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[DWARF] Support new TAG DW_TAG_LLVM_annotation 

A new LLVM specific TAG DW_TAG_LLVM_annotation is added.
The name is suggested by Paul Robinson ([1]).
Currently, this tag is used to output __attribute__((btf_tag("string")))
annotations in dwarf. The following is an example for a global
variable with two btf_tag attributes:
  0x0000002a:   DW_TAG_variable
                  DW_AT_name      ("g1")
                  DW_AT_type      (0x00000052 "int")
                  DW_AT_external  (true)
                  DW_AT_decl_file ("/tmp/home/yhs/work/tests/llvm/btf_tag/t.c")
                  DW_AT_decl_line (8)
                  DW_AT_location  (DW_OP_addr 0x0)

  0x0000003f:     DW_TAG_LLVM_annotation
                    DW_AT_name    ("btf_tag")
                    DW_AT_const_value     ("tag1")

  0x00000048:     DW_TAG_LLVM_annotation
                    DW_AT_name    ("btf_tag")
                    DW_AT_const_value     ("tag2")

  0x00000051:     NULL

In the future, DW_TAG_LLVM_annotation may encode other type
of non-string const value.

 [1] https://lists.llvm.org/pipermail/llvm-dev/2021-June/151250.html

Differential Revision: https://reviews.llvm.org/D106621
This commit is contained in:
Yonghong Song 2021-07-19 09:54:33 -07:00
parent 1688b4cf8e
commit 89424a829f
5 changed files with 169 additions and 1 deletions
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3
llvm/include/llvm/BinaryFormat/Dwarf.def
View File

@ -248,6 +248,9 @@ HANDLE_DW_TAG(0x5103, ALTIUM_rev_carry_type, 0, ALTIUM, DW_KIND_NONE)
// M16 __rom qualifier
HANDLE_DW_TAG(0x5111, ALTIUM_rom, 0, ALTIUM, DW_KIND_NONE)
// LLVM
HANDLE_DW_TAG(0x6000, LLVM_annotation, 0, LLVM, DW_KIND_NONE)
// Green Hills.
HANDLE_DW_TAG(0x8004, GHS_namespace, 0, GHS, DW_KIND_NONE)
HANDLE_DW_TAG(0x8005, GHS_using_namespace, 0, GHS, DW_KIND_NONE)

6
llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
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@ -183,6 +183,8 @@ DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(
else
addGlobalName(GV->getName(), *VariableDIE, DeclContext);
addAnnotation(*VariableDIE, GV->getAnnotations());
if (uint32_t AlignInBytes = GV->getAlignInBytes())
addUInt(*VariableDIE, dwarf::DW_AT_alignment, dwarf::DW_FORM_udata,
AlignInBytes);
@ -1480,10 +1482,12 @@ void DwarfCompileUnit::applyVariableAttributes(const DbgVariable &Var,
if (!Name.empty())
addString(VariableDie, dwarf::DW_AT_name, Name);
const auto *DIVar = Var.getVariable();
if (DIVar)
if (DIVar) {
if (uint32_t AlignInBytes = DIVar->getAlignInBytes())
addUInt(VariableDie, dwarf::DW_AT_alignment, dwarf::DW_FORM_udata,
AlignInBytes);
addAnnotation(VariableDie, DIVar->getAnnotations());
}
addSourceLine(VariableDie, DIVar);
addType(VariableDie, Var.getType());

