From: Joseph Myers Date: Mon, 9 Apr 2012 22:32:45 +0000 (+0000) Subject: Fix spurious overflow exceptions from x86/x86_64 powl (bug 13872). X-Git-Tag: upstream/2.30~11256 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=8f9a2faee0619ed5fad7b9c54b64f866b0264bde;p=external%2Fglibc.git Fix spurious overflow exceptions from x86/x86_64 powl (bug 13872). --- diff --git a/ChangeLog b/ChangeLog index 3686491..a85a1c0 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,13 @@ 2012-04-09 Joseph Myers + [BZ #13872] + * sysdeps/i386/fpu/e_powl.S (p78): New object. + (__ieee754_powl): Saturate large exponents rather than testing for + overflow of y*log2(x). + * sysdeps/x86_64/fpu/e_powl.S: Likewise. + * math/libm-test.inc (pow_test): Do not permit spurious overflow + exceptions. + [BZ #11521] * math/s_ctan.c: Include . (__ctan): Avoid internal overflow or cancellation in calculating diff --git a/NEWS b/NEWS index bb303f8..357f3b4 100644 --- a/NEWS +++ b/NEWS @@ -18,9 +18,10 @@ Version 2.16 13530, 13531, 13532, 13533, 13547, 13551, 13552, 13553, 13555, 13559, 13566, 13583, 13592, 13618, 13637, 13656, 13658, 13673, 13691, 13695, 13704, 13705, 13706, 13726, 13738, 13760, 13761, 13786, 13792, 13806, - 13824, 13840, 13841, 13844, 13846, 13851, 13852, 13854, 13871, 13873, - 13879, 13883, 13892, 13895, 13908, 13910, 13911, 13912, 13913, 13915, - 13916, 13917, 13918, 13919, 13920, 13921, 13926, 13928, 13938, 13963 + 13824, 13840, 13841, 13844, 13846, 13851, 13852, 13854, 13871, 13872, + 13873, 13879, 13883, 13892, 13895, 13908, 13910, 13911, 13912, 13913, + 13915, 13916, 13917, 13918, 13919, 13920, 13921, 13926, 13928, 13938, + 13963 * ISO C11 support: diff --git a/math/libm-test.inc b/math/libm-test.inc index a551b9f..2809d57 100644 --- a/math/libm-test.inc +++ b/math/libm-test.inc @@ -5682,8 +5682,7 @@ pow_test (void) TEST_ff_f (pow, 0x1p72L, 0x1p72L, plus_infty, OVERFLOW_EXCEPTION); TEST_ff_f (pow, 10, -0x1p72L, 0); TEST_ff_f (pow, max_value, max_value, plus_infty, OVERFLOW_EXCEPTION); - /* Bug 13872: spurious OVERFLOW exception may be present. */ - TEST_ff_f (pow, 10, -max_value, 0, OVERFLOW_EXCEPTION_OK); + TEST_ff_f (pow, 10, -max_value, 0); TEST_ff_f (pow, 0, 1, 0); TEST_ff_f (pow, 0, 11, 0); @@ -5997,8 +5996,7 @@ pow_test (void) TEST_ff_f (pow, -max_value, -0x1.ffffffffffffffffffffffffffffp+113L, plus_zero); # endif #endif - /* Bug 13872: spurious OVERFLOW exception may be present. */ - TEST_ff_f (pow, -max_value, -max_value, plus_zero, OVERFLOW_EXCEPTION_OK); + TEST_ff_f (pow, -max_value, -max_value, plus_zero); TEST_ff_f (pow, -max_value, 0xffffff, minus_infty, OVERFLOW_EXCEPTION); TEST_ff_f (pow, -max_value, 0x1fffffe, plus_infty, OVERFLOW_EXCEPTION); @@ -6122,8 +6120,7 @@ pow_test (void) TEST_ff_f (pow, -min_value, 0x1.ffffffffffffffffffffffffffffp+113L, plus_zero); # endif #endif - /* Bug 13872: spurious OVERFLOW exception may be present. */ - TEST_ff_f (pow, -min_value, max_value, plus_zero, OVERFLOW_EXCEPTION_OK); + TEST_ff_f (pow, -min_value, max_value, plus_zero); #ifndef TEST_LDOUBLE /* Bug 13881. */ TEST_ff_f (pow, 0x0.ffffffp0, 10, 0.999999403953712118183885036774764444747L); diff --git a/sysdeps/i386/fpu/e_powl.S b/sysdeps/i386/fpu/e_powl.S index 0e7c05b..5b166ea 100644 --- a/sysdeps/i386/fpu/e_powl.S +++ b/sysdeps/i386/fpu/e_powl.S @@ -35,6 +35,9 @@ p63: .byte 0, 0, 0, 0, 0, 0, 0xe0, 0x43 ASM_TYPE_DIRECTIVE(p64,@object) p64: .byte 0, 0, 0, 0, 0, 0, 0xf0, 0x43 