[DebugInfo][BPF] Add 'btf:type_tag' annotation in DWARF #91423
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✅ With the latest revision this PR passed the C/C++ code formatter. |
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Hi @dwblaikie, @yonghong-song, Could you please take a look at this pull request? |
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@llvm/pr-subscribers-clang-codegen @llvm/pr-subscribers-llvm-ir Author: None (eddyz87) ChangesThis commit is a follow-up for BPF mailing list discussion at [1]. It changes the way Prior to this commit type tags could only be attached to pointers. Such attachments associated the tags with a pointee type. E.g. for the following C code: Generated DWARF looked as follows: The goal of this commit is to allow attachment of type tags to the tagged types instead. E.g. for the same example DWARF should look as follows: A new tag name, This feature is mostly used by Linux Kernel in combination with tool named pahole [2]. Reasonably recent versions of pahole generate errors (1.23, 1.24) or warnings (1.25) when The commit includes the following changes:
[1] https://lore.kernel.org/bpf/87r0w9jjoq.fsf@oracle.com/ This was previously tracked as differential revision: Note: the new place for annotation is DWARF was already agreed as a part of D143967, however the switch enabling or disabling this is a new addition. Patch is 74.29 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/91423.diff 25 Files Affected:
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index fac278f0e20a4..9518a75a3b1f1 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -56,6 +56,16 @@
using namespace clang;
using namespace clang::CodeGen;
+// Temporarily hide new format for btf_type_tags / DW_TAG_LLVM_annotation
+// behind an option to allow transitory period for tooling dependent on
+// this annotation. The goal is to remove this flag after transitory period.
+static llvm::cl::opt<bool> BTFTypeTagV2(
+ "btf-type-tag-v2", llvm::cl::Hidden,
+ llvm::cl::desc("For __attribute__((btf_type_tag(...))) generate "
+ "DW_TAG_LLVM_annotation tags with DW_AT_name 'btf:type_tag' "
+ "attached to annotated type itself"),
+ llvm::cl::init(false));
+
static uint32_t getTypeAlignIfRequired(const Type *Ty, const ASTContext &Ctx) {
auto TI = Ctx.getTypeInfo(Ty);
return TI.isAlignRequired() ? TI.Align : 0;
@@ -1185,6 +1195,129 @@ CGDebugInfo::getOrCreateRecordFwdDecl(const RecordType *Ty,
return RetTy;
}
+static QualType collectBTFTypeTagAnnotations(
+ llvm::LLVMContext &Context, llvm::DIBuilder &DBuilder,
+ llvm::SmallVectorImpl<llvm::Metadata *> &Annots,
+ const BTFTagAttributedType *BTFAttrTy, const char *TagName) {
+ QualType WrappedTy;
+
+ do {
+ StringRef TagValue = BTFAttrTy->getAttr()->getBTFTypeTag();
+ if (!TagValue.empty()) {
+ llvm::Metadata *Ops[] = {
+ llvm::MDString::get(Context, TagName),
+ llvm::MDString::get(Context, TagValue),
+ };
+ Annots.insert(Annots.begin(), llvm::MDNode::get(Context, Ops));
+ }
+ WrappedTy = BTFAttrTy->getWrappedType();
+ BTFAttrTy = dyn_cast<BTFTagAttributedType>(WrappedTy);
+ } while (BTFAttrTy);
+
+ return WrappedTy;
+}
+
+static bool retreiveCVR(llvm::DIDerivedType *DTy, QualifierCollector &Qc) {
+ switch (DTy->getTag()) {
+ case llvm::dwarf::DW_TAG_const_type:
+ Qc.addConst();
+ return true;
+ case llvm::dwarf::DW_TAG_volatile_type:
+ Qc.addVolatile();
+ return true;
+ case llvm::dwarf::DW_TAG_restrict_type:
+ Qc.addRestrict();
+ return true;
+ default:
+ return false;
+ }
+}
+
+// Tags returned by QualifierCollector::getNextQualifier() should be
+// applied in the reverse order, thus use recursive function.
