From 59a63cca1133a8e1e3219970ee95979ac1f810df Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Fri, 2 Oct 2015 17:11:13 +0000 Subject: [PATCH] Fix nexttoward overflow in non-default rounding modes (bug 19059). ISO C requires overflowing results from nexttoward to be the appropriate infinity independent of the rounding mode, but some implementations use a rounding-mode-dependent result (this is the same issue as was fixed for nextafter in bug 16677). This patch fixes the problem by making the nexttoward implementations discard the result from the floating-point computation that forced an overflow exception and then return the infinity previously computed with integer arithmetic. Tested for x86_64, x86, mips64 and powerpc. [BZ #19059] * math/s_nexttowardf.c (__nexttowardf): Do not return value from overflowing computation. * sysdeps/i386/fpu/s_nexttoward.c (__nexttoward): Likewise. * sysdeps/i386/fpu/s_nexttowardf.c (__nexttowardf): Likewise. * sysdeps/ieee754/ldbl-128/s_nexttoward.c (__nexttoward): Likewise. * sysdeps/ieee754/ldbl-128/s_nexttowardf.c (__nexttowardf): Likewise. * sysdeps/ieee754/ldbl-128ibm/s_nexttoward.c (__nexttoward): Likewise. * sysdeps/ieee754/ldbl-128ibm/s_nexttowardf.c (__nexttowardf): Likewise. * sysdeps/ieee754/ldbl-96/s_nexttoward.c (__nexttoward): Likewise. * sysdeps/ieee754/ldbl-96/s_nexttowardf.c (__nexttowardf): Likewise. * sysdeps/ieee754/ldbl-opt/s_nexttowardfd.c (__nldbl_nexttowardf): Likewise. * math/libm-test.inc (nexttoward_test_data): Add more tests. --- ChangeLog | 20 ++++++++++++++++++++ NEWS | 2 +- math/libm-test.inc | 4 ++++ math/s_nexttowardf.c | 4 ++-- sysdeps/i386/fpu/s_nexttoward.c | 4 ++-- sysdeps/i386/fpu/s_nexttowardf.c | 4 ++-- sysdeps/ieee754/ldbl-128/s_nexttoward.c | 4 ++-- sysdeps/ieee754/ldbl-128/s_nexttowardf.c | 5 ++++- sysdeps/ieee754/ldbl-128ibm/s_nexttoward.c | 4 ++-- sysdeps/ieee754/ldbl-128ibm/s_nexttowardf.c | 4 ++-- sysdeps/ieee754/ldbl-96/s_nexttoward.c | 4 ++-- sysdeps/ieee754/ldbl-96/s_nexttowardf.c | 4 ++-- sysdeps/ieee754/ldbl-opt/s_nexttowardfd.c | 4 ++-- 13 files changed, 47 insertions(+), 20 deletions(-) diff --git a/ChangeLog b/ChangeLog index 51476e69790..e03132aebab 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,25 @@ 2015-10-02 Joseph Myers + [BZ #19059] + * math/s_nexttowardf.c (__nexttowardf): Do not return value from + overflowing computation. + * sysdeps/i386/fpu/s_nexttoward.c (__nexttoward): Likewise. + * sysdeps/i386/fpu/s_nexttowardf.c (__nexttowardf): Likewise. + * sysdeps/ieee754/ldbl-128/s_nexttoward.c (__nexttoward): + Likewise. + * sysdeps/ieee754/ldbl-128/s_nexttowardf.c (__nexttowardf): + Likewise. + * sysdeps/ieee754/ldbl-128ibm/s_nexttoward.c (__nexttoward): + Likewise. + * sysdeps/ieee754/ldbl-128ibm/s_nexttowardf.c (__nexttowardf): + Likewise. + * sysdeps/ieee754/ldbl-96/s_nexttoward.c (__nexttoward): Likewise. + * sysdeps/ieee754/ldbl-96/s_nexttowardf.c (__nexttowardf): + Likewise. + * sysdeps/ieee754/ldbl-opt/s_nexttowardfd.c (__nldbl_nexttowardf): + Likewise. + * math/libm-test.inc (nexttoward_test_data): Add more tests. + * nss/rewrite_field.c (__nss_rewrite_field): Use internal_function. * nss/valid_field.c (__nss_valid_field): Likewise. diff --git a/NEWS b/NEWS index 4634b74ebf6..05d962221bd 100644 --- a/NEWS +++ b/NEWS @@ -17,7 +17,7 @@ Version 2.23 18778, 18781, 18787, 18789, 18790, 18795, 18796, 18803, 18820, 18823, 18824, 18825, 18857, 18863, 18870, 18872, 18873, 18875, 18887, 18921, 18951, 18952, 18956, 18961, 18966, 18967, 18969, 18970, 18977, 18980, - 18981, 18985, 19003, 19016, 19032, 19046. + 18981, 18985, 19003, 19016, 19032, 19046, 19059. * The obsolete header has been removed. Programs that require this header must be updated to use instead. diff --git a/math/libm-test.inc b/math/libm-test.inc index f627296d661..ac1fe85fc1a 100644 --- a/math/libm-test.inc +++ b/math/libm-test.inc @@ -8536,6 +8536,10 @@ static const struct test_ff_f_data_nexttoward nexttoward_test_data[] = TEST_ff_f (nexttoward, 1.1L, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED), TEST_ff_f (nexttoward, qnan_value, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED), + /* Bug 6799: errno setting may be missing. */ + TEST_ff_f (nexttoward, max_value, plus_infty, plus_infty, INEXACT_EXCEPTION|OVERFLOW_EXCEPTION), + TEST_ff_f (nexttoward, -max_value, minus_infty, minus_infty, INEXACT_EXCEPTION|OVERFLOW_EXCEPTION), + #ifdef TEST_FLOAT TEST_ff_f (nexttoward, 1.0, 1.1L, 0x1.000002p0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED), TEST_ff_f (nexttoward, 1.0, LDBL_MAX, 0x1.000002p0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED), diff --git a/math/s_nexttowardf.c b/math/s_nexttowardf.c index 06e1bb10cbc..06350d47bfd 100644 --- a/math/s_nexttowardf.c +++ b/math/s_nexttowardf.c @@ -59,8 +59,8 @@ float __nexttowardf(float x, long double y) } hy = hx&0x7f800000; if(hy>=0x7f800000) { - x = math_narrow_eval (x+x); /* overflow */ - return x; + float u = x+x; /* overflow */ + math_force_eval (u); } if(hy<0x00800000) { float u = x*x; /* underflow */ diff --git a/sysdeps/i386/fpu/s_nexttoward.c b/sysdeps/i386/fpu/s_nexttoward.c index be65b8ce297..839efe6c052 100644 --- a/sysdeps/i386/fpu/s_nexttoward.c +++ b/sysdeps/i386/fpu/s_nexttoward.c @@ -73,8 +73,8 @@ double __nexttoward(double x, long double y) } hy = hx&0x7ff00000; if(hy>=0x7ff00000) { - x = math_narrow_eval (x+x); /* overflow */ - return x; + double u = x+x; /* overflow */ + math_force_eval (u); } if(hy<0x00100000) { double u = x*x; /* underflow */ diff --git a/sysdeps/i386/fpu/s_nexttowardf.c b/sysdeps/i386/fpu/s_nexttowardf.c index 8379eff8b8e..29b4f12775a 100644 --- a/sysdeps/i386/fpu/s_nexttowardf.c +++ b/sysdeps/i386/fpu/s_nexttowardf.c @@ -61,8 +61,8 @@ float __nexttowardf(float x, long double y) } hy = hx&0x7f800000; if(hy>=0x7f800000) { - x = math_narrow_eval (x+x); /* overflow */ - return x; + float u = x+x; /* overflow */ + math_force_eval (u); } if(hy<0x00800000) { float u = x*x; /* underflow */ diff --git a/sysdeps/ieee754/ldbl-128/s_nexttoward.c b/sysdeps/ieee754/ldbl-128/s_nexttoward.c index e62ca3fef83..2ee7a1be5cf 100644 --- a/sysdeps/ieee754/ldbl-128/s_nexttoward.c +++ b/sysdeps/ieee754/ldbl-128/s_nexttoward.c @@ -73,8 +73,8 @@ double __nexttoward(double x, long double y) } hy = hx&0x7ff00000; if(hy>=0x7ff00000) { - x = math_narrow_eval (x+x); /* overflow */ - return