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[BZ4997]

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* sysdeps/powerpc/powerpc32/fpu/s_lround.S (__lround): Fixed erroneous
	result when x is +/-nextafter(+/-0.5,-/+1) i.e. all 1's in the
	mantissa.
	* sysdeps/powerpc/powerpc32/power4/fpu/s_llround.S (__llround):
	Likewise.  Also account for when x is an odd number between 2^52
	and 2^53-1.
	* sysdeps/powerpc/powerpc64/fpu/s_llround.S (__llround): Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_llroundf.S (__llroundf): Likewise.
	* math/libm-test.inc (lround_test, llround_test): Added test cases to
	detect aforementioned erroneous conditions.
This commit is contained in:
Ulrich Drepper
2008-04-11 19:32:37 +00:00
parent 22dca1ea77
commit c1e6b459c8
6 changed files with 203 additions and 87 deletions
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43
math/libm-test.inc
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@@ -4300,6 +4300,17 @@ lround_test (void)
# endif
TEST_f_l (lround, 2097152.5, 2097153);
TEST_f_l (lround, -2097152.5, -2097153);
/* nextafter(0.5,-1) */
TEST_f_l (lround, 0x1.fffffffffffffp-2, 0);
/* nextafter(-0.5,1) */
TEST_f_l (lround, -0x1.fffffffffffffp-2, 0);
#else
/* nextafter(0.5,-1) */
TEST_f_l (lround, 0x1.fffffp-2, 0);
/* nextafter(-0.5,1) */
TEST_f_l (lround, -0x1.fffffp-2, 0);
TEST_f_l (lround, 0x1.fffffep+23, 16777215);
TEST_f_l (lround, -0x1.fffffep+23, -16777215);
#endif
END (lround);
}
@@ -4359,8 +4370,40 @@ llround_test (void)
TEST_f_L (llround, 4294967295.5, 4294967296LL);
/* 0x200000000 */
TEST_f_L (llround, 8589934591.5, 8589934592LL);
/* nextafter(0.5,-1) */
TEST_f_L (llround, 0x1.fffffffffffffp-2, 0);
/* nextafter(-0.5,1) */
TEST_f_L (llround, -0x1.fffffffffffffp-2, 0);
/* On PowerPC an exponent of '52' is the largest incrementally
* representable sequence of whole-numbers in the 'double' range. We test
* lround to make sure that a guard bit set during the lround operation
* hasn't forced an erroneous shift giving us an incorrect result. The odd
* numbers between +-(2^52+1 and 2^53-1) are affected since they have the
* rightmost bit set. */
/* +-(2^52+1) */
TEST_f_L (llround, 0x1.0000000000001p+52,4503599627370497LL);
TEST_f_L (llround, -0x1.0000000000001p+52,-4503599627370497LL);
/* +-(2^53-1): Input is the last (positive and negative) incrementally
* representable whole-number in the 'double' range that might round
* erroneously. */
TEST_f_L (llround, 0x1.fffffffffffffp+52, 9007199254740991LL);
TEST_f_L (llround, -0x1.fffffffffffffp+52, -9007199254740991LL);
#else
/* nextafter(0.5,-1) */
TEST_f_L (llround, 0x1.fffffep-2, 0);
/* nextafter(-0.5,1) */
TEST_f_L (llround, -0x1.fffffep-2, 0);
/* As above, on PowerPC an exponent of '23' is the largest incrementally
* representable sequence of whole-numbers in the 'float' range.
* Likewise, numbers between +-(2^23+1 and 2^24-1) are affected. */
TEST_f_L (llround, 0x1.000002p+23,8388609);
TEST_f_L (llround, -0x1.000002p+23,-8388609);
TEST_f_L (llround, 0x1.fffffep+23, 16777215);
TEST_f_L (llround, -0x1.fffffep+23, -16777215);
#endif
#ifdef TEST_LDOUBLE
/* The input can only be represented in long double. */
TEST_f_L (llround, 4503599627370495.5L, 4503599627370496LL);