[llvm] r210143 - DebugInfo: Partial revert r209984 due to more cases where abstract DbgVariables do not have associated DIEs.
David Blaikie
dblaikie at gmail.com
Wed Sep 17 17:38:38 PDT 2014
On Wed, Sep 17, 2014 at 5:29 PM, Duncan P. N. Exon Smith <
dexonsmith at apple.com> wrote:
>
> > 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.)
>
Without the debug info verifier enabled by default (at least by default
when reading textual IR in llc - preferably when reading textual IR in
clang too) many test cases bit rot /really/ quickly. We (or at leanst I)
tend to only fix the tests that cause failures when I make a schema change.
I assume these ones were affected by the changes to move disciminators to
DILexicalBlockFile from DILexicalBlock.
>
> > +!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}
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>
>
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