+static llvm::DIType *applyQualifiers(llvm::DIBuilder &DBuilder,
+ llvm::DIType *Ty, QualifierCollector &Qc) {
+ llvm::dwarf::Tag Tag = getNextQualifier(Qc);
+ if (!Tag)
+ return Ty;
+ Ty = applyQualifiers(DBuilder, Ty, Qc);
+ return DBuilder.createQualifiedType(Tag, Ty);
+}
+
+static bool isAnnotationsPlaceholder(llvm::DIDerivedType *DTy) {
+ return DTy->isTemporary() &&
+ DTy->getTag() == llvm::dwarf::DW_TAG_LLVM_annotation;
+}
+
+llvm::DIType *CGDebugInfo::CreateType(const BTFTagAttributedType *Ty,
+ llvm::DIFile *Unit) {
+ SmallVector<llvm::Metadata *, 4> Annotations;
+ auto WrappedTy = collectBTFTypeTagAnnotations(
+ CGM.getLLVMContext(), DBuilder, Annotations, Ty, "btf:type_tag");
+
+ if (!BTFTypeTagV2 || Annotations.empty())
+ return getOrCreateType(WrappedTy, Unit);
+
+ // After discussion with GCC BPF team in [1] it was decided to avoid
+ // attaching BTF type tags to const/volatile/restrict DWARF DIEs.
+ // So, strip qualifiers from WrappedTy and apply those to a final
+ // annotations placeholder instance at the end of this function.
+ //
+ // [1] https://reviews.llvm.org/D143967
+ QualifierCollector Qc;
+ Qc.addCVRQualifiers(WrappedTy.getLocalCVRQualifiers());
+ WrappedTy.removeLocalFastQualifiers(Qualifiers::CVRMask);
+
+ llvm::DIType *WrappedDI = getOrCreateType(WrappedTy, Unit);
+ if (!WrappedDI)
+ WrappedDI = DBuilder.createUnspecifiedType("void");
+
+ // Stripping local CVR qualifiers might not be enough in cases like this:
+ //
+ // #define __tag __attribute__((btf_type_tag("tag")))
+ // const int *foo;
+ // const int *bar(void) {
+ // return (typeof(*foo) __tag *)(0);
+ // }
+ //
+ // Here the AST looks like:
+ //
+ // BTFTagAttributedType
+ // | 'typeof (*foo) __attribute__((btf_type_tag("tag")))' sugar
+ // `-TypeOfExprType 'typeof (*foo)' sugar
+ // |-ParenExpr 'const int' lvalue
+ // | `- ...
+ // `-QualType 'const int' const
+ // `-BuiltinType 'int'
+ //
+ // The BTFTagAttributedType is applied to TypeOfExpr.
+ // For TypeOfExpr the getOrCreateType(), would return instance of
+ // DIDerivedType with tag DW_TAG_const_type.
+ //
+ // To avoid repeating UnwrapTypeForDebugInfo() logic here just
+ // rebuild CVR metadata nodes if necessary.
+ // The above local CVR qualifiers processing is redundant,
+ // but avoids rebuilding metadata nodes in the most common case.
+ while (auto *DTy = dyn_cast<llvm::DIDerivedType>(WrappedDI)) {
+ if (!retreiveCVR(DTy, Qc))
+ break;
+ WrappedDI = DTy->getBaseType();
+ }
+
+ if (auto *DTy = dyn_cast<llvm::DIDerivedType>(WrappedDI))
+ if (isAnnotationsPlaceholder(DTy)) {
+ WrappedDI = DTy->getBaseType();
+ for (llvm::Metadata *O : DTy->getAnnotations()->operands())
+ Annotations.push_back(O);
+ }
+
+ auto *Placeholder = DBuilder.createAnnotationsPlaceholder(
+ WrappedDI, DBuilder.getOrCreateArray(Annotations));
+ AnnotationPlaceholders.push_back(Placeholder);
+
+ return applyQualifiers(DBuilder, Placeholder, Qc);
+}
+
llvm::DIType *CGDebugInfo::CreatePointerLikeType(llvm::dwarf::Tag Tag,
const Type *Ty,
QualType PointeeTy,
@@ -1197,32 +1330,23 @@ llvm::DIType *CGDebugInfo::CreatePointerLikeType(llvm::dwarf::Tag Tag,
CGM.getTarget().getDWARFAddressSpace(
CGM.getTypes().getTargetAddressSpace(PointeeTy));
- SmallVector<llvm::Metadata *, 4> Annots;
- auto *BTFAttrTy = dyn_cast<BTFTagAttributedType>(PointeeTy);
- while (BTFAttrTy) {
- StringRef Tag = BTFAttrTy->getAttr()->getBTFTypeTag();
- if (!Tag.empty()) {
- llvm::Metadata *Ops[2] = {
