Re: Inlining policy

[Paul Eggert]

On 4/5/20 3:23 AM, Andrea Corallo wrote:
> what about having a new macro to control the key operations we want to
> always have inlined at -O0 and -Og instead of falling back into defining
> these as macros?

I looked into this some more, and found some problems with using 
__attribute__((always_inline)), such as GCC complaining that it can't inline 
some functions in some cases on some platforms. It was a pain to suss out what 
would improve performance while avoiding the warnings, and while fiddling with 
this a bit I found a simpler change that had even better performance than 
__attribute__((always_inline)) did, at least on one platform for my standard 
benchmark of 'make compile-always'. So I installed the two attached patches 
instead. Together they improve Emacs CPU performance for 'gcc -Og' by about 60% 
on my benchmark.

I kept the DEFINE_KEY_OPS_AS_MACROS stuff because of the -O0 performance issues 
that we discussed earlier. Once we no longer need to worry about -O0 performance 
when debugging, we can get rid of that stuff.

Thanks for suggesting inlining as a way to improve Emacs performance when 
compiled with -Og.

0001-Improve-inlining-when-compiling-with-Og.patch
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0002-Revert-my-KEY_OPS_CFLAGS-change-to-src-Makefile.in.patch
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