[LLVMdev] Dropping the DW_ prefix from names in dwarfdump
Eric Christopher
echristo at gmail.com
Mon Jan 19 10:54:04 PST 2015
On Mon Jan 19 2015 at 10:42:52 AM Frédéric Riss <friss at apple.com> wrote:
> On Jan 19, 2015, at 10:34 AM, David Blaikie <dblaikie at gmail.com> wrote:
>
>
>
> 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.
>
>
> As I said in the review thread, I dropped the DW_ prefix for expressions
> as they can be multiple of them on the same line. I have no strong feeling
> one way or another for Attributes or Tags.
>
> 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.
>
>
> One of the next things I wanted to do was to drop the FORM display by
> default. This would actually save a lot more horizontal space than the DW_
> prefixes and in my experience you nearly never need it. Of course there
> needs to be a flag to get it back, because ‘nearly never’ ain’t ‘never :-).
>
>
Like if you're looking for the actual enum constant ;)
That said, I like the ideas. I'm good with it.
Thanks!
-eric
> Fred
>
>
>
>>
>> -- 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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