- llvm::MDString::get(CGM.getLLVMContext(), StringRef("btf_type_tag")),
- llvm::MDString::get(CGM.getLLVMContext(), Tag)};
- Annots.insert(Annots.begin(),
- llvm::MDNode::get(CGM.getLLVMContext(), Ops));
- }
- BTFAttrTy = dyn_cast<BTFTagAttributedType>(BTFAttrTy->getWrappedType());
- }
-
llvm::DINodeArray Annotations = nullptr;
- if (Annots.size() > 0)
- Annotations = DBuilder.getOrCreateArray(Annots);
+ auto *BTFAttrTy = dyn_cast<BTFTagAttributedType>(PointeeTy.getTypePtr());
+ if (!BTFTypeTagV2 && BTFAttrTy) {
+ SmallVector<llvm::Metadata *, 4> AnnotationsVec;
+ collectBTFTypeTagAnnotations(CGM.getLLVMContext(), DBuilder, AnnotationsVec,
+ BTFAttrTy, "btf_type_tag");
+ Annotations = DBuilder.getOrCreateArray(AnnotationsVec);
+ }
if (Tag == llvm::dwarf::DW_TAG_reference_type ||
Tag == llvm::dwarf::DW_TAG_rvalue_reference_type)
return DBuilder.createReferenceType(Tag, getOrCreateType(PointeeTy, Unit),
Size, Align, DWARFAddressSpace);
- else
- return DBuilder.createPointerType(getOrCreateType(PointeeTy, Unit), Size,
- Align, DWARFAddressSpace, StringRef(),
- Annotations);
+
+ return DBuilder.createPointerType(getOrCreateType(PointeeTy, Unit), Size,
+ Align, DWARFAddressSpace, StringRef(),
+ Annotations);
}
llvm::DIType *CGDebugInfo::getOrCreateStructPtrType(StringRef Name,
@@ -3543,9 +3667,6 @@ static QualType UnwrapTypeForDebugInfo(QualType T, const ASTContext &C) {
case Type::Attributed:
T = cast<AttributedType>(T)->getEquivalentType();
break;
- case Type::BTFTagAttributed:
- T = cast<BTFTagAttributedType>(T)->getWrappedType();
- break;
case Type::CountAttributed:
T = cast<CountAttributedType>(T)->desugar();
break;
@@ -3745,10 +3866,12 @@ llvm::DIType *CGDebugInfo::CreateTypeNode(QualType Ty, llvm::DIFile *Unit) {
case Type::TemplateSpecialization:
return CreateType(cast<TemplateSpecializationType>(Ty), Unit);
+ case Type::BTFTagAttributed:
+ return CreateType(cast<BTFTagAttributedType>(Ty), Unit);
+
case Type::CountAttributed:
case Type::Auto:
case Type::Attributed:
- case Type::BTFTagAttributed:
case Type::Adjusted:
case Type::Decayed:
case Type::DeducedTemplateSpecialization:
@@ -5921,6 +6044,35 @@ void CGDebugInfo::setDwoId(uint64_t Signature) {
TheCU->setDWOId(Signature);
}
+static llvm::DIType *copyAnnotations(llvm::DIBuilder &DBuilder,
+ llvm::DIDerivedType *Placeholder) {
+ auto *WrappedDI = Placeholder->getBaseType();
+ SmallVector<llvm::Metadata *, 4> Annotations;
+
+ for (const llvm::Metadata *O : Placeholder->getAnnotations()->operands())
+ Annotations.push_back(const_cast<llvm::Metadata *>(O));
+
+ auto AddAnnotations = [&](auto *Type) {
+ if (llvm::DINodeArray OldAnnotations = Type->getAnnotations())
+ for (const llvm::Metadata *O : OldAnnotations->operands())
+ Annotations.push_back(const_cast<llvm::Metadata *>(O));
+ auto Clone = Type->clone();
+ Clone->replaceAnnotations(DBuilder.getOrCreateArray(Annotations));
+ return llvm::MDNode::replaceWithPermanent(std::move(Clone));
+ };
+
+ if (auto *Ty = dyn_cast<llvm::DIBasicType>(WrappedDI))
+ return AddAnnotations(Ty);
+ if (auto *Ty = dyn_cast<llvm::DICompositeType>(WrappedDI))
+ return AddAnnotations(Ty);
+ if (auto *Ty = dyn_cast<llvm::DIDerivedType>(WrappedDI))
+ return AddAnnotations(Ty);
+ if (auto *Ty = dyn_cast<llvm::DISubroutineType>(WrappedDI))
+ return AddAnnotations(Ty);
+
+ return WrappedDI;
+}
+
void CGDebugInfo::finalize() {
// Creating types might create further types - invalidating the current
// element and the size(), so don't cache/reference them.
