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[BPF] Allow struct pointee member btf generation with annotations #141719

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May 28, 2025
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[BPF] Allow struct pointee member btf generation with annotations #141719

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5 changes: 3 additions & 2 deletions llvm/lib/Target/BPF/BTFDebug.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -816,7 +816,7 @@ void BTFDebug::visitDerivedType(const DIDerivedType *DTy, uint32_t &TypeId,
/// Try to avoid chasing pointees, esp. structure pointees which may
/// unnecessary bring in a lot of types.
if (CheckPointer && !SeenPointer) {
SeenPointer = Tag == dwarf::DW_TAG_pointer_type;
SeenPointer = Tag == dwarf::DW_TAG_pointer_type && !DTy->getAnnotations();
}

if (CheckPointer && SeenPointer) {
Expand Down Expand Up @@ -916,7 +916,8 @@ void BTFDebug::visitTypeEntry(const DIType *Ty, uint32_t &TypeId,
if (DIToIdMap.find(BaseTy) != DIToIdMap.end()) {
DTy = dyn_cast<DIDerivedType>(BaseTy);
} else {
if (CheckPointer && DTy->getTag() == dwarf::DW_TAG_pointer_type) {
if (CheckPointer && DTy->getTag() == dwarf::DW_TAG_pointer_type &&
!DTy->getAnnotations()) {
SeenPointer = true;
if (IsForwardDeclCandidate(BaseTy))
break;
Expand Down
86 changes: 86 additions & 0 deletions llvm/test/CodeGen/BPF/BTF/annot-dup-ptr-struct.ll
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@@ -0,0 +1,86 @@
; RUN: llc -mtriple=bpfel -mcpu=v3 -filetype=obj -o %t1 %s
; RUN: llvm-objcopy --dump-section='.BTF'=%t2 %t1
; RUN: %python %p/print_btf.py %t2 | FileCheck -check-prefixes=CHECK-BTF %s
; Source:
; #define __tag1 __attribute__((btf_type_tag("tag1")))
;
; struct t1 {
; int a;
; };
; struct t2 {
; struct t1 *p1;
; struct t1 __tag1 *p2;
; int b;
; };
; int foo(struct t2 *arg) {
; return arg->b;
; }
; Compilation flags:
; clang -target bpf -O2 -g -S -emit-llvm t.c

; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(argmem: read)
define dso_local i32 @foo(ptr nocapture noundef readonly %0) local_unnamed_addr #0 !dbg !8 {
#dbg_value(ptr %0, !26, !DIExpression(), !27)
%2 = getelementptr inbounds nuw i8, ptr %0, i64 16, !dbg !28
%3 = load i32, ptr %2, align 8, !dbg !28, !tbaa !29
ret i32 %3, !dbg !36
}

; CHECK-BTF: [1] PTR '(anon)' type_id=2
; CHECK-BTF: [2] STRUCT 't2' size=24 vlen=3
; CHECK-BTF: 'p1' type_id=3 bits_offset=0
; CHECK-BTF: 'p2' type_id=5 bits_offset=64
; CHECK-BTF: 'b' type_id=7 bits_offset=128
; CHECK-BTF: [3] PTR '(anon)' type_id=6
; CHECK-BTF: [4] TYPE_TAG 'tag1' type_id=6
; CHECK-BTF: [5] PTR '(anon)' type_id=4
; CHECK-BTF: [6] STRUCT 't1' size=4 vlen=1
; CHECK-BTF: 'a' type_id=7 bits_offset=0
; CHECK-BTF: [7] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED
; CHECK-BTF: [8] FUNC_PROTO '(anon)' ret_type_id=7 vlen=1
; CHECK-BTF: 'arg' type_id=1
; CHECK-BTF: [9] FUNC 'foo' type_id=8 linkage=global

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(argmem: read) "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" }

!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2, !3, !4, !5, !6}
!llvm.ident = !{!7}

