remove memcmp calls for better performance where size is known

so i have been doing some profiling on my rpi3 ... and it seems
memcmp() is like the number one top used function - especially running
e in wayland compositor mode. it uses accoring to perf top about 9-15%
of samples (samples are not adding up to 100%). no - i cant seem to
get a call graph because all that happens is the whole kernel locks up
solid if i try, so i can only get the leaf node call stats. what
function was currently active at the sample time. memcmp is the
biggest by far. 2-3 times anything else.

  13.47%  libarmmem.so                [.] memcmp
   6.43%  libevas.so.1.18.99          [.] _evas_render_phase1_object_pro
   4.74%  libevas.so.1.18.99          [.] evas_render_updates_internal.c
   2.84%  libeo.so.1.18.99            [.] _eo_obj_pointer_get
   2.49%  libevas.so.1.18.99          [.] evas_render_updates_internal_l
   2.03%  libpthread-2.24.so          [.] pthread_getspecific
   1.61%  libeo.so.1.18.99            [.] efl_data_scope_get
   1.60%  libevas.so.1.18.99          [.] _evas_event_object_list_raw_in
   1.54%  libevas.so.1.18.99          [.] evas_object_smart_changed_get
   1.32%  libgcc_s.so.1               [.] __udivsi3
   1.21%  libevas.so.1.18.99          [.] evas_object_is_active
   1.14%  libc-2.24.so                [.] malloc
   0.96%  libevas.so.1.18.99          [.] evas_render_mapped
   0.85%  libeo.so.1.18.99            [.] efl_isa

yeah. it's perf. it's sampling so not 100% accurate, but close to
"good enough" for the bigger stuff. so interestingly memcmp() is
actually in a special library/module (libarmmem.so) and is a REAL
function call. so doing memcmp's for small bits of memory ESPECIALLY
when we know their size in advance is not great. i am not sure our own
use of memcmp() is the actual culprit because even with this patch
memcmp still is right up there. we use it for stringshare which is
harder to remove as stringshare has variable sized memory blobs to
compare.

but the point remains - memcmp() is an ACTUAL function call. even on
x86 (i checked the assembly). and replacing it with a static inline
custom comparer is better. in fact i did that and benchmarked it as a
sample case for eina_tiler which has 4 ints (16 bytes) to compare
every time. i also compiled to assembly on x86 to inspect and make sure
things made sense.

the text color compare was just comparing 4 bytes as a color (an int
worth) which was silly to use memcmp on as it could just cast to an
int and do a == b. the map was a little more evil as it was 2 ptrs
plus 2 bitfields, but the way bitfields work means i can assume the
last byte is both bitfields combined. i can be a little more evil for
the rect tests as 4 ints compared is the same as comparing 2 long
longs (64bit types). yes. don't get pedantic. all platforms efl works
on work this way and this is a base assumption in efl and it's true
everywhere worth talking about.

yes - i tried __int128 too. it was not faster on x86 anyway and can't
compile on armv7. in my speed tests on x86-64, comparing 2 rects by
casting to a struct of 2 long long's and comparing just those is 70%
faster than comapring 4 ints. and the 2 long longs is 360% faster than
a memcmp. on arm (my rpi3) the long long is 12% faster than the 4 ints,
and it is 226% faster than a memcmp().

it'd be best if we didnt even have to compare at all, but with these
algorithms we do, so doing it faster is better.

we probably should nuke all the memcmp's we have that are not of large
bits of memory or variable sized bits of memory.

i set breakpoints for memcmp and found at least a chunk in efl. but
also it seems the vc4 driver was also doing it too. i have no idea how
much memory it was doing this to and it may ultimately be the biggest
culprit here, BUT we may as well reduce our overhead since i've found
this anyway. less "false positives" when hunting problems.

why am i doing this? i'm setting framerate hiccups. eg like we drop 3,
5 or 10 frames, then drop another bunch, then go back to smooth, then
this hiccup again. finding out WHAT is causing that hiccup is hard. i
can only SEE the hiccups on my rpi3 - not on x86. i am not so sure
it's cpufreq bouncing about as i've locked cpu to 600mhz and it still
happens. it's something else. maybe something we are polling? maybe
it's something in our drm/kms backend? maybe its in the vc4 drivers or
kernel parts? i have no idea. trying to hunt this is hard, but this is
important as this is something that possibly is affecting everyone but
other hw is fast enough to hide it...

in the meantime find and optimize what i find along the way.

@optimize

1 files changed, 2 insertions, 0 deletions

diff --git a/src/lib/evas/include/evas_private.h b/src/lib/evas/include/evas_private.h
index 6b0ff6862c..5271ac5805 100644
--- a/src/lib/evas/include/evas_private.h
+++ b/src/lib/evas/include/evas_private.h
@@ -1002,6 +1002,8 @@ struct _Evas_Object_Proxy_Data
 
 struct _Evas_Object_Map_Data
 {
+   // WARNING - you cannot change the below cur/prev layout, content or size
+   // unless you also update evas_object_main.c _map_same() func
    struct {
       Evas_Map             *map;
       Evas_Object          *map_parent;