[gcc r9-9307] rs6000: Correct Power8 cost of l2 cache size [PR97329]

[Xiong Hu Luo]

https://gcc.gnu.org/g:48354138267e0682f61866003b67a9851d3be3a2

commit r9-9307-g48354138267e0682f61866003b67a9851d3be3a2
Author: Xionghu Luo <luoxhu@linux.ibm.com>
Date:   Wed Mar 24 23:45:58 2021 -0500

    rs6000: Correct Power8 cost of l2 cache size [PR97329]
    
    This patch is a backport to gcc 9 from master.
    L2 cache size for Power8 is 512kB, it was copied from Power7 before
    public.  Tested no performance change for SPEC2017.
    
    gcc/
    2021-03-25  Xionghu Luo  <luoxhu@linux.ibm.com>
    
            PR target/97329
            * config/rs6000/rs6000.c (power8_costs): Change l2 cache
            from 256 to 512.
    
    (cherry picked from commit 08103e4d6ada9b57366f2df2a2b745babfab914c)

Diff:
---
 gcc/config/rs6000/rs6000.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index deec1e08e5c..62250433c16 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -1218,7 +1218,7 @@ struct processor_costs power8_cost = {
   COSTS_N_INSNS (17),	/* ddiv */
   128,			/* cache line size */
   32,			/* l1 cache */
-  256,			/* l2 cache */
+  512,			/* l2 cache */
   12,			/* prefetch streams */
   COSTS_N_INSNS (3),	/* SF->DF convert */
 };