Re: [PATCH] Add testcase for expl

[Stefan Liebler <stli at linux dot vnet dot ibm dot com>]

On 02/06/2014 05:22 PM, Joseph S. Myers wrote:
> On Thu, 6 Feb 2014, Stefan Liebler wrote:
>
> > Hi,
> >
> > due to Bug 16447, the function __erfcl
> > in sysdeps/ieee754/ldbl-128/s_erfl.c
> > calls __ieee754_expl in sysdeps/ieee754/ldbl-128/e_expl.c.
> > The value returned by expl is a normalized value, but FE_UNDERFLOW is set on
> > S/390. Therefore the testcase shows the problem directly.
>
> "Bug N" comments in auto-libm-test-in are present as justification for
> xfail, missing-* or spurious-* annotations for tests (searching for "bug"
> in the file shows exactly what's marked as expected to fail because of
> known bugs).  Thus, if adding the test on its own (and normally the test
> would be added by the same patch fixing the bug, rather than before the
> fix), there should be a spurious-underflow:ldbl-128 annotation.

okay. Here is the testcase with the fix for expl (see Bug 16447).

But now the double test fails:

testing double (without inline functions)
Failure: Test: exp_upward (-0x2.c4edp+12)
Result:
 is:          0.00000000000000000000e+00   0x0.00000000000000000000p+0
 should be:   4.94065645841246544177e-324   0x0.00000000000010000000p-1022
 difference:  4.94065645841246544177e-324   0x0.00000000000010000000p-1022
 ulp       :  1.0000
 max.ulp   :  0.0000

The same thing for the inlined version.

In all rounding-modes, the exp-function returns zero and 
errno=ERANGE,FE_INEXACT and FE_UNDERFLOW are set.

---
2014-02-07  Stefan Liebler  <stli@linux.vnet.ibm.com>

    * math/auto-libm-test-in: Add testcase for expl
    * math/auto-libm-test-out: Likewise
    * sysdeps/ieee754/ldbl-128/e_expl.c: Fix calculation of unsafe
---

diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in
index b919dbc..c620361 100644
--- a/math/auto-libm-test-in
+++ b/math/auto-libm-test-in
@@ -725,6 +725,7 @@ exp max xfail-rounding:dbl-64 xfail-rounding:ldbl-128ibm
 exp -7.4444006192138124e+02
 exp -0x1.75f113c30b1c8p+9
 exp -max
+exp -11342.8125

 exp10 0
 exp10 -0
diff --git a/math/auto-libm-test-out b/math/auto-libm-test-out
index 8955e18..93818e8 100644
--- a/math/auto-libm-test-out
+++ b/math/auto-libm-test-out
@@ -62149,6 +62149,31 @@ exp -max
 = exp tonearest ldbl-128ibm -0xf.ffffffffffffbffffffffffffcp+1020L : 
0x0p+0L : inexact-ok underflow errno-erange
 = exp towardzero ldbl-128ibm -0xf.ffffffffffffbffffffffffffcp+1020L : 
0x0p+0L : inexact-ok underflow errno-erange
 = exp upward ldbl-128ibm -0xf.ffffffffffffbffffffffffffcp+1020L : 
0x4p-1076L : inexact-ok underflow errno-erange-ok
+exp -11342.8125
+= exp downward flt-32 -0x2.c4edp+12f : 0x0p+0f : inexact-ok underflow 
errno-erange
+= exp tonearest flt-32 -0x2.c4edp+12f : 0x0p+0f : inexact-ok underflow 
errno-erange
+= exp towardzero flt-32 -0x2.c4edp+12f : 0x0p+0f : inexact-ok underflow 
errno-erange
+= exp upward flt-32 -0x2.c4edp+12f : 0x8p-152f : inexact-ok underflow 
errno-erange-ok
+= exp downward dbl-64 -0x2.c4edp+12 : 0x0p+0 : inexact-ok underflow 
errno-erange
+= exp tonearest dbl-64 -0x2.c4edp+12 : 0x0p+0 : inexact-ok underflow 
errno-erange
+= exp towardzero dbl-64 -0x2.c4edp+12 : 0x0p+0 : inexact-ok underflow 
errno-erange
+= exp upward dbl-64 -0x2.c4edp+12 : 0x4p-1076 : inexact-ok underflow 
errno-erange-ok
+= exp downward ldbl-96-intel -0x2.c4edp+12L : 
0xd.be48e2532594eccp-16368L : inexact-ok
+= exp tonearest ldbl-96-intel -0x2.c4edp+12L : 
0xd.be48e2532594eccp-16368L : inexact-ok
+= exp towardzero ldbl-96-intel -0x2.c4edp+12L : 
0xd.be48e2532594eccp-16368L : inexact-ok
+= exp upward ldbl-96-intel -0x2.c4edp+12L : 0xd.be48e2532594ecdp-16368L 
: inexact-ok
+= exp downward ldbl-96-m68k -0x2.c4edp+12L : 
0xd.be48e2532594eccp-16368L : inexact-ok
+= exp tonearest ldbl-96-m68k -0x2.c4edp+12L : 
0xd.be48e2532594eccp-16368L : inexact-ok
+= exp towardzero ldbl-96-m68k -0x2.c4edp+12L : 
0xd.be48e2532594eccp-16368L : inexact-ok
+= exp upward ldbl-96-m68k -0x2.c4edp+12L : 0xd.be48e2532594ecdp-16368L 
: inexact-ok
+= exp downward ldbl-128 -0x2.c4edp+12L : 
0xd.be48e2532594ecc1a3b8f7ce2038p-16368L : inexact-ok
+= exp tonearest ldbl-128 -0x2.c4edp+12L : 
0xd.be48e2532594ecc1a3b8f7ce2038p-16368L : inexact-ok
+= exp towardzero ldbl-128 -0x2.c4edp+12L : 
0xd.be48e2532594ecc1a3b8f7ce2038p-16368L : inexact-ok
+= exp upward ldbl-128 -0x2.c4edp+12L : 
0xd.be48e2532594ecc1a3b8f7ce204p-16368L : inexact-ok
+= exp downward ldbl-128ibm -0x2.c4edp+12L : 0x0p+0L : inexact-ok 
underflow errno-erange
+= exp tonearest ldbl-128ibm -0x2.c4edp+12L : 0x0p+0L : inexact-ok 
underflow errno-erange
+= exp towardzero ldbl-128ibm -0x2.c4edp+12L : 0x0p+0L : inexact-ok 
underflow errno-erange
+= exp upward ldbl-128ibm -0x2.c4edp+12L : 0x4p-1076L : inexact-ok 
underflow errno-erange-ok
 exp10 0
 = exp10 downward flt-32 0x0p+0f : 0x1p+0f : inexact-ok
 = exp10 tonearest flt-32 0x0p+0f : 0x1p+0f : inexact-ok
diff --git a/sysdeps/ieee754/ldbl-128/e_expl.c 
b/sysdeps/ieee754/ldbl-128/e_expl.c
index 8259758..ae2604e 100644
--- a/sysdeps/ieee754/ldbl-128/e_expl.c
+++ b/sysdeps/ieee754/ldbl-128/e_expl.c
@@ -181,7 +181,7 @@ __ieee754_expl (long double x)
 		* __expl_table[T_EXPL_RES2 + tval2];
       n_i = (int)n;
       /* 'unsafe' is 1 iff n_1 != 0.  */
-      unsafe = abs(n_i) >= -LDBL_MIN_EXP - 1;
+      unsafe = abs(n_i) >= 15000;
       ex2_u.ieee.exponent += n_i >> unsafe;

       /* Compute scale = 2^n_1.  */