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Fix scalb spurious "invalid" exceptions (bug 16770).

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This patch fixes bug 16770, spurious "invalid" exceptions from scalb
when testing whether the second argument is an integer, by inserting
appropriate range checks to determine whether a cast to int is safe.
(Note that invalid_fn is a function that handles both nonintegers and
large integers, distinguishing them reliably using functions such as
__rint; note also that there are no issues with scalb needing to avoid
spurious "inexact" exceptions - it's an old-POSIX XSI function, not a
standard C function bound to an IEEE 754 operation - although the
return value is still fully determined.)

Tested x86_64 and x86.

	[BZ #16770]
	* math/e_scalb.c (__ieee754_scalb): Check second argument is not
	too large before casting to int.
	* math/e_scalbf.c (__ieee754_scalbf): Likewise.
	* math/e_scalbl.c (__ieee754_scalbl): Likewise.
	* math/libm-test.inc (scalb_test_data): Add more tests.
This commit is contained in:
Joseph Myers 2014-03-29 17:22:14 +00:00
parent 5673750800
commit ea6029b19c
6 changed files with 30 additions and 4 deletions
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9
ChangeLog
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@ -1,3 +1,12 @@
2014-03-29 Joseph Myers <joseph@codesourcery.com>
[BZ #16770]
* math/e_scalb.c (__ieee754_scalb): Check second argument is not
too large before casting to int.
* math/e_scalbf.c (__ieee754_scalbf): Likewise.
* math/e_scalbl.c (__ieee754_scalbl): Likewise.
* math/libm-test.inc (scalb_test_data): Add more tests.
2014-03-29 Siddhesh Poyarekar <siddhesh@redhat.com>
* benchtests/Makefile (DETAILED_OPT): New make option.

2
NEWS
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@ -13,7 +13,7 @@ Version 2.20
16532, 16545, 16574, 16599, 16600, 16609, 16610, 16611, 16613, 16623,
16632, 16634, 16639, 16642, 16649, 16670, 16674, 16677, 16680, 16683,
16689, 16695, 16701, 16706, 16707, 16712, 16713, 16714, 16731, 16743,
16758, 16759, 16760.
16758, 16759, 16760, 16770.
* Running the testsuite no longer terminates as soon as a test fails.
Instead, a file tests.sum (xtests.sum from "make xcheck") is generated,

2
math/e_scalb.c
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@ -50,7 +50,7 @@ __ieee754_scalb (double x, double fn)
return x;
return x / -fn;
}
if (__glibc_unlikely ((double) (int) fn != fn))
if (__glibc_unlikely (fabs (fn) >= 0x1p31 || (double) (int) fn != fn))
return invalid_fn (x, fn);
return __scalbn (x, (int) fn);

2
math/e_scalbf.c
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@ -50,7 +50,7 @@ __ieee754_scalbf (float x, float fn)
return x;
return x / -fn;
}
if (__glibc_unlikely ((float) (int) fn != fn))
if (__glibc_unlikely (fabsf (fn) >= 0x1p31f || (float) (int) fn != fn))
return invalid_fn (x, fn);
return __scalbnf (x, (int) fn);

2
math/e_scalbl.c
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@ -50,7 +50,7 @@ __ieee754_scalbl (long double x, long double fn)
return x;
return x / -fn;
}
if (__glibc_unlikely ((long double) (int) fn != fn))
if (__glibc_unlikely (fabsl (fn) >= 0x1p31L || (long double) (int) fn != fn))
return invalid_fn (x, fn);
return __scalbnl (x, (int) fn);

17
math/libm-test.inc
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@ -9134,6 +9134,23 @@ static const struct test_ff_f_data scalb_test_data[] =
TEST_ff_f (scalb, plus_infty, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
TEST_ff_f (scalb, qnan_value, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
TEST_ff_f (scalb, max_value, max_value, plus_oflow, OVERFLOW_EXCEPTION),
TEST_ff_f (scalb, max_value, -max_value, plus_uflow, UNDERFLOW_EXCEPTION),
TEST_ff_f (scalb, 1, max_value, plus_oflow, OVERFLOW_EXCEPTION),
TEST_ff_f (scalb, 1, -max_value, plus_uflow, UNDERFLOW_EXCEPTION),
TEST_ff_f (scalb, min_value, max_value, plus_oflow, OVERFLOW_EXCEPTION),
TEST_ff_f (scalb, min_value, -max_value, plus_uflow, UNDERFLOW_EXCEPTION),
TEST_ff_f (scalb, min_subnorm_value, max_value, plus_oflow, OVERFLOW_EXCEPTION),
TEST_ff_f (scalb, min_subnorm_value, -max_value, plus_uflow, UNDERFLOW_EXCEPTION),
TEST_ff_f (scalb, -max_value, max_value, minus_oflow, OVERFLOW_EXCEPTION),
TEST_ff_f (scalb, -max_value, -max_value, minus_uflow, UNDERFLOW_EXCEPTION),
TEST_ff_f (scalb, -1, max_value, minus_oflow, OVERFLOW_EXCEPTION),
TEST_ff_f (scalb, -1, -max_value, minus_uflow, UNDERFLOW_EXCEPTION),
TEST_ff_f (scalb, -min_value, max_value, minus_oflow, OVERFLOW_EXCEPTION),
TEST_ff_f (scalb, -min_value, -max_value, minus_uflow, UNDERFLOW_EXCEPTION),
TEST_ff_f (scalb, -min_subnorm_value, max_value, minus_oflow, OVERFLOW_EXCEPTION),
TEST_ff_f (scalb, -min_subnorm_value, -max_value, minus_uflow, UNDERFLOW_EXCEPTION),
TEST_ff_f (scalb, 0.8L, 4, 12.8L),
TEST_ff_f (scalb, -0.854375L, 5, -27.34L),
};