d0ea05d5ef
Previously, debuginfo types are annotated to
IR builtin preserve_struct_access_index() and
preserve_union_access_index(), but not
preserve_array_access_index(). The debug info
is useful to identify the root type name which
later will be used for type comparison.
For user access without explicit type conversions,
the previous scheme works as we can ignore intermediate
compiler generated type conversions (e.g., from union types to
union members) and still generate correct access index string.
The issue comes with user explicit type conversions, e.g.,
converting an array to a structure like below:
struct t { int a; char b[40]; };
struct p { int c; int d; };
struct t *var = ...;
... __builtin_preserve_access_index(&(((struct p *)&(var->b[0]))->d)) ...
Although BPF backend can derive the type of &(var->b[0]),
explicit type annotation make checking more consistent
and less error prone.
Another benefit is for multiple dimension array handling.
For example,
struct p { int c; int d; } g[8][9][10];
... __builtin_preserve_access_index(&g[2][3][4].d) ...
It would be possible to calculate the number of "struct p"'s
before accessing its member "d" if array debug info is
available as it contains each dimension range.
This patch enables to annotate IR builtin preserve_array_access_index()
with proper debuginfo type. The unit test case and language reference
is updated as well.
Signed-off-by: Yonghong Song <yhs@fb.com>
Differential Revision: https://reviews.llvm.org/D65664
llvm-svn: 367724
81 lines
4.4 KiB
LLVM
81 lines
4.4 KiB
LLVM
; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck %s
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;
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; Source code:
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; #define _(x) (__builtin_preserve_access_index(x))
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; struct s { int a; int b; };
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; int get_value(const void *addr);
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; int test(struct s *arg) { return get_value(_(&arg[2].b)); }
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; Compiler flag to generate IR:
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; clang -target bpf -S -O2 -g -emit-llvm test.c
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%struct.s = type { i32, i32 }
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; Function Attrs: nounwind
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define dso_local i32 @test(%struct.s* %arg) local_unnamed_addr #0 !dbg !7 {
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entry:
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call void @llvm.dbg.value(metadata %struct.s* %arg, metadata !17, metadata !DIExpression()), !dbg !18
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%0 = tail call %struct.s* @llvm.preserve.array.access.index.p0s_struct.ss.p0s_struct.ss(%struct.s* %arg, i32 0, i32 2), !dbg !19, !llvm.preserve.access.index !11
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%1 = tail call i32* @llvm.preserve.struct.access.index.p0i32.p0s_struct.ss(%struct.s* %0, i32 1, i32 1), !dbg !19, !llvm.preserve.access.index !12
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%2 = bitcast i32* %1 to i8*, !dbg !19
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%call = tail call i32 @get_value(i8* %2) #4, !dbg !20
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ret i32 %call, !dbg !21
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}
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; CHECK-LABEL: test
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; CHECK: [[RELOC:.Ltmp[0-9]+]]
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; CHECK: r2 = 20
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; CHECK: r1 += r2
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; CHECK: call get_value
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; CHECK: exit
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;
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; CHECK: .section .BTF.ext,"",@progbits
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; CHECK: .long 12 # OffsetReloc
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; CHECK-NEXT: .long 20 # Offset reloc section string offset=20
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; CHECK-NEXT: .long 1
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; CHECK-NEXT: .long [[RELOC]]
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; CHECK-NEXT: .long 2
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; CHECK-NEXT: .long 26
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declare dso_local i32 @get_value(i8*) local_unnamed_addr #1
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; Function Attrs: nounwind readnone
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declare %struct.s* @llvm.preserve.array.access.index.p0s_struct.ss.p0s_struct.ss(%struct.s*, i32 immarg, i32 immarg) #2
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; Function Attrs: nounwind readnone
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declare i32* @llvm.preserve.struct.access.index.p0i32.p0s_struct.ss(%struct.s*, i32 immarg, i32 immarg) #2
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; Function Attrs: nounwind readnone speculatable
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declare void @llvm.dbg.value(metadata, metadata, metadata) #3
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attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #2 = { nounwind readnone }
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attributes #3 = { nounwind readnone speculatable }
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attributes #4 = { nounwind }
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!3, !4, !5}
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!llvm.ident = !{!6}
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!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 9.0.0 (trunk 365789)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
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!1 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/core")
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!2 = !{}
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!3 = !{i32 2, !"Dwarf Version", i32 4}
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!4 = !{i32 2, !"Debug Info Version", i32 3}
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!5 = !{i32 1, !"wchar_size", i32 4}
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!6 = !{!"clang version 9.0.0 (trunk 365789)"}
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!7 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 4, type: !8, scopeLine: 4, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !16)
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!8 = !DISubroutineType(types: !9)
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!9 = !{!10, !11}
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!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64)
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!12 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "s", file: !1, line: 2, size: 64, elements: !13)
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!13 = !{!14, !15}
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!14 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !12, file: !1, line: 2, baseType: !10, size: 32)
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!15 = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: !12, file: !1, line: 2, baseType: !10, size: 32, offset: 32)
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!16 = !{!17}
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!17 = !DILocalVariable(name: "arg", arg: 1, scope: !7, file: !1, line: 4, type: !11)
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!18 = !DILocation(line: 0, scope: !7)
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!19 = !DILocation(line: 4, column: 44, scope: !7)
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!20 = !DILocation(line: 4, column: 34, scope: !7)
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!21 = !DILocation(line: 4, column: 27, scope: !7)
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