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Optimize 1+' and 1-' on fixnums.

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* libguile/vm-i-scheme.c (INUM_MAX, INUM_MIN): New macros.
  (add1, sub1): Add/subtract without untagging the operand.  This leads
  to a 44% run time improvement compared to the previous
  implementation.

* libguile/vm.c: Include <stdint.h>.

* test-suite/tests/numbers.test ("1+", "1-"): Add tests for
  MOST-POSITIVE-FIXNUM, resp. MOST-NEGATIVE-FIXNUM, for 32-bit and
  34-bit values thereof.

* benchmark-suite/benchmarks/arithmetic.bm: New file.

* benchmark-suite/Makefile.am (SCM_BENCHMARKS): Add it.
This commit is contained in:
Ludovic Courtès 2010-10-13 01:31:19 +02:00
parent de6b3a5cb9
commit e78d4bf9a9
5 changed files with 92 additions and 10 deletions
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38
libguile/vm-i-scheme.c
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@ -209,6 +209,10 @@ VM_DEFINE_FUNCTION (149, ge, "ge?", 2)
* Numeric functions
*/
/* The maximum/minimum tagged integers. */
#define INUM_MAX (INTPTR_MAX - 1)
#define INUM_MIN (INTPTR_MIN + scm_tc2_int)
#undef FUNC2
#define FUNC2(CFUNC,SFUNC) \
{ \
@ -231,12 +235,21 @@ VM_DEFINE_FUNCTION (150, add, "add", 2)
VM_DEFINE_FUNCTION (151, add1, "add1", 1)
{
ARGS1 (x);
if (SCM_I_INUMP (x))
/* Check for overflow. */
if (SCM_LIKELY ((scm_t_intptr) x < INUM_MAX))
{
scm_t_int64 n = SCM_I_INUM (x) + 1;
if (SCM_FIXABLE (n))
RETURN (SCM_I_MAKINUM (n));
SCM result;
/* Add the integers without untagging. */
result = SCM_PACK ((scm_t_intptr) x
+ (scm_t_intptr) SCM_I_MAKINUM (1)
- scm_tc2_int);
if (SCM_LIKELY (SCM_I_INUMP (result)))
RETURN (result);
}
SYNC_REGISTER ();
RETURN (scm_sum (x, SCM_I_MAKINUM (1)));
}
@ -249,12 +262,21 @@ VM_DEFINE_FUNCTION (152, sub, "sub", 2)
VM_DEFINE_FUNCTION (153, sub1, "sub1", 1)
{
ARGS1 (x);
if (SCM_I_INUMP (x))
/* Check for underflow. */
if (SCM_LIKELY ((scm_t_intptr) x > INUM_MIN))
{
scm_t_int64 n = SCM_I_INUM (x) - 1;
if (SCM_FIXABLE (n))
RETURN (SCM_I_MAKINUM (n));
SCM result;
/* Substract the integers without untagging. */
result = SCM_PACK ((scm_t_intptr) x
- (scm_t_intptr) SCM_I_MAKINUM (1)
+ scm_tc2_int);
if (SCM_LIKELY (SCM_I_INUMP (result)))
RETURN (result);
}
SYNC_REGISTER ();
RETURN (scm_difference (x, SCM_I_MAKINUM (1)));
}