https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90579
--- Comment #7 from Hongtao.liu <crazylht at gmail dot com> ---
Transform second loop as
diff --git a/loop.c b/loop.c
index feea9ea..81a3ea6 100644
--- a/loop.c
+++ b/loop.c
@@ -9,6 +9,6 @@ loop (int k, double x)
for (i=0;i<6;i++)
r[i] = x * a[i + k];
for (i=0;i<6;i++)
- t+=r[5-i];
+ t+=r[i]; -------- using ascending order, align with former loop.
return t;
}
}
Can avoid store forward stalls.
Before loop transform:
loop_avx256: 3710992
loop : 671995
loop_avx128: 650882
After loop transform:
loop_avx256: 661386
loop : 652932
loop_avx128: 568710
