> Vladimir Makarov wrote:
> > On SPECINT2k performance is ~0.5% worse (5.5% regression on perlbmk), and
> > SPECFP is ~0.2% faster.
> Thanks for reporting this. It is important for me as I have no aarch64
> machine for benchmarking.
>
> Perlbmk performance degradation is too big and I'll definitely look at
> this problem.
Looking at the diffs in regexec.c which has the hot function regmatch(),
nothing obvious stands out that could cause a serious regression.
I did notice this around line 2300:
.L802:
ldr x1, [x23, 48]
adrp x5, PL_savestack_ix
ldr w0, [x23]
str x5, [sp, 104]
str x1, [x24, #:lo12:PL_regcc]
ldr w27, [x1, 4]
bl regcppush
- ldr x5, [sp, 104]
str w0, [sp, 112]
ldr x0, [x23, 32]
+ adrp x5, PL_savestack_ix
ldr w28, [x5, #:lo12:PL_savestack_ix]
+ str x5, [sp, 104]
bl regmatch
ldr x5, [sp, 104]
mov w19, w0
ldr w1, [sp, 112]
ldr w0, [x5, #:lo12:PL_savestack_ix]
So it rematerializes once instance, but fails to rematerialize the second use.
An extra store is inserted, and the first adrp and store are not removed as
dead.
Wilco
