https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109690
Bug ID: 109690
Summary: bad SLP vectorization on zen
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: hubicka at gcc dot gnu.org
Target Milestone: ---
model name : AMD Ryzen 7 5800X 8-Core Processor
reproduces on my znver1 laptop too.
h@ryzen3:~/gcc-kub/build/gcc> cat tt.c
int a[100];
[[gnu::noipa]]
void loop()
{
for (int i = 0; i < 3; i++)
a[i]+=a[i];
}
int
main()
{
for (int j = 0; j < 1000000000; j++)
loop ();
return 0;
}
jh@ryzen3:~/gcc-kub/build/gcc> ./xgcc -B ./ -O2 -march=native tt.c ; perf stat
./a.out
Performance counter stats for './a.out':
2683.95 msec task-clock:u # 1.000 CPUs
utilized
0 context-switches:u # 0.000 /sec
0 cpu-migrations:u # 0.000 /sec
52 page-faults:u # 19.374 /sec
13001141361 cycles:u # 4.844 GHz
(83.31%)
691180 stalled-cycles-frontend:u # 0.01% frontend
cycles idle (83.31%)
101980 stalled-cycles-backend:u # 0.00% backend
cycles idle (83.31%)
12999928665 instructions:u # 1.00 insn per
cycle
# 0.00 stalled cycles per
insn (83.31%)
3000013809 branches:u # 1.118 G/sec
(83.41%)
1525 branch-misses:u # 0.00% of all
branches (83.36%)
2.684376360 seconds time elapsed
2.684369000 seconds user
0.000000000 seconds sys
jh@ryzen3:~/gcc-kub/build/gcc> ./xgcc -B ./ -O2 -march=native tt.c
-fno-tree-vectorize ; perf stat ./a.out
Performance counter stats for './a.out':
1238.92 msec task-clock:u # 1.000 CPUs
utilized
0 context-switches:u # 0.000 /sec
0 cpu-migrations:u # 0.000 /sec
52 page-faults:u # 41.972 /sec
6000338140 cycles:u # 4.843 GHz
(83.21%)
314660 stalled-cycles-frontend:u # 0.01% frontend
cycles idle (83.21%)
0 stalled-cycles-backend:u # 0.00% backend
cycles idle (83.23%)
7999796562 instructions:u # 1.33 insn per
cycle
# 0.00 stalled cycles per
insn (83.53%)
2999887795 branches:u # 2.421 G/sec
(83.53%)
698 branch-misses:u # 0.00% of all
branches (83.28%)
1.239116606 seconds time elapsed
1.239121000 seconds user
0.000000000 seconds sys
