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

[Sean Silva]

On Mon, Nov 25, 2013 at 2:21 PM, David Blaikie <dblaikie at gmail.com> wrote:

>
>
>
> 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).

-- 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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>>
>>
>
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