[llvm] r210143 - DebugInfo: Partial revert r209984 due to more cases where abstract DbgVariables do not have associated DIEs.
Duncan P. N. Exon Smith
dexonsmith at apple.com
Wed Sep 17 17:29:29 PDT 2014
> On 2014-Jun-03, at 18:31, David Blaikie <dblaikie at gmail.com> wrote:
>
> Author: dblaikie
> Date: Tue Jun 3 20:30:59 2014
> New Revision: 210143
>
> URL: http://llvm.org/viewvc/llvm-project?rev=210143&view=rev
> Log:
> DebugInfo: Partial revert r209984 due to more cases where abstract DbgVariables do not have associated DIEs.
>
> Along with a test case to demonstrate that due to inlining order there
> are cases where abstract variable DIEs are not constructed since the
> abstract subprogram was built due to a previous inlining that optimized
> away those variables. This produces incorrect debug info (the 'missing'
> abstract variable causes the inlined instance of that variable to be
> emitted with a full description (name, line, file) rather than
> referencing the abstract origin), but this commit at least ensures that
> it doesn't crash...
>
> Added:
> llvm/trunk/test/DebugInfo/missing-abstract-variable.ll
> Modified:
> llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp?rev=210143&r1=210142&r2=210143&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp Tue Jun 3 20:30:59 2014
> @@ -1781,7 +1781,11 @@ std::unique_ptr<DIE> DwarfUnit::construc
>
> // Define variable debug information entry.
> auto VariableDie = make_unique<DIE>(DV.getTag());
> - if (DbgVariable *AbsVar = DV.getAbstractVariable())
> + DbgVariable *AbsVar = DV.getAbstractVariable();
> + // FIXME: any missing abstract variable missing a DIE will result in incorrect
> + // DWARF. More details in test/DebugInfo/missing-abstract-variable.ll for an
> + // example of why this is happening.
> + if (AbsVar && AbsVar->getDIE())
> addDIEEntry(*VariableDie, dwarf::DW_AT_abstract_origin, *AbsVar->getDIE());
> else {
> if (!Name.empty())
>
> Added: llvm/trunk/test/DebugInfo/missing-abstract-variable.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/missing-abstract-variable.ll?rev=210143&view=auto
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/missing-abstract-variable.ll (added)
> +++ llvm/trunk/test/DebugInfo/missing-abstract-variable.ll Tue Jun 3 20:30:59 2014
> @@ -0,0 +1,181 @@
> +; REQUIRES: object-emission
> +
> +; RUN: %llc_dwarf -O0 -filetype=obj < %s | llvm-dwarfdump -debug-dump=info - | FileCheck %s
> +
> +; Build from the following source with clang -O2.
> +
> +; The important details are that 'x's abstract definition is first built during
> +; the definition of 'b', where the parameter to 'x' is constant and so 'x's 's'
> +; variable is optimized away. No abstract definition DIE for 's' is constructed.
> +; Then, during 'a' emission, the abstract DbgVariable for 's' is created, but
> +; the abstract DIE isn't (since the abstract definition for 'b' is already
> +; built). This results in 's' inlined in 'a' being emitted with its name, line,
> +; file there, rather than referencing an abstract definition.
> +
> +; extern int t;
> +;
> +; void f(int);
> +;
> +; inline void x(bool b) {
> +; if (b) {
> +; int s = t;
> +; f(s);
> +; }
> +; f(0);
> +; }
> +;
> +; void b() {
> +; x(false);
> +; }
> +;
> +; void a(bool u) {
> +; x(u);
> +; }
> +
> +; CHECK: [[ABS_X:.*]]: DW_TAG_subprogram
> +; CHECK-NOT: DW_TAG
> +; CHECK: DW_AT_name {{.*}} "x"
> +; CHECK-NOT: {{DW_TAG|NULL}}
> +; CHECK: [[ABS_B:.*]]: DW_TAG_formal_parameter
> +; CHECK-NOT: DW_TAG
> +; CHECK: DW_AT_name {{.*}} "b"
> +; FIXME: Missing 'x's local 's' variable.
> +
> +; CHECK: DW_TAG_subprogram
> +; CHECK-NOT: DW_TAG
> +; CHECK: DW_AT_name {{.*}} "b"
> +; CHECK-NOT: {{DW_TAG|NULL}}
> +; CHECK: DW_TAG_inlined_subroutine
> +; CHECK-NOT: DW_TAG
> +; CHECK: DW_AT_abstract_origin {{.*}} {[[ABS_X]]}
> +; CHECK-NOT: {{DW_TAG|NULL}}
> +; CHECK: DW_TAG_formal_parameter
> +; CHECK-NOT: DW_TAG
> +; CHECK: DW_AT_abstract_origin {{.*}} {[[ABS_B]]}
> +; Notice 'x's local variable 's' is missing. Not necessarily a bug here,
> +; since it's been optimized entirely away and it should be described in
> +; abstract subprogram.