ASM_SIZE_DIRECTIVE(p64) + ASM_TYPE_DIRECTIVE(p78,@object) +p78: .byte 0, 0, 0, 0, 0, 0, 0xd0, 0x44 + ASM_SIZE_DIRECTIVE(p78) .section .rodata.cst16,"aM",@progbits,16 @@ -166,6 +169,21 @@ ENTRY(__ieee754_powl) fxch // x : y fabs // |x| : y fxch // y : |x| + // If y has absolute value at least 1L<<78, then any finite + // nonzero x will result in 0 (underflow), 1 or infinity (overflow). + // Saturate y to those bounds to avoid overflow in the calculation + // of y*log2(x). + fld %st // y : y : |x| + fabs // |y| : y : |x| + fcompl MO(p78) // y : |x| + fnstsw + sahf + jc 3f + fstp %st(0) // pop y + fldl MO(p78) // 1L<<78 : |x| + testb $2, %dl + jz 3f // y > 0 + fchs // -(1L<<78) : |x| .align ALIGNARG(4) 3: /* y is a real number. */ fxch // x : y @@ -185,11 +203,6 @@ ENTRY(__ieee754_powl) 7: fyl2x // log2(x) : y 8: fmul %st(1) // y*log2(x) : y - fxam - fnstsw - andb $0x45, %ah - cmpb $0x05, %ah // is y*log2(x) == ±inf ? - je 28f fst %st(1) // y*log2(x) : y*log2(x) frndint // int(y*log2(x)) : y*log2(x) fsubr %st, %st(1) // int(y*log2(x)) : fract(y*log2(x)) @@ -198,13 +211,7 @@ ENTRY(__ieee754_powl) faddl MO(one) // 2^fract(y*log2(x)) : int(y*log2(x)) fscale // 2^fract(y*log2(x))*2^int(y*log2(x)) : int(y*log2(x)) fstp %st(1) // 2^fract(y*log2(x))*2^int(y*log2(x)) - jmp 29f - -28: fstp %st(1) // y*log2(x) - fldl MO(one) // 1 : y*log2(x) - fscale // 2^(y*log2(x)) : y*log2(x) - fstp %st(1) // 2^(y*log2(x)) -29: testb $2, %dh + testb $2, %dh jz 292f // x is negative. If y is an odd integer, negate the result. fldt 24(%esp) // y : abs(result) diff --git a/sysdeps/x86_64/fpu/e_powl.S b/sysdeps/x86_64/fpu/e_powl.S index 0626ce4..10ede22 100644 --- a/sysdeps/x86_64/fpu/e_powl.S +++ b/sysdeps/x86_64/fpu/e_powl.S @@ -35,6 +35,9 @@ p63: .byte 0, 0, 0, 0, 0, 0, 0xe0, 0x43 ASM_TYPE_DIRECTIVE(p64,@object) p64: .byte 0, 0, 0, 0, 0, 0, 0xf0, 0x43 ASM_SIZE_DIRECTIVE(p64) + ASM_TYPE_DIRECTIVE(p78,@object) +p78: .byte 0, 0, 0, 0, 0, 0, 0xd0, 0x44 + ASM_SIZE_DIRECTIVE(p78) .section .rodata.cst16,"aM",@progbits,16 @@ -151,6 +154,21 @@ ENTRY(__ieee754_powl) fxch // x : y fabs // |x| : y fxch // y : |x| + // If y has absolute value at least 1L<<78, then any finite + // nonzero x will result in 0 (underflow), 1 or infinity (overflow). + // Saturate y to those bounds to avoid overflow in the calculation + // of y*log2(x). + fldl MO(p78) // 1L<<78 : y : |x| + fld %st(1) // y : 1L<<78 : y : |x| + fabs // |y| : 1L<<78 : y : |x| + fcomip %st(1), %st // 1L<<78 : y : |x| + fstp %st(0) // y : |x| + jc 3f + fstp %st(0) // pop y + fldl MO(p78) // 1L<<78 : |x| + testb $2, %dl + jz 3f // y > 0 + fchs // -(1L<<78) : |x| .align ALIGNARG(4) 3: /* y is a real number. */ fxch // x : y @@ -170,11 +188,6 @@ ENTRY(__ieee754_powl) 7: fyl2x // log2(x) : y 8: fmul %st(1) // y*log2(x) : y - fxam - fnstsw - andb $0x45, %ah - cmpb $0x05, %ah // is y*log2(x) == ±inf ? - je 28f fst %st(1) // y*log2(x) : y*log2(x) frndint // int(y*log2(x)) : y*log2(x) fsubr %st, %st(1) // int(y*log2(x)) : fract(y*log2(x)) @@ -183,13 +196,7 @@ ENTRY(__ieee754_powl) faddl MO(one) // 2^fract(y*log2(x)) : int(y*log2(x)) fscale // 2^fract(y*log2(x))*2^int(y*log2(x)) : int(y*log2(x)) fstp %st(1) // 2^fract(y*log2(x))*2^int(y*log2(x)) - jmp 29f - -28: fstp %st(1) // y*log2(x) - fldl MO(one) // 1 : y*log2(x) - fscale // 2^(y*log2(x)) : y*log2(x) - fstp %st(1) // 2^(y*log2(x)) -29: testb $2, %dh + testb $2, %dh jz 292f // x is negative. If y is an odd integer, negate the result. fldt 24(%rsp) // y : abs(result)