@@ -5994,6 +6146,10 @@ void CGDebugInfo::finalize() {
if (auto MD = TypeCache[RT])
DBuilder.retainType(cast<llvm::DIType>(MD));
+ for (auto &Placeholder : AnnotationPlaceholders)
+ DBuilder.replaceTemporary(llvm::TempDIType(Placeholder),
+ copyAnnotations(DBuilder, Placeholder));
+
DBuilder.finalize();
}
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index d6db4d711366a..43a093c725f6a 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -170,6 +170,8 @@ class CGDebugInfo {
/// The key is coroutine real parameters, value is DIVariable in LLVM IR.
Param2DILocTy ParamDbgMappings;
+ std::vector<llvm::DIDerivedType *> AnnotationPlaceholders;
+
/// Helper functions for getOrCreateType.
/// @{
/// Currently the checksum of an interface includes the number of
@@ -217,6 +219,7 @@ class CGDebugInfo {
llvm::DIType *CreateType(const MemberPointerType *Ty, llvm::DIFile *F);
llvm::DIType *CreateType(const AtomicType *Ty, llvm::DIFile *F);
llvm::DIType *CreateType(const PipeType *Ty, llvm::DIFile *F);
+ llvm::DIType *CreateType(const BTFTagAttributedType *Ty, llvm::DIFile *F);
/// Get enumeration type.
llvm::DIType *CreateEnumType(const EnumType *Ty);
llvm::DIType *CreateTypeDefinition(const EnumType *Ty);
diff --git a/clang/test/CodeGen/attr-btf_type_tag-circular.c b/clang/test/CodeGen/attr-btf_type_tag-circular.c
new file mode 100644
index 0000000000000..4bcb20e63bead
--- /dev/null
+++ b/clang/test/CodeGen/attr-btf_type_tag-circular.c
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 \
+// RUN: -triple %itanium_abi_triple -debug-info-kind=limited \
+// RUN: -mllvm -btf-type-tag-v2 -S -emit-llvm -o - %s | FileCheck %s
+
+#define __tag1 __attribute__((btf_type_tag("tag1")))
+
+struct st {
+ struct st __tag1 *self;
+} g;
+
+// CHECK: distinct !DIGlobalVariable(name: "g", scope: ![[#]], file: ![[#]], line: [[#]], type: ![[L1:[0-9]+]], isLocal: false, isDefinition: true)
+// CHECK: ![[L1]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "st", file: ![[#]], line: [[#]], size: [[#]], elements: ![[L2:[0-9]+]])
+// CHECK: ![[L2]] = !{![[L3:[0-9]+]]}
+// CHECK: ![[L3]] = !DIDerivedType(tag: DW_TAG_member, name: "self", scope: ![[L1]], file: ![[#]], line: [[#]], baseType: ![[L4:[0-9]+]], size: [[#]])
+// CHECK: ![[L4]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[L5:[0-9]+]], size: [[#]])
+// CHECK: ![[L5]] = !DICompositeType(tag: DW_TAG_structure_type, name: "st", file: ![[#]], line: [[#]], size: [[#]], elements: ![[L2]], annotations: ![[L7:[0-9]+]])
+// CHECK: ![[L7]] = !{![[L8:[0-9]+]]}
+// CHECK: ![[L8]] = !{!"btf:type_tag", !"tag1"}
diff --git a/clang/test/CodeGen/attr-btf_type_tag-const.c b/clang/test/CodeGen/attr-btf_type_tag-const.c
new file mode 100644
index 0000000000000..94d9c05f5345a
--- /dev/null
+++ b/clang/test/CodeGen/attr-btf_type_tag-const.c
@@ -0,0 +1,41 @@
+// RUN: %clang_cc1 \
+// RUN: -triple %itanium_abi_triple -debug-info-kind=limited \
+// RUN: -mllvm -btf-type-tag-v2 -S -emit-llvm -o - %s | FileCheck %s
+
+// Check that BTF type tags are not attached to DW_TAG_const_type DIEs
+// in presence of "sugar" expressions that are transparent for
+// CGDebugInfo.cpp:UnwrapTypeForDebugInfo(), but are not transparent
+// for local qualifiers.