!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 20.1.6 (https://github.com/llvm/llvm-project.git aa804fd3e624cb92c6e7665182504c6049387f35)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
!1 = !DIFile(filename: "t.c", directory: "/tmp/home/yhs/tmp3/tests", checksumkind: CSK_MD5, checksum: "73ef5b93654cc4e2667f383d5c3a9cd3")
!2 = !{i32 7, !"Dwarf Version", i32 5}
!3 = !{i32 2, !"Debug Info Version", i32 3}
!4 = !{i32 1, !"wchar_size", i32 4}
!5 = !{i32 7, !"frame-pointer", i32 2}
!6 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
!7 = !{!"clang version 20.1.6 (https://github.com/llvm/llvm-project.git aa804fd3e624cb92c6e7665182504c6049387f35)"}
!8 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 11, type: !9, scopeLine: 11, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !25)
!9 = !DISubroutineType(types: !10)
!10 = !{!11, !12}
!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!12 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !13, size: 64)
!13 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "t2", file: !1, line: 6, size: 192, elements: !14)
!14 = !{!15, !20, !24}
!15 = !DIDerivedType(tag: DW_TAG_member, name: "p1", scope: !13, file: !1, line: 7, baseType: !16, size: 64)
!16 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !17, size: 64)
!17 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "t1", file: !1, line: 3, size: 32, elements: !18)
!18 = !{!19}
!19 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !17, file: !1, line: 4, baseType: !11, size: 32)
!20 = !DIDerivedType(tag: DW_TAG_member, name: "p2", scope: !13, file: !1, line: 8, baseType: !21, size: 64, offset: 64)
!21 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !17, size: 64, annotations: !22)
!22 = !{!23}
!23 = !{!"btf_type_tag", !"tag1"}
!24 = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: !13, file: !1, line: 9, baseType: !11, size: 32, offset: 128)
!25 = !{!26}
!26 = !DILocalVariable(name: "arg", arg: 1, scope: !8, file: !1, line: 11, type: !12)
!27 = !DILocation(line: 0, scope: !8)
!28 = !DILocation(line: 12, column: 15, scope: !8)
!29 = !{!30, !35, i64 16}
!30 = !{!"t2", !31, i64 0, !31, i64 8, !35, i64 16}
!31 = !{!"p1 _ZTS2t1", !32, i64 0}
!32 = !{!"any pointer", !33, i64 0}
!33 = !{!"omnipotent char", !34, i64 0}
!34 = !{!"Simple C/C++ TBAA"}
!35 = !{!"int", !33, i64 0}
!36 = !DILocation(line: 12, column: 3, scope: !8)
81 changes: 22 additions & 59 deletions llvm/test/CodeGen/BPF/BTF/type-tag-fixup-resolved.ll
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Original file line number Diff line number Diff line change
@@ -1,5 +1,9 @@
; RUN: llc -mtriple=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
; RUN: llc -mtriple=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
; RUN: llc -mtriple=bpfel -filetype=obj -o %t1 %s
; RUN: llvm-objcopy --dump-section='.BTF'=%t2 %t1
; RUN: %python %p/print_btf.py %t2 | FileCheck -check-prefixes=CHECK-BTF %s
; RUN: llc -mtriple=bpfeb -filetype=obj -o %t1 %s
; RUN: llvm-objcopy --dump-section='.BTF'=%t2 %t1
; RUN: %python %p/print_btf.py %t2 | FileCheck -check-prefixes=CHECK-BTF %s
;
; Source:
; #define __tag1 __attribute__((btf_type_tag("tag1")))
Expand Down Expand Up @@ -37,63 +41,22 @@ entry:
ret void, !dbg !26
}

