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llvm-mirror/test/DebugInfo/X86/string-offsets-table-order.ll

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[DebugInfo] Reduce debug_str_offsets section size Summary: The accelerator tables use the debug_str section to store their strings. However, they do not support the indirect method of access that is available for the debug_info section (DW_FORM_strx et al.). Currently our code is assuming that all strings can/will be referenced indirectly, and puts all of them into the debug_str_offsets section. This is generally true for regular (unsplit) dwarf, but in the DWO case, most of the strings in the debug_str section will only be used from the accelerator tables. Therefore the contents of the debug_str_offsets section will be largely unused and bloating the main executable. This patch rectifies this by teaching the DwarfStringPool to differentiate between strings accessed directly and indirectly. When a user inserts a string into the pool it has to declare whether that string will be referenced directly or not. If at least one user requsts indirect access, that string will be assigned an index ID and put into debug_str_offsets table. Otherwise, the offset table is skipped. This approach reduces the overall binary size (when compiled with -gdwarf-5 -gsplit-dwarf) in my tests by about 2% (debug_str_offsets is shrunk by 99%). Reviewers: probinson, dblaikie, JDevlieghere Subscribers: aprantl, mgrang, llvm-commits Differential Revision: https://reviews.llvm.org/D49493 llvm-svn: 339122
2018-08-07 09:54:52 +00:00
; REQUIRES: object-emission
; RUN: llc -mtriple=x86_64-unknown-linux-gnu -split-dwarf-file=foo.dwo -filetype=obj < %s \
; RUN: | llvm-dwarfdump -v - | FileCheck %s
; This triggers a situation where the order of entries in the .debug_str and
; .debug_str_offsets sections does not match and makes sure that all entries are
; still wired up correctly.
; Produced with "clang -S -emit-llvm -gdwarf-5" from source "int X;", copied
Clarify comment in the string-offsets-table-order.ll test llvm-svn: 340826
2018-08-28 14:46:29 +00:00
; three times and modified by hand. The modifications consisted of modifying the
; compilation directory and the variable names to trigger the insertion of names
; in different order.
[DebugInfo] Reduce debug_str_offsets section size Summary: The accelerator tables use the debug_str section to store their strings. However, they do not support the indirect method of access that is available for the debug_info section (DW_FORM_strx et al.). Currently our code is assuming that all strings can/will be referenced indirectly, and puts all of them into the debug_str_offsets section. This is generally true for regular (unsplit) dwarf, but in the DWO case, most of the strings in the debug_str section will only be used from the accelerator tables. Therefore the contents of the debug_str_offsets section will be largely unused and bloating the main executable. This patch rectifies this by teaching the DwarfStringPool to differentiate between strings accessed directly and indirectly. When a user inserts a string into the pool it has to declare whether that string will be referenced directly or not. If at least one user requsts indirect access, that string will be assigned an index ID and put into debug_str_offsets table. Otherwise, the offset table is skipped. This approach reduces the overall binary size (when compiled with -gdwarf-5 -gsplit-dwarf) in my tests by about 2% (debug_str_offsets is shrunk by 99%). Reviewers: probinson, dblaikie, JDevlieghere Subscribers: aprantl, mgrang, llvm-commits Differential Revision: https://reviews.llvm.org/D49493 llvm-svn: 339122
2018-08-07 09:54:52 +00:00
; CHECK: .debug_info contents:
; CHECK: DW_TAG_compile_unit