x; + double u = x+x; /* overflow */ + math_force_eval (u); } if(hy<0x00100000) { double u = x*x; /* underflow */ diff --git a/sysdeps/ieee754/ldbl-128/s_nexttowardf.c b/sysdeps/ieee754/ldbl-128/s_nexttowardf.c index ccd49d235d3..9c9c7e5283a 100644 --- a/sysdeps/ieee754/ldbl-128/s_nexttowardf.c +++ b/sysdeps/ieee754/ldbl-128/s_nexttowardf.c @@ -59,7 +59,10 @@ float __nexttowardf(float x, long double y) } } hy = hx&0x7f800000; - if(hy>=0x7f800000) return x+x; /* overflow */ + if(hy>=0x7f800000) { + float u = x+x; /* overflow */ + math_force_eval (u); + } if(hy<0x00800000) { float u = x*x; /* underflow */ math_force_eval (u); /* raise underflow flag */ diff --git a/sysdeps/ieee754/ldbl-128ibm/s_nexttoward.c b/sysdeps/ieee754/ldbl-128ibm/s_nexttoward.c index 85140c1d028..8c6119825e9 100644 --- a/sysdeps/ieee754/ldbl-128ibm/s_nexttoward.c +++ b/sysdeps/ieee754/ldbl-128ibm/s_nexttoward.c @@ -74,8 +74,8 @@ double __nexttoward(double x, long double y) } hy = hx&0x7ff00000; if(hy>=0x7ff00000) { - x = math_narrow_eval (x+x); /* overflow */ - return x; + double u = x+x; /* overflow */ + math_force_eval (u); } if(hy<0x00100000) { double u = x*x; /* underflow */ diff --git a/sysdeps/ieee754/ldbl-128ibm/s_nexttowardf.c b/sysdeps/ieee754/ldbl-128ibm/s_nexttowardf.c index b27f0bb380a..4000a93e690 100644 --- a/sysdeps/ieee754/ldbl-128ibm/s_nexttowardf.c +++ b/sysdeps/ieee754/ldbl-128ibm/s_nexttowardf.c @@ -63,8 +63,8 @@ float __nexttowardf(float x, long double y) } hy = hx&0x7f800000; if(hy>=0x7f800000) { - x = math_narrow_eval (x+x); /* overflow */ - return x; + float u = x+x; /* overflow */ + math_force_eval (u); } if(hy<0x00800000) { /* underflow */ float u = x*x; diff --git a/sysdeps/ieee754/ldbl-96/s_nexttoward.c b/sysdeps/ieee754/ldbl-96/s_nexttoward.c index b972a3eb3a7..7908f9c0ff6 100644 --- a/sysdeps/ieee754/ldbl-96/s_nexttoward.c +++ b/sysdeps/ieee754/ldbl-96/s_nexttoward.c @@ -70,8 +70,8 @@ double __nexttoward(double x, long double y) } hy = hx&0x7ff00000; if(hy>=0x7ff00000) { - x = math_narrow_eval (x+x); /* overflow */ - return x; + double u = x+x; /* overflow */ + math_force_eval (u); } if(hy<0x00100000) { double u = x*x; /* underflow */ diff --git a/sysdeps/ieee754/ldbl-96/s_nexttowardf.c b/sysdeps/ieee754/ldbl-96/s_nexttowardf.c index f1fe4e7ca71..53c527d9ac8 100644 --- a/sysdeps/ieee754/ldbl-96/s_nexttowardf.c +++ b/sysdeps/ieee754/ldbl-96/s_nexttowardf.c @@ -58,8 +58,8 @@ float __nexttowardf(float x, long double y) } hy = hx&0x7f800000; if(hy>=0x7f800000) { - x = math_narrow_eval (x+x); /* overflow */ - return x; + float u = x+x; /* overflow */ + math_force_eval (u); } if(hy<0x00800000) { float u = x*x; /* underflow */ diff --git a/sysdeps/ieee754/ldbl-opt/s_nexttowardfd.c b/sysdeps/ieee754/ldbl-opt/s_nexttowardfd.c index 782e1a33401..dbcf840f2c0 100644 --- a/sysdeps/ieee754/ldbl-opt/s_nexttowardfd.c +++ b/sysdeps/ieee754/ldbl-opt/s_nexttowardfd.c @@ -62,8 +62,8 @@ float __nldbl_nexttowardf(float x, double y) } hy = hx&0x7f800000; if(hy>=0x7f800000) { - x = math_narrow_eval (x+x); /* overflow */ - return x; + float u = x+x; /* overflow */ + math_force_eval (u); } if(hy<0x00800000) { float u = x*x; /* underflow */ -- 2.47.2