From 7748ef218cd7a9cffa984d165abe261cd60fae1a Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Sun, 4 Aug 2019 10:04:18 -0700 Subject: [PATCH] Tweak time arithmetic performance * src/timefns.c (lispint_arith): New function, which should be a bit faster if B is 0, or if A is a bignum and B a fixnum with absolute value in unsigned long range. (time_arith): Use it. --- src/timefns.c | 44 ++++++++++++++++++++++++++++++++------------ 1 file changed, 32 insertions(+), 12 deletions(-) diff --git a/src/timefns.c b/src/timefns.c index cce9dd51ba9..ee43014979e 100644 --- a/src/timefns.c +++ b/src/timefns.c @@ -965,6 +965,37 @@ lisp_seconds_argument (Lisp_Object specified_time) return t.tv_sec; } +/* Return the sum of the Lisp integers A and B. + Subtract instead of adding if SUBTRACT. + This function is tuned for small B. */ +static Lisp_Object +lispint_arith (Lisp_Object a, Lisp_Object b, bool subtract) +{ + bool mpz_done = false; + + if (FASTER_TIMEFNS && FIXNUMP (b)) + { + if (EQ (b, make_fixnum (0))) + return a; + if (FIXNUMP (a)) + return make_int (subtract + ? XFIXNUM (a) - XFIXNUM (b) + : XFIXNUM (a) + XFIXNUM (b)); + if (eabs (XFIXNUM (b)) <= ULONG_MAX) + { + ((XFIXNUM (b) < 0) == subtract ? mpz_add_ui : mpz_sub_ui) + (mpz[0], XBIGNUM (a)->value, eabs (XFIXNUM (b))); + mpz_done = true; + } + } + + if (!mpz_done) + (subtract ? mpz_sub : mpz_add) (mpz[0], + *bignum_integer (&mpz[0], a), + *bignum_integer (&mpz[1], b)); + return make_integer_mpz (); +} + /* Given Lisp operands A and B, add their values, and return the result as a Lisp timestamp that is in (TICKS . HZ) form if either A or B are in that form, (HI LO US PS) form otherwise. Subtract @@ -989,18 +1020,7 @@ time_arith (Lisp_Object a, Lisp_Object b, bool subtract) if (FASTER_TIMEFNS && EQ (ta.hz, tb.hz)) { hz = ta.hz; - if (FIXNUMP (ta.ticks) && FIXNUMP (tb.ticks)) - ticks = make_int (subtract - ? XFIXNUM (ta.ticks) - XFIXNUM (tb.ticks) - : XFIXNUM (ta.ticks) + XFIXNUM (tb.ticks)); - else - { - (subtract ? mpz_sub : mpz_add) - (mpz[0], - *bignum_integer (&mpz[0], ta.ticks), - *bignum_integer (&mpz[1], tb.ticks)); - ticks = make_integer_mpz (); - } + ticks = lispint_arith (ta.ticks, tb.ticks, subtract); } else { -- 2.39.2