Do we use -fno-omit-frame-pointers by accident?

I was about to propose on BSDCan to turn on -fno-omit-frame-pointer
for the base system userland and most ports.[*]

So I went benchmarking the performance impact.

I discovered that CFLAGS+=-fno-omit-frame-pointer changes nothing
about our binaries and shared libraries.  CFLAGS+=-fomit-frame-pointer
makes them a little smaller.  So it looks like we default to having
frame pointers... somehow.  I verified in the compiler stdout that the
flags I set are in fact in effect.

Sizes for 16-current 283959bbe0863917c4fc3200a92d1055a4c89bdc /bin/sh:

   text    data     bss     dec     hex filename
- default: 
 164503    3712    5520  173735   2a6a7
- -fomit-frame-pointer
 163831    3712    6192  173735   2a6a7
- -fno-omit-frame-pointer
 164503    3712    5520  173735   2a6a7


[*] The reason why I bring this up now is that Ubuntu is doing the
work for use of determining which pieces of software have actually too
high overhead with FPs.  Such as the CPython interpreter.  Depending
on further benchmarking the base userland this changes the
effort/benefit balance.

More words here:
https://docs.google.com/presentation/d/17AGf6a0IxIzqcgd4-5FWdQhLzBV9DfLEhNTm-xL0vyc/edit?usp=sharing

Martin
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Martin Cracauer <[email protected]>   http://www.cons.org/cracauer/