DebugInfo: Avoid using split DWARF when the split unit would be empty. In ThinLTO many split CUs may be effectively empty because of the lack of support for cross-unit references in split DWARF. Using a split unit in those cases is just a waste/overhead - and turned out to be one contributor to a significant symbolizer performance issue when global variable debug info was being imported (see r348416 for the primary fix) due to symbolizers seeing CUs with no ranges, assuming there might still be addresses covered and walking into the split CU to see if there are any ranges (when that split CU was in a DWP file, that meant loading the DWP and its index, the index was extra large because of all these fractured/empty CUs... and so was very expensive to load). (the 3rd fix which will follow, is to assume that a CU with no ranges is empty rather than merely missing its CU level range data - and to not walk into its DIEs (split or otherwise) in search of address information that is generally not present) llvm-svn: 349207
2018-12-14 22:44:46 +00:00
; CHECK: DW_AT_comp_dir [DW_FORM_strx1] ( indexed (00000000) string = "X3")
[DebugInfo] Reduce debug_str_offsets section size Summary: The accelerator tables use the debug_str section to store their strings. However, they do not support the indirect method of access that is available for the debug_info section (DW_FORM_strx et al.). Currently our code is assuming that all strings can/will be referenced indirectly, and puts all of them into the debug_str_offsets section. This is generally true for regular (unsplit) dwarf, but in the DWO case, most of the strings in the debug_str section will only be used from the accelerator tables. Therefore the contents of the debug_str_offsets section will be largely unused and bloating the main executable. This patch rectifies this by teaching the DwarfStringPool to differentiate between strings accessed directly and indirectly. When a user inserts a string into the pool it has to declare whether that string will be referenced directly or not. If at least one user requsts indirect access, that string will be assigned an index ID and put into debug_str_offsets table. Otherwise, the offset table is skipped. This approach reduces the overall binary size (when compiled with -gdwarf-5 -gsplit-dwarf) in my tests by about 2% (debug_str_offsets is shrunk by 99%). Reviewers: probinson, dblaikie, JDevlieghere Subscribers: aprantl, mgrang, llvm-commits Differential Revision: https://reviews.llvm.org/D49493 llvm-svn: 339122
2018-08-07 09:54:52 +00:00
; CHECK: DW_TAG_compile_unit
DebugInfo: Avoid using split DWARF when the split unit would be empty. In ThinLTO many split CUs may be effectively empty because of the lack of support for cross-unit references in split DWARF. Using a split unit in those cases is just a waste/overhead - and turned out to be one contributor to a significant symbolizer performance issue when global variable debug info was being imported (see r348416 for the primary fix) due to symbolizers seeing CUs with no ranges, assuming there might still be addresses covered and walking into the split CU to see if there are any ranges (when that split CU was in a DWP file, that meant loading the DWP and its index, the index was extra large because of all these fractured/empty CUs... and so was very expensive to load). (the 3rd fix which will follow, is to assume that a CU with no ranges is empty rather than merely missing its CU level range data - and to not walk into its DIEs (split or otherwise) in search of address information that is generally not present) llvm-svn: 349207
2018-12-14 22:44:46 +00:00
; CHECK: DW_AT_comp_dir [DW_FORM_strx1] ( indexed (00000001) string = "X2")
[DebugInfo] Reduce debug_str_offsets section size Summary: The accelerator tables use the debug_str section to store their strings. However, they do not support the indirect method of access that is available for the debug_info section (DW_FORM_strx et al.). Currently our code is assuming that all strings can/will be referenced indirectly, and puts all of them into the debug_str_offsets section. This is generally true for regular (unsplit) dwarf, but in the DWO case, most of the strings in the debug_str section will only be used from the accelerator tables. Therefore the contents of the debug_str_offsets section will be largely unused and bloating the main executable. This patch rectifies this by teaching the DwarfStringPool to differentiate between strings accessed directly and indirectly. When a user inserts a string into the pool it has to declare whether that string will be referenced directly or not. If at least one user requsts indirect access, that string will be assigned an index ID and put into debug_str_offsets table. Otherwise, the offset table is skipped. This approach reduces the overall binary size (when compiled with -gdwarf-5 -gsplit-dwarf) in my tests by about 2% (debug_str_offsets is shrunk by 99%). Reviewers: probinson, dblaikie, JDevlieghere Subscribers: aprantl, mgrang, llvm-commits Differential Revision: https://reviews.llvm.org/D49493 llvm-svn: 339122
