[llvm] r203690 - When computing the size of a base type be conservative if the type

Wed Mar 12 13:48:39 PDT 2014

Realized some more elaboration may help here:

Basically what was happening is that we were determining that the size
of the base class was 0 as it was a declaration without size (with the
vtable emission optimization for debug info) and so we were noticing
that the size of the field wasn't the size of the base type for the
field. This was because we didn't know the size of the field.

-eric

On Wed, Mar 12, 2014 at 11:18 AM, Eric Christopher <echristo at gmail.com> wrote:
> Author: echristo
> Date: Wed Mar 12 13:18:05 2014
> New Revision: 203690
>
> URL: http://llvm.org/viewvc/llvm-project?rev=203690&view=rev
> Log:
> When computing the size of a base type be conservative if the type
> is a declaration and return the size of the type.
>
> Added:
>     llvm/trunk/test/DebugInfo/decl-derived-member.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=203690&r1=203689&r2=203690&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp Wed Mar 12 13:18:05 2014
> @@ -751,8 +751,9 @@ static uint64_t getBaseTypeSize(DwarfDeb
>
>    DIType BaseType = DD->resolve(Ty.getTypeDerivedFrom());
>
> -  // If this type is not derived from any type then take conservative approach.
> -  if (!BaseType.isValid())
> +  // If this type is not derived from any type or the type is a declaration then
> +  // take conservative approach.
> +  if (!BaseType.isValid() || BaseType.isForwardDecl())
>      return Ty.getSizeInBits();
>
>    // If this is a derived type, go ahead and get the base type, unless it's a
>
> Added: llvm/trunk/test/DebugInfo/decl-derived-member.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/decl-derived-member.ll?rev=203690&view=auto
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/decl-derived-member.ll (added)
> +++ llvm/trunk/test/DebugInfo/decl-derived-member.ll Wed Mar 12 13:18:05 2014
> @@ -0,0 +1,142 @@
> +; REQUIRES: object-emission
> +
> +; RUN: %llc_dwarf -O0 -filetype=obj %s -o %t
> +; RUN: llvm-dwarfdump %t | FileCheck %s
> +
> +; Testcase from:
> +; struct base {
> +;  virtual ~base();
> +; };
> +; struct foo {
> +;  base b;
> +; };
> +; foo f;
> +
> +; Where member b should be seen as a field at an offset and not a bitfield.
> +
> +; CHECK: DW_AT_member
> +; CHECK: DW_AT_name{{.*}}"b"
> +; CHECK-NOT: DW_AT_bit_offset
> +
> + at f = global %struct.foo zeroinitializer, align 8
> + at __dso_handle = external global i8
> + at _ZTV4base = external unnamed_addr constant [4 x i8*]
> + at llvm.global_ctors = appending global [1 x { i32, void ()* }] [{ i32, void ()* } { i32 65535, void ()* @_GLOBAL__I_a }]
> +
> +define internal void @__cxx_global_var_init() section ".text.startup" {
> +entry:
> +  call void @_ZN3fooC2Ev(%struct.foo* @f) #2, !dbg !35
> +  %0 = call i32 @__cxa_atexit(void (i8*)* bitcast (void (%struct.foo*)* @_ZN3fooD2Ev to void (i8*)*), i8* bitcast (%struct.foo* @f to i8*), i8* @__dso_handle) #2, !dbg !35
> +  ret void, !dbg !35
> +}
> +
> +; Function Attrs: inlinehint nounwind uwtable
> +define linkonce_odr void @_ZN3fooC2Ev(%struct.foo* %this) unnamed_addr #0 align 2 {
> +entry:
> +  %this.addr = alloca %struct.foo*, align 8
> +  store %struct.foo* %this, %struct.foo** %this.addr, align 8
> +  call void @llvm.dbg.declare(metadata !{%struct.foo** %this.addr}, metadata !36), !dbg !38
> +  %this1 = load %struct.foo** %this.addr
> +  %b = getelementptr inbounds %struct.foo* %this1, i32 0, i32 0, !dbg !39
> +  call void @_ZN4baseC2Ev(%struct.base* %b) #2, !dbg !39
> +  ret void, !dbg !39
> +}
> +
> +; Function Attrs: inlinehint uwtable
> +define linkonce_odr void @_ZN3fooD2Ev(%struct.foo* %this) unnamed_addr #1 align 2 {
> +entry:
> +  %this.addr = alloca %struct.foo*, align 8
> +  store %struct.foo* %this, %struct.foo** %this.addr, align 8
> +  call void @llvm.dbg.declare(metadata !{%struct.foo** %this.addr}, metadata !40), !dbg !41
> +  %this1 = load %struct.foo** %this.addr
> +  %b = getelementptr inbounds %struct.foo* %this1, i32 0, i32 0, !dbg !42
> +  call void @_ZN4baseD1Ev(%struct.base* %b), !dbg !42
