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* time.c (long_mul): extracted from mul and avoid integer overflow.

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(wi_mul): extracted from wmul and avoid integer overflow.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@27129 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
akr 2010-03-31 14:35:13 +00:00
parent fbc42054e8
commit 6024074540
2 changed files with 111 additions and 30 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
Wed Mar 31 23:33:29 2010 Tanaka Akira <akr@fsij.org>
* time.c (long_mul): extracted from mul and avoid integer overflow.
(wi_mul): extracted from wmul and avoid integer overflow.
Wed Mar 31 21:30:38 2010 Tanaka Akira <akr@fsij.org>
* time.c: less bignum allocations.

136
time.c
View file

@ -78,6 +78,50 @@ sub(VALUE x, VALUE y)
return rb_funcall(x, '-', 1, y);
}
#if !(HAVE_LONG_LONG && SIZEOF_LONG * 2 <= SIZEOF_LONG_LONG)
static int
long_mul(long x, long y, long *z)
{
unsigned long a, b, c;
int s;
if (x == 0 || y == 0) {
*z = 0;
return 1;
}
if (x < 0) {
s = -1;
a = (unsigned long)-x;
}
else {
s = 1;
a = (unsigned long)x;
}
if (y < 0) {
s = -s;
b = (unsigned long)-y;
}
else {
b = (unsigned long)y;
}
c = a * b;
if (c / b == a) {
if (s < 0) {
if (c <= (unsigned long)LONG_MAX + 1) {
*z = -(long)c;
return 1;
}
}
else {
if (c <= (unsigned long)LONG_MAX) {
*z = (long)c;
return 1;
}
}
}
return 0;
}
#endif
static VALUE
mul(VALUE x, VALUE y)
{
@ -88,14 +132,9 @@ mul(VALUE x, VALUE y)
return LONG2FIX(ll);
return LL2NUM(ll);
#else
long a, b, c;
a = FIX2LONG(x);
if (a == 0)
return x;
b = FIX2LONG(y);
c = a * b;
if (c / a == b)
return LONG2NUM(c);
long z;
if (long_mul(FIX2LONG(x), FIX2LONG(y), &z))
return LONG2NUM(z);
#endif
}
if (TYPE(x) == T_BIGNUM)
@ -171,13 +210,14 @@ divmodv(VALUE n, VALUE d, VALUE *q, VALUE *r)
typedef uint64_t WIDEVALUE;
typedef int64_t SIGNED_WIDEVALUE;
# define WIDEVALUE_IS_WIDER 1
# define UWIDEINT_MAX UINT64_MAX
# define WIDEINT_MAX INT64_MAX
# define WIDEINT_MIN INT64_MIN
# define FIXWINT_P(tv) ((tv) & 1)
# define FIXWVtoINT64(tv) RSHIFT((SIGNED_WIDEVALUE)(tv), 1)
# define INT64toFIXWV(wi) ((WIDEVALUE)((SIGNED_WIDEVALUE)(wi) << 1 | FIXNUM_FLAG))
# define FIXWV_MAX (((int64_t)1 << 62) - 1)
# define FIXWV_MIN (-((int64_t)1 << 62))
# define POSFIXWVABLE(wi) ((wi) < FIXWV_MAX+1)
# define NEGFIXWVABLE(wi) ((wi) >= FIXWV_MIN)
# define FIXWVABLE(wi) (POSFIXWVABLE(wi) && NEGFIXWVABLE(wi))
# define WINT2FIXWV(i) WIDEVAL_WRAP(INT64toFIXWV(i))
# define FIXWV2WINT(w) FIXWVtoINT64(WIDEVAL_GET(w))
@ -187,15 +227,23 @@ divmodv(VALUE n, VALUE d, VALUE *q, VALUE *r)
typedef VALUE WIDEVALUE;
typedef SIGNED_VALUE SIGNED_WIDEVALUE;
# define WIDEVALUE_IS_WIDER 0
# define UWIDEINT_MAX ULONG_MAX
# define WIDEINT_MAX LONG_MAX
# define WIDEINT_MIN LONG_MIN
# define FIXWINT_P(v) FIXNUM_P(v)
# define FIXWV_MAX FIXNUM_MAX
# define FIXWV_MIN FIXNUM_MIN
# define FIXWVABLE(i) FIXABLE(i)
# define WINT2FIXWV(i) WIDEVAL_WRAP(LONG2FIX(i))
# define FIXWV2WINT(w) FIX2LONG(WIDEVAL_GET(w))
#endif
#define POSFIXWVABLE(wi) ((wi) < FIXWV_MAX+1)
#define NEGFIXWVABLE(wi) ((wi) >= FIXWV_MIN)
#define FIXWV_P(w) FIXWINT_P(WIDEVAL_GET(w))
/* #define STRUCT_WIDEVAL */
#define STRUCT_WIDEVAL
#ifdef STRUCT_WIDEVAL
/* for type checking */
typedef struct {
@ -406,20 +454,57 @@ wsub(wideval_t wx, wideval_t wy)
return v2w(rb_funcall(x, '-', 1, w2v(wy)));
}
static int
wi_mul(wideint_t x, wideint_t y, wideint_t *z)
{
uwideint_t a, b, c;
int s;
if (x == 0 || y == 0) {
*z = 0;
return 1;
}
if (x < 0) {
s = -1;
a = (uwideint_t)-x;
}
else {
s = 1;
a = (uwideint_t)x;
}
if (y < 0) {
s = -s;
b = (uwideint_t)-y;
}
else {
b = (uwideint_t)y;
}
c = a * b;
if (c / b == a) {
if (s < 0) {
if (c <= (uwideint_t)WIDEINT_MAX + 1) {
*z = -(wideint_t)c;
return 1;
}
}
else {
if (c <= (uwideint_t)WIDEINT_MAX) {
*z = (wideint_t)c;
return 1;
}
}
}
return 0;
}
static wideval_t
wmul(wideval_t wx, wideval_t wy)
{
VALUE x, z;
#if WIDEVALUE_IS_WIDER
if (FIXWV_P(wx) && FIXWV_P(wy)) {
wideint_t a, b, c;
a = FIXWV2WINT(wx);
if (a == 0) return wx;
b = FIXWV2WINT(wy);
c = a * b;
if (c / a == b) {
return WINT2WV(c);
}
wideint_t z;
if (wi_mul(FIXWV2WINT(wx), FIXWV2WINT(wy), &z))
return WINT2WV(z);
}
#endif
x = w2v(wx);
@ -643,18 +728,9 @@ static wideval_t
rb_time_magnify(wideval_t w)
{
if (FIXWV_P(w)) {
wideint_t a, b, c;
a = FIXWV2WINT(w);
if (a == 0) {
return WINT2FIXWV(0);
}
b = TIME_SCALE;
c = a * b;
if (c / b == a) {
if (FIXWVABLE(c)) {
return WINT2FIXWV(c);
}
}
wideint_t z;
if (wi_mul(FIXWV2WINT(w), TIME_SCALE, &z))
return WINT2WV(z);
}
return wmul(w, WINT2FIXWV(TIME_SCALE));
}