeType : public DIType {
StringRef Identifier = "", DIDerivedType *Discriminator = nullptr,
Metadata *DataLocation = nullptr, Metadata *Associated = nullptr,
Metadata *Allocated = nullptr, Metadata *Rank = nullptr,
- DINodeArray Annotations = nullptr, uint32_t NumExtraInhabitants = 0),
+ DINodeArray Annotations = nullptr, DIType *SpecificationOf = nullptr,
+ uint32_t NumExtraInhabitants = 0),
(Tag, Name, File, Line, Scope, BaseType, SizeInBits, AlignInBits,
- OffsetInBits, NumExtraInhabitants, Flags, Elements, RuntimeLang,
- VTableHolder, TemplateParams, Identifier, Discriminator, DataLocation,
- Associated, Allocated, Rank, Annotations))
+ OffsetInBits, SpecificationOf, NumExtraInhabitants, Flags, Elements,
+ RuntimeLang, VTableHolder, TemplateParams, Identifier, Discriminator,
+ DataLocation, Associated, Allocated, Rank, Annotations))
DEFINE_MDNODE_GET(
DICompositeType,
(unsigned Tag, MDString *Name, Metadata *File, unsigned Line,
@@ -1264,11 +1267,11 @@ class DICompositeType : public DIType {
Metadata *Discriminator = nullptr, Metadata *DataLocation = nullptr,
Metadata *Associated = nullptr, Metadata *Allocated = nullptr,
Metadata *Rank = nullptr, Metadata *Annotations = nullptr,
- uint32_t NumExtraInhabitants = 0),
+ Metadata *SpecificationOf = nullptr, uint32_t NumExtraInhabitants = 0),
(Tag, Name, File, Line, Scope, BaseType, SizeInBits, AlignInBits,
OffsetInBits, Flags, Elements, RuntimeLang, VTableHolder, TemplateParams,
Identifier, Discriminator, DataLocation, Associated, Allocated, Rank,
- Annotations, NumExtraInhabitants))
+ Annotations, SpecificationOf, NumExtraInhabitants))
TempDICompositeType clone() const { return cloneImpl(); }
@@ -1283,8 +1286,9 @@ class DICompositeType : public DIType {
getODRType(LLVMContext &Context, MDString &Identifier, unsigned Tag,
MDString *Name, Metadata *File, unsigned Line, Metadata *Scope,
Metadata *BaseType, uint64_t SizeInBits, uint32_t AlignInBits,
- uint64_t OffsetInBits, uint32_t NumExtraInhabitants, DIFlags Flags,
- Metadata *Elements, unsigned RuntimeLang, Metadata *VTableHolder,
+ uint64_t OffsetInBits, Metadata *SpecificationOf,
+ uint32_t NumExtraInhabitants, DIFlags Flags, Metadata *Elements,
+ unsigned RuntimeLang, Metadata *VTableHolder,
Metadata *TemplateParams, Metadata *Discriminator,
Metadata *DataLocation, Metadata *Associated, Metadata *Allocated,
Metadata *Rank, Metadata *Annotations);
@@ -1300,14 +1304,16 @@ class DICompositeType : public DIType {
///
/// If not \a LLVMContext::isODRUniquingDebugTypes(), this function returns
/// nullptr.
- static DICompositeType *buildODRType(
- LLVMContext &Context, MDString &Identifier, unsigned Tag, MDString *Name,
- Metadata *File, unsigned Line, Metadata *Scope, Metadata *BaseType,
- uint64_t SizeInBits, uint32_t AlignInBits, uint64_t OffsetInBits,
- uint32_t NumExtraInhabitants, DIFlags Flags, Metadata *Elements,
- unsigned RuntimeLang, Metadata *VTableHolder, Metadata *TemplateParams,
- Metadata *Discriminator, Metadata *DataLocation, Metadata *Associated,
- Metadata *Allocated, Metadata *Rank, Metadata *Annotations);
+ static DICompositeType *
+ buildODRType(LLVMContext &Context, MDString &Identifier, unsigned Tag,
+ MDString *Name, Metadata *File, unsigned Line, Metadata *Scope,
+ Metadata *BaseType, uint64_t SizeInBits, uint32_t AlignInBits,
+ uint64_t OffsetInBits, Metadata *SpecificationOf,
+ uint32_t NumExtraInhabitants, DIFlags Flags, Metadata *Elements,
+ unsigned RuntimeLang, Metadata *VTableHolder,
+ Metadata *TemplateParams, Metadata *Discriminator,
+ Metadata *DataLocation, Metadata *Associated,
+ Metadata *Allocated, Metadata *Rank, Metadata *Annotations);
DIType *getBaseType() const { return cast_or_null<DIType>(getRawBaseType()); }
DINodeArray getElements() const {
@@ -1367,6 +1373,10 @@ class DICompositeType : public DIType {
return cast_or_null<MDTuple>(getRawAnnotations());
}
+ Metadata *getRawSpecificationOf() const { return getOperand(14); }
+ DIType *getSpecificationOf() const {
+ return cast_or_null<DIType>(getRawSpecificationOf());
+ }
/// Replace operands.
