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.

1 files changed, 13 insertions, 10 deletions

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