Fix lgammaf spurious underflow (bug 15427).

6 files changed, 176 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index 015ef93877..f8e9f9a32a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2013-09-03  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #15427]
+	* sysdeps/ieee754/flt-32/e_lgammaf_r.c (__ieee754_lgammaf_r): Use
+	2**-30 instead of 2**-70 as threshold for returning -log(|x|).
+	* math/libm-test.inc (lgamma_test_data): Add more tests.
+	* sysdeps/i386/fpu/libm-test-ulps: Update.
+	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
+
 2013-09-03   Ondřej Bílka  <neleai@seznam.cz>
 
 	* sysdeps/x86_64/multiarch/strcmp-sse2-unaligned.S: New file.
diff --git a/NEWS b/NEWS
index ee78ea44c9..d29f0d937e 100644
--- a/NEWS
+++ b/NEWS
@@ -9,8 +9,8 @@ Version 2.19
 
 * The following bugs are resolved with this release:
 
-  14155, 14699, 15522, 15531, 15532, 15736, 15749, 15797, 15867, 15886,
-  15887, 15890, 15897, 15905, 15909, 15921.
+  14155, 14699, 15427, 15522, 15531, 15532, 15736, 15749, 15797, 15867,
+  15886, 15887, 15890, 15897, 15905, 15909, 15921.
 
 * CVE-2013-4237 The readdir_r function could write more than NAME_MAX bytes
   to the d_name member of struct dirent, or omit the terminating NUL
diff --git a/math/libm-test.inc b/math/libm-test.inc
index fb5e977670..fe85bb9f1d 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -9978,6 +9978,61 @@ static const struct test_f_f1_data lgamma_test_data[] =
     TEST_f_f1 (lgamma, -0.5, M_LOG_2_SQRT_PIl, -1),
     TEST_f_f1 (lgamma, 0.7L, 0.260867246531666514385732417016759578L, 1),
     TEST_f_f1 (lgamma, 1.2L, -0.853740900033158497197028392998854470e-1L, 1),
+
+    TEST_f_f1 (lgamma, 0x1p-5L, 3.4484891277979584796832693452686366085801e+00L, 1),
+    TEST_f_f1 (lgamma, -0x1p-5L, 3.4845895751341394376217526729956836492792e+00L, -1),
+    TEST_f_f1 (lgamma, 0x1p-10L, 6.9309089024194618895406190646600805357273e+00L, 1),
+    TEST_f_f1 (lgamma, -0x1p-10L, 6.9320362775113082175565786721095494761582e+00L, -1),
+    TEST_f_f1 (lgamma, 0x1p-15L, 1.0397190093941001762077888432721419773538e+01L, 1),
+    TEST_f_f1 (lgamma, -0x1p-15L, 1.0397225324389321751118257981741350715545e+01L, -1),
+    TEST_f_f1 (lgamma, 0x1p-20L, 1.3862943060723899573457963336920089012399e+01L, 1),
+    TEST_f_f1 (lgamma, -0x1p-20L, 1.3862944161675408862049886226750366625112e+01L, -1),
+    TEST_f_f1 (lgamma, 0x1p-25L, 1.7328679496796266133304874243201700664713e+01L, 1),
+    TEST_f_f1 (lgamma, -0x1p-25L, 1.7328679531201000798551671833865469674673e+01L, -1),
+    TEST_f_f1 (lgamma, 0x1p-30L, 2.0794415416260785304085859198055798098863e+01L, 1),
+    TEST_f_f1 (lgamma, -0x1p-30L, 2.0794415417335933262374820960532606449975e+01L, -1),
+    TEST_f_f1 (lgamma, 0x1p-40L, 2.7725887222397287402100277256545578941303e+01L, 1),
+    TEST_f_f1 (lgamma, -0x1p-40L, 2.7725887222398337351278293820766115529596e+01L, -1),
+    TEST_f_f1 (lgamma, 0x1p-50L, 3.4657359027997264958191108994508978906983e+01L, 1),
+    TEST_f_f1 (lgamma, -0x1p-50L, 3.4657359027997265983532103151309975524744e+01L, -1),
+    TEST_f_f1 (lgamma, 0x1p-60L, 4.1588830833596718564533272505187468598519e+01L, 1),
+    TEST_f_f1 (lgamma, -0x1p-60L, 4.1588830833596718565534582069793719571779e+01L, -1),
+    TEST_f_f1 (lgamma, 0x1p-64L, 4.4361419555836499802671564849429355013920e+01L, 1),
+    TEST_f_f1 (lgamma, -0x1p-64L, 4.4361419555836499802734146697217245699749e+01L, -1),
+    TEST_f_f1 (lgamma, 0x1p-70L, 4.8520302639196171659205759581386516869302e+01L, 1),
+    TEST_f_f1 (lgamma, -0x1p-70L, 4.8520302639196171659206737422758202661268e+01L, -1),
+    TEST_f_f1 (lgamma, 0x1p-100L, 6.9314718055994530941723212145817201464678e+01L, 1),
+    TEST_f_f1 (lgamma, -0x1p-100L, 6.9314718055994530941723212145818112150422e+01L, -1),
+    TEST_f_f1 (lgamma, 0x1p-126L, 8.7336544750553108986571247303730247577506e+01L, 1),
+    TEST_f_f1 (lgamma, -0x1p-126L, 8.7336544750553108986571247303730247577520e+01L, -1),
+    TEST_f_f1 (lgamma, 0x1p-149L, 1.0327892990343185110316758609726830864325e+02L, 1),
+    TEST_f_f1 (lgamma, -0x1p-149L, 1.0327892990343185110316758609726830864325e+02L, -1),
+#ifndef TEST_FLOAT
+    TEST_f_f1 (lgamma, 0x1p-200L, 1.3862943611198906188344642429163531361510e+02L, 1),
+    TEST_f_f1 (lgamma, -0x1p-200L, 1.3862943611198906188344642429163531361510e+02L, -1),
+    TEST_f_f1 (lgamma, 0x1p-500L, 3.4657359027997265470861606072908828403775e+02L, 1),
+    TEST_f_f1 (lgamma, -0x1p-500L, 3.4657359027997265470861606072908828403775e+02L, -1),
+    TEST_f_f1 (lgamma, 0x1p-1000L, 6.9314718055994530941723212145817656807550e+02L, 1),
+    TEST_f_f1 (lgamma, -0x1p-1000L, 6.9314718055994530941723212145817656807550e+02L, -1),
+    TEST_f_f1 (lgamma, 0x1p-1022L, 7.0839641853226410622441122813025645257316e+02L, 1),
+    TEST_f_f1 (lgamma, -0x1p-1022L, 7.0839641853226410622441122813025645257316e+02L, -1),
+    TEST_f_f1 (lgamma, 0x1p-1074L, 7.4444007192138126231410729844608163411309e+02L, 1),
+    TEST_f_f1 (lgamma, -0x1p-1074L, 7.4444007192138126231410729844608163411309e+02L, -1),
+#endif
+#if defined TEST_LDOUBLE && LDBL_MIN_EXP <= -16381
+    TEST_f_f1 (lgamma, 0x1p-5000L, 3.4657359027997265470861606072908828403775e+03L, 1),
+    TEST_f_f1 (lgamma, -0x1p-5000L, 3.4657359027997265470861606072908828403775e+03L, -1),
+    TEST_f_f1 (lgamma, 0x1p-10000L, 6.9314718055994530941723212145817656807550e+03L, 1),
+    TEST_f_f1 (lgamma, -0x1p-10000L, 6.9314718055994530941723212145817656807550e+03L, -1),
+    TEST_f_f1 (lgamma, 0x1p-16382L, 1.1355137111933024058873096613727848538213e+04L, 1),
+    TEST_f_f1 (lgamma, -0x1p-16382L, 1.1355137111933024058873096613727848538213e+04L, -1),
+    TEST_f_f1 (lgamma, 0x1p-16445L, 1.1398805384308300613366382237379713662002e+04L, 1),
+    TEST_f_f1 (lgamma, -0x1p-16445L, 1.1398805384308300613366382237379713662002e+04L, -1),
+# if LDBL_MANT_DIG >= 113
+    TEST_f_f1 (lgamma, 0x1p-16494L, 1.1432769596155737933527826611331164313837e+04L, 1),
+    TEST_f_f1 (lgamma, -0x1p-16494L, 1.1432769596155737933527826611331164313837e+04L, -1),
+# endif
+#endif
   };
 
 static void
diff --git a/sysdeps/i386/fpu/libm-test-ulps b/sysdeps/i386/fpu/libm-test-ulps
index 8244863ef6..4759aa9f7f 100644
--- a/sysdeps/i386/fpu/libm-test-ulps
+++ b/sysdeps/i386/fpu/libm-test-ulps
@@ -5470,9 +5470,35 @@ double: 1
 idouble: 1
 ildouble: 1
 ldouble: 1
+Test "gamma (-0x1p-10)":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+Test "gamma (-0x1p-15)":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+Test "gamma (-0x1p-20)":
+double: 1
+idouble: 1
+Test "gamma (-0x1p-30)":
+double: 1
+idouble: 1
+ildouble: 1
+ldouble: 1
+Test "gamma (-0x1p-5)":
+double: 1
+idouble: 1
 Test "gamma (0.7)":
 float: 1
 ifloat: 1
+Test "gamma (0x1p-40)":
+ildouble: 1
+ldouble: 1
 Test "gamma (1.2)":
 double: 1
 float: 2
@@ -5723,9 +5749,35 @@ double: 1
 idouble: 1
 ildouble: 1
 ldouble: 1
+Test "lgamma (-0x1p-10)":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+Test "lgamma (-0x1p-15)":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+Test "lgamma (-0x1p-20)":
+double: 1
+idouble: 1
+Test "lgamma (-0x1p-30)":
+double: 1
+idouble: 1
+ildouble: 1
+ldouble: 1
+Test "lgamma (-0x1p-5)":
+double: 1
+idouble: 1
 Test "lgamma (0.7)":
 float: 1
 ifloat: 1
+Test "lgamma (0x1p-40)":
+ildouble: 1
+ldouble: 1
 Test "lgamma (1.2)":
 double: 1
 float: 2
diff --git a/sysdeps/ieee754/flt-32/e_lgammaf_r.c b/sysdeps/ieee754/flt-32/e_lgammaf_r.c
index 2e92269085..0dba9af8d7 100644
--- a/sysdeps/ieee754/flt-32/e_lgammaf_r.c
+++ b/sysdeps/ieee754/flt-32/e_lgammaf_r.c
@@ -150,8 +150,8 @@ __ieee754_lgammaf_r(float x, int *signgamp)
 	      *signgamp = -1;
 	    return one/fabsf(x);
 	  }
-	if(__builtin_expect(ix<0x1c800000, 0)) {
-	    /* |x|<2**-70, return -log(|x|) */
+	if(__builtin_expect(ix<0x30800000, 0)) {
+	    /* |x|<2**-30, return -log(|x|) */
 	    if(hx<0) {
 		*signgamp = -1;
 		return -__ieee754_logf(-x);
diff --git a/sysdeps/x86_64/fpu/libm-test-ulps b/sysdeps/x86_64/fpu/libm-test-ulps
index 477eedc311..6fbfa64ae1 100644
--- a/sysdeps/x86_64/fpu/libm-test-ulps
+++ b/sysdeps/x86_64/fpu/libm-test-ulps
@@ -6222,11 +6222,39 @@ idouble: 1
 Test "gamma (-0.5)":
 ildouble: 1
 ldouble: 1
+Test "gamma (-0x1p-10)":
+double: 1
+idouble: 1
+ildouble: 1
+ldouble: 1
+Test "gamma (-0x1p-15)":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+Test "gamma (-0x1p-20)":
+double: 1
+idouble: 1
+Test "gamma (-0x1p-30)":
+ildouble: 1
+ldouble: 1
+Test "gamma (-0x1p-5)":
+double: 1
+idouble: 1
 Test "gamma (0.7)":
 double: 1
 float: 1
 idouble: 1
 ifloat: 1
+Test "gamma (0x1p-10)":
+float: 1
+ifloat: 1
+Test "gamma (0x1p-30)":
+double: 1
+idouble: 1
+Test "gamma (0x1p-40)":
+ildouble: 1
+ldouble: 1
 Test "gamma (1.2)":
 double: 1
 float: 2
@@ -6491,11 +6519,39 @@ ldouble: 2
 Test "lgamma (-0.5)":
 ildouble: 1
 ldouble: 1
+Test "lgamma (-0x1p-10)":
+double: 1
+idouble: 1
+ildouble: 1
+ldouble: 1
+Test "lgamma (-0x1p-15)":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+Test "lgamma (-0x1p-20)":
+double: 1
+idouble: 1
+Test "lgamma (-0x1p-30)":
+ildouble: 1
+ldouble: 1
+Test "lgamma (-0x1p-5)":
+double: 1
+idouble: 1
 Test "lgamma (0.7)":
 double: 1
 float: 1
 idouble: 1
 ifloat: 1
+Test "lgamma (0x1p-10)":
+float: 1
+ifloat: 1
+Test "lgamma (0x1p-30)":
+double: 1
+idouble: 1
+Test "lgamma (0x1p-40)":
+ildouble: 1
+ldouble: 1
 Test "lgamma (1.2)":
 double: 1
 float: 2