[llvm] r227827 - Debug Info: Relax assertion in isUnsignedDIType() to allow floats to be

[David Blaikie]

On Mon, Feb 2, 2015 at 10:31 AM, Adrian Prantl <aprantl at apple.com> wrote:

> Author: adrian
> Date: Mon Feb  2 12:31:58 2015
> New Revision: 227827
>
> URL: http://llvm.org/viewvc/llvm-project?rev=227827&view=rev
> Log:
> Debug Info: Relax assertion in isUnsignedDIType() to allow floats to be
> described by integer constants. This is a bit ugly, but if the source
> language allows arbitrary type casting, the debug info must follow suit.
>
> For example:
>   void foo() {
>     float a;
>     *(int *)&a = 0;
>   }
> For the curious: SROA replaces the float alloca with an i32 alloca, which
> is then optimized away and described via dbg.value(i32 0, ...).
>

Not sure this is the right answer - even if the IR looks like that, it may
be that we need to convert the constant back to the appropriate type before
emitting the debug info?

- David


>
> Added:
>     llvm/trunk/test/DebugInfo/X86/float_const.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=227827&r1=227826&r2=227827&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp Mon Feb  2 12:31:58
> 2015
> @@ -606,6 +606,7 @@ static bool isUnsignedDIType(DwarfDebug
>            Encoding == dwarf::DW_ATE_unsigned_char ||
>            Encoding == dwarf::DW_ATE_signed ||
>            Encoding == dwarf::DW_ATE_signed_char ||
> +          Encoding == dwarf::DW_ATE_float ||
>            Encoding == dwarf::DW_ATE_UTF || Encoding ==
> dwarf::DW_ATE_boolean ||
>            (Ty.getTag() == dwarf::DW_TAG_unspecified_type &&
>             Ty.getName() == "decltype(nullptr)")) &&
>
> Added: llvm/trunk/test/DebugInfo/X86/float_const.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/float_const.ll?rev=227827&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/X86/float_const.ll (added)
> +++ llvm/trunk/test/DebugInfo/X86/float_const.ll Mon Feb  2 12:31:58 2015
> @@ -0,0 +1,55 @@
> +; RUN: llc < %s -filetype=obj | llvm-dwarfdump -debug-dump=info - |
> FileCheck %s
> +; from (at -Os):
> +; void foo() {
> +;   float a = 3.14;
> +;   *(int *)&a = 0;
> +; }
> +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
> +target triple = "x86_64-apple-macosx10.10.0"
> +
> +; Function Attrs: nounwind optsize readnone uwtable
> +define void @foo() #0 {
> +entry:
> +  tail call void @llvm.dbg.declare(metadata float* undef, metadata !13,
> metadata !19), !dbg !20
> +  tail call void @llvm.dbg.value(metadata i32 1078523331, i64 0, metadata
> !13, metadata !19), !dbg !20
> +  tail call void @llvm.dbg.value(metadata i32 0, i64 0, metadata !13,
> metadata !19), !dbg !20
> +; CHECK:  DW_AT_const_value [DW_FORM_sdata]    (0)
> +; CHECK-NEXT: DW_AT_name {{.*}}"a"
> +  ret void, !dbg !21
> +}
> +
> +; Function Attrs: nounwind readnone
> +declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
> +
> +; Function Attrs: nounwind readnone
> +declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #1
> +
> +attributes #0 = { nounwind optsize readnone uwtable }
> +attributes #1 = { nounwind readnone }
> +
> +!llvm.dbg.cu = !{!0}
> +!llvm.module.flags = !{!15, !16, !17}
> +!llvm.ident = !{!18}
> +
> +!0 = !{!"0x11\0012\00clang version 3.7.0 (trunk
> 227686)\001\00\000\00\001", !1, !2, !3, !6, !2, !2} ; [ DW_TAG_compile_unit
> ] [foo.c] [DW_LANG_C99]
> +!1 = !{!"foo.c", !""}
> +!2 = !{}
> +!3 = !{!4}
> +!4 = !{!"0xf\00\000\0064\0064\000\000", null, null, !5} ; [
> DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from int]
> +!5 = !{!"0x24\00int\000\0032\0032\000\000\005", null, null} ; [
> DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc
> DW_ATE_signed]
> +!6 = !{!7}
> +!7 = !{!"0x2e\00foo\00foo\00\001\000\001\000\000\000\001\001", !8, !9,
> !10, null, void ()* @foo, null, null, !12} ; [ DW_TAG_subprogram ] [line 1]
> [def] [foo]
> +!8 = !{!"foo.c", !""}
> +!9 = !{!"0x29", !8}                               ; [ DW_TAG_file_type ]
> +!10 = !{!"0x15\00\000\000\000\000\000\000", null, null, null, !11, null,
> null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset
> 0] [from ]
> +!11 = !{null}
> +!12 = !{!13}
> +!13 = !{!"0x100\00a\002\000", !7, !9, !14}        ; [
> DW_TAG_auto_variable ] [a] [line 2]
> +!14 = !{!"0x24\00float\000\0032\0032\000\000\004", null, null} ; [
> DW_TAG_base_type ] [float] [line 0, size 32, align 32, offset 0, enc
> DW_ATE_float]
> +!15 = !{i32 2, !"Dwarf Version", i32 2}
> +!16 = !{i32 2, !"Debug Info Version", i32 2}
> +!17 = !{i32 1, !"PIC Level", i32 2}
> +!18 = !{!"clang version 3.7.0 (trunk 227686)"}
> +!19 = !{!"0x102"}                                 ; [ DW_TAG_expression ]
> +!20 = !MDLocation(line: 2, column: 9, scope: !7)
> +!21 = !MDLocation(line: 4, column: 1, scope: !7)
>
>
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