testsoftfloat
John R. Hauser
2017 February 10
The testsoftfloat
program tests that a build of the Berkeley
SoftFloat library conforms to the IEEE Standard for Binary Floating-Point
Arithmetic as expected.
Program testsoftfloat
is part of the Berkeley TestFloat package, a
small collection of programs for performing such tests.
For general information about TestFloat, as well as for basics about the
operation of testsoftfloat
and how to interpret its output, see
file
TestFloat-general.html
Note that, even if there are no bugs in the source code for SoftFloat (not guaranteed), a build of SoftFloat might still fail due to an issue with the build process, such as an incompatible compiler option or a compiler bug.
The testsoftfloat
program will ordinarily test a function for all
five rounding modes defined by the IEEE Floating-Point Standard, one after the
other, plus possibly a sixth mode, round to odd (depending on the
options selected when testsoftfloat
was compiled).
If an operation is not supposed to require rounding, it will by default be
tested only with the rounding mode set to near_even
(nearest/even).
In the same way, if an operation is affected by the way in which underflow
tininess is detected, testsoftfloat
tests the function with
tininess detected both before rounding and after rounding.
For testsoftfloat
also tests the function
for all three rounding precision modes, one after the other.
Testing can be limited to a single rounding mode, a single tininess mode,
and/or a single rounding precision with appropriate command-line options.
The testsoftfloat
program is executed as a command with this
syntax:
Square brackets (testsoftfloat [<option>...] <function>
[ ]
) denote optional arguments,
<option>
is a supported option, and
<function>
is the name of either a testable function
or a function set.
The available options and function sets are documented below.
If testsoftfloat
is executed without any arguments, a summary of
usage is written.
The testsoftfloat
program accepts several command options.
If mutually contradictory options are given, the last one has priority.
-help
The -help
option causes a summary of program usage to be written,
after which the program exits.
-seed <num>
The -seed
option sets the seed for the pseudo-random number
generator used for generating test cases.
The argument to -seed
is a nonnegative integer.
Executing the same testsoftfloat
program with the same arguments
(including the same pseudo-random number seed) should always perform the same
sequence of tests, whereas changing the pseudo-random number seed should result
in a different sequence of tests.
The default seed number
-level <num>
The -level
option sets the level of testing.
The argument to -level
can be either 1
-errors <num>
The -errors
option instructs testsoftfloat
to report
no more than the specified number of errors for any combination of function,
rounding mode, etc.
The argument to -errors
must be a nonnegative decimal integer.
Once the specified number of error reports has been generated,
testsoftfloat
ends the current test and begins the next one, if
any.
The default is -errors
20
Against intuition, -errors
0
testsoftfloat
to report every error it finds.
-errorstop
The -errorstop
option causes the program to exit after the first
function for which any errors are reported.
-forever
The -forever
option causes a single function to be repeatedly
tested.
Only one rounding mode and/or rounding precision can be tested in a single
execution.
If not specified, the rounding mode defaults to nearest/even.
For
-precision32, -precision64, -precision80
For -precision32
option restricts
testing to only the cases in which the rounding precision is
-precision64
fixes the rounding precision to
-precision80
fixes the rounding precision to the full
-rnear_even, -rnear_maxMag, -rminMag, -rmin, -rmax, -rodd
The -rnear_even
option restricts testing to only the cases in
which the rounding mode is nearest/even.
The other rounding mode choices are not tested.
Likewise, -rnear_maxMag
forces rounding to nearest/maximum
magnitude (nearest-away), -rminMag
forces rounding to minimum
magnitude (toward zero), -rmin
forces rounding to minimum (down,
toward negative infinity), -rmax
forces rounding to maximum (up,
toward positive infinity), and -rodd
, if supported, forces
rounding to odd.
These options are ignored for operations that are exact and thus do not round.
-tininessbefore, -tininessafter
The -tininessbefore
option restricts testing to only the cases in
which tininess on underflow is detected before rounding.
Likewise, -tininessafter
restricts testing to only the cases in
which tininess on underflow is detected after rounding.
-notexact, -exact
For functions that round to an integer (conversions to integer types and the
roundToInt
functions), the -notexact
option restricts
testing to only the cases for which the exact
operand
(specifying whether the inexact exception flag may be raised) is
false
.
Likewise, the -exact
option restricts testing to only the cases
for which the exact
operand is true
.
Just as testsoftfloat
can test a function for all five or six
rounding modes in sequence, multiple functions can be tested with a single
execution of testsoftfloat
.
Two sets are recognized: -all1
and -all2
.
The set -all1
is all one-operand operations, while
-all2
is all two-operand operations.
A function set is used in place of a function name in the
testsoftfloat
command line, such as
testsoftfloat [<option>...] -all1
For the purpose of deciding the number of operands of an operation, any
roundingMode
and exact
arguments are
ignored.
(Such arguments specify the rounding mode and whether the inexact
exception flag may be raised, respectively.)
Thus, functions that convert to integer type and the roundToInt
functions are included in the set of one-operand operations tested by
-all1
.