[LLVMdev] Dropping the DW_ prefix from names in dwarfdump

[David Blaikie]

On Mon, Jan 19, 2015 at 10:29 AM, Adrian Prantl <aprantl at apple.com> wrote:

>
> On Jan 19, 2015, at 10:26 AM, Adrian Prantl <aprantl at apple.com> wrote:
>
>
> On Jan 19, 2015, at 10:08 AM, David Blaikie <dblaikie at gmail.com> wrote:
>
> Hey guys,
>
> Frederic is introducing the expression dumping support and in the
> interests of tersity is skipping the "DW_" in every "DW_OP" (heck, we could
> even skip the "OP" given the context - nothing else textual can appear
> there, right?)
>
>
> I think it always depends on what you are debugging. When I’m interested
> whether the encoding is correct, I think I’d prefer to have all these
> details in there, even if they are redundant. When I’m debugging, e.g., the
> source location associated with a function argument, I wouldn’t care about
> which Form is used to encode the information.
>

Well all I was suggesting was dropping the prefixes - this wouldn't result
in any information loss, but possibly readability loss.

apart from that, I think we could drop some verbosity too - just like we
now print constants, file/directory names, without their form, etc, etc -
we could probably do the same for strings (printing out the offset in the
string table all the time is mostly excessive) and probably other types.
That would actually be a loss of information that would certainly need a
flag.


>
> -- adrian
>
>
> Any thoughts on skipping the "DW_" (maybe even the AT/TAG/FORM too) in the
> rest of dwarfdump? (skipping the AT/TAG (FORM would be relatively easy I
> think) would be a bit trickier, but still identifiable/solvable) I haven't
> tried it to see how it looks/reads.
>
>
> I think we should have a switchable level of verbosity. I think that the
> Darwin dwarfdump utility could serve as an example (at least to fuel the
> discussion):
> Here is Darwin's dwarfdump output with the default settings
>
> ----------------------------------------------------------------------
>  File: out.o (x86_64)
> ----------------------------------------------------------------------
> .debug_info contents:
>
> 0x00000000: Compile Unit: length = 0x0000005b  version = 0x0004
> abbr_offset = 0x00000000  addr_size = 0x08  (next CU at 0x0000005f)
>
> 0x0000000b: TAG_compile_unit [1] *
>              AT_producer( "clang version 3.5.0 (209308)" )
>              AT_language( DW_LANG_C_plus_plus )
>              AT_name( "test.cc" )
>              AT_stmt_list( 0x00000000 )
>              AT_comp_dir( "/llvm_cmake" )
>              AT_low_pc( 0x0000000000000000 )
>              AT_high_pc( 0x00000184 )
>
> 0x0000002a:     TAG_subprogram [2] *
>                  AT_low_pc( 0x0000000000000000 )
>                  AT_high_pc( 0x00000184 )
>                  AT_frame_base( rbp )
>                  AT_MIPS_linkage_name( "_Z3bari" )
>                  AT_name( "bar" )
>                  AT_decl_file( "/llvm_cmake/test.cc" )
>                  AT_decl_line( 1 )
>                  AT_type( {0x00000057} ( int ) )
>                  AT_external( true )
>
> 0x00000047:         TAG_formal_parameter [3]
>                      AT_location( 0x00000000
>                         0x0000000000000000 - 0x00000000000000b9: rdi+0
>                         0x00000000000000b9 - 0x0000000000000184: rsp+16,
> deref )
>                      AT_name( "y" )
>                      AT_decl_file( "/llvm_cmake/test.cc" )
>                      AT_decl_line( 1 )
>                      AT_type( {0x00000057} ( int ) )
>
> 0x00000056:         NULL
>
> 0x00000057:     TAG_base_type [4]
>                  AT_name( "int" )
>                  AT_encoding( DW_ATE_signed )
>                  AT_byte_size( 0x04 )
>
> 0x0000005e:     NULL
>
>
> and here is the same file with -v:
>
> ----------------------------------------------------------------------
>  File: out.o {mach64-x86_64-MH_OBJECT} (x86_64)
> ----------------------------------------------------------------------
> .debug_info contents:
>
> 0x00000000: Compile Unit: length = 0x0000005b  version = 0x0004
> abbr_offset = 0x00000000  addr_size = 0x08  (next CU at 0x0000005f)
>
> 0x0000000b: TAG_compile_unit [1] *
> 0x0000000c:  AT_producer( .debug_str[0x00000000] = "clang version 3.5.0
> (209308)" )
> 0x00000010:  AT_language( 0x0004 ( DW_LANG_C_plus_plus ) )
> 0x00000012:  AT_name( .debug_str[0x0000001d] = "test.cc" )
> 0x00000016:  AT_stmt_list( 0x00000000 ( 0x00000000 ) )
> 0x0000001a:  AT_comp_dir( .debug_str[0x00000025] = "/llvm_cmake" )
> 0x0000001e:  AT_low_pc( 0x0000000000000000 )
> 0x00000026:  AT_high_pc( 0x00000184 )
>
> 0x0000002a:     TAG_subprogram [2] *
> 0x0000002b:      AT_low_pc( 0x0000000000000000 )
> 0x00000033:      AT_high_pc( 0x00000184 )
> 0x00000037:      AT_frame_base( <0x0000000000000001> 56  ( reg6 ) )
> 0x00000039:      AT_MIPS_linkage_name( .debug_str[0x00000039] = "_Z3bari"
> )
> 0x0000003d:      AT_name( .debug_str[0x00000035] = "bar" )
> 0x00000041:      AT_decl_file( 0x01 ( "/llvm_cmake/test.cc" ) )
> 0x00000042:      AT_decl_line( 0x01 ( 1 ) )
> 0x00000043:      AT_type( cu + 0x00000057 => {0x00000057} ( int ) )
> 0x00000047:      AT_external( true )
>
> 0x00000047:         TAG_formal_parameter [3]
> 0x00000048:          AT_location( 0x00000000
>                         0x0000000000000000 - 0x00000000000000b9: breg5 +0
>                         0x00000000000000b9 - 0x0000000000000184: breg7
> +16, deref )
> 0x0000004c:          AT_name( .debug_str[0x00000045] = "y" )
> 0x00000050:          AT_decl_file( 0x01 ( "/llvm_cmake/test.cc" ) )
> 0x00000051:          AT_decl_line( 0x01 ( 1 ) )
> 0x00000052:          AT_type( cu + 0x00000057 => {0x00000057} ( int ) )
>
> 0x00000056:         NULL
>
> 0x00000057:     TAG_base_type [4]
> 0x00000058:      AT_name( .debug_str[0x00000041] = "int" )
> 0x0000005c:      AT_encoding( 0x05 ( DW_ATE_signed ) )
> 0x0000005d:      AT_byte_size( 0x04 )
>
> 0x0000005e:     NULL
>
> I particularly like the inline location expressions.
>
> -- adrian
>
>
>
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