> +  ret void, !dbg !44
> +}
> +
> +; Function Attrs: nounwind
> +declare i32 @__cxa_atexit(void (i8*)*, i8*, i8*) #2
> +
> +; Function Attrs: nounwind readnone
> +declare void @llvm.dbg.declare(metadata, metadata) #3
> +
> +declare void @_ZN4baseD1Ev(%struct.base*) #4
> +
> +; Function Attrs: inlinehint nounwind uwtable
> +define linkonce_odr void @_ZN4baseC2Ev(%struct.base* %this) unnamed_addr #0 align 2 {
> +entry:
> +  %this.addr = alloca %struct.base*, align 8
> +  store %struct.base* %this, %struct.base** %this.addr, align 8
> +  call void @llvm.dbg.declare(metadata !{%struct.base** %this.addr}, metadata !45), !dbg !47
> +  %this1 = load %struct.base** %this.addr
> +  %0 = bitcast %struct.base* %this1 to i8***, !dbg !48
> +  store i8** getelementptr inbounds ([4 x i8*]* @_ZTV4base, i64 0, i64 2), i8*** %0, !dbg !48
> +  ret void, !dbg !48
> +}
> +
> +define internal void @_GLOBAL__I_a() section ".text.startup" {
> +entry:
> +  call void @__cxx_global_var_init(), !dbg !49
> +  ret void, !dbg !49
> +}
> +
> +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" }
> +attributes #1 = { inlinehint 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" }
> +attributes #2 = { nounwind }
> +attributes #3 = { nounwind readnone }
> +attributes #4 = { "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" }
> +
> +!llvm.dbg.cu = !{!0}
> +!llvm.module.flags = !{!32, !33}
> +!llvm.ident = !{!34}
> +
> +!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.5.0 (trunk 203673) (llvm/trunk 203681)", i1 false, metadata !"", i32 0, metadata !2, metadata !3, metadata !8, metadata !30, metadata !2, metadata !"", i32 1} ; [ DW_TAG_compile_unit ] [/usr/local/google/home/echristo/foo.cc] [DW_LANG_C_plus_plus]
> +!1 = metadata !{metadata !"foo.cc", metadata !"/usr/local/google/home/echristo"}
> +!2 = metadata !{}
> +!3 = metadata !{metadata !4, metadata !7}
> +!4 = metadata !{i32 786451, metadata !1, null, metadata !"foo", i32 5, i64 64, i64 64, i32 0, i32 0, null, metadata !5, i32 0, null, null, metadata !"_ZTS3foo"} ; [ DW_TAG_structure_type ] [foo] [line 5, size 64, align 64, offset 0] [def] [from ]
> +!5 = metadata !{metadata !6}
> +!6 = metadata !{i32 786445, metadata !1, metadata !"_ZTS3foo", metadata !"b", i32 6, i64 64, i64 64, i64 0, i32 0, metadata !"_ZTS4base"} ; [ DW_TAG_member ] [b] [line 6, size 64, align 64, offset 0] [from _ZTS4base]
> +!7 = metadata !{i32 786451, metadata !1, null, metadata !"base", i32 1, i64 0, i64 0, i32 0, i32 4, null, null, i32 0, null, null, metadata !"_ZTS4base"} ; [ DW_TAG_structure_type ] [base] [line 1, size 0, align 0, offset 0] [decl] [from ]
> +!8 = metadata !{metadata !9, metadata !13, metadata !19, metadata !22, metadata !28}
> +!9 = metadata !{i32 786478, metadata !1, metadata !10, metadata !"__cxx_global_var_init", metadata !"__cxx_global_var_init", metadata !"", i32 9, metadata !11, i1 true, i1 true, i32 0, i32 0, null, i32 256, i1 false, void ()* @__cxx_global_var_init, null, null, metadata !2, i32 9} ; [ DW_TAG_subprogram ] [line 9] [local] [def] [__cxx_global_var_init]
> +!10 = metadata !{i32 786473, metadata !1}         ; [ DW_TAG_file_type ] [/usr/local/google/home/echristo/foo.cc]
> +!11 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !12, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
> +!12 = metadata !{null}
> +!13 = metadata !{i32 786478, metadata !1, metadata !"_ZTS3foo", metadata !"~foo", metadata !"~foo", metadata !"_ZN3fooD2Ev", i32 5, metadata !14, i1 false, i1 true, i32 0, i32 0, null, i32 320, i1 false, void (%struct.foo*)* @_ZN3fooD2Ev, null, metadata !17, metadata !2, i32 5} ; [ DW_TAG_subprogram ] [line 5] [def] [~foo]
> +!14 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !15, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
> +!15 = metadata !{null, metadata !16}
> +!16 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 1088, metadata !"_ZTS3foo"} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [artificial] [from _ZTS3foo]