2018-08-07 09:54:52 +00:00
; CHECK: DW_TAG_compile_unit
DebugInfo: Avoid using split DWARF when the split unit would be empty. In ThinLTO many split CUs may be effectively empty because of the lack of support for cross-unit references in split DWARF. Using a split unit in those cases is just a waste/overhead - and turned out to be one contributor to a significant symbolizer performance issue when global variable debug info was being imported (see r348416 for the primary fix) due to symbolizers seeing CUs with no ranges, assuming there might still be addresses covered and walking into the split CU to see if there are any ranges (when that split CU was in a DWP file, that meant loading the DWP and its index, the index was extra large because of all these fractured/empty CUs... and so was very expensive to load). (the 3rd fix which will follow, is to assume that a CU with no ranges is empty rather than merely missing its CU level range data - and to not walk into its DIEs (split or otherwise) in search of address information that is generally not present) llvm-svn: 349207
2018-12-14 22:44:46 +00:00
; CHECK: DW_AT_comp_dir [DW_FORM_strx1] ( indexed (00000002) string = "X1")
[DebugInfo] Reduce debug_str_offsets section size Summary: The accelerator tables use the debug_str section to store their strings. However, they do not support the indirect method of access that is available for the debug_info section (DW_FORM_strx et al.). Currently our code is assuming that all strings can/will be referenced indirectly, and puts all of them into the debug_str_offsets section. This is generally true for regular (unsplit) dwarf, but in the DWO case, most of the strings in the debug_str section will only be used from the accelerator tables. Therefore the contents of the debug_str_offsets section will be largely unused and bloating the main executable. This patch rectifies this by teaching the DwarfStringPool to differentiate between strings accessed directly and indirectly. When a user inserts a string into the pool it has to declare whether that string will be referenced directly or not. If at least one user requsts indirect access, that string will be assigned an index ID and put into debug_str_offsets table. Otherwise, the offset table is skipped. This approach reduces the overall binary size (when compiled with -gdwarf-5 -gsplit-dwarf) in my tests by about 2% (debug_str_offsets is shrunk by 99%). Reviewers: probinson, dblaikie, JDevlieghere Subscribers: aprantl, mgrang, llvm-commits Differential Revision: https://reviews.llvm.org/D49493 llvm-svn: 339122
2018-08-07 09:54:52 +00:00
; CHECK: .debug_info.dwo contents:
; CHECK: .debug_str contents:
; CHECK: 0x[[X3:[0-9a-f]*]]: "X3"
; CHECK: 0x[[X1:[0-9a-f]*]]: "X1"
; CHECK: 0x[[X2:[0-9a-f]*]]: "X2"
; CHECK: .debug_str_offsets contents:
; CHECK: Format = DWARF32, Version = 5
; CHECK-NEXT: [[X3]] "X3"
; CHECK-NEXT: [[X2]] "X2"
; CHECK-NEXT: [[X1]] "X1"
DebugInfo: Avoid using split DWARF when the split unit would be empty. In ThinLTO many split CUs may be effectively empty because of the lack of support for cross-unit references in split DWARF. Using a split unit in those cases is just a waste/overhead - and turned out to be one contributor to a significant symbolizer performance issue when global variable debug info was being imported (see r348416 for the primary fix) due to symbolizers seeing CUs with no ranges, assuming there might still be addresses covered and walking into the split CU to see if there are any ranges (when that split CU was in a DWP file, that meant loading the DWP and its index, the index was extra large because of all these fractured/empty CUs... and so was very expensive to load). (the 3rd fix which will follow, is to assume that a CU with no ranges is empty rather than merely missing its CU level range data - and to not walk into its DIEs (split or otherwise) in search of address information that is generally not present) llvm-svn: 349207
