Fix dbl-64 atan in non-default rounding modes (bug 18197).

The dbl-64 implementation of atan does computations that expect to run
in round-to-nearest mode, and in other modes the errors can accumulate
to more than the maximum accepted 9ulp.  This patch makes it use
FE_TONEAREST internally, similar to other functions with such issues.

Tested for x86_64 and x86; no ulps updates needed.

	[BZ #18197]
	* sysdeps/ieee754/dbl-64/s_atan.c: Include <fenv.h>.
	(atan): Set FE_TONEAREST mode for internal computations.
	* math/auto-libm-test-in: Add more tests of atan.
	* math/auto-libm-test-out: Regenerated.

2 files changed, 52 insertions, 0 deletions

diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in
index 939f6eaba1..d0026d5c0d 100644
--- a/math/auto-libm-test-in
+++ b/math/auto-libm-test-in
@@ -240,6 +240,8 @@ atan 1e6
 atan 0x1p-100
 atan 0x1p-600
 atan 0x1p-10000
+atan -0x3.b02d84p-4
+atan -0x3.3fb708p-4
 atan min
 atan -min
 atan min_subnorm
diff --git a/math/auto-libm-test-out b/math/auto-libm-test-out
index 68435abd35..3550f33d9e 100644
--- a/math/auto-libm-test-out
+++ b/math/auto-libm-test-out
@@ -7877,6 +7877,56 @@ atan 0x1p-10000
 = atan tonearest ldbl-128 0x1p-10000L : 0x1p-10000L : inexact-ok
 = atan towardzero ldbl-128 0x1p-10000L : 0xf.fffffffffffffffffffffffffff8p-10004L : inexact-ok
 = atan upward ldbl-128 0x1p-10000L : 0x1p-10000L : inexact-ok
+atan -0x3.b02d84p-4
+= atan downward flt-32 -0x3.b02d84p-4f : -0x3.9ff7e4p-4f : inexact-ok
+= atan tonearest flt-32 -0x3.b02d84p-4f : -0x3.9ff7ep-4f : inexact-ok
+= atan towardzero flt-32 -0x3.b02d84p-4f : -0x3.9ff7ep-4f : inexact-ok
+= atan upward flt-32 -0x3.b02d84p-4f : -0x3.9ff7ep-4f : inexact-ok
+= atan downward dbl-64 -0x3.b02d84p-4 : -0x3.9ff7e1f81370cp-4 : inexact-ok
+= atan tonearest dbl-64 -0x3.b02d84p-4 : -0x3.9ff7e1f81370cp-4 : inexact-ok
+= atan towardzero dbl-64 -0x3.b02d84p-4 : -0x3.9ff7e1f81370ap-4 : inexact-ok
+= atan upward dbl-64 -0x3.b02d84p-4 : -0x3.9ff7e1f81370ap-4 : inexact-ok
+= atan downward ldbl-96-intel -0x3.b02d84p-4L : -0x3.9ff7e1f81370b934p-4L : inexact-ok
+= atan tonearest ldbl-96-intel -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93p-4L : inexact-ok
+= atan towardzero ldbl-96-intel -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93p-4L : inexact-ok
+= atan upward ldbl-96-intel -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93p-4L : inexact-ok
+= atan downward ldbl-96-m68k -0x3.b02d84p-4L : -0x3.9ff7e1f81370b934p-4L : inexact-ok
+= atan tonearest ldbl-96-m68k -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93p-4L : inexact-ok
+= atan towardzero ldbl-96-m68k -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93p-4L : inexact-ok
+= atan upward ldbl-96-m68k -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93p-4L : inexact-ok
+= atan downward ldbl-128 -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93195e0357d0b5ap-4L : inexact-ok
+= atan tonearest ldbl-128 -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93195e0357d0b5ap-4L : inexact-ok
