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

Wed Mar 12 14:05:42 PDT 2014

On Wed, Mar 12, 2014 at 2:01 PM, David Blaikie <dblaikie at gmail.com> wrote:
> On Wed, Mar 12, 2014 at 1:48 PM, Eric Christopher <echristo at gmail.com> wrote:
>> 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.
>
> Sort of the other way around, right - we knew the size of the field

Right. :)

> I'm somewhat inclined to rename some of the naming here to avoid the
> use of the word "base" in favor of "underlying" - the "base"
> terminology seems to just be here - it doesn't leak out into the
> DIDerivedType itself at least.
>

*nod* If you've got specific things in mind I'm all for it :)

-eric

>>
>> -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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