> +!17 = metadata !{i32 786478, null, metadata !"_ZTS3foo", metadata !"~foo", metadata !"~foo", metadata !"", i32 0, metadata !14, i1 false, i1 false, i32 0, i32 0, null, i32 320, i1 false, null, null, i32 0, metadata !18, i32 0} ; [ DW_TAG_subprogram ] [line 0] [~foo]
> +!18 = metadata !{i32 786468}
> +!19 = metadata !{i32 786478, metadata !1, metadata !"_ZTS3foo", metadata !"foo", metadata !"foo", metadata !"_ZN3fooC2Ev", i32 5, metadata !14, i1 false, i1 true, i32 0, i32 0, null, i32 320, i1 false, void (%struct.foo*)* @_ZN3fooC2Ev, null, metadata !20, metadata !2, i32 5} ; [ DW_TAG_subprogram ] [line 5] [def] [foo]
> +!20 = metadata !{i32 786478, null, metadata !"_ZTS3foo", metadata !"foo", metadata !"foo", metadata !"", i32 0, metadata !14, i1 false, i1 false, i32 0, i32 0, null, i32 320, i1 false, null, null, i32 0, metadata !21, i32 0} ; [ DW_TAG_subprogram ] [line 0] [foo]
> +!21 = metadata !{i32 786468}
> +!22 = metadata !{i32 786478, metadata !1, metadata !"_ZTS4base", metadata !"base", metadata !"base", metadata !"_ZN4baseC2Ev", i32 1, metadata !23, i1 false, i1 true, i32 0, i32 0, null, i32 320, i1 false, void (%struct.base*)* @_ZN4baseC2Ev, null, metadata !26, metadata !2, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [base]
> +!23 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !24, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
> +!24 = metadata !{null, metadata !25}
> +!25 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 1088, metadata !"_ZTS4base"} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [artificial] [from _ZTS4base]
> +!26 = metadata !{i32 786478, null, metadata !"_ZTS4base", metadata !"base", metadata !"base", metadata !"", i32 0, metadata !23, i1 false, i1 false, i32 0, i32 0, null, i32 320, i1 false, null, null, i32 0, metadata !27, i32 0} ; [ DW_TAG_subprogram ] [line 0] [base]
> +!27 = metadata !{i32 786468}
> +!28 = metadata !{i32 786478, metadata !1, metadata !10, metadata !"", metadata !"", metadata !"_GLOBAL__I_a", i32 1, metadata !29, i1 true, i1 true, i32 0, i32 0, null, i32 64, i1 false, void ()* @_GLOBAL__I_a, null, null, metadata !2, i32 1} ; [ DW_TAG_subprogram ] [line 1] [local] [def]
> +!29 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !2, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
> +!30 = metadata !{metadata !31}
> +!31 = metadata !{i32 786484, i32 0, null, metadata !"f", metadata !"f", metadata !"", metadata !10, i32 9, metadata !4, i32 0, i32 1, %struct.foo* @f, null} ; [ DW_TAG_variable ] [f] [line 9] [def]
> +!32 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
> +!33 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}
> +!34 = metadata !{metadata !"clang version 3.5.0 (trunk 203673) (llvm/trunk 203681)"}
> +!35 = metadata !{i32 9, i32 0, metadata !9, null}
> +!36 = metadata !{i32 786689, metadata !19, metadata !"this", null, i32 16777216, metadata !37, i32 1088, i32 0} ; [ DW_TAG_arg_variable ] [this] [line 0]
> +!37 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 0, metadata !"_ZTS3foo"} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from _ZTS3foo]
> +!38 = metadata !{i32 0, i32 0, metadata !19, null}
> +!39 = metadata !{i32 5, i32 0, metadata !19, null}
> +!40 = metadata !{i32 786689, metadata !13, metadata !"this", null, i32 16777216, metadata !37, i32 1088, i32 0} ; [ DW_TAG_arg_variable ] [this] [line 0]
> +!41 = metadata !{i32 0, i32 0, metadata !13, null}
> +!42 = metadata !{i32 5, i32 0, metadata !43, null}
> +!43 = metadata !{i32 786443, metadata !1, metadata !13, i32 5, i32 0, i32 0, i32 0} ; [ DW_TAG_lexical_block ] [/usr/local/google/home/echristo/foo.cc]
> +!44 = metadata !{i32 5, i32 0, metadata !13, null}
> +!45 = metadata !{i32 786689, metadata !22, metadata !"this", null, i32 16777216, metadata !46, i32 1088, i32 0} ; [ DW_TAG_arg_variable ] [this] [line 0]
> +!46 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 0, metadata !"_ZTS4base"} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from _ZTS4base]
> +!47 = metadata !{i32 0, i32 0, metadata !22, null}
> +!48 = metadata !{i32 1, i32 0, metadata !22, null}
> +!49 = metadata !{i32 1, i32 0, metadata !28, null}
>
>
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