Re: [WIP] Remove nested function in elf/dl-lookup.c? (Nested functions considered harmful?)

[Mike Frysinger <vapier at gentoo dot org>]

On Monday 16 December 2013 11:12:09 Carlos O'Donell wrote:
> On 12/16/2013 09:40 AM, Siddhesh Poyarekar wrote:
> > On Mon, Dec 16, 2013 at 09:32:12AM -0500, Carlos O'Donell wrote:
> >> Maybe, maybe not, but that would be a distinct patch *after*
> >> this initial checkin to make the function distinct.
> >> 
> >> I don't want to wrap the elements in a struct because that
> >> breaks the optimizations used during inlining.
> > 
> > Yeah, making a struct out of it is pointless.  We could clean up the
> > arguments later.
> 
> It's not entirely pointless. A pointer to a structure makes the call
> optimal when the ABI requires pass by stack, you need only push a
> single register, and pop a single register before doing register+offset
> loads.

but you still need to create the struct on the stack unless gcc is super 
intelligent and lays out the local vars in such a way that it also matches the 
struct layout.  but that seems pretty fragile to rely upon.

> One question I had was: Why is the original function
> __attribute_noinline__?

the original commit that added this:
commit 021723ab784461de9eac57398ea16a47d4ab9366
Author: Ulrich Drepper <drepper@redhat.com>
Date:   Sun Mar 7 05:26:02 2004 +0000

    Update.

and the actual diff doesn't indicate a compelling reason.

have i mentioned i fsckin hate the glibc commit history ?  current history 
sometimes isn't too much better.
-mike

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