Fix pow overflow in non-default rounding modes (bug 16315).

This patch fixes bug 16315, bad pow handling of overflow/underflow in
non-default rounding modes.  Tests of pow are duly converted to
ALL_RM_TEST to run all tests in all rounding modes.

There are two main issues here.  First, various implementations
compute a negative result by negating a positive result, but this
yields inappropriate overflow / underflow values for directed
rounding, so either overflow / underflow results need recomputing in
the correct sign, or the relevant overflowing / underflowing operation
needs to be made to have a result of the correct sign.  Second, the
dbl-64 implementation sets FE_TONEAREST internally; in the overflow /
underflow case, the result needs recomputing in the original rounding
mode.

Tested x86_64 and x86 and ulps updated accordingly.

	[BZ #16315]
	* sysdeps/i386/fpu/e_pow.S (__ieee754_pow): Ensure possibly
	overflowing or underflowing operations take place with sign of
	result.
	* sysdeps/i386/fpu/e_powf.S (__ieee754_powf): Likewise.
	* sysdeps/i386/fpu/e_powl.S (__ieee754_powl): Likewise.
	* sysdeps/ieee754/dbl-64/e_pow.c: Include <math.h>.
	(__ieee754_pow): Recompute overflowing and underflowing results in
	original rounding mode.
	* sysdeps/x86/fpu/powl_helper.c: Include <stdbool.h>.
	(__powl_helper): Allow negative argument X and scale negated value
	as needed.  Avoid passing value outside [-1, 1] to f2xm1.
	* sysdeps/x86_64/fpu/e_powl.S (__ieee754_powl): Ensure possibly
	overflowing or underflowing operations take place with sign of
	result.
	* sysdeps/x86_64/fpu/multiarch/e_pow.c [HAVE_FMA4_SUPPORT]:
	Include <math.h>.
	* math/auto-libm-test-in: Add more tests of pow.
	* math/auto-libm-test-out: Regenerated.
	* math/libm-test.inc (pow_test): Use ALL_RM_TEST.
	(pow_tonearest_test_data): Remove.
	(pow_test_tonearest): Likewise.
	(pow_towardzero_test_data): Likewise.
	(pow_test_towardzero): Likewise.
	(pow_downward_test_data): Likewise.
	(pow_test_downward): Likewise.
	(pow_upward_test_data): Likewise.
	(pow_test_upward): Likewise.
	(main): Don't call removed functions.
	* sysdeps/i386/fpu/libm-test-ulps: Update.
	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.

1 files changed, 65 insertions, 0 deletions

diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in
index 6edad5a..0053340 100644
--- a/math/auto-libm-test-in
+++ b/math/auto-libm-test-in
@@ -1613,6 +1613,71 @@ pow -max 0x1.ffffffffffffffffffffffffffffp+112
 pow -max 0x1.ffffffffffffffffffffffffffffp+113
 pow -max max
 
+pow -0x1p65 2
+pow -0x1p65 3
+pow -0x1p65 4
+pow -0x1p65 5
+pow -0x1p43 3
+pow -0x1p43 4
+pow -0x1p43 5
+pow -0x1p33 4
+pow -0x1p33 5
+pow -0x1p26 5
+pow -0x1p-65 -2
+pow -0x1p-65 -3
+pow -0x1p-65 -4
+pow -0x1p-65 -5
+pow -0x1p-43 -3
+pow -0x1p-43 -4
+pow -0x1p-43 -5
+pow -0x1p-33 -4
+pow -0x1p-33 -5
+pow -0x1p-26 -5
+
+pow -0x1p513 2
+pow -0x1p513 3
+pow -0x1p513 4
+pow -0x1p513 5
+pow -0x1p342 3
+pow -0x1p342 4
+pow -0x1p342 5
+pow -0x1p257 4
+pow -0x1p257 5
+pow -0x1p205 5
+pow -0x1p-513 -2
+pow -0x1p-513 -3
+pow -0x1p-513 -4
+pow -0x1p-513 -5
+pow -0x1p-342 -3
+pow -0x1p-342 -4
+pow -0x1p-342 -5
+pow -0x1p-257 -4
+pow -0x1p-257 -5
+pow -0x1p-205 -5
+
+pow -0x1p8192 2
+pow -0x1p8192 3
+pow -0x1p8192 4
+pow -0x1p8192 5
+pow -0x1p5462 3
+pow -0x1p5462 4
+pow -0x1p5462 5
+pow -0x1p4097 4
+pow -0x1p4097 5
+pow -0x1p3277 5
+pow -0x1p64 257
+pow -0x1p-8192 -2
+pow -0x1p-8192 -3
+pow -0x1p-8192 -4
+pow -0x1p-8192 -5
+pow -0x1p-5462 -3
+pow -0x1p-5462 -4
+pow -0x1p-5462 -5
+pow -0x1p-4097 -4
+pow -0x1p-4097 -5
+pow -0x1p-3277 -5
+pow -0x1p-64 -257
+
 pow -0.5 126
 pow -0.5 127
 pow -0.5 -126