master 24e1123241 06/16: Improve time-equal-p etc. performance

[Paul Eggert]

branch: master
commit 24e1123241b5692628de08e2de23448e07861111
Author: Paul Eggert <eggert@cs.ucla.edu>
Commit: Paul Eggert <eggert@cs.ucla.edu>

    Improve time-equal-p etc. performance
    
    * src/timefns.c (time_cmp): Return EMACS_INT, not int; no need to
    change callers.  Compare (X . Z) to (Y . Z) quickly if X and Y are
    fixnums.
---
 src/timefns.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/timefns.c b/src/timefns.c
index 078e1f40fb..990b23a508 100644
--- a/src/timefns.c
+++ b/src/timefns.c
@@ -1192,7 +1192,7 @@ For example, nil stands for the current time.  */)
 
 /* Return negative, 0, positive if A < B, A == B, A > B respectively.
    A and B should be Lisp time values.  */
-static int
+static EMACS_INT
 time_cmp (Lisp_Object a, Lisp_Object b)
 {
   /* Compare nil to nil correctly, and handle other eq values quicker
@@ -1201,6 +1201,12 @@ time_cmp (Lisp_Object a, Lisp_Object b)
   if (BASE_EQ (a, b))
     return 0;
 
+  /* Compare (X . Z) to (Y . Z) quickly if X and Y are fixnums.
+     Do not inspect Z, as it is OK to not signal if A and B are invalid.  */
+  if (FASTER_TIMEFNS && CONSP (a) && CONSP (b) && BASE_EQ (XCDR (a), XCDR (b))
+      && FIXNUMP (XCAR (a)) && FIXNUMP (XCAR (b)))
+    return XFIXNUM (XCAR (a)) - XFIXNUM (XCAR (b));
+
   /* Compare (ATICKS . AZ) to (BTICKS . BHZ) by comparing
      ATICKS * BHZ to BTICKS * AHZ.  */
   struct lisp_time ta = lisp_time_struct (a, 0);