> +; CHECK-NOT: DW_TAG
> +; CHECK: NULL
> +; CHECK-NOT: DW_TAG
> +; CHECK: NULL
> +
> +; CHECK: DW_TAG_subprogram
> +; CHECK-NOT: DW_TAG
> +; CHECK: DW_AT_name {{.*}} "a"
> +; CHECK-NOT: {{DW_TAG|NULL}}
> +; CHECK: DW_TAG_formal_parameter
> +; CHECK-NOT: {{DW_TAG|NULL}}
> +; CHECK: DW_TAG_inlined_subroutine
> +; CHECK-NOT: DW_TAG
> +; CHECK: DW_AT_abstract_origin {{.*}} {[[ABS_X]]}
> +; CHECK-NOT: {{DW_TAG|NULL}}
> +; FIXME: This formal parameter goes missing at least at -O2, maybe before that.
> +; CHECK: DW_TAG_formal_parameter
> +; CHECK-NOT: DW_TAG
> +; CHECK: DW_AT_abstract_origin {{.*}} {[[ABS_B]]}
> +
> +; The two lexical blocks here are caused by the scope of the if that includes
> +; the condition variable, and the scope within the if's composite statement. I'm
> +; not sure we really need both of them.
> +
> +; CHECK-NOT: {{DW_TAG|NULL}}
> +; CHECK: DW_TAG_lexical_block
> +; CHECK-NOT: {{DW_TAG|NULL}}
> +; CHECK: DW_TAG_lexical_block
> +; CHECK-NOT: {{DW_TAG|NULL}}
> +; CHECK: DW_TAG_variable
> +; CHECK-NOT: DW_TAG
> +
> +; FIXME: This shouldn't have a name here, it should use DW_AT_abstract_origin
> +; to reference an abstract variable definition instead
> +
> +; CHECK: DW_AT_name {{.*}} "s"
> +
> +
> + at t = external global i32
> +
> +; Function Attrs: uwtable
> +define void @_Z1bv() #0 {
> +entry:
> + tail call void @llvm.dbg.value(metadata !24, i64 0, metadata !25), !dbg !27
> + tail call void @_Z1fi(i32 0), !dbg !28
> + ret void, !dbg !29
> +}
> +
> +; Function Attrs: uwtable
> +define void @_Z1ab(i1 zeroext %u) #0 {
> +entry:
> + tail call void @llvm.dbg.value(metadata !{i1 %u}, i64 0, metadata !13), !dbg !30
> + tail call void @llvm.dbg.value(metadata !{i1 %u}, i64 0, metadata !31), !dbg !33
> + br i1 %u, label %if.then.i, label %_Z1xb.exit, !dbg !34
> +
> +if.then.i: ; preds = %entry
> + %0 = load i32* @t, align 4, !dbg !35, !tbaa !36
> + tail call void @llvm.dbg.value(metadata !{i32 %0}, i64 0, metadata !40), !dbg !35
> + tail call void @_Z1fi(i32 %0), !dbg !41
> + br label %_Z1xb.exit, !dbg !42
> +
> +_Z1xb.exit: ; preds = %entry, %if.then.i
> + tail call void @_Z1fi(i32 0), !dbg !43
> + ret void, !dbg !44
> +}
> +
> +declare void @_Z1fi(i32) #1
> +
> +; Function Attrs: nounwind readnone
> +declare void @llvm.dbg.value(metadata, i64, metadata) #2
> +
> +attributes #0 = { uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
> +attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
> +attributes #2 = { nounwind readnone }
> +
> +!llvm.dbg.cu = !{!0}
> +!llvm.module.flags = !{!21, !22}
> +!llvm.ident = !{!23}
> +
> +!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.5.0 ", i1 true, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2, metadata !"", i32 1} ; [ DW_TAG_compile_unit ] [/tmp/dbginfo/missing-abstract-variables.cc] [DW_LANG_C_plus_plus]
> +!1 = metadata !{metadata !"missing-abstract-variables.cc", metadata !"/tmp/dbginfo"}
> +!2 = metadata !{}
> +!3 = metadata !{metadata !4, metadata !8, metadata !14}
> +!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"b", metadata !"b", metadata !"_Z1bv", i32 13, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, void ()* @_Z1bv, null, null, metadata !2, i32 13} ; [ DW_TAG_subprogram ] [line 13] [def] [b]
> +!5 = metadata !{i32 786473, metadata !1} ; [ DW_TAG_file_type ] [/tmp/dbginfo/missing-abstract-variables.cc]
> +!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 ]
> +!7 = metadata !{null}
> +!8 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"a", metadata !"a", metadata !"_Z1ab", i32 17, metadata !9, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, void (i1)* @_Z1ab, null, null, metadata !12, i32 17} ; [ DW_TAG_subprogram ] [line 17] [def] [a]
