[llvm-dev] [RFC][ThinLTO] llvm-dis ThinLTO summary dump format

[Peter Collingbourne via llvm-dev]

On Fri, Jun 2, 2017 at 12:49 PM, Teresa Johnson <tejohnson at google.com>
wrote:

>
>
> On Fri, Jun 2, 2017 at 12:39 PM, Peter Collingbourne <peter at pcc.me.uk>
> wrote:
>
>> On Fri, Jun 2, 2017 at 12:29 PM, Teresa Johnson <tejohnson at google.com>
>> wrote:
>>
>>> On Fri, Jun 2, 2017 at 12:18 PM, Peter Collingbourne via llvm-dev <
>>> llvm-dev at lists.llvm.org> wrote:
>>>
>>>> Why do we need a custom dumping format for the summary? Since we
>>>> already need the YAML format anyway, wouldn't it be better to extend that
>>>> to cover the entire summary?
>>>>
>>>
>>> IMO it is useful/convenient to be able to see the summary in the
>>> llvm-dis output.
>>>
>>
>> There are two things:
>> 1) the format of the summary
>> 2) where to add the dumper
>> I'm not too concerned about 2 (I wouldn't add it to llvm-dis, but rather
>> as a subcommand to llvm-lto2, but I don't have a strong opinion about that).
>>
>> So that leaves the text based summary format. We need a format that is
>> easily parseable so that we can test components that manipulate summaries
>> in isolation. That is what the YAML format is. Why add a second format that
>> is not parseable?
>>
>
> So in this case it is purely for visual inspection - I suggested that
> Charles add this as LLVM assembly comments, to make it clear that we can't
> currently reconstruct the summary if the LLVM assembly file is re-assembled
> (we currently need to rebuild the summary from scratch).  I know you have
> added support for inputing the type id summaries in YAML form for testing
> purposes, since they were/are not being generated from IR during the
> current module summary index builder, but we have the opposite issue with
> the rest of the summaries (no serialization, but can build from IR).
>

Again: we could address that issue by adding the rest of the summary to the
YAML serialization, no? I don't want to have to update the tests and the
YAML dumper and the new-format dumper when I make a change to the summary
format.

Peter


>
> Teresa
>
>
>> Peter
>>
>> Teresa
>>>
>>>
>>>> Peter
>>>>
>>>> On Fri, Jun 2, 2017 at 8:46 AM, Charles Saternos via llvm-dev <
>>>> llvm-dev at lists.llvm.org> wrote:
>>>>
>>>>> Hey all,
>>>>>
>>>>> Below is the proposed format for the dump of the ThinLTO module
>>>>> summary in the llvm-dis utility:
>>>>>
>>>>> > ../build/bin/llvm-dis t.o && cat t.o.ll
>>>>> ; ModuleID = '2.o'
>>>>> source_filename = "2.ll"
>>>>> target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
>>>>> target triple = "x86_64-unknown-linux-gnu"
>>>>>
>>>>> @X = constant i32 42, section "foo", align 4
>>>>>
>>>>> @a = weak alias i32, i32* @X
>>>>>
>>>>> define void @afun() {
>>>>>   %1 = load i32, i32* @a
>>>>>   ret void
>>>>> }
>>>>>
>>>>> define void @testtest() {
>>>>>   tail call void @boop()
>>>>>   ret void
>>>>> }
>>>>>
>>>>> declare void @boop()
>>>>>
>>>>> ; Module summary:
>>>>> ;  testtest (External linkage)
>>>>> ;    Function (2 instructions)
>>>>> ;    Calls: boop
>>>>> ;  X (External linkage)
>>>>> ;    Global Variable
>>>>> ;  afun (External linkage)
>>>>> ;    Function (2 instructions)
>>>>> ;    Refs:
>>>>> ;      a
>>>>> ;  a (Weak any linkage)
>>>>> ;    Alias (aliasee X)
>>>>>
>>>>> I've implemented the above format in the llvm-dis utility, since there
>>>>> currently isn't really a way of getting ThinLTO summaries in a
>>>>> human-readable format.
>>>>>
>>>>> Let me know what you think of this format, and what information you
>>>>> think should be added/removed.
>>>>>
>>>>> Thanks,
>>>>> Charles
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> LLVM Developers mailing list
>>>>> llvm-dev at lists.llvm.org
>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> --
>>>> Peter
>>>>
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> llvm-dev at lists.llvm.org
>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>
>>>>
>>>
>>>
>>> --
>>> Teresa Johnson |  Software Engineer |  tejohnson at google.com |
>>> 408-460-2413 <(408)%20460-2413>
>>>
>>
>>
>>
>> --
>> --
>> Peter
>>
>
>
>
> --
> Teresa Johnson |  Software Engineer |  tejohnson at google.com |
> 408-460-2413 <(408)%20460-2413>
>



-- 
-- 
Peter
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