[Bug middle-end/87256] hppa spends huge amount of time in synth_mult()

[slyfox at inbox dot ru]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87256

--- Comment #5 from Sergei Trofimovich <slyfox at inbox dot ru> ---
(In reply to dave.anglin from comment #3)
> On 2018-09-08 3:11 PM, slyfox at inbox dot ru wrote:
> > -#define NUM_ALG_HASH_ENTRIES 1031
> > +#define NUM_ALG_HASH_ENTRIES 10311
> Does this help the compile time for xxhash?

A bit: it shrinks compile time from 80s to 13s (other targets do it in
sub-second times).

Ran the build against gcc master as:

${HOME}/dev/git/gcc-hppa2.0/gcc/xgcc -B${HOME}/dev/git/gcc-hppa2.0/gcc/ -O2
-pipe -fdiagnostics-show-option -frecord-gcc-switches -Wall -Wextra -Wcast-qual
-Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum
-Wdeclaration-after-statement -Wstrict-prototypes -Wundef   -c -o xxhash.o
xxhash.c -ftime-report

  Before the patch:
    Time variable                                   usr           sys         
wall               GGC
     expand                             :  82.20 ( 93%)   0.01 (  7%)  82.94 (
93%)    4372 kB ( 11%)
     TOTAL                              :  88.11          0.14         89.06   
      40621 kB

  After the patch:
    Time variable                                   usr           sys         
wall               GGC
     expand                             :   8.95 ( 68%)   0.00 (  0%)   8.93 (
67%)    4372 kB ( 11%)
     TOTAL                              :  13.15          0.08         13.24   
      40623 kB

perf record/report still shows most of time is dominated by synth_mult():
    64.59%  cc1              cc1               [.] synth_mult
     3.00%  cc1              cc1               [.] sd_lists_size