///
/// If this \a isUniqued() and not \a isResolved(), on a uniquing collision
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index dd1baabc7e9ac4..4bae02c069b9f9 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -5437,7 +5437,8 @@ bool LLParser::parseDICompositeType(MDNode *&Result, bool IsDistinct) {
OPTIONAL(allocated, MDField, ); \
OPTIONAL(rank, MDSignedOrMDField, ); \
OPTIONAL(annotations, MDField, ); \
- OPTIONAL(num_extra_inhabitants, MDUnsignedField, (0, UINT32_MAX));
+ OPTIONAL(num_extra_inhabitants, MDUnsignedField, (0, UINT32_MAX)); \
+ OPTIONAL(specification_of, MDField, );
PARSE_MD_FIELDS();
#undef VISIT_MD_FIELDS
@@ -5453,10 +5454,10 @@ bool LLParser::parseDICompositeType(MDNode *&Result, bool IsDistinct) {
if (auto *CT = DICompositeType::buildODRType(
Context, *identifier.Val, tag.Val, name.Val, file.Val, line.Val,
scope.Val, baseType.Val, size.Val, align.Val, offset.Val,
- num_extra_inhabitants.Val, flags.Val, elements.Val, runtimeLang.Val,
- vtableHolder.Val, templateParams.Val, discriminator.Val,
- dataLocation.Val, associated.Val, allocated.Val, Rank,
- annotations.Val)) {
+ specification_of.Val, num_extra_inhabitants.Val, flags.Val,
+ elements.Val, runtimeLang.Val, vtableHolder.Val, templateParams.Val,
+ discriminator.Val, dataLocation.Val, associated.Val, allocated.Val,
+ Rank, annotations.Val)) {
Result = CT;
return false;
}
@@ -5469,7 +5470,7 @@ bool LLParser::parseDICompositeType(MDNode *&Result, bool IsDistinct) {
size.Val, align.Val, offset.Val, flags.Val, elements.Val,
runtimeLang.Val, vtableHolder.Val, templateParams.Val, identifier.Val,
discriminator.Val, dataLocation.Val, associated.Val, allocated.Val, Rank,
- annotations.Val, num_extra_inhabitants.Val));
+ annotations.Val, specification_of.Val, num_extra_inhabitants.Val));
return false;
}
diff --git a/llvm/lib/Bitcode/Reader/MetadataLoader.cpp b/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
index 8ca46a4ce821a5..b4936870d7a6df 100644
--- a/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
+++ b/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
@@ -1600,7 +1600,7 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
break;
}
case bitc::METADATA_COMPOSITE_TYPE: {
- if (Record.size() < 16 || Record.size() > 23)
+ if (Record.size() < 16 || Record.size() > 24)
return error("Invalid record");
// If we have a UUID and this is not a forward declaration, lookup the
@@ -1630,6 +1630,7 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
Metadata *Allocated = nullptr;
Metadata *Rank = nullptr;
Metadata *Annotations = nullptr;
+ Metadata *SpecificationOf = nullptr;
auto *Identifier = getMDString(Record[15]);
// If this module is being parsed so that it can be ThinLTO imported
// into another module, composite types only need to be imported as
@@ -1678,14 +1679,18 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
if (Record.size() > 21) {
Annotations = getMDOrNull(Record[21]);
}
+ if (Record.size() > 23) {
+ SpecificationOf = getMDOrNull(Record[23]);
+ }
}
DICompositeType *CT = nullptr;
if (Identifier)
CT = DICompositeType::buildODRType(
Context, *Identifier, Tag, Name, File, Line, Scope, BaseType,
- SizeInBits, AlignInBits, OffsetInBits, NumExtraInhabitants, Flags,
- Elements, RuntimeLang, VTableHolder, TemplateParams, Discriminator,
- DataLocation, Associated, Allocated, Rank, Annotations);
+ SizeInBits, AlignInBits, OffsetInBits, SpecificationOf,
+ NumExtraInhabitants, Flags, Elements, RuntimeLang, VTableHolder,
+ TemplateParams, Discriminator, DataLocation, Associated, Allocated,
+ Rank, Annotations);
// Create a node if we didn't get a lazy ODR type.
