[cfe-dev] Optionally suppress debug info for inlined calls?

[Eric Christopher]

On Mon, Nov 25, 2013 at 1:31 PM, Sean Silva <silvas at purdue.edu> wrote:
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> On Mon, Nov 25, 2013 at 2:21 PM, David Blaikie <dblaikie at gmail.com> wrote:
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>>
>>
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>> On Mon, Nov 25, 2013 at 11:18 AM, Robinson, Paul
>> <Paul_Robinson at playstation.sony.com> wrote:
>>>
>>> I have _already_ turned it off for my target,
>>
>>
>> Right, I got that - was just trying to understand if/why that was the
>> right choice.
>>
>>>
>>> per request from licensees who don’t like seeing fake call frames that
>>> don’t reflect actual calls in the generated code.
>>
>>
>> Just tossing around ideas to accommodate your licensees/Clang users: would
>> this make more sense as a feature of debuggers/stack trace tools, etc? Are
>> there particular places where this shows up and confuses users?
>
>
> Aside from getter/setters like Paul mentioned, also SIMD vector types (as
> you might expect, game engines are heavy users of SIMD vector types).
> Essentially every arithmetic operation becomes a function call, and it's not
> out of the ordinary to have, say, 30+ arithmetic operations in a single
> short function (each compiling down to a single instruction of machine
> code).
>

__attribute__((__always_inline__, __nodebug__))?

-eric

> -- Sean Silva
>
>>
>>
>>>
>>> The size win doesn’t hurt but is secondary.
>>>
>>>
>>>
>>> The problem now is that not everybody likes it that way, and so I want to
>>> make it optional, and I’d rather have the feature upstream than keep it
>>> private.
>>>
>>>
>>>
>>> (While I’m not ready to file any bugs, I did notice some strangeness in
>>> the low/hi_pc ranges for some inlined ctors; the ranges mostly or completely
>>> overlapped, which didn’t seem right but I didn’t look into it.  That’s not
>>> my focus right now.)
>>>
>>> --paulr
>>>
>>>
>>>
>>> From: David Blaikie [mailto:dblaikie at gmail.com]
>>> Sent: Monday, November 25, 2013 11:02 AM
>>> To: Robinson, Paul
>>> Cc: cfe-dev at cs.uiuc.edu
>>> Subject: Re: [cfe-dev] Optionally suppress debug info for inlined calls?
>>>
>>>
>>>
>>> Why do you want to turn this off?
>>>
>>> Is it buggy? Could we fix it?
>>> Is it too big? Could we reduce size in ways that are strict-wins instead?
>>>
>>>
>>>
>>> On Mon, Nov 25, 2013 at 10:57 AM, Robinson, Paul
>>> <Paul_Robinson at playstation.sony.com> wrote:
>>>
>>> In general on our platform we don't want debug info for inlined calls
>>> (messy, awkward things) but some people still like to see them.
>>> Currently
>>> we turn them off unconditionally in our private tree, but we'd like to
>>> put
>>> this under command-line control and send it upstream.  Does anyone mind
>>> if
>>> I do this?  I was thinking a command-line option along the lines of
>>>       -g[no-]inlined-scopes
>>> We'd default to No on our target, Yes everywhere else.  If you turn these
>>> off, you don't get DW_TAG_inlined_scope, and the source location info for
>>> all the inlined code becomes the call site (single-stepping would act
>>> like
>>> it's an external call that you step over).
>>>
>>> Thanks,
>>> --paulr
>>>
>>>
>>>
>>> _______________________________________________
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>>> cfe-dev at cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>>>
>>>
>>
>>
>>
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>