pp_tms should use a local struct tms, instead of PL_timesbuf.

PL_timesbuf is effectively a vestige of Perl 1, and doesn't actually need to
be an interpreter variable. It will be removed early in v5.21.x, but it's a
good idea to refactor the code not to use it before then. A local struct tms
will be on the C stack, which will be in the CPU's L1 cache, whereas the
relevant part of the interpreter struct may well not be in the CPU cache at
all. Therefore this change might reduce cache pressure fractionally. A local
variable access should also be simpler machine code on most CPU architectures.

3 files changed, 14 insertions, 14 deletions

diff --git a/intrpvar.h b/intrpvar.h
index 2c1b73ee49..5d27ad5fb4 100644
--- a/intrpvar.h
+++ b/intrpvar.h
@@ -174,6 +174,7 @@ PERLVAR(I, statgv,	GV *)
 PERLVARI(I, statname,	SV *,	NULL)
 
 #ifdef HAS_TIMES
+/* Will be removed soon after v5.21.0. See RT #121351 */
 PERLVAR(I, timesbuf,	struct tms)
 #endif
 
diff --git a/pp_sys.c b/pp_sys.c
index 6c4e2c7f63..f1eabba39c 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -4397,20 +4397,23 @@ PP(pp_tms)
 #ifdef HAS_TIMES
     dVAR;
     dSP;
-    EXTEND(SP, 4);
-#ifndef VMS
-    (void)PerlProc_times(&PL_timesbuf);
+#ifdef VMS
+    /* time.h uses different name for struct tms, though the same data is
+       returned.
+     */
+    struct tbuffer_t timesbuf;
 #else
-    (void)PerlProc_times((tbuffer_t *)&PL_timesbuf);  /* time.h uses different name for */
-                                                   /* struct tms, though same data   */
-                                                   /* is returned.                   */
+    struct tms timesbuf;
 #endif
 
-    mPUSHn(((NV)PL_timesbuf.tms_utime)/(NV)PL_clocktick);
+    EXTEND(SP, 4);
+    (void)PerlProc_times(&timesbuf);
+
+    mPUSHn(((NV)timesbuf.tms_utime)/(NV)PL_clocktick);
     if (GIMME == G_ARRAY) {
-	mPUSHn(((NV)PL_timesbuf.tms_stime)/(NV)PL_clocktick);
-	mPUSHn(((NV)PL_timesbuf.tms_cutime)/(NV)PL_clocktick);
-	mPUSHn(((NV)PL_timesbuf.tms_cstime)/(NV)PL_clocktick);
+	mPUSHn(((NV)timesbuf.tms_stime)/(NV)PL_clocktick);
+	mPUSHn(((NV)timesbuf.tms_cutime)/(NV)PL_clocktick);
+	mPUSHn(((NV)timesbuf.tms_cstime)/(NV)PL_clocktick);
     }
     RETURN;
 #else
diff --git a/sv.c b/sv.c
index b7563b95f3..dcb1d5e646 100644
--- a/sv.c
+++ b/sv.c
@@ -13559,10 +13559,6 @@ perl_clone_using(PerlInterpreter *proto_perl, UV flags,
     PL_statbuf		= proto_perl->Istatbuf;
     PL_statcache	= proto_perl->Istatcache;
 
-#ifdef HAS_TIMES
-    PL_timesbuf		= proto_perl->Itimesbuf;
-#endif
-
 #ifndef NO_TAINT_SUPPORT
     PL_tainted		= proto_perl->Itainted;
 #else