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llvm-project/llvm/test/DebugInfo/omit-empty.ll

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DebugInfo: Do not emit empty CUs Consistent with GCC and addresses a shortcoming with ThinLTO where many imported CUs may end up being empty (because the functions imported from them either ended up not being used (and were then discarded, since they're imported as available_externally) or optimized away entirely). Test cases previously testing empty CUs (either intentionally, or because they didn't need anything more complicated) had a trivial 'int' or similar basic type added to their retained types list. This is a first order approximation - a deeper implementation could do things like: 1) Be more lazy about construction of the CU - for example if two CUs containing a single identical retained type are linked together, with this change one of the two CUs will be produced but empty (since a duplicate type won't be produced). 2) Go further and invert all the CU links the same way the subprogram link is inverted - keep named CU lists of retained types, macros, etc, and have those link back to the CU. Then if they're emitted, the CU is emitted, but never otherwise - this would allow the metadata itself to be dropped earlier too, though it seems unlikely that's an important optimization as there shouldn't be many CUs relative to the number of other entities. llvm-svn: 304020
2017-05-27 02:52:56 +08:00
; RUN: %llc_dwarf %s -filetype=obj -o - | llvm-objdump -h - | FileCheck %s
Mark a test as requiring a default triple This test assumes that llc can infer a default triple. I'm not sure why exactly, but the Verify MachineInstrs bot requires tests to be explicit about this dependency. This commit follows the lead from r248452 and adds in 'REQUIRES: default_triple' to omit-empty.ll. Bot URL: http://lab.llvm.org:8080/green/job/Verify-Machineinstrs_AArch64/7500 llvm-svn: 304269
2017-05-31 09:42:55 +08:00
; REQUIRES: default_triple
DebugInfo: Do not emit empty CUs Consistent with GCC and addresses a shortcoming with ThinLTO where many imported CUs may end up being empty (because the functions imported from them either ended up not being used (and were then discarded, since they're imported as available_externally) or optimized away entirely). Test cases previously testing empty CUs (either intentionally, or because they didn't need anything more complicated) had a trivial 'int' or similar basic type added to their retained types list. This is a first order approximation - a deeper implementation could do things like: 1) Be more lazy about construction of the CU - for example if two CUs containing a single identical retained type are linked together, with this change one of the two CUs will be produced but empty (since a duplicate type won't be produced). 2) Go further and invert all the CU links the same way the subprogram link is inverted - keep named CU lists of retained types, macros, etc, and have those link back to the CU. Then if they're emitted, the CU is emitted, but never otherwise - this would allow the metadata itself to be dropped earlier too, though it seems unlikely that's an important optimization as there shouldn't be many CUs relative to the number of other entities. llvm-svn: 304020
2017-05-27 02:52:56 +08:00
; CHECK-NOT: .debug_
DebugInfo: Consider a CU containing only local imported entities to be 'empty' This can come up in ThinLTO & wastes space & makes degenerate IR. As per the added FIXME, ultimately, local imported entities should hang off the function and that way the imported entity list on the CU can be tested for emptiness like all the other CU lists. (function-attached local imported entities are probably also the best path forward for fixing how imported entities are handled both in cross-module use (currently, while ThinLTO preserves the imported entities, they would not get used at the imported inlined location - only in the abstract origin that appears in the partial CU created by the import (which isn't emitted under Fission due to cross-CU limitations there)) and to reduce the number of points where imported entities are emitted (they're currently emitted into every inlined instance, concrete instance, and abstract origin - they should only go in teh abstract origin if there is one, otherwise in the concrete instance - but this requires lots of delayed handling and wiring up, same as abstract variables & subprograms)) llvm-svn: 309354
2017-07-28 11:06:25 +08:00
!llvm.dbg.cu = !{!0, !5}
DebugInfo: Do not emit empty CUs Consistent with GCC and addresses a shortcoming with ThinLTO where many imported CUs may end up being empty (because the functions imported from them either ended up not being used (and were then discarded, since they're imported as available_externally) or optimized away entirely). Test cases previously testing empty CUs (either intentionally, or because they didn't need anything more complicated) had a trivial 'int' or similar basic type added to their retained types list. This is a first order approximation - a deeper implementation could do things like: 1) Be more lazy about construction of the CU - for example if two CUs containing a single identical retained type are linked together, with this change one of the two CUs will be produced but empty (since a duplicate type won't be produced). 2) Go further and invert all the CU links the same way the subprogram link is inverted - keep named CU lists of retained types, macros, etc, and have those link back to the CU. Then if they're emitted, the CU is emitted, but never otherwise - this would allow the metadata itself to be dropped earlier too, though it seems unlikely that's an important optimization as there shouldn't be many CUs relative to the number of other entities. llvm-svn: 304020
2017-05-27 02:52:56 +08:00
!llvm.module.flags = !{!3, !4}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "LLVM", isOptimized: false, runtimeVersion: 2, emissionKind: FullDebug, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
!1 = !DIFile(filename: "<stdin>", directory: "/")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
DebugInfo: Consider a CU containing only local imported entities to be 'empty' This can come up in ThinLTO & wastes space & makes degenerate IR. As per the added FIXME, ultimately, local imported entities should hang off the function and that way the imported entity list on the CU can be tested for emptiness like all the other CU lists. (function-attached local imported entities are probably also the best path forward for fixing how imported entities are handled both in cross-module use (currently, while ThinLTO preserves the imported entities, they would not get used at the imported inlined location - only in the abstract origin that appears in the partial CU created by the import (which isn't emitted under Fission due to cross-CU limitations there)) and to reduce the number of points where imported entities are emitted (they're currently emitted into every inlined instance, concrete instance, and abstract origin - they should only go in teh abstract origin if there is one, otherwise in the concrete instance - but this requires lots of delayed handling and wiring up, same as abstract variables & subprograms)) llvm-svn: 309354
2017-07-28 11:06:25 +08:00
!5 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "LLVM", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, imports: !6)
!6 = !{!7}
!7 = !DIImportedEntity(tag: DW_TAG_imported_module, scope: !8, entity: !8, file: !1, line: 3)
!8 = distinct !DISubprogram(name: "f2", linkageName: "_Z2f2v", scope: !1, file: !1, line: 2, type: !9, isLocal: false, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: false, unit: !5, variables: !2)
!9 = !DISubroutineType(types: !10)
!10 = !{null}
!11 = !DINamespace(name: "ns", scope: null)