; CHECK: .long 0 # BTF_KIND_FUNC_PROTO(id = 1)
; CHECK-NEXT: .long 218103808 # 0xd000000
; CHECK-NEXT: .long 0
; CHECK-NEXT: .long 1 # BTF_KIND_FUNC(id = 2)
; CHECK-NEXT: .long 201326593 # 0xc000001
; CHECK-NEXT: .long 1
; CHECK-NEXT: .long 0 # BTF_KIND_FUNC_PROTO(id = 3)
; CHECK-NEXT: .long 218103810 # 0xd000002
; CHECK-NEXT: .long 0
; CHECK-NEXT: .long 0
; CHECK-NEXT: .long 4
; CHECK-NEXT: .long 0
; CHECK-NEXT: .long 7
; CHECK-NEXT: .long 0 # BTF_KIND_PTR(id = 4)
; CHECK-NEXT: .long 33554432 # 0x2000000
; CHECK-NEXT: .long 5
; CHECK-NEXT: .long 63 # BTF_KIND_STRUCT(id = 5)
; CHECK-NEXT: .long 67108865 # 0x4000001
; CHECK-NEXT: .long 8
; CHECK-NEXT: .long 73
; CHECK-NEXT: .long 6
; CHECK-NEXT: .long 0 # 0x0
; CHECK-NEXT: .long 0 # BTF_KIND_PTR(id = 6)
; CHECK-NEXT: .long 33554432 # 0x2000000
; CHECK-NEXT: .long 12
; CHECK-NEXT: .long 0 # BTF_KIND_PTR(id = 7)
; CHECK-NEXT: .long 33554432 # 0x2000000
; CHECK-NEXT: .long 8
; CHECK-NEXT: .long 77 # BTF_KIND_STRUCT(id = 8)
; CHECK-NEXT: .long 67108865 # 0x4000001
; CHECK-NEXT: .long 4
; CHECK-NEXT: .long 81
; CHECK-NEXT: .long 9
; CHECK-NEXT: .long 0 # 0x0
; CHECK-NEXT: .long 83 # BTF_KIND_INT(id = 9)
; CHECK-NEXT: .long 16777216 # 0x1000000
; CHECK-NEXT: .long 4
; CHECK-NEXT: .long 16777248 # 0x1000020
; CHECK-NEXT: .long 87 # BTF_KIND_FUNC(id = 10)
; CHECK-NEXT: .long 201326594 # 0xc000002
; CHECK-NEXT: .long 3
; CHECK-NEXT: .long 92 # BTF_KIND_TYPE_TAG(id = 11)
; CHECK-NEXT: .long 301989888 # 0x12000000
; CHECK-NEXT: .long 8
; CHECK-NEXT: .long 97 # BTF_KIND_TYPE_TAG(id = 12)
; CHECK-NEXT: .long 301989888 # 0x12000000
; CHECK-NEXT: .long 11

; CHECK: .ascii "test" # string offset=1
; CHECK: .ascii "map_value" # string offset=63
; CHECK: .ascii "ptr" # string offset=73
; CHECK: .ascii "foo" # string offset=77
; CHECK: .byte 105 # string offset=81
; CHECK: .ascii "int" # string offset=83
; CHECK: .ascii "func" # string offset=87
; CHECK: .ascii "tag2" # string offset=92
; CHECK: .ascii "tag1" # string offset=97
; CHECK-BTF: [1] FUNC_PROTO '(anon)' ret_type_id=0 vlen=0
; CHECK-BTF: [2] FUNC 'test' type_id=1 linkage=global
; CHECK-BTF: [3] FUNC_PROTO '(anon)' ret_type_id=0 vlen=2
; CHECK-BTF: '(anon)' type_id=4
; CHECK-BTF: '(anon)' type_id=11
; CHECK-BTF: [4] PTR '(anon)' type_id=5
; CHECK-BTF: [5] STRUCT 'map_value' size=8 vlen=1
; CHECK-BTF: 'ptr' type_id=8 bits_offset=0
; CHECK-BTF: [6] TYPE_TAG 'tag2' type_id=9
; CHECK-BTF: [7] TYPE_TAG 'tag1' type_id=6
; CHECK-BTF: [8] PTR '(anon)' type_id=7
; CHECK-BTF: [9] STRUCT 'foo' size=4 vlen=1
; CHECK-BTF: 'i' type_id=10 bits_offset=0
; CHECK-BTF: [10] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED
; CHECK-BTF: [11] PTR '(anon)' type_id=9
; CHECK-BTF: [12] FUNC 'func' type_id=3 linkage=extern

; Function Attrs: argmemonly mustprogress nofree nosync nounwind willreturn
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1
Expand Down
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