mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-05 21:00:05 +00:00
108 lines
4.1 KiB
Plaintext
108 lines
4.1 KiB
Plaintext
|
README for libm-test math test suite
|
||
|
|
====================================
|
||
|
|
|
||
|
|
The libm-test math test suite tests a number of function points of
|
||
|
|
math functions in the GNU C library. The following sections contain a
|
||
|
|
brief overview. Please note that the test drivers and the Perl script
|
||
|
|
"gen-libm-test.pl" have some options. A full list of options is
|
||
|
|
available with --help (for the test drivers) and -h for
|
||
|
|
"gen-libm-test.pl".
|
||
|
|
|
||
|
|
|
||
|
|
What is tested?
|
||
|
|
===============
|
||
|
|
The tests just evaluate the functions at specified points and compare
|
||
|
|
the results with precomputed values and the requirements of the ISO
|
||
|
|
C99 standard.
|
||
|
|
|
||
|
|
Besides testing the special values mandated by IEEE 754 (infinities,
|
||
|
|
NaNs and minus zero), some more or less random values are tested.
|
||
|
|
|
||
|
|
Files that are part of libm-test
|
||
|
|
================================
|
||
|
|
|
||
|
|
The main file is "libm-test.inc". It is platform and floating point
|
||
|
|
format independent. The file must be preprocessed by the Perl script
|
||
|
|
"gen-libm-test.pl". The results are "libm-test.c" and a file
|
||
|
|
"libm-test-ulps.h" with platform specific deltas.
|
||
|
|
|
||
|
|
The test drivers test-double.c, test-float.c, test-ldouble.c test the
|
||
|
|
normal double, float and long double implementation of libm. The test
|
||
|
|
drivers with an i in it (test-idouble.c, test-ifloat.c,
|
||
|
|
test-ildoubl.c) test the corresponding inline functions (where
|
||
|
|
available - otherwise they also test the real functions in libm).
|
||
|
|
|
||
|
|
"gen-libm-test.pl" needs a platform specific files with ULPs (Units of
|
||
|
|
Last Precision). The file is called "libm-test-ulps" and lives in
|
||
|
|
platform specific sysdep directory.
|
||
|
|
|
||
|
|
How can I generate "libm-test-ulps"?
|
||
|
|
====================================
|
||
|
|
|
||
|
|
The test drivers have an option "-u" to output an unsorted list of all
|
||
|
|
epsilons that the functions have. The output can be read in directly
|
||
|
|
but it's better to pretty print it first. "gen-libm-test.pl" has an option
|
||
|
|
to generate a pretty-printed and sorted new ULPs file from the output
|
||
|
|
of the test drivers.
|
||
|
|
|
||
|
|
To generate a new "libm-test-ulps" file, you can execute for example:
|
||
|
|
test-double -u --ignore-max-ulp=yes
|
||
|
|
This generates a file "ULPs" with all double ULPs in it, ignoring any
|
||
|
|
previous calculated ULPs.
|
||
|
|
Now move this away, e.g. "mv ULPs allULPs" and generate the ULPs
|
||
|
|
for all other formats and concat all ULP files together (e.g. "cat
|
||
|
|
ULPs >> allULPs"). As final step run "gen-libm-test.pl" with the file
|
||
|
|
as input and ask to generate a pretty printed output in the file "NewUlps":
|
||
|
|
gen-libm-test.pl -u allULPs -n
|
||
|
|
|
||
|
|
Now you can rename "NewUlps" to "libm-test-ulps" and move it into
|
||
|
|
sysdeps.
|
||
|
|
|
||
|
|
Contents of libm-test-ulps
|
||
|
|
==========================
|
||
|
|
Since libm-test-ulps can be generated automatically, just a few
|
||
|
|
notes. The file contains lines for single tests, like:
|
||
|
|
Test "cos (pi/2) == 0":
|
||
|
|
float: 1
|
||
|
|
|
||
|
|
and lines for maximal errors of single functions, like:
|
||
|
|
Function "yn":
|
||
|
|
idouble: 6.0000
|
||
|
|
|
||
|
|
The keywords are float, ifloat, double, idouble, ldouble and ildouble
|
||
|
|
(the prefix i stands for inline). You can also specify known
|
||
|
|
failures, e.g.:
|
||
|
|
|
||
|
|
Test "cos (pi/2) == 0":
|
||
|
|
float: 1
|
||
|
|
float: fail
|
||
|
|
|
||
|
|
Adding tests to libm-test.inc
|
||
|
|
=============================
|
||
|
|
|
||
|
|
The tests are evaluated by a set of special test macros. The macros
|
||
|
|
start with "TEST_" followed by a specification the input values, an
|
||
|
|
underscore and a specification of the output values. As an example,
|
||
|
|
the test macro for a function with input of type FLOAT (FLOAT is
|
||
|
|
either float, double, long double) and output of type FLOAT is
|
||
|
|
"TEST_f_f". The macro's parameter are the name of the function, the
|
||
|
|
input parameter, output parameter and optionally one exception
|
||
|
|
parameter.
|
||
|
|
|
||
|
|
The accepted parameter types are:
|
||
|
|
- "f" for FLOAT
|
||
|
|
- "b" for boolean - just tests if the output parameter evaluates to 0
|
||
|
|
or 1 (only for output).
|
||
|
|
- "c" for complex. This parameter needs two values, first the real,
|
||
|
|
then the imaginary part.
|
||
|
|
- "i" for int.
|
||
|
|
- "l" for long int.
|
||
|
|
- "L" for long long int.
|
||
|
|
- "F" for the address of a FLOAT (only as input parameter)
|
||
|
|
- "I" for the address of an int (only as input parameter)
|
||
|
|
|
||
|
|
Some functions need special handling. For example gamma sets the
|
||
|
|
global variable signgam and frexp takes an argument to &int. This
|
||
|
|
special treatment is coded in "gen-libm-test.pl" and used while
|
||
|
|
parsing "libm-test.inc".
|