0e4c7fabd3
Since ce0c205813c74b4225180ac8a6e40fd52ea88229, we are doing that if a single (LTO) compilation contains more than one compile unit, but the same thing can happen if the non-lto and single-cu lto compilations, typically when the CU ends up (nearly) empty. In my case, this happened when LTO emptied two compile units. Note that the source file name is already a part of the hash, so this can only happen when a single file is compiled and linked twice into the same application (most likely with different preprocessor defintiions). While not exactly common, this pattern is used by some C code to implement "templates". The 2017 patch already hinted at the possibility of doing this unconditionally, and this patch implements that. While the DWARF spec hints at the option of using the type signature hashing algorithm for the DWO_id purposes, AFAICT it does not actually require it, so I believe this change is still conforming. The relevant section of the spec is in Section 3.1.2 "Skeleton Compilation Unit Entries" (in non-normative text): ``` The means of determining a compilation unit ID does not need to be similar or related to the means of determining a type unit signature. However, it should be suitable for detecting file version skew or other kinds of mismatched files and for looking up a full split unit in a DWARF package file (see Section 7.3.5 on page 190). ```
115 lines
4.6 KiB
LLVM
115 lines
4.6 KiB
LLVM
; RUN: llc -dwarf-version=4 -generate-type-units \
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; RUN: -filetype=obj -O0 -mtriple=wasm32-unknown-unknown < %s \
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; RUN: | llvm-dwarfdump -v - | FileCheck %s --check-prefix=SINGLE-4
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; RUN: llc -split-dwarf-file=foo.dwo -split-dwarf-output=%t.dwo \
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; RUN: -dwarf-version=4 -generate-type-units \
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; RUN: -filetype=obj -O0 -mtriple=wasm32-unknown-unknown < %s \
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; RUN: | llvm-dwarfdump -v - | FileCheck %s --check-prefix=O-4
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; RUN: llvm-dwarfdump -v %t.dwo | FileCheck %s --check-prefix=DWO-4
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; RUN: llc -dwarf-version=5 -generate-type-units \
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; RUN: -filetype=obj -O0 -mtriple= < %s \
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; RUN: | llvm-dwarfdump -v - | FileCheck %s --check-prefix=SINGLE-5
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; RUN: llc -split-dwarf-file=foo.dwo \
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; RUN: -dwarf-version=5 -generate-type-units \
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; RUN: -filetype=obj -O0 -mtriple= < %s \
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; RUN: | llvm-dwarfdump -v - | FileCheck %s --check-prefix=O-5
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; This test is derived from test/CodeGen/X86/dwarf-headers.ll
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; Looking for DWARF headers to be generated correctly.
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; There are 8 variants with 5 formats: v4 CU, v4 TU, v5 normal/partial CU,
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; v5 skeleton/split CU, v5 normal/split TU. Some v5 variants differ only
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; in the unit_type code, and the skeleton/split CU differs from normal/partial
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; by having one extra field (dwo_id).
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; (v2 thru v4 CUs are all the same, and TUs were invented in v4,
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; so we don't bother checking older versions.)
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; Test case built from:
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;struct S {
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; int s1;
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;};
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;
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;S s;
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; Verify the v4 non-split headers.
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; Note that we check the exact offset of the DIEs because that tells us
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; the length of the header.
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;
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; SINGLE-4: .debug_info contents:
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; SINGLE-4: 0x00000000: Compile Unit: {{.*}} version = 0x0004, abbr_offset
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; SINGLE-4: 0x0000000b: DW_TAG_compile_unit
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;
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; SINGLE-4: .debug_types contents:
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; SINGLE-4: 0x00000000: Type Unit: {{.*}} version = 0x0004, abbr_offset
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; SINGLE-4: 0x00000017: DW_TAG_type_unit
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; Verify the v4 split headers.
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;
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; O-4: .debug_info contents:
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; O-4: 0x00000000: Compile Unit: {{.*}} version = 0x0004, abbr_offset
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; O-4: 0x0000000b: DW_TAG_compile_unit
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;
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; DWO-4: .debug_info.dwo contents:
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; DWO-4: 0x00000000: Compile Unit: {{.*}} version = 0x0004, abbr_offset
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; DWO-4: 0x0000000b: DW_TAG_compile_unit
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;
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; DWO-4: .debug_types.dwo contents:
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; DWO-4: 0x00000000: Type Unit: {{.*}} version = 0x0004, abbr_offset
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; DWO-4: 0x00000017: DW_TAG_type_unit
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; Verify the v5 non-split headers. Type units come first.
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; All .debug_info sections are reported in one go, but the offset resets for
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; each new section.
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;
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; SINGLE-5: .debug_info contents:
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; SINGLE-5: 0x00000000: Type Unit: {{.*}} version = 0x0005, unit_type = DW_UT_type, abbr_offset
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; SINGLE-5: 0x00000018: DW_TAG_type_unit
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; SINGLE-5-NOT: contents:
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; SINGLE-5: 0x00000000: Compile Unit: {{.*}} version = 0x0005, unit_type = DW_UT_compile, abbr_offset
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; SINGLE-5: 0x0000000c: DW_TAG_compile_unit
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; Verify the v5 split headers.
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;
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; O-5: .debug_info contents:
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; O-5: 0x00000000: Compile Unit: {{.*}} version = 0x0005, unit_type = DW_UT_skeleton, abbr_offset
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; O-5-SAME: DWO_id = [[HASH:0x[0-9a-f]*]]
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; O-5: 0x00000014: DW_TAG_skeleton_unit
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;
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; O-5: .debug_info.dwo contents:
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; O-5: 0x00000000: Type Unit: {{.*}} version = 0x0005, unit_type = DW_UT_split_type, abbr_offset
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; O-5: 0x00000018: DW_TAG_type_unit
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; O-5: 0x00000035: Compile Unit: {{.*}} version = 0x0005, unit_type = DW_UT_split_compile, abbr_offset
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; O-5-SAME: DWO_id = [[HASH]]
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; O-5: 0x00000049: DW_TAG_compile_unit
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; ModuleID = 't.cpp'
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source_filename = "t.cpp"
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target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
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target triple = "wasm32-unknown-unknown-wasm"
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%struct.S = type { i32 }
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@s = global %struct.S zeroinitializer, align 4, !dbg !0
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!llvm.dbg.cu = !{!2}
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!llvm.module.flags = !{!10, !11}
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!llvm.ident = !{!12}
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!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
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!1 = distinct !DIGlobalVariable(name: "s", scope: !2, file: !3, line: 5, type: !6, isLocal: false, isDefinition: true)
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!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "clang version 5.0.0 (trunk 295942)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5)
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!3 = !DIFile(filename: "t.cpp", directory: "/home/probinson/projects/scratch")
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!4 = !{}
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!5 = !{!0}
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!6 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "S", file: !3, line: 1, size: 32, elements: !7, identifier: "_ZTS1S")
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!7 = !{!8}
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!8 = !DIDerivedType(tag: DW_TAG_member, name: "s1", scope: !6, file: !3, line: 2, baseType: !9, size: 32)
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!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!10 = !{i32 2, !"Dwarf Version", i32 4}
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!11 = !{i32 2, !"Debug Info Version", i32 3}
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!12 = !{!"clang version 5.0.0 (trunk 295942)"}
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