23
llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
View File

@ -833,6 +833,23 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DISubroutineType *CTy) {
addFlag(Buffer, dwarf::DW_AT_rvalue_reference);
}
void DwarfUnit::addAnnotation(DIE &Buffer, DINodeArray Annotations) {
if (!Annotations)
return;
for (const Metadata *Annotation : Annotations->operands()) {
const MDNode *MD = cast<MDNode>(Annotation);
const MDString *Name = cast<MDString>(MD->getOperand(0));
// Currently, only MDString is supported with btf_tag attribute.
const MDString *Value = cast<MDString>(MD->getOperand(1));
DIE &AnnotationDie = createAndAddDIE(dwarf::DW_TAG_LLVM_annotation, Buffer);
addString(AnnotationDie, dwarf::DW_AT_name, Name->getString());
addString(AnnotationDie, dwarf::DW_AT_const_value, Value->getString());
}
}
void DwarfUnit::constructTypeDIE(DIE &Buffer, const DICompositeType *CTy) {
// Add name if not anonymous or intermediate type.
StringRef Name = CTy->getName();
@ -961,6 +978,8 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DICompositeType *CTy) {
if (!Name.empty())
addString(Buffer, dwarf::DW_AT_name, Name);
addAnnotation(Buffer, CTy->getAnnotations());
if (Tag == dwarf::DW_TAG_enumeration_type ||
Tag == dwarf::DW_TAG_class_type || Tag == dwarf::DW_TAG_structure_type ||
Tag == dwarf::DW_TAG_union_type) {
@ -1197,6 +1216,8 @@ void DwarfUnit::applySubprogramAttributes(const DISubprogram *SP, DIE &SPDie,
if (!SP->getName().empty())
addString(SPDie, dwarf::DW_AT_name, SP->getName());
addAnnotation(SPDie, SP->getAnnotations());
if (!SkipSPSourceLocation)
addSourceLine(SPDie, SP);
@ -1547,6 +1568,8 @@ DIE &DwarfUnit::constructMemberDIE(DIE &Buffer, const DIDerivedType *DT) {
if (!Name.empty())
addString(MemberDie, dwarf::DW_AT_name, Name);
addAnnotation(MemberDie, DT->getAnnotations());
if (DIType *Resolved = DT->getBaseType())
addType(MemberDie, Resolved);

3
llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
View File

@ -294,6 +294,9 @@ public:
void addSectionLabel(DIE &Die, dwarf::Attribute Attribute,
const MCSymbol *Label, const MCSymbol *Sec);
/// Add DW_TAG_LLVM_annotation.
void addAnnotation(DIE &Buffer, DINodeArray Annotations);
/// Get context owner's DIE.
DIE *createTypeDIE(const DICompositeType *Ty);

