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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.
This commit is contained in:
Joseph Myers
parent
ef6b619f73
commit
59a63cca11
20
ChangeLog
20
ChangeLog
@ -1,5 +1,25 @@
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2015-10-02 Joseph Myers <joseph@codesourcery.com>
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[BZ #19059]
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* math/s_nexttowardf.c (__nexttowardf): Do not return value from
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overflowing computation.
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* sysdeps/i386/fpu/s_nexttoward.c (__nexttoward): Likewise.
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* sysdeps/i386/fpu/s_nexttowardf.c (__nexttowardf): Likewise.
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* sysdeps/ieee754/ldbl-128/s_nexttoward.c (__nexttoward):
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Likewise.
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* sysdeps/ieee754/ldbl-128/s_nexttowardf.c (__nexttowardf):
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Likewise.
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* sysdeps/ieee754/ldbl-128ibm/s_nexttoward.c (__nexttoward):
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Likewise.
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* sysdeps/ieee754/ldbl-128ibm/s_nexttowardf.c (__nexttowardf):
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Likewise.
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* sysdeps/ieee754/ldbl-96/s_nexttoward.c (__nexttoward): Likewise.
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* sysdeps/ieee754/ldbl-96/s_nexttowardf.c (__nexttowardf):
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Likewise.
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* sysdeps/ieee754/ldbl-opt/s_nexttowardfd.c (__nldbl_nexttowardf):
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Likewise.
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* math/libm-test.inc (nexttoward_test_data): Add more tests.
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* nss/rewrite_field.c (__nss_rewrite_field): Use
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internal_function.
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* nss/valid_field.c (__nss_valid_field): Likewise.
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2
NEWS
2
NEWS
@ -17,7 +17,7 @@ Version 2.23
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18778, 18781, 18787, 18789, 18790, 18795, 18796, 18803, 18820, 18823,
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18824, 18825, 18857, 18863, 18870, 18872, 18873, 18875, 18887, 18921,
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18951, 18952, 18956, 18961, 18966, 18967, 18969, 18970, 18977, 18980,
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18981, 18985, 19003, 19016, 19032, 19046.
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18981, 18985, 19003, 19016, 19032, 19046, 19059.
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* The obsolete header <regexp.h> has been removed. Programs that require
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this header must be updated to use <regex.h> instead.
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@ -8536,6 +8536,10 @@ static const struct test_ff_f_data_nexttoward nexttoward_test_data[] =
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TEST_ff_f (nexttoward, 1.1L, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
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TEST_ff_f (nexttoward, qnan_value, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
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/* Bug 6799: errno setting may be missing. */
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TEST_ff_f (nexttoward, max_value, plus_infty, plus_infty, INEXACT_EXCEPTION|OVERFLOW_EXCEPTION),
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TEST_ff_f (nexttoward, -max_value, minus_infty, minus_infty, INEXACT_EXCEPTION|OVERFLOW_EXCEPTION),
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#ifdef TEST_FLOAT
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TEST_ff_f (nexttoward, 1.0, 1.1L, 0x1.000002p0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
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TEST_ff_f (nexttoward, 1.0, LDBL_MAX, 0x1.000002p0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
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@ -59,8 +59,8 @@ float __nexttowardf(float x, long double y)
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}
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hy = hx&0x7f800000;
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if(hy>=0x7f800000) {
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x = math_narrow_eval (x+x); /* overflow */
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return x;
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float u = x+x; /* overflow */
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math_force_eval (u);
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}
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if(hy<0x00800000) {
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float u = x*x; /* underflow */
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@ -73,8 +73,8 @@ double __nexttoward(double x, long double y)
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}
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hy = hx&0x7ff00000;
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if(hy>=0x7ff00000) {
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x = math_narrow_eval (x+x); /* overflow */
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return x;
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double u = x+x; /* overflow */
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math_force_eval (u);
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}
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if(hy<0x00100000) {
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double u = x*x; /* underflow */
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@ -61,8 +61,8 @@ float __nexttowardf(float x, long double y)
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}
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hy = hx&0x7f800000;
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if(hy>=0x7f800000) {
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x = math_narrow_eval (x+x); /* overflow */
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return x;
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float u = x+x; /* overflow */
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math_force_eval (u);
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}
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if(hy<0x00800000) {
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float u = x*x; /* underflow */
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@ -73,8 +73,8 @@ double __nexttoward(double x, long double y)
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}
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hy = hx&0x7ff00000;
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if(hy>=0x7ff00000) {
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x = math_narrow_eval (x+x); /* overflow */
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return x;
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double u = x+x; /* overflow */
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math_force_eval (u);
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}
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if(hy<0x00100000) {
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double u = x*x; /* underflow */
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@ -59,7 +59,10 @@ float __nexttowardf(float x, long double y)
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}
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}
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hy = hx&0x7f800000;
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if(hy>=0x7f800000) return x+x; /* overflow */
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if(hy>=0x7f800000) {
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float u = x+x; /* overflow */
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math_force_eval (u);
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}
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if(hy<0x00800000) {
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float u = x*x; /* underflow */
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math_force_eval (u); /* raise underflow flag */
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@ -74,8 +74,8 @@ double __nexttoward(double x, long double y)
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}
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hy = hx&0x7ff00000;
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if(hy>=0x7ff00000) {
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x = math_narrow_eval (x+x); /* overflow */
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return x;
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double u = x+x; /* overflow */
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math_force_eval (u);
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}
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if(hy<0x00100000) {
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double u = x*x; /* underflow */
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@ -63,8 +63,8 @@ float __nexttowardf(float x, long double y)
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}
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hy = hx&0x7f800000;
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if(hy>=0x7f800000) {
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x = math_narrow_eval (x+x); /* overflow */
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return x;
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float u = x+x; /* overflow */
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math_force_eval (u);
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}
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if(hy<0x00800000) { /* underflow */
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float u = x*x;
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@ -70,8 +70,8 @@ double __nexttoward(double x, long double y)
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}
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hy = hx&0x7ff00000;
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if(hy>=0x7ff00000) {
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x = math_narrow_eval (x+x); /* overflow */
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return x;
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double u = x+x; /* overflow */
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math_force_eval (u);
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}
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if(hy<0x00100000) {
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double u = x*x; /* underflow */
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@ -58,8 +58,8 @@ float __nexttowardf(float x, long double y)
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}
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hy = hx&0x7f800000;
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if(hy>=0x7f800000) {
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x = math_narrow_eval (x+x); /* overflow */
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return x;
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float u = x+x; /* overflow */
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math_force_eval (u);
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}
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if(hy<0x00800000) {
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float u = x*x; /* underflow */
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@ -62,8 +62,8 @@ float __nldbl_nexttowardf(float x, double y)
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}
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hy = hx&0x7f800000;
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if(hy>=0x7f800000) {
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x = math_narrow_eval (x+x); /* overflow */
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return x;
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float u = x+x; /* overflow */
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math_force_eval (u);
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}
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if(hy<0x00800000) {
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float u = x*x; /* underflow */
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