if (!CT)
@@ -1694,7 +1699,8 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
SizeInBits, AlignInBits, OffsetInBits, Flags,
Elements, RuntimeLang, VTableHolder, TemplateParams,
Identifier, Discriminator, DataLocation, Associated,
- Allocated, Rank, Annotations, NumExtraInhabitants));
+ Allocated, Rank, Annotations, SpecificationOf,
+ NumExtraInhabitants));
if (!IsNotUsedInTypeRef && Identifier)
MetadataList.addTypeRef(*Identifier, *cast<DICompositeType>(CT));
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index de01750857bba3..97994b0e913508 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -1947,6 +1947,7 @@ void ModuleBitcodeWriter::writeDICompositeType(
Record.push_back(VE.getMetadataOrNullID(N->getRawRank()));
Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
Record.push_back(N->getNumExtraInhabitants());
+ Record.push_back(VE.getMetadataOrNullID(N->getRawSpecificationOf()));
Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
Record.clear();
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index c6d9fcfb0b76c1..0e6ef631bff0f9 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -1043,6 +1043,11 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DICompositeType *CTy) {
addUInt(Buffer, dwarf::DW_AT_calling_convention, dwarf::DW_FORM_data1,
CC);
}
+
+ if (auto *SpecifiedFrom = CTy->getSpecificationOf())
+ addDIEEntry(Buffer, dwarf::DW_AT_specification,
+ *getOrCreateContextDIE(SpecifiedFrom));
+
break;
}
default:
diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 8716a7ce2aec36..1cad4be4db73e3 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -2235,6 +2235,8 @@ static void writeDICompositeType(raw_ostream &Out, const DICompositeType *N,
else
Printer.printMetadata("rank", N->getRawRank(), /*ShouldSkipNull */ true);
Printer.printMetadata("annotations", N->getRawAnnotations());
+ if (auto *SpecificationOf = N->getRawSpecificationOf())
+ Printer.printMetadata("specification_of", SpecificationOf);
Out << ")";
}
diff --git a/llvm/lib/IR/DIBuilder.cpp b/llvm/lib/IR/DIBuilder.cpp
index 8bc8c2d81fb01a..bfc33ff0f955cf 100644
--- a/llvm/lib/IR/DIBuilder.cpp
+++ b/llvm/lib/IR/DIBuilder.cpp
@@ -521,13 +521,13 @@ DICompositeType *DIBuilder::createStructType(
DIScope *Context, StringRef Name, DIFile *File, unsigned LineNumber,
uint64_t SizeInBits, uint32_t AlignInBits, DINode::DIFlags Flags,
DIType *DerivedFrom, DINodeArray Elements, unsigned RunTimeLang,
- DIType *VTableHolder, StringRef UniqueIdentifier,
+ DIType *VTableHolder, StringRef UniqueIdentifier, DIType *SpecificationOf,
uint32_t NumExtraInhabitants) {
auto *R = DICompositeType::get(
VMContext, dwarf::DW_TAG_structure_type, Name, File, LineNumber,
getNonCompileUnitScope(Context), DerivedFrom, SizeInBits, AlignInBits, 0,
Flags, Elements, RunTimeLang, VTableHolder, nullptr, UniqueIdentifier,
- nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
+ nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, SpecificationOf,
NumExtraInhabitants);
trackIfUnresolved(R);
return R;
@@ -554,7 +554,8 @@ DIBuilder::createVariantPart(DIScope *Scope, StringRef Name, DIFile *File,
auto *R = DICompositeType::get(
VMContext, dwarf::DW_TAG_variant_part, Name, File, LineNumber,
getNonCompileUnitScope(Scope), nullptr, SizeInBits, AlignInBits, 0, Flags,
- Elements, 0, nullptr, nullptr, UniqueIdentifier, 0, Discriminator);
+ Elements, 0, nullptr, nullptr, UniqueIdentifier, nullptr, 0,
+ Discriminator);
trackIfUnresolved(R);
return R;
}
diff --git a/llvm/lib/IR/DebugInfoMetadata.cpp b/llvm/lib/IR/DebugInfoMetadata.cpp
index f7268a51406283..a06db3f8387136 100644
--- a/llvm/lib/IR/DebugInfoMetadata.cpp
+++ b/llvm/lib/IR/DebugInfoMetadata.cpp
@@ -770,21 +770,21 @@ DICompositeType *DICompositeType::getImpl(
Metadata *Elements, unsigned RuntimeLang, Metadata *VTableHolder,
Metadata *TemplateParams, MDString *Identifier, Metadata *Discriminator,
Metadata *DataLocation, Metadata *Associated, Metadata *Allocated,
- Metadata *Rank, Metadata *Annotations, uint32_t NumExtraInhabitants,
- StorageType Storage, bool ShouldCreate) {
+ Metadata *Rank, Metadata *Annotations, Metadata *SpecificationOf,
+ uint32_t NumExtraInhabitants, StorageType Storage, bool ShouldCreate) {
assert(isCanonical(Name) && "Expected canonical MDString");
// Keep this in sync with buildODRType.