+//
+// For details see:
+// CGDebugInfo::CreateType(const BTFTagAttributedType, llvm::DIFile)
+
+#define __tag1 __attribute__((btf_type_tag("tag1")))
+#define __tag2 __attribute__((btf_type_tag("tag2")))
+#define __tag3 __attribute__((btf_type_tag("tag3")))
+
+const int *foo;
+typeof(*foo) __tag1 bar;
+
+// CHECK: distinct !DIGlobalVariable(name: "bar", {{.*}}, type: ![[L01:[0-9]+]], {{.*}})
+// CHECK: ![[L01]] = !DIDerivedType(tag: DW_TAG_const_type, baseType: ![[L02:[0-9]+]])
+// CHECK: ![[L02]] = !DIBasicType(name: "int", {{.*}}, annotations: ![[L03:[0-9]+]])
+// CHECK: ![[L03]] = !{![[L04:[0-9]+]]}
+// CHECK: ![[L04]] = !{!"btf:type_tag", !"tag1"}
+
+const int __tag2 *buz;
+
+// CHECK: distinct !DIGlobalVariable(name: "buz", {{.*}}, type: ![[L05:[0-9]+]], {{.*}})
+// CHECK: ![[L05]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[L06:[0-9]+]], {{.*}})
+// CHECK: ![[L06]] = !DIDerivedType(tag: DW_TAG_const_type, baseType: ![[L08:[0-9]+]])
+// CHECK: ![[L08]] = !DIBasicType(name: "int", size: [[#]], {{.*}}, annotations: ![[L09:[0-9]+]])
+// CHECK: ![[L09]] = !{![[L10:[0-9]+]]}
+// CHECK: ![[L10]] = !{!"btf:type_tag", !"tag2"}
+
+typeof(*buz) __tag3 quux;
+
+// CHECK: distinct !DIGlobalVariable(name: "quux", {{.*}}, type: ![[L12:[0-9]+]], {{.*}})
+// CHECK: ![[L12]] = !DIDerivedType(tag: DW_TAG_const_type, baseType: ![[L13:[0-9]+]])
+// CHECK: ![[L13]] = !DIBasicType(name: "int", {{.*}}, annotations: ![[L14:[0-9]+]])
+// CHECK: ![[L14]] = !{![[L15:[0-9]+]], ![[L10]]}
+// CHECK: ![[L15]] = !{!"btf:type_tag", !"tag3"}
diff --git a/clang/test/CodeGen/attr-btf_type_tag-func-ptr.c b/clang/test/CodeGen/attr-btf_type_tag-func-ptr.c
index 26935c882a017..8567864692202 100644
--- a/clang/test/CodeGen/attr-btf_type_tag-func-ptr.c
+++ b/clang/test/CodeGen/attr-btf_type_tag-func-ptr.c
@@ -1,4 +1,8 @@
// RUN: %clang_cc1 -triple %itanium_abi_triple -debug-info-kind=limited -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 \
+// RUN: -triple %itanium_abi_triple -debug-info-kind=limited \
+// RUN: -mllvm -btf-type-tag-v2 -emit-llvm -o - %s \
+// RUN: | FileCheck --check-prefix CHECK-V2 %s
struct t {
int (__attribute__((btf_type_tag("rcu"))) *f)();
@@ -8,8 +12,13 @@ int foo(struct t *arg) {
return arg->a;
}
-// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "f"
-// CHECK-SAME: baseType: ![[L18:[0-9]+]]
-// CHECK: ![[L18]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[#]], size: [[#]], annotations: ![[L21:[0-9]+]])
-// CHECK: ![[L21]] = !{![[L22:[0-9]+]]}
-// CHECK: ![[L22]] = !{!"btf_type_tag", !"rcu"}
+// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "f", scope: ![[#]], file: ![[#]], line: [[#]], baseType: ![[L1:[0-9]+]], size: [[#]])
+// CHECK: ![[L1]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[#]], size: [[#]], annotations: ![[L2:[0-9]+]])
+// CHECK: ![[L2]] = !{![[L3:[0-9]+]]}
+// CHECK: ![[L3]] = !{!"btf_type_tag", !"rcu"}
+
+// CHECK-V2: !DIDerivedType(tag: DW_TAG_member, name: "f", scope: ![[#]], file: ![[#]], line: [[#]], baseType: ![[L1:[0-9]+]], size: [[#]])
+// CHECK-V2: ![[L1]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[L2:[0-9]+]], size: [[#]])
+// CHECK-V2: ![[L2]] = !DISubroutineType(types: ![[#]], annotations: ![[L4:[0-9]+]])
+// CHECK-V2: ![[L4]] = !{![[L5:[0-9]+]]}
+// CHECK-V2: ![[L5]] = !{!"btf:type_tag", !"rcu"}
diff --git a/clang/test/CodeGen/attr-btf_type_tag-func.c b/clang/test/CodeGen/attr-btf_type_tag-func.c