135
llvm/test/DebugInfo/attr-btf_tag.ll Normal file
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@ -0,0 +1,135 @@
; REQUIRES: x86-registered-target
; RUN: llc -filetype=obj -o %t %s
; RUN: llvm-dwarfdump -debug-info %t | FileCheck %s
; Source:
; #define __tag1 __attribute__((btf_tag("tag1")))
; #define __tag2 __attribute__((btf_tag("tag2")))
;
; struct t1 {
; int a __tag1 __tag2;
; } __tag1 __tag2;
;
; int g1 __tag1 __tag2;
;
; int __tag1 __tag2 foo(struct t1 *arg __tag1 __tag2) {
; return arg->a;
; }
; Compilation flag:
; clang -target x86_64 -g -S -emit-llvm t.c
%struct.t1 = type { i32 }
@g1 = dso_local global i32 0, align 4, !dbg !0
; Function Attrs: noinline nounwind optnone uwtable
define dso_local i32 @foo(%struct.t1* %arg) #0 !dbg !16 {
entry:
%arg.addr = alloca %struct.t1*, align 8
store %struct.t1* %arg, %struct.t1** %arg.addr, align 8
call void @llvm.dbg.declare(metadata %struct.t1** %arg.addr, metadata !23, metadata !DIExpression()), !dbg !24
%0 = load %struct.t1*, %struct.t1** %arg.addr, align 8, !dbg !25
%a = getelementptr inbounds %struct.t1, %struct.t1* %0, i32 0, i32 0, !dbg !26
%1 = load i32, i32* %a, align 4, !dbg !26
ret i32 %1, !dbg !27
}
; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
attributes #0 = { noinline nounwind optnone uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #1 = { nofree nosync nounwind readnone speculatable willreturn }
!llvm.dbg.cu = !{!2}
!llvm.module.flags = !{!10, !11, !12, !13, !14}
!llvm.ident = !{!15}
!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
!1 = distinct !DIGlobalVariable(name: "g1", scope: !2, file: !3, line: 8, type: !6, isLocal: false, isDefinition: true, annotations: !7)
; CHECK: DW_TAG_variable
; CHECK-NEXT: DW_AT_name ("g1")
; CHECK: DW_TAG_LLVM_annotation
; CHECK-NEXT: DW_AT_name ("btf_tag")
; CHECK-NEXT: DW_AT_const_value ("tag1")
; CHECK-EMPTY:
; CHECK-NEXT: DW_TAG_LLVM_annotation
; CHECK-NEXT: DW_AT_name ("btf_tag")
; CHECK-NEXT: DW_AT_const_value ("tag2")
; CHECK-EMPTY:
; CHECK-NEXT: NULL
!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 13.0.0 (https://github.com/llvm/llvm-project.git 305231a4f71b68945b4dd92925c76ff49e377c86)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, splitDebugInlining: false, nameTableKind: None)
!3 = !DIFile(filename: "t.c", directory: "/tmp/home/yhs/work/tests/llvm/btf_tag")
!4 = !{}
!5 = !{!0}
!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!7 = !{!8, !9}
!8 = !{!"btf_tag", !"tag1"}
!9 = !{!"btf_tag", !"tag2"}
!10 = !{i32 7, !"Dwarf Version", i32 4}
!11 = !{i32 2, !"Debug Info Version", i32 3}
!12 = !{i32 1, !"wchar_size", i32 4}
!13 = !{i32 7, !"uwtable", i32 1}
!14 = !{i32 7, !"frame-pointer", i32 2}
!15 = !{!"clang version 13.0.0 (https://github.com/llvm/llvm-project.git 305231a4f71b68945b4dd92925c76ff49e377c86)"}
!16 = distinct !DISubprogram(name: "foo", scope: !3, file: !3, line: 10, type: !17, scopeLine: 10, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !4, annotations: !7)
; CHECK: DW_TAG_subprogram
; CHECK: DW_AT_name ("foo")
; CHECK: DW_TAG_formal_parameter
; CHECK: DW_TAG_LLVM_annotation
; CHECK-NEXT: DW_AT_name ("btf_tag")
; CHECK-NEXT: DW_AT_const_value ("tag1")
; CHECK-EMPTY:
; CHECK-NEXT: DW_TAG_LLVM_annotation
; CHECK-NEXT: DW_AT_name ("btf_tag")
; CHECK-NEXT: DW_AT_const_value ("tag2")
; CHECK-EMPTY:
; CHECK-NEXT: NULL
; CHECK-EMPTY:
; CHECK-NEXT: DW_TAG_LLVM_annotation
; CHECK-NEXT: DW_AT_name ("btf_tag")
; CHECK-NEXT: DW_AT_const_value ("tag1")
; CHECK-EMPTY:
; CHECK-NEXT: DW_TAG_LLVM_annotation
; CHECK-NEXT: DW_AT_name ("btf_tag")
; CHECK-NEXT: DW_AT_const_value ("tag2")
; CHECK-EMPTY:
; CHECK-NEXT: NULL
!17 = !DISubroutineType(types: !18)
!18 = !{!6, !19}
!19 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !20, size: 64)
!20 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "t1", file: !3, line: 4, size: 32, elements: !21, annotations: !7)
!21 = !{!22}
!22 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !20, file: !3, line: 5, baseType: !6, size: 32, annotations: !7)
; CHECK: DW_TAG_structure_type
; CHECK-NEXT: DW_AT_name ("t1")
; CHECK: DW_TAG_member
; CHECK-NEXT: DW_AT_name ("a")
; CHECK: DW_TAG_LLVM_annotation
; CHECK-NEXT: DW_AT_name ("btf_tag")
; CHECK-NEXT: DW_AT_const_value ("tag1")
; CHECK-EMPTY:
; CHECK-NEXT: DW_TAG_LLVM_annotation
; CHECK-NEXT: DW_AT_name ("btf_tag")
; CHECK-NEXT: DW_AT_const_value ("tag2")
; CHECK-EMPTY:
; CHECK-NEXT: NULL
; CHECK-EMPTY:
; CHECK-NEXT: DW_TAG_LLVM_annotation
; CHECK-NEXT: DW_AT_name ("btf_tag")
; CHECK-NEXT: DW_AT_const_value ("tag1")
; CHECK-EMPTY:
; CHECK-NEXT: DW_TAG_LLVM_annotation
; CHECK-NEXT: DW_AT_name ("btf_tag")
; CHECK-NEXT: DW_AT_const_value ("tag2")
; CHECK-EMPTY:
; CHECK-NEXT: NULL
!23 = !DILocalVariable(name: "arg", arg: 1, scope: !16, file: !3, line: 10, type: !19, annotations: !7)
!24 = !DILocation(line: 10, column: 48, scope: !16)
!25 = !DILocation(line: 11, column: 10, scope: !16)
!26 = !DILocation(line: 11, column: 15, scope: !16)
!27 = !DILocation(line: 11, column: 3, scope: !16)