- DEFINE_GETIMPL_LOOKUP(DICompositeType,
- (Tag, Name, File, Line, Scope, BaseType, SizeInBits,
- AlignInBits, OffsetInBits, Flags, Elements,
- RuntimeLang, VTableHolder, TemplateParams, Identifier,
- Discriminator, DataLocation, Associated, Allocated,
- Rank, Annotations, NumExtraInhabitants));
+ DEFINE_GETIMPL_LOOKUP(
+ DICompositeType,
+ (Tag, Name, File, Line, Scope, BaseType, SizeInBits, AlignInBits,
+ OffsetInBits, Flags, Elements, RuntimeLang, VTableHolder, TemplateParams,
+ Identifier, Discriminator, DataLocation, Associated, Allocated, Rank,
+ Annotations, SpecificationOf, NumExtraInhabitants));
Metadata *Ops[] = {File, Scope, Name, BaseType,
Elements, VTableHolder, TemplateParams, Identifier,
Discriminator, DataLocation, Associated, Allocated,
- Rank, Annotations};
+ Rank, Annotations, SpecificationOf};
DEFINE_GETIMPL_STORE(DICompositeType,
(Tag, Line, RuntimeLang, SizeInBits, AlignInBits,
OffsetInBits, NumExtraInhabitants, Flags),
@@ -795,10 +795,11 @@ DICompositeType *DICompositeType::buildODRType(
LLVMContext &Context, MDString &Identifier, unsigned Tag, MDString *Name,
Metadata *File, unsigned Line, Metadata *Scope, Metadata *BaseType,
uint64_t SizeInBits, uint32_t AlignInBits, uint64_t OffsetInBits,
- uint32_t NumExtraInhabitants, DIFlags Flags, Metadata *Elements,
- unsigned RuntimeLang, Metadata *VTableHolder, Metadata *TemplateParams,
- Metadata *Discriminator, Metadata *DataLocation, Metadata *Associated,
- Metadata *Allocated, Metadata *Rank, Metadata *Annotations) {
+ Metadata *SpecificationOf, uint32_t NumExtraInhabitants, DIFlags Flags,
+ Metadata *Elements, unsigned RuntimeLang, Metadata *VTableHolder,
+ Metadata *TemplateParams, Metadata *Discriminator, Metadata *DataLocation,
+ Metadata *Associated, Metadata *Allocated, Metadata *Rank,
+ Metadata *Annotations) {
assert(!Identifier.getString().empty() && "Expected valid identifier");
if (!Context.isODRUniquingDebugTypes())
return nullptr;
@@ -809,8 +810,7 @@ DICompositeType *DICompositeType::buildODRType(
AlignInBits, OffsetInBits, Flags, Elements, RuntimeLang,
VTableHolder, TemplateParams, &Identifier, Discriminator,
DataLocation, Associated, Allocated, Rank, Annotations,
- NumExtraInhabitants);
-
+ SpecificationOf, NumExtraInhabitants);
if (CT->getTag() != Tag)
return nullptr;
@@ -825,7 +825,7 @@ DICompositeType *DICompositeT...