index dbb8864759148..890d3ab35428b 100644
--- a/clang/test/CodeGen/attr-btf_type_tag-func.c
+++ b/clang/test/CodeGen/attr-btf_type_tag-func.c
@@ -1,5 +1,17 @@
-// RUN: %clang_cc1 -triple %itanium_abi_triple -debug-info-kind=limited -emit-llvm -o - %s | FileCheck %s
-// RUN: %clang_cc1 -triple %itanium_abi_triple -DDOUBLE_BRACKET_ATTRS=1 -debug-info-kind=limited -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 \
+// RUN: -triple %itanium_abi_triple -debug-info-kind=limited \
+// RUN: -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 \
+// RUN: -triple %itanium_abi_triple -DDOUBLE_BRACKET_ATTRS=1 -debug-info-kind=limited \
+// RUN: -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 \
+// RUN: -triple %itanium_abi_triple -debug-info-kind=limited \
+// RUN: -mllvm -btf-type-tag-v2 -emit-llvm -o - %s \
+// RUN: | FileCheck --check-prefixes CHECK-V2 %s
+// RUN: %clang_cc1 \
+// RUN: -triple %itanium_abi_triple -DDOUBLE_BRACKET_ATTRS=1 \
+// RUN: -debug-info-kind=limited -mllvm -btf-type-tag-v2 -emit-llvm -o - %s \
+// RUN: | FileCheck --check-prefixes CHECK-V2 %s
#if DOUBLE_BRACKET_ATTRS
#define __tag1 [[clang::btf_type_tag("tag1")]]
@@ -15,14 +27,26 @@
int __tag1 * __tag2 *foo(int __tag1 * __tag2 *arg) { return arg; }
-// CHECK: distinct !DISubprogram(name: "foo", scope: ![[#]], file: ![[#]], line: [[#]], type: ![[L9:[0-9]+]]
-// CHECK: ![[L9]] = !DISubroutineType(types: ![[L10:[0-9]+]]
-// CHECK: ![[L10]] = !{![[L11:[0-9]+]], ![[L11]]}
-// CHECK: ![[L11]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[L12:[0-9]+]], size: [[#]], annotations: ![[L16:[0-9]+]]
-// CHECK: ![[L12]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[L13:[0-9]+]], size: [[#]], annotations: ![[L14:[0-9]+]]
-// CHECK: ![[L13]] = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed
-// CHECK: ![[L14]] = !{![[L15:[0-9]+]]}
-// CHECK: ![[L15]] = !{!"btf_type_tag", !"tag1"}
-// CHECK: ![[L16]] = !{![[L17:[0-9]+]]}
-// CHECK: ![[L17]] = !{!"btf_type_tag", !"tag2"}
-// CHECK: !DILocalVariable(name: "arg", arg: 1, scope: ![[#]], file: ![[#]], line: [[#]], type: ![[L11]])
+// CHECK: distinct !DISubprogram(name: "foo", scope: ![[#]], file: ![[#]], line: [[#]], type: ![[L01:[0-9]+]], {{.*}})
+// CHECK: ![[L01]] = !DISubroutineType(types: ![[L02:[0-9]+]])
+// CHECK: ![[L02]] = !{![[L03:[0-9]+]], ![[L03]]}
+// CHECK: ![[L03]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[L04:[0-9]+]], size: [[#]], annotations: ![[L05:[0-9]+]])
+// CHECK: ![[L04]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[L06:[0-9]+]], size: [[#]], annotations: ![[L07:[0-9]+]])
+// CHECK: ![[L06]] = !DIBasicType(name: "int", size: [[#]], encoding: DW_ATE_signed)
+// CHECK: ![[L07]] = !{![[L11:[0-9]+]]}
+// CHECK: ![[L11]] = !{!"btf_type_tag", !"tag1"}
+// CHECK: ![[L05]] = !{![[L12:[0-9]+]]}
+// CHECK: ![[L12]] = !{!"btf_type_tag", !"tag2"}
+// CHECK: !DILocalVariable(name: "arg", arg: 1, scope: ![[#]], file: ![[#]], line: [[#]], type: ![[L03]])
+
+// CHECK-V2: distinct !DISubprogram(name: "foo", scope: ![[#]], file: ![[#]], line: [[#]], type: ![[L01:[0-9]+]], {{.*}})
+// CHECK-V2: ![[L01]] = !DISubroutineType(types: ![[L02:[0-9]+]])
+// CHECK-V2: ![[L02]] = !{![[L03:[0-9]+]], ![[L03]]}
+// CHECK-V2: ![[L03]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[L04:[0-9]+]], size: [[#]])
+// CHECK-V2: ![[L04]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[L06:[0-9]+]], size: [[#]], annotations: ![[L07:[0-9...
