dc1c43d726
Current BTF only supports 32-bit value. For example,
enum T { VAL = 0xffffFFFF00000008 };
the generated BTF looks like
.long 16 # BTF_KIND_ENUM(id = 4)
.long 100663297 # 0x6000001
.long 8
.long 18
.long 8
The encoded value is 8 which equals to (uint32_t)0xffffFFFF00000008
and this is incorrect.
This patch introduced BTF_KIND_ENUM64 which permits to encode
64-bit value. The format for each enumerator looks like:
.long name_offset
.long (uint32_t)value # lower-32 bit value
.long value >> 32 # high-32 bit value
We use two 32-bit values to represent a 64-bit value as current
BTF type subsection has 4-byte alignment and gaps are not permitted
in the subsection.
This patch also added support for kflag (the bit 31 of CommonType.Info)
such that kflag = 1 implies the value is signed and kflag = 0
implies the value is unsigned. The kernel UAPI enumerator definition is
struct btf_enum {
__u32 name_off;
__s32 val;
};
so kflag = 0 with unsigned value provides backward compatability.
With this patch, for
enum T { VAL = 0xffffFFFF00000008 };
the generated BTF looks like
.long 16 # BTF_KIND_ENUM64(id = 4)
.long 3187671053 # 0x13000001
.long 8
.long 18
.long 8 # 0x8
.long 4294967295 # 0xffffffff
and the enumerator value and signedness are encoded correctly.
Differential Revision: https://reviews.llvm.org/D124641
52 lines
2.3 KiB
LLVM
52 lines
2.3 KiB
LLVM
; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
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; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
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; Source code:
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; enum { A = -1, B = 2 } a;
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; Compilation flag:
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; clang -target bpf -O2 -g -S -emit-llvm t.c
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@a = common dso_local local_unnamed_addr global i32 0, align 4, !dbg !0
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!llvm.dbg.cu = !{!2}
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!llvm.module.flags = !{!11, !12, !13}
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!llvm.ident = !{!14}
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; CHECK: .section .BTF,"",@progbits
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; CHECK-NEXT: .short 60319 # 0xeb9f
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; CHECK-NEXT: .byte 1
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; CHECK-NEXT: .byte 0
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; CHECK-NEXT: .long 24
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; CHECK-NEXT: .long 0
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; CHECK-NEXT: .long 28
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; CHECK-NEXT: .long 28
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; CHECK-NEXT: .long 5
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; CHECK-NEXT: .long 0 # BTF_KIND_ENUM(id = 1)
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; CHECK-NEXT: .long 2248146946 # 0x86000002
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; CHECK-NEXT: .long 4
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; CHECK-NEXT: .long 1
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; CHECK-NEXT: .long -1
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; CHECK-NEXT: .long 3
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; CHECK-NEXT: .long 2
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; CHECK-NEXT: .byte 0 # string offset=0
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; CHECK-NEXT: .byte 65 # string offset=1
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; CHECK-NEXT: .byte 0
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; CHECK-NEXT: .byte 66 # string offset=3
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; CHECK-NEXT: .byte 0
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!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
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!1 = distinct !DIGlobalVariable(name: "a", scope: !2, file: !3, line: 1, type: !5, isLocal: false, isDefinition: true)
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!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 8.0.0 (trunk 344789) (llvm/trunk 344782)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !10, nameTableKind: None)
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!3 = !DIFile(filename: "t.c", directory: "/home/yhs/tmp")
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!4 = !{!5}
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!5 = !DICompositeType(tag: DW_TAG_enumeration_type, file: !3, line: 1, baseType: !6, size: 32, elements: !7)
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!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!7 = !{!8, !9}
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!8 = !DIEnumerator(name: "A", value: -1)
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!9 = !DIEnumerator(name: "B", value: 2)
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!10 = !{!0}
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!11 = !{i32 2, !"Dwarf Version", i32 4}
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!12 = !{i32 2, !"Debug Info Version", i32 3}
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!13 = !{i32 1, !"wchar_size", i32 4}
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!14 = !{!"clang version 8.0.0 (trunk 344789) (llvm/trunk 344782)"}
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