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e27d5a0047
Reverted by Eric Christopher (Thanks!) in r212203 after Bob Wilson reported LTO issues. Duncan Exon Smith and Aditya Nandakumar helped provide a reduced reproduction, though the failure wasn't too hard to guess, and even easier with the example to confirm. The assertion that the subprogram metadata associated with an llvm::Function matches the scope data referenced by the DbgLocs on the instructions in that function is not valid under LTO. In LTO, a C++ inline function might exist in multiple CUs and the subprogram metadata nodes will refer to the same llvm::Function. In this case, depending on the order of the CUs, the first intance of the subprogram metadata may not be the one referenced by the instructions in that function and the assertion will fail. A test case (test/DebugInfo/cross-cu-linkonce-distinct.ll) is added, the assertion removed and a comment added to explain this situation. This was then reverted again in r213581 as it caused PR20367. The root cause of this was the early exit in LiveDebugVariables meant that spurious DBG_VALUE intrinsics that referenced dead variables were not removed, causing an assertion/crash later on. The fix is to have LiveDebugVariables strip all DBG_VALUE intrinsics in functions without debug info as they're not needed anyway. Test case added to cover this situation (that occurs when a debug-having function is inlined into a nodebug function) in test/DebugInfo/X86/nodebug_with_debug_loc.ll Original commit message: If a function isn't actually in a CU's subprogram list in the debug info metadata, ignore all the DebugLocs and don't try to build scopes, track variables, etc. While this is possibly a minor optimization, it's also a correctness fix for an incoming patch that will add assertions to LexicalScopes and the debug info verifier to ensure that all scope chains lead to debug info for the current function. Fix up a few test cases that had broken/incomplete debug info that could violate this constraint. Add a test case where this occurs by design (inlining a debug-info-having function in an attribute nodebug function - we want this to work because /if/ the nodebug function is then inlined into a debug-info-having function, it should be fine (and will work fine - we just stitch the scopes up as usual), but should the inlining not happen we need to not assert fail either). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213952 91177308-0d34-0410-b5e6-96231b3b80d8
96 lines
5.5 KiB
LLVM
96 lines
5.5 KiB
LLVM
; REQUIRES: object-emission
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; RUN: %llc_dwarf -O0 -filetype=obj < %s | llvm-dwarfdump -debug-dump=info - | FileCheck %s
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; Testing that two distinct (distinct by writing them in separate files, while
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; still fulfilling C++'s ODR by having identical token sequences) functions,
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; linked under LTO, get plausible debug info (and don't crash).
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; Built from source:
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; $ clang++ a.cpp b.cpp -g -c -emit-llvm
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; $ llvm-link a.bc b.bc -o ab.bc
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; This change is intended to tickle a case where the subprogram MDNode
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; associated with the llvm::Function will differ from the subprogram
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; referenced by the DbgLocs in the function.
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; $ sed -ie "s/!12, !0/!0, !12/" ab.ll
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; $ cat a.cpp
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; inline int func(int i) {
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; return i * 2;
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; }
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; int (*x)(int) = &func;
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; $ cat b.cpp
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; inline int func(int i) {
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; return i * 2;
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; }
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; int (*y)(int) = &func;
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; CHECK: DW_TAG_compile_unit
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; CHECK: DW_TAG_subprogram
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; CHECK-NOT: DW_TAG
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; CHECK: DW_AT_name {{.*}} "func"
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; CHECK: DW_TAG_compile_unit
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; FIXME: Maybe we should drop the subprogram here - since the function was
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; emitted in one CU, due to linkonce_odr uniquing. We certainly don't emit the
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; subprogram here if the source location for this definition is the same (see
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; test/DebugInfo/cross-cu-linkonce.ll), though it's very easy to tickle that
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; into failing even without duplicating the source as has been done in this
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; case (two cpp files in different directories, including the same header that
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; contains an inline function - clang will produce distinct subprogram metadata
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; that won't deduplicate owing to the file location information containing the
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; directory of the source file even though the file name is absolute, not
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; relative)
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; CHECK: DW_TAG_subprogram
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@x = global i32 (i32)* @_Z4funci, align 8
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@y = global i32 (i32)* @_Z4funci, align 8
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; Function Attrs: inlinehint nounwind uwtable
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define linkonce_odr i32 @_Z4funci(i32 %i) #0 {
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%1 = alloca i32, align 4
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store i32 %i, i32* %1, align 4
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call void @llvm.dbg.declare(metadata !{i32* %1}, metadata !22), !dbg !23
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%2 = load i32* %1, align 4, !dbg !24
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%3 = mul nsw i32 %2, 2, !dbg !24
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ret i32 %3, !dbg !24
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}
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; Function Attrs: nounwind readnone
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declare void @llvm.dbg.declare(metadata, metadata) #1
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attributes #0 = { inlinehint nounwind uwtable "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" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #1 = { nounwind readnone }
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!llvm.dbg.cu = !{!12, !0}
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!llvm.module.flags = !{!19, !20}
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!llvm.ident = !{!21, !21}
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!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.5.0 ", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !9, metadata !2, metadata !"", i32 1} ; [ DW_TAG_compile_unit ] [/tmp/dbginfo/a.cpp] [DW_LANG_C_plus_plus]
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!1 = metadata !{metadata !"a.cpp", metadata !"/tmp/dbginfo"}
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!2 = metadata !{}
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!3 = metadata !{metadata !4}
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!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"func", metadata !"func", metadata !"_Z4funci", i32 1, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (i32)* @_Z4funci, null, null, metadata !2, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [func]
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!5 = metadata !{i32 786473, metadata !1} ; [ DW_TAG_file_type ] [/tmp/dbginfo/a.cpp]
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!6 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !7, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
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!7 = metadata !{metadata !8, metadata !8}
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!8 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
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!9 = metadata !{metadata !10}
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!10 = metadata !{i32 786484, i32 0, null, metadata !"x", metadata !"x", metadata !"", metadata !5, i32 4, metadata !11, i32 0, i32 1, i32 (i32)** @x, null} ; [ DW_TAG_variable ] [x] [line 4] [def]
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!11 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 0, metadata !6} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from ]
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!12 = metadata !{i32 786449, metadata !13, i32 4, metadata !"clang version 3.5.0 ", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !14, metadata !17, metadata !2, metadata !"", i32 1} ; [ DW_TAG_compile_unit ] [/tmp/dbginfo/b.cpp] [DW_LANG_C_plus_plus]
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!13 = metadata !{metadata !"b.cpp", metadata !"/tmp/dbginfo"}
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!14 = metadata !{metadata !15}
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!15 = metadata !{i32 786478, metadata !13, metadata !16, metadata !"func", metadata !"func", metadata !"_Z4funci", i32 1, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (i32)* @_Z4funci, null, null, metadata !2, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [func]
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!16 = metadata !{i32 786473, metadata !13} ; [ DW_TAG_file_type ] [/tmp/dbginfo/b.cpp]
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!17 = metadata !{metadata !18}
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!18 = metadata !{i32 786484, i32 0, null, metadata !"y", metadata !"y", metadata !"", metadata !16, i32 4, metadata !11, i32 0, i32 1, i32 (i32)** @y, null} ; [ DW_TAG_variable ] [y] [line 4] [def]
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!19 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
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!20 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}
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!21 = metadata !{metadata !"clang version 3.5.0 "}
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!22 = metadata !{i32 786689, metadata !4, metadata !"i", metadata !5, i32 16777217, metadata !8, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [i] [line 1]
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!23 = metadata !{i32 1, i32 0, metadata !4, null}
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!24 = metadata !{i32 2, i32 0, metadata !4, null}
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