[truncated]
|
|
Looks like some changes are duplicate from #91422, e.g., llvm/lib/Bitcode/Reader/MetadataLoader.cpp. There are some other files are duplicated as well. Could you do a cleanup here? This will make it easy to compare to https://reviews.llvm.org/D143967. |
As far as I understand, this is how one makes "revision stacks" after migration from Phabriactor to Github: I have three branches, one for each patch I want to land, each branch is forked from a previous one. Until first branch is landed, Github will show two pending commits (one from the previous branch, one from this branch). To check changes specific to this branch please refer to the top-most commit of the branch: ba6a989 Please let me know if I understand the new process in a wrong way. |
|
Okay, I see. Thanks for explanation. I checked the top commit and it looks good to me. it is very similar to https://reviews.llvm.org/D143967 except a few additions like new llvm internal flag and a couple of places to generate type tags based on v1 format. Test "buildkite/github-pull-requests " failed and I don't know what is the reason. I think it is worthwhile to rerun the test to ensure all tests passed. |
|
Test "buildkite/github-pull-requests " failed and I don't know what is the
reason. I think it is worthwhile to rerun the test to ensure all tests
passed.
CI failure seems to be a fluke as it is reported for
DataFlowSanitizer-x86_64 :: release_shadow_space.c which is completely
unrelated, also CI for 91424 passed (91424 adds one commit to the bpf
backend on top of this revision).
… |
Right, I am aware of this. I just want to have test status 'green' :-) |
yonghong-song
approved these changes
May 19, 2024
dwblaikie
approved these changes
May 29, 2024
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This commit is a follow-up for BPF mailing list discussion at [1].
It changes the way `__attribute__((btf_type_tag("...")))`s are
represented in DWARF.
Prior to this commit type tags could only be attached to pointers.
Such attachments associated the tags with a pointee type.
E.g. for the following C code:
int __attribute__((btf_type_tag("tag1"))) *g;
Generated DWARF looked as follows:
0x0000001e: DW_TAG_variable
DW_AT_name ("g")
DW_AT_type (0x00000029 "int *")
0x00000029: DW_TAG_pointer_type
DW_AT_type (0x00000032 "int")
0x0000002e: DW_TAG_LLVM_annotation
DW_AT_name ("btf_type_tag")
DW_AT_const_value ("tag1")
0x00000032: DW_TAG_base_type
DW_AT_name ("int")
The goal of this commit is to allow attachment of type tags to the
tagged types instead. E.g. for the same example DWARF should look as
follows:
0x0000001e: DW_TAG_variable
DW_AT_name ("g")
DW_AT_type (0x00000029 "int *")
0x00000029: DW_TAG_pointer_type
DW_AT_type (0x00000032 "int")
0x00000032: DW_TAG_base_type
DW_AT_name ("int")
0x00000036: DW_TAG_LLVM_annotation
DW_AT_name ("btf:type_tag")
DW_AT_const_value ("tag1")
A new tag name, `btf:type_tag`, is used so that DWARF consumers
could distinguish between old and new attachment semantics.
