On 10/11/2023 10:17, Wilco Dijkstra wrote:
Hi Kyrill,
+ /* Reduce the maximum size with -Os. */
+ if (optimize_function_for_size_p (cfun))
+ max_set_size = 96;
+
.... This is a new "magic" number in this code. It looks sensible, but how did
you arrive at it?
We need 1 instruction to create the value to store (DUP or MOVI) and 1 STP
for every 32 bytes, so the 96 means 4 instructions for typical sizes
(sizes not
a multiple of 16 can add one extra instruction).
I checked codesize on SPECINT2017, and 96 had practically identical size.
Using 128 would also be a reasonable Os value with a very slight size
increase,
and 384 looks good for O2 - however I didn't want to tune these values
as this
is a cleanup patch.
Cheers,
Wilco
Shouldn't this be a param then? Also, manifest constants in the middle
of code are a potential nightmare, please move it to a #define (even if
that's then used as the default value for the param).
