Fix ldbl-128/ldbl-128ibm lgamma spurious "invalid", incorrect signgam (bug 18952).

The ldbl-128 / ldbl-128ibm implementation of lgammal converts (the
floor of minus) non-integer negative arguments to int to determine the
value of signgam.  When those values are outside the range of int,
this produces spurious "invalid" exceptions and incorrect values of
signgam.  This patch fixes this by instead determining signgam through
comparing half the integer in question to floor of half the integer.

Tested for mips64, x86_64 and x86.

	[BZ #18952]
	* sysdeps/ieee754/ldbl-128/e_lgammal_r.c (__ieee754_lgammal_r): Do
	not convert non-integer negative arguments to int to determine the
	value of signgam.
	* math/auto-libm-test-in: Add more tests of lgamma.
	* math/auto-libm-test-out: Regenerated.

2 files changed, 45 insertions, 0 deletions

diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in
index 84b3df0bee..83eb4cf8c3 100644
--- a/math/auto-libm-test-in
+++ b/math/auto-libm-test-in
@@ -2047,6 +2047,9 @@ lgamma -0xffffffffffffffffp-1
 lgamma -0x3ffffffffffffffffffffffffffp-1
 lgamma -0x1ffffffffffffffffffffffffffffp-1
 
+lgamma -0x100000000.8p0
+lgamma -0x100000001.8p0
+
 lgamma -0.25
 lgamma -0.5
 lgamma -0.75
diff --git a/math/auto-libm-test-out b/math/auto-libm-test-out
index 14caa1d842..747815b1c9 100644
--- a/math/auto-libm-test-out
+++ b/math/auto-libm-test-out
@@ -153351,6 +153351,48 @@ lgamma -0x1ffffffffffffffffffffffffffffp-1
 = lgamma tonearest ldbl-128 -0xf.fffffffffffffffffffffffffff8p+108L : -0x4.ca1ea7c6bcac53b28539e9281ba4p+116L 1 : inexact-ok
 = lgamma towardzero ldbl-128 -0xf.fffffffffffffffffffffffffff8p+108L : -0x4.ca1ea7c6bcac53b28539e9281ba4p+116L 1 : inexact-ok
 = lgamma upward ldbl-128 -0xf.fffffffffffffffffffffffffff8p+108L : -0x4.ca1ea7c6bcac53b28539e9281ba4p+116L 1 : inexact-ok
+lgamma -0x100000000.8p0
+= lgamma downward dbl-64 -0x1.000000008p+32 : -0x1.52e42ff102e65p+36 -1 : inexact-ok
+= lgamma tonearest dbl-64 -0x1.000000008p+32 : -0x1.52e42ff102e65p+36 -1 : inexact-ok
+= lgamma towardzero dbl-64 -0x1.000000008p+32 : -0x1.52e42ff102e64p+36 -1 : inexact-ok
+= lgamma upward dbl-64 -0x1.000000008p+32 : -0x1.52e42ff102e64p+36 -1 : inexact-ok
+= lgamma downward ldbl-96-intel -0x1.000000008p+32L : -0x1.52e42ff102e64be4p+36L -1 : inexact-ok
+= lgamma tonearest ldbl-96-intel -0x1.000000008p+32L : -0x1.52e42ff102e64be2p+36L -1 : inexact-ok
+= lgamma towardzero ldbl-96-intel -0x1.000000008p+32L : -0x1.52e42ff102e64be2p+36L -1 : inexact-ok
+= lgamma upward ldbl-96-intel -0x1.000000008p+32L : -0x1.52e42ff102e64be2p+36L -1 : inexact-ok
+= lgamma downward ldbl-96-m68k -0x1.000000008p+32L : -0x1.52e42ff102e64be4p+36L -1 : inexact-ok
+= lgamma tonearest ldbl-96-m68k -0x1.000000008p+32L : -0x1.52e42ff102e64be2p+36L -1 : inexact-ok
+= lgamma towardzero ldbl-96-m68k -0x1.000000008p+32L : -0x1.52e42ff102e64be2p+36L -1 : inexact-ok
+= lgamma upward ldbl-96-m68k -0x1.000000008p+32L : -0x1.52e42ff102e64be2p+36L -1 : inexact-ok
+= lgamma downward ldbl-128 -0x1.000000008p+32L : -0x1.52e42ff102e64be289794d246256p+36L -1 : inexact-ok
+= lgamma tonearest ldbl-128 -0x1.000000008p+32L : -0x1.52e42ff102e64be289794d246255p+36L -1 : inexact-ok
+= lgamma towardzero ldbl-128 -0x1.000000008p+32L : -0x1.52e42ff102e64be289794d246255p+36L -1 : inexact-ok
+= lgamma upward ldbl-128 -0x1.000000008p+32L : -0x1.52e42ff102e64be289794d246255p+36L -1 : inexact-ok
+= lgamma downward ldbl-128ibm -0x1.000000008p+32L : -0x1.52e42ff102e64be289794d24628p+36L -1 : inexact-ok
+= lgamma tonearest ldbl-128ibm -0x1.000000008p+32L : -0x1.52e42ff102e64be289794d24628p+36L -1 : inexact-ok
+= lgamma towardzero ldbl-128ibm -0x1.000000008p+32L : -0x1.52e42ff102e64be289794d2462p+36L -1 : inexact-ok
+= lgamma upward ldbl-128ibm -0x1.000000008p+32L : -0x1.52e42ff102e64be289794d2462p+36L -1 : inexact-ok
+lgamma -0x100000001.8p0
+= lgamma downward dbl-64 -0x1.000000018p+32 : -0x1.52e42ff265ca8p+36 1 : inexact-ok
+= lgamma tonearest dbl-64 -0x1.000000018p+32 : -0x1.52e42ff265ca8p+36 1 : inexact-ok
+= lgamma towardzero dbl-64 -0x1.000000018p+32 : -0x1.52e42ff265ca7p+36 1 : inexact-ok
+= lgamma upward dbl-64 -0x1.000000018p+32 : -0x1.52e42ff265ca7p+36 1 : inexact-ok
+= lgamma downward ldbl-96-intel -0x1.000000018p+32L : -0x1.52e42ff265ca7bd4p+36L 1 : inexact-ok
+= lgamma tonearest ldbl-96-intel -0x1.000000018p+32L : -0x1.52e42ff265ca7bd2p+36L 1 : inexact-ok
+= lgamma towardzero ldbl-96-intel -0x1.000000018p+32L : -0x1.52e42ff265ca7bd2p+36L 1 : inexact-ok
+= lgamma upward ldbl-96-intel -0x1.000000018p+32L : -0x1.52e42ff265ca7bd2p+36L 1 : inexact-ok
+= lgamma downward ldbl-96-m68k -0x1.000000018p+32L : -0x1.52e42ff265ca7bd4p+36L 1 : inexact-ok
+= lgamma tonearest ldbl-96-m68k -0x1.000000018p+32L : -0x1.52e42ff265ca7bd2p+36L 1 : inexact-ok
+= lgamma towardzero ldbl-96-m68k -0x1.000000018p+32L : -0x1.52e42ff265ca7bd2p+36L 1 : inexact-ok
+= lgamma upward ldbl-96-m68k -0x1.000000018p+32L : -0x1.52e42ff265ca7bd2p+36L 1 : inexact-ok
+= lgamma downward ldbl-128 -0x1.000000018p+32L : -0x1.52e42ff265ca7bd24518407be41dp+36L 1 : inexact-ok
+= lgamma tonearest ldbl-128 -0x1.000000018p+32L : -0x1.52e42ff265ca7bd24518407be41dp+36L 1 : inexact-ok
+= lgamma towardzero ldbl-128 -0x1.000000018p+32L : -0x1.52e42ff265ca7bd24518407be41cp+36L 1 : inexact-ok
+= lgamma upward ldbl-128 -0x1.000000018p+32L : -0x1.52e42ff265ca7bd24518407be41cp+36L 1 : inexact-ok
+= lgamma downward ldbl-128ibm -0x1.000000018p+32L : -0x1.52e42ff265ca7bd24518407be48p+36L 1 : inexact-ok
+= lgamma tonearest ldbl-128ibm -0x1.000000018p+32L : -0x1.52e42ff265ca7bd24518407be4p+36L 1 : inexact-ok
+= lgamma towardzero ldbl-128ibm -0x1.000000018p+32L : -0x1.52e42ff265ca7bd24518407be4p+36L 1 : inexact-ok
+= lgamma upward ldbl-128ibm -0x1.000000018p+32L : -0x1.52e42ff265ca7bd24518407be4p+36L 1 : inexact-ok
 lgamma -0.25
 = lgamma downward flt-32 -0x4p-4f : 0x1.96ee68p+0f -1 : inexact-ok
 = lgamma tonearest flt-32 -0x4p-4f : 0x1.96ee68p+0f -1 : inexact-ok