This feature is mostly used by Linux Kernel in combination with tool
named pahole [2]. Reasonably recent versions of pahole generate
errors (1.23, 1.24) or warnings (1.25) when `DW_TAG_LLVM_annotation`
is attached to `DW_TAG_base_type` or `DW_TAG_unspecified_type`.
Hence the `btf:type_tag` generation is controlled by a hidden option
`-mllvm -btf-type-tag-v2`. The goal is to provide a way for tooling to
work on adding support `btf:type_tag` and eventually replace
`btf_type_tag` by `btf:type_tag`, removing the above option.
The commit includes the following changes:
- Changes in debug info generation:
- New method `DIBuilder::createAnnotationsPlaceholder()` is added,
it creates a temporary `DIDerivedType` that plays as annotations
placeholder while debug info metadata is being constructed;
- New overload for `CGDebugInfo::CreateType` method is added:
llvm::DIType *CGDebugInfo::CreateType(const BTFTagAttributedType *Ty,
llvm::DIFile *Unit);
This overload collects BTF type tags in `Ty`, creates annotations
placeholder pointing to the base type of `Ty`, registers the
placeholder in the `CGDebugInfo::AnnotationsPlaceholder` vector.
- `CGDebugInfo::finalize()` is updated to do the following for each
annotation placeholder:
- clone underlying base type;
- attach annotations the clone using `replaceAnnotations()` call;
- replace all placeholder usages by a clone.
Such scheme allows to deal with type cycles.
- Changes in AST construction:
- `ASTContext::getBTFTagAttributedType()` is updated to ensure that
`BTFTagAttributedType` always wraps `QualType` w/o local
constant/volatile/restricted qualifiers. This simplifies debug info
generation.
[1] https://lore.kernel.org/bpf/87r0w9jjoq.fsf@oracle.com/
[2] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/
This was previously tracked as differential revision:
https://reviews.llvm.org/D143967
Newly added btf_type_tag related tests use 'clang -S -emit-llvm', which is now not accepted by 'clang'. Fix these tests by using only '-emit-llvm'. To be squashed with the main commit when when branch would be merged.
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This commit is a follow-up for BPF mailing list discussion at [1]. It changes the way
__attribute__((btf_type_tag("...")))s are represented in DWARF.Prior to this commit type tags could only be attached to pointers. Such attachments associated the tags with a pointee type. E.g. for the following C code:
Generated DWARF looked as follows:
The goal of this commit is to allow attachment of type tags to the tagged types instead. E.g. for the same example DWARF should look as follows:
A new tag name,
btf:type_tag, is used so that DWARF consumers could distinguish between old and new attachment semantics.This feature is mostly used by Linux Kernel in combination with tool named pahole [2]. Reasonably recent versions of pahole generate errors (1.23, 1.24) or warnings (1.25) when
DW_TAG_LLVM_annotationis attached toDW_TAG_base_typeorDW_TAG_unspecified_type. Hence thebtf:type_taggeneration is controlled by a hidden option-mllvm -btf-type-tag-v2. The goal is to provide a way for tooling to work on adding supportbtf:type_tagand eventually replacebtf_type_tagbybtf:type_tag, removing the above option.The commit includes the following changes:
Changes in debug info generation:
New method
DIBuilder::createAnnotationsPlaceholder()is added, it creates a temporaryDIDerivedTypethat plays as annotations placeholder while debug info metadata is being constructed;New overload for
CGDebugInfo::CreateTypemethod is added:llvm::DIType *CGDebugInfo::CreateType(const BTFTagAttributedType *Ty,
llvm::DIFile *Unit);
This overload collects BTF type tags in
Ty, creates annotations placeholder pointing to the base type ofTy, registers the placeholder in theCGDebugInfo::AnnotationsPlaceholdervector.CGDebugInfo::finalize()is updated to do the following for each annotation placeholder:replaceAnnotations()call;Such scheme allows to deal with type cycles.
Changes in AST construction:
ASTContext::getBTFTagAttributedType()is updated to ensure thatBTFTagAttributedTypealways wrapsQualTypew/o local constant/volatile/restricted qualifiers. This simplifies debug info generation.[1] https://lore.kernel.org/bpf/87r0w9jjoq.fsf@oracle.com/
[2] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/
This was previously tracked as differential revision:
https://reviews.llvm.org/D143967
Note: the new place for annotation is DWARF was already agreed as a part of D143967, however the switch enabling or disabling this is a new addition.