[truncated]
|
|
I'm upstreaming this from the downstream |
|
I'd probably call the attribute just "specification" same as DWARF does? but also it worries me a bit - the reason we haven't had "specification" in LLVM IR debug info for types so far is that we never have a declaration and a definition of the same type simultaneously - we deduplicate them via the So, yeah, maybe a bit more detail on how this works - and maybe it deserves a different name once we look at the details. |
I see. On the Swift side this works since the identifiers (type mangled names) are different: you have a generic "Type" and a specification "Type", "Type", etc. I can remove any references to C++ if needed, but I'll leave it to @Michael137 to decide if we can adapt this for C++ or not. |
augusto2112
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Could you add a more complete description/examples of the Swift situation this is used for currently? |
Do you mean in the commit message? |
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Sure, that would be fine |
Add a specification attribute to LLVM DebugInfo, which is analogous
to DWARF's DW_AT_specification. According to the DWARF spec:
"A debugging information entry that represents a declaration that
completes another (earlier) non-defining declaration may have a
DW_AT_specification attribute whose value is a reference to the
debugging information entry representing the non-defining declaration."
This patch allows types to be specifications of other types. This is
used by Swift to represent generic types. For example, given this Swift
program:
```
struct MyStruct<T> {
let t: T
}
let variable = MyStruct<Int>(t: 43)
```
The Swift compiler emits (roughly) an unsubtituted type for MyStruct<T>:
```
DW_TAG_structure_type
DW_AT_name ("MyStruct")
// "$s1w8MyStructVyxGD" is a Swift mangled name roughly equivalent to
// MyStruct<T>
DW_AT_linkage_name ("$s1w8MyStructVyxGD")
// other attributes here
```
And a specification for MyStruct<Int>:
```
DW_TAG_structure_type
DW_AT_specification (<link to "MyStruct">)
// "$s1w8MyStructVySiGD" is a Swift mangled name equivalent to
// MyStruct<Int>
DW_AT_linkage_name ("$s1w8MyStructVySiGD")
DW_AT_byte_size (0x08)
// other attributes here
```
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augusto2112
changed the title
|
I updated the description. |
dwblaikie
approved these changes
Nov 12, 2024
There was a problem hiding this comment.
Could be worth splitting this into smaller steps - asm reading/writing, separate from the functional change in LLVM AsmPrinter, etc.
I still have reservations about using DW_AT_specification for this, but DWARF is permissive and all that, so if it's what you folks want to use for Swift, guess that's fine.
|
Testing locally, looks like |
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to augusto2112/llvm-project
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Nov 13, 2024
) Add a specification attribute to LLVM DebugInfo, which is analogous to DWARF's DW_AT_specification. According to the DWARF spec: "A debugging information entry that represents a declaration that completes another (earlier) non-defining declaration may have a DW_AT_specification attribute whose value is a reference to the debugging information entry representing the non-defining declaration." This patch allows types to be specifications of other types. This is used by Swift to represent generic types. For example, given this Swift program: ``` struct MyStruct<T> { let t: T } let variable = MyStruct<Int>(t: 43) ``` The Swift compiler emits (roughly) an unsubtituted type for MyStruct<T>: ``` DW_TAG_structure_type DW_AT_name ("MyStruct") // "$s1w8MyStructVyxGD" is a Swift mangled name roughly equivalent to // MyStruct<T> DW_AT_linkage_name ("$s1w8MyStructVyxGD") // other attributes here ``` And a specification for MyStruct<Int>: ``` DW_TAG_structure_type DW_AT_specification (<link to "MyStruct">) // "$s1w8MyStructVySiGD" is a Swift mangled name equivalent to // MyStruct<Int> DW_AT_linkage_name ("$s1w8MyStructVySiGD") DW_AT_byte_size (0x08) // other attributes here ``` (cherry picked from commit 67fb268)
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Nov 18, 2024
[DebugInfo] Add a specification attribute to LLVM DebugInfo (llvm#115362)
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Add a specification attribute to LLVM DebugInfo, which is analogous
to DWARF's DW_AT_specification. According to the DWARF spec:
"A debugging information entry that represents a declaration that
completes another (earlier) non-defining declaration may have a
DW_AT_specification attribute whose value is a reference to the
debugging information entry representing the non-defining declaration."
This patch allows types to be specifications of other types. This is
used by Swift to represent generic types. For example, given this Swift
program:
The Swift compiler emits (roughly) an unsubtituted type for MyStruct:
And a specification for MyStruct: