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Fix tgamma missing underflows (bug 18951) [committed]
- From: Joseph Myers <joseph at codesourcery dot com>
- To: <libc-alpha at sourceware dot org>
- Date: Thu, 17 Sep 2015 15:52:59 +0000
- Subject: Fix tgamma missing underflows (bug 18951) [committed]
- Authentication-results: sourceware.org; auth=none
Similar to various other bugs in this area, tgamma functions can fail
to raise the underflow exception when the result is tiny and inexact
but one or more low bits of the intermediate result that is scaled
down are zero. This patch forces the exception in a similar way to
previous fixes.
Tested for x86_64, x86, mips64 and powerpc. Committed.
(auto-libm-test-out diffs omitted below.)
2015-09-17 Joseph Myers <joseph@codesourcery.com>
[BZ #18951]
* sysdeps/ieee754/dbl-64/e_gamma_r.c (__ieee754_gamma_r): Force
underflow exception for small results.
* sysdeps/ieee754/flt-32/e_gammaf_r.c (__ieee754_gammaf_r):
Likewise.
* sysdeps/ieee754/ldbl-128/e_gammal_r.c (__ieee754_gammal_r):
Likewise.
* sysdeps/ieee754/ldbl-128ibm/e_gammal_r.c (__ieee754_gammal_r):
Likewise.
* sysdeps/ieee754/ldbl-96/e_gammal_r.c (__ieee754_gammal_r):
Likewise.
* math/auto-libm-test-in: Add more tests of tgamma.
* math/auto-libm-test-out: Regenerated.
diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in
index 8e236c3..8dea2b4 100644
--- a/math/auto-libm-test-in
+++ b/math/auto-libm-test-in
@@ -3855,6 +3855,47 @@ tgamma 1e3
tgamma -100000.5
tgamma max
+tgamma -0x22.30p0
+tgamma -0x22.31p0
+tgamma -0x22.32p0
+tgamma -0x22.33p0
+tgamma -0x22.34p0
+tgamma -0x22.35p0
+tgamma -0x22.36p0
+tgamma -0x22.37p0
+tgamma -0xa3.70p0
+tgamma -0xa3.71p0
+tgamma -0xa3.72p0
+tgamma -0xa3.73p0
+tgamma -0xa3.74p0
+tgamma -0xa3.75p0
+tgamma -0xa3.76p0
+tgamma -0xa3.77p0
+tgamma -0xab.0d0p0
+tgamma -0xab.0d1p0
+tgamma -0xab.0d2p0
+tgamma -0xab.0d3p0
+tgamma -0xab.0d4p0
+tgamma -0xab.0d5p0
+tgamma -0xab.0d6p0
+tgamma -0xab.0d7p0
+tgamma -0x6db.030p0
+tgamma -0x6db.031p0
+tgamma -0x6db.032p0
+tgamma -0x6db.033p0
+tgamma -0x6db.034p0
+tgamma -0x6db.035p0
+tgamma -0x6db.036p0
+tgamma -0x6db.037p0
+tgamma -0x6db.050p0
+tgamma -0x6db.051p0
+tgamma -0x6db.052p0
+tgamma -0x6db.053p0
+tgamma -0x6db.054p0
+tgamma -0x6db.055p0
+tgamma -0x6db.056p0
+tgamma -0x6db.057p0
+
tgamma -0x3.06644cp+0
tgamma -0x6.fe4636e0c5064p+0
tgamma -0x7.a13d7a2945cd5718p+0
diff --git a/sysdeps/ieee754/dbl-64/e_gamma_r.c b/sysdeps/ieee754/dbl-64/e_gamma_r.c
index adeb61a..d1acaa6 100644
--- a/sysdeps/ieee754/dbl-64/e_gamma_r.c
+++ b/sysdeps/ieee754/dbl-64/e_gamma_r.c
@@ -194,6 +194,11 @@ __ieee754_gamma_r (double x, int *signgamp)
double tret = M_PI / (-x * sinpix
* gamma_positive (-x, &exp2_adj));
ret = __scalbn (tret, -exp2_adj);
+ if (ret < DBL_MIN)
+ {
+ double force_underflow = ret * ret;
+ math_force_eval (force_underflow);
+ }
}
}
}
diff --git a/sysdeps/ieee754/flt-32/e_gammaf_r.c b/sysdeps/ieee754/flt-32/e_gammaf_r.c
index 29fe8b4..250e412 100644
--- a/sysdeps/ieee754/flt-32/e_gammaf_r.c
+++ b/sysdeps/ieee754/flt-32/e_gammaf_r.c
@@ -186,6 +186,11 @@ __ieee754_gammaf_r (float x, int *signgamp)
float tret = (float) M_PI / (-x * sinpix
* gammaf_positive (-x, &exp2_adj));
ret = __scalbnf (tret, -exp2_adj);
+ if (ret < FLT_MIN)
+ {
+ float force_underflow = ret * ret;
+ math_force_eval (force_underflow);
+ }
}
}
}
diff --git a/sysdeps/ieee754/ldbl-128/e_gammal_r.c b/sysdeps/ieee754/ldbl-128/e_gammal_r.c
index c51b050..c44f031 100644
--- a/sysdeps/ieee754/ldbl-128/e_gammal_r.c
+++ b/sysdeps/ieee754/ldbl-128/e_gammal_r.c
@@ -194,6 +194,11 @@ __ieee754_gammal_r (long double x, int *signgamp)
ret = M_PIl / (-x * sinpix
* gammal_positive (-x, &exp2_adj));
ret = __scalbnl (ret, -exp2_adj);
+ if (ret < LDBL_MIN)
+ {
+ long double force_underflow = ret * ret;
+ math_force_eval (force_underflow);
+ }
}
}
}
diff --git a/sysdeps/ieee754/ldbl-128ibm/e_gammal_r.c b/sysdeps/ieee754/ldbl-128ibm/e_gammal_r.c
index 48098c1..420842e 100644
--- a/sysdeps/ieee754/ldbl-128ibm/e_gammal_r.c
+++ b/sysdeps/ieee754/ldbl-128ibm/e_gammal_r.c
@@ -194,6 +194,11 @@ __ieee754_gammal_r (long double x, int *signgamp)
ret = M_PIl / (-x * sinpix
* gammal_positive (-x, &exp2_adj));
ret = __scalbnl (ret, -exp2_adj);
+ if (ret < LDBL_MIN)
+ {
+ long double force_underflow = ret * ret;
+ math_force_eval (force_underflow);
+ }
}
}
}
diff --git a/sysdeps/ieee754/ldbl-96/e_gammal_r.c b/sysdeps/ieee754/ldbl-96/e_gammal_r.c
index 9da5db3..a5767e7 100644
--- a/sysdeps/ieee754/ldbl-96/e_gammal_r.c
+++ b/sysdeps/ieee754/ldbl-96/e_gammal_r.c
@@ -186,6 +186,11 @@ __ieee754_gammal_r (long double x, int *signgamp)
ret = M_PIl / (-x * sinpix
* gammal_positive (-x, &exp2_adj));
ret = __scalbnl (ret, -exp2_adj);
+ if (ret < LDBL_MIN)
+ {
+ long double force_underflow = ret * ret;
+ math_force_eval (force_underflow);
+ }
}
}
}
--
Joseph S. Myers
joseph@codesourcery.com