[glibc/release/2.34/master] x86: Fix misordered logic for setting `rep_movsb_stop_threshold`

[glibc/release/2.34/master] x86: Fix misordered logic for setting `rep_movsb_stop_threshold`

[Sunil Pandey]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=6e008c884dad5a25f91085c68d044bb5e2d63761

commit 6e008c884dad5a25f91085c68d044bb5e2d63761
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date:   Tue Jun 14 13:50:11 2022 -0700

    x86: Fix misordered logic for setting `rep_movsb_stop_threshold`
    
    Move the setting of `rep_movsb_stop_threshold` to after the tunables
    have been collected so that the `rep_movsb_stop_threshold` (which
    is used to redirect control flow to the non_temporal case) will
    use any user value for `non_temporal_threshold` (set using
    glibc.cpu.x86_non_temporal_threshold)
    
    (cherry picked from commit 035591551400cfc810b07244a015c9411e8bff7c)

Diff:
---
 sysdeps/x86/dl-cacheinfo.h | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/sysdeps/x86/dl-cacheinfo.h b/sysdeps/x86/dl-cacheinfo.h
index 2e43e67e4f..560bf260e8 100644
--- a/sysdeps/x86/dl-cacheinfo.h
+++ b/sysdeps/x86/dl-cacheinfo.h
@@ -898,18 +898,6 @@ dl_init_cacheinfo (struct cpu_features *cpu_features)
   if (CPU_FEATURE_USABLE_P (cpu_features, FSRM))
     rep_movsb_threshold = 2112;
 
-  unsigned long int rep_movsb_stop_threshold;
-  /* ERMS feature is implemented from AMD Zen3 architecture and it is
-     performing poorly for data above L2 cache size. Henceforth, adding
-     an upper bound threshold parameter to limit the usage of Enhanced
-     REP MOVSB operations and setting its value to L2 cache size.  */
-  if (cpu_features->basic.kind == arch_kind_amd)
-    rep_movsb_stop_threshold = core;
-  /* Setting the upper bound of ERMS to the computed value of
-     non-temporal threshold for architectures other than AMD.  */
-  else
-    rep_movsb_stop_threshold = non_temporal_threshold;
-
   /* The default threshold to use Enhanced REP STOSB.  */
   unsigned long int rep_stosb_threshold = 2048;
 
@@ -951,6 +939,18 @@ dl_init_cacheinfo (struct cpu_features *cpu_features)
 			   SIZE_MAX);
 #endif
 
+  unsigned long int rep_movsb_stop_threshold;
+  /* ERMS feature is implemented from AMD Zen3 architecture and it is
+     performing poorly for data above L2 cache size. Henceforth, adding
+     an upper bound threshold parameter to limit the usage of Enhanced
+     REP MOVSB operations and setting its value to L2 cache size.  */
+  if (cpu_features->basic.kind == arch_kind_amd)
+    rep_movsb_stop_threshold = core;
+  /* Setting the upper bound of ERMS to the computed value of
+     non-temporal threshold for architectures other than AMD.  */
+  else
+    rep_movsb_stop_threshold = non_temporal_threshold;
+
   cpu_features->data_cache_size = data;
   cpu_features->shared_cache_size = shared;
   cpu_features->non_temporal_threshold = non_temporal_threshold;