2018-12-14 22:44:46 +00:00
; CHECK-NEXT: "foo.dwo"
[DebugInfo] Reduce debug_str_offsets section size Summary: The accelerator tables use the debug_str section to store their strings. However, they do not support the indirect method of access that is available for the debug_info section (DW_FORM_strx et al.). Currently our code is assuming that all strings can/will be referenced indirectly, and puts all of them into the debug_str_offsets section. This is generally true for regular (unsplit) dwarf, but in the DWO case, most of the strings in the debug_str section will only be used from the accelerator tables. Therefore the contents of the debug_str_offsets section will be largely unused and bloating the main executable. This patch rectifies this by teaching the DwarfStringPool to differentiate between strings accessed directly and indirectly. When a user inserts a string into the pool it has to declare whether that string will be referenced directly or not. If at least one user requsts indirect access, that string will be assigned an index ID and put into debug_str_offsets table. Otherwise, the offset table is skipped. This approach reduces the overall binary size (when compiled with -gdwarf-5 -gsplit-dwarf) in my tests by about 2% (debug_str_offsets is shrunk by 99%). Reviewers: probinson, dblaikie, JDevlieghere Subscribers: aprantl, mgrang, llvm-commits Differential Revision: https://reviews.llvm.org/D49493 llvm-svn: 339122
2018-08-07 09:54:52 +00:00
; CHECK-EMPTY:
!llvm.dbg.cu = !{!10, !20, !30}
!llvm.module.flags = !{!0, !1, !2}
!llvm.ident = !{!3}
!0 = !{i32 2, !"Dwarf Version", i32 5}
!1 = !{i32 2, !"Debug Info Version", i32 3}
!2 = !{i32 1, !"wchar_size", i32 4}
!3 = !{!"clang version 7.0.0 (trunk 337353) (llvm/trunk 337361)"}
@X1 = dso_local global i32 0, align 4, !dbg !11
!10 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !13, producer: "clang version 7.0.0 (trunk 337353) (llvm/trunk 337361)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !14, globals: !15)
!11 = !DIGlobalVariableExpression(var: !12, expr: !DIExpression())
!12 = distinct !DIGlobalVariable(name: "X1", scope: !10, file: !16, line: 1, type: !17, isLocal: false, isDefinition: true)
!13 = !DIFile(filename: "-", directory: "X3", checksumkind: CSK_MD5, checksum: "f2e6e10e303927a308f1645fbf6f710e")
!14 = !{}
!15 = !{!11}
!16 = !DIFile(filename: "<stdin>", directory: "X3", checksumkind: CSK_MD5, checksum: "f2e6e10e303927a308f1645fbf6f710e")
!17 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
@X2 = dso_local global i32 0, align 4, !dbg !21
!20 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !23, producer: "clang version 7.0.0 (trunk 337353) (llvm/trunk 337361)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !24, globals: !25)
!21 = !DIGlobalVariableExpression(var: !22, expr: !DIExpression())
!22 = distinct !DIGlobalVariable(name: "X2", scope: !20, file: !26, line: 1, type: !27, isLocal: false, isDefinition: true)
!23 = !DIFile(filename: "-", directory: "X2", checksumkind: CSK_MD5, checksum: "f2e6e10e303927a308f1645fbf6f710e")
!24 = !{}
!25 = !{!21}
!26 = !DIFile(filename: "<stdin>", directory: "X2", checksumkind: CSK_MD5, checksum: "f2e6e10e303927a308f1645fbf6f710e")
!27 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
@X3 = dso_local global i32 0, align 4, !dbg !31
!30 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !33, producer: "clang version 7.0.0 (trunk 337353) (llvm/trunk 337361)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !34, globals: !35)
!31 = !DIGlobalVariableExpression(var: !32, expr: !DIExpression())
!32 = distinct !DIGlobalVariable(name: "X3", scope: !30, file: !36, line: 1, type: !37, isLocal: false, isDefinition: true)
!33 = !DIFile(filename: "-", directory: "X1", checksumkind: CSK_MD5, checksum: "f2e6e10e303927a308f1645fbf6f710e")
!34 = !{}
!35 = !{!31}
!36 = !DIFile(filename: "<stdin>", directory: "X1", checksumkind: CSK_MD5, checksum: "f2e6e10e303927a308f1645fbf6f710e")
!37 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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