+= atan towardzero ldbl-128 -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93195e0357d0b58p-4L : inexact-ok
+= atan upward ldbl-128 -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93195e0357d0b58p-4L : inexact-ok
+= atan downward ldbl-128ibm -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93195e0357d0cp-4L : inexact-ok
+= atan tonearest ldbl-128ibm -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93195e0357d0bp-4L : inexact-ok
+= atan towardzero ldbl-128ibm -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93195e0357d0bp-4L : inexact-ok
+= atan upward ldbl-128ibm -0x3.b02d84p-4L : -0x3.9ff7e1f81370b93195e0357d0bp-4L : inexact-ok
+atan -0x3.3fb708p-4
+= atan downward flt-32 -0x3.3fb708p-4f : -0x3.348f0cp-4f : inexact-ok
+= atan tonearest flt-32 -0x3.3fb708p-4f : -0x3.348f08p-4f : inexact-ok
+= atan towardzero flt-32 -0x3.3fb708p-4f : -0x3.348f08p-4f : inexact-ok
+= atan upward flt-32 -0x3.3fb708p-4f : -0x3.348f08p-4f : inexact-ok
+= atan downward dbl-64 -0x3.3fb708p-4 : -0x3.348f092072332p-4 : inexact-ok
+= atan tonearest dbl-64 -0x3.3fb708p-4 : -0x3.348f092072332p-4 : inexact-ok
+= atan towardzero dbl-64 -0x3.3fb708p-4 : -0x3.348f09207233p-4 : inexact-ok
+= atan upward dbl-64 -0x3.3fb708p-4 : -0x3.348f09207233p-4 : inexact-ok
+= atan downward ldbl-96-intel -0x3.3fb708p-4L : -0x3.348f092072331fdcp-4L : inexact-ok
+= atan tonearest ldbl-96-intel -0x3.3fb708p-4L : -0x3.348f092072331fd8p-4L : inexact-ok
+= atan towardzero ldbl-96-intel -0x3.3fb708p-4L : -0x3.348f092072331fd8p-4L : inexact-ok
+= atan upward ldbl-96-intel -0x3.3fb708p-4L : -0x3.348f092072331fd8p-4L : inexact-ok
+= atan downward ldbl-96-m68k -0x3.3fb708p-4L : -0x3.348f092072331fdcp-4L : inexact-ok
+= atan tonearest ldbl-96-m68k -0x3.3fb708p-4L : -0x3.348f092072331fd8p-4L : inexact-ok
+= atan towardzero ldbl-96-m68k -0x3.3fb708p-4L : -0x3.348f092072331fd8p-4L : inexact-ok
+= atan upward ldbl-96-m68k -0x3.3fb708p-4L : -0x3.348f092072331fd8p-4L : inexact-ok
+= atan downward ldbl-128 -0x3.3fb708p-4L : -0x3.348f092072331fd8ca0cbff348d8p-4L : inexact-ok
+= atan tonearest ldbl-128 -0x3.3fb708p-4L : -0x3.348f092072331fd8ca0cbff348d6p-4L : inexact-ok
+= atan towardzero ldbl-128 -0x3.3fb708p-4L : -0x3.348f092072331fd8ca0cbff348d6p-4L : inexact-ok
+= atan upward ldbl-128 -0x3.3fb708p-4L : -0x3.348f092072331fd8ca0cbff348d6p-4L : inexact-ok
+= atan downward ldbl-128ibm -0x3.3fb708p-4L : -0x3.348f092072331fd8ca0cbff349p-4L : inexact-ok
+= atan tonearest ldbl-128ibm -0x3.3fb708p-4L : -0x3.348f092072331fd8ca0cbff349p-4L : inexact-ok
+= atan towardzero ldbl-128ibm -0x3.3fb708p-4L : -0x3.348f092072331fd8ca0cbff348p-4L : inexact-ok
+= atan upward ldbl-128ibm -0x3.3fb708p-4L : -0x3.348f092072331fd8ca0cbff348p-4L : inexact-ok
 atan min
 = atan downward flt-32 0x4p-128f : 0x3.fffff8p-128f : inexact-ok underflow-ok errno-erange-ok
 = atan tonearest flt-32 0x4p-128f : 0x4p-128f : inexact-ok underflow-ok errno-erange-ok