> +!9 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !10, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
> +!10 = metadata !{null, metadata !11}
> +!11 = metadata !{i32 786468, null, null, metadata !"bool", i32 0, i64 8, i64 8, i64 0, i32 0, i32 2} ; [ DW_TAG_base_type ] [bool] [line 0, size 8, align 8, offset 0, enc DW_ATE_boolean]
> +!12 = metadata !{metadata !13}
> +!13 = metadata !{i32 786689, metadata !8, metadata !"u", metadata !5, i32 16777233, metadata !11, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [u] [line 17]
> +!14 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"x", metadata !"x", metadata !"_Z1xb", i32 5, metadata !9, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, null, null, null, metadata !15, i32 5} ; [ DW_TAG_subprogram ] [line 5] [def] [x]
> +!15 = metadata !{metadata !16, metadata !17}
> +!16 = metadata !{i32 786689, metadata !14, metadata !"b", metadata !5, i32 16777221, metadata !11, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [b] [line 5]
> +!17 = metadata !{i32 786688, metadata !18, metadata !"s", metadata !5, i32 7, metadata !20, i32 0, i32 0} ; [ DW_TAG_auto_variable ] [s] [line 7]
> +!18 = metadata !{i32 786443, metadata !1, metadata !19, i32 6, i32 0, i32 0, i32 1} ; [ DW_TAG_lexical_block ] [/tmp/dbginfo/missing-abstract-variables.cc]
> +!19 = metadata !{i32 786443, metadata !1, metadata !14, i32 6, i32 0, i32 0, i32 0} ; [ DW_TAG_lexical_block ] [/tmp/dbginfo/missing-abstract-variables.cc]
These lexical blocks are invalid IR with too many operands, and wouldn't
pass DILexicalBlock::Verify(). Is that intentional, or should I fix it?
(I'm looking at r217978, which hasn't changed since this commit. I'm not
sure if it was valid at the time.)
> +!20 = 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]
> +!21 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
> +!22 = metadata !{i32 2, metadata !"Debug Info Version", i32 1}
> +!23 = metadata !{metadata !"clang version 3.5.0 "}
> +!24 = metadata !{i1 false}
> +!25 = metadata !{i32 786689, metadata !14, metadata !"b", metadata !5, i32 16777221, metadata !11, i32 0, metadata !26} ; [ DW_TAG_arg_variable ] [b] [line 5]
> +!26 = metadata !{i32 14, i32 0, metadata !4, null}
> +!27 = metadata !{i32 5, i32 0, metadata !14, metadata !26}
> +!28 = metadata !{i32 10, i32 0, metadata !14, metadata !26}
> +!29 = metadata !{i32 15, i32 0, metadata !4, null}
> +!30 = metadata !{i32 17, i32 0, metadata !8, null}
> +!31 = metadata !{i32 786689, metadata !14, metadata !"b", metadata !5, i32 16777221, metadata !11, i32 0, metadata !32} ; [ DW_TAG_arg_variable ] [b] [line 5]
> +!32 = metadata !{i32 18, i32 0, metadata !8, null}
> +!33 = metadata !{i32 5, i32 0, metadata !14, metadata !32}
> +!34 = metadata !{i32 6, i32 0, metadata !19, metadata !32}
> +!35 = metadata !{i32 7, i32 0, metadata !18, metadata !32}
> +!36 = metadata !{metadata !37, metadata !37, i64 0}
> +!37 = metadata !{metadata !"int", metadata !38, i64 0}
> +!38 = metadata !{metadata !"omnipotent char", metadata !39, i64 0}
> +!39 = metadata !{metadata !"Simple C/C++ TBAA"}
> +!40 = metadata !{i32 786688, metadata !18, metadata !"s", metadata !5, i32 7, metadata !20, i32 0, metadata !32} ; [ DW_TAG_auto_variable ] [s] [line 7]
> +!41 = metadata !{i32 8, i32 0, metadata !18, metadata !32} ; [ DW_TAG_imported_declaration ]
> +!42 = metadata !{i32 9, i32 0, metadata !18, metadata !32}
> +!43 = metadata !{i32 10, i32 0, metadata !14, metadata !32}
> +!44 = metadata !{i32 19, i32 0, metadata !8, null}
>
>
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