#!/usr/bin/python

# Copyright (C) 2014-2018 Free Software Foundation, Inc.

# This file is part of the GNU C Library.

#

# The GNU C Library is free software; you can redistribute it and/or

# modify it under the terms of the GNU Lesser General Public

# License as published by the Free Software Foundation; either

# version 2.1 of the License, or (at your option) any later version.

#

# The GNU C Library is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

# Lesser General Public License for more details.

#

# You should have received a copy of the GNU Lesser General Public

# License along with the GNU C Library; if not, see

# <http://www.gnu.org/licenses/>.

"""Benchmark program generator script

This script takes a function name as input and generates a program using

an input file located in the benchtests directory.  The name of the

input file should be of the form foo-inputs where 'foo' is the name of

the function.

"""

from __future__ import print_function

import sys

import os

import itertools

# Macro definitions for functions that take no arguments.  For functions

# that take arguments, the STRUCT_TEMPLATE, ARGS_TEMPLATE and

# VARIANTS_TEMPLATE are used instead.

DEFINES_TEMPLATE = '''

#define CALL_BENCH_FUNC(v, i) %(func)s ()

#define NUM_VARIANTS (1)

#define NUM_SAMPLES(v) (1)

#define VARIANT(v) FUNCNAME "()"

'''

# Structures to store arguments for the function call.  A function may

# have its inputs partitioned to represent distinct performance

# characteristics or distinct flavors of the function.  Each such

# variant is represented by the _VARIANT structure.  The ARGS structure

# represents a single set of arguments.

STRUCT_TEMPLATE = '''

#define CALL_BENCH_FUNC(v, i, x) %(func)s (x %(func_args)s)

struct args

{

%(args)s

  double timing;

};

struct _variants

{

  const char *name;

  int count;

  struct args *in;

};

'''

# The actual input arguments.

ARGS_TEMPLATE = '''

struct args in%(argnum)d[%(num_args)d] = {

%(args)s

};

'''

# The actual variants, along with macros defined to access the variants.

VARIANTS_TEMPLATE = '''

struct _variants variants[%(num_variants)d] = {

%(variants)s

};

#define NUM_VARIANTS %(num_variants)d

#define NUM_SAMPLES(i) (variants[i].count)

#define VARIANT(i) (variants[i].name)

'''

# Epilogue for the generated source file.

EPILOGUE = '''

#define RESULT(__v, __i) (variants[(__v)].in[(__i)].timing)

#define RESULT_ACCUM(r, v, i, old, new) \\

        ((RESULT ((v), (i))) = (RESULT ((v), (i)) * (old) + (r)) / ((new) + 1))

#define BENCH_FUNC(i, j) ({%(getret)s CALL_BENCH_FUNC (i, j, );})

#define BENCH_FUNC_LAT(i, j) ({%(getret)s CALL_BENCH_FUNC (i, j, %(latarg)s);})

#define BENCH_VARS %(defvar)s

#define FUNCNAME "%(func)s"

#include "bench-skeleton.c"'''

def gen_source(func, directives, all_vals):

    """Generate source for the function

    Generate the C source for the function from the values and

    directives.

    Args:

      func: The function name

      directives: A dictionary of directives applicable to this function

      all_vals: A dictionary input values

    """

    # The includes go in first.

    for header in directives['includes']:

        print('#include <%s>' % header)

    for header in directives['include-sources']:

        print('#include "%s"' % header)

    # Print macros.  This branches out to a separate routine if

    # the function takes arguments.

    if not directives['args']:

        print(DEFINES_TEMPLATE % {'func': func})

        outargs = []

    else:

        outargs = _print_arg_data(func, directives, all_vals)

    # Print the output variable definitions if necessary.

    for out in outargs:

        print(out)

    # If we have a return value from the function, make sure it is

    # assigned to prevent the compiler from optimizing out the

    # call.

    getret = ''

    latarg = ''

    defvar = ''

    if directives['ret']:

        print('static %s volatile ret;' % directives['ret'])

        print('static %s zero __attribute__((used)) = 0;' % directives['ret'])

        getret = 'ret = func_res = '

        # Note this may not work if argument and result type are incompatible.

        latarg = 'func_res * zero +'

        defvar = '%s func_res = 0;' % directives['ret']

    # Test initialization.

    if directives['init']:

        print('#define BENCH_INIT %s' % directives['init'])

    print(EPILOGUE % {'getret': getret, 'func': func, 'latarg': latarg, 'defvar': defvar })

def _print_arg_data(func, directives, all_vals):

    """Print argument data

    This is a helper function for gen_source that prints structure and

    values for arguments and their variants and returns output arguments

    if any are found.

    Args:

      func: Function name

      directives: A dictionary of directives applicable to this function

      all_vals: A dictionary input values

    Returns:

      Returns a list of definitions for function arguments that act as

      output parameters.

    """

    # First, all of the definitions.  We process writing of

    # CALL_BENCH_FUNC, struct args and also the output arguments

    # together in a single traversal of the arguments list.

    func_args = []

    arg_struct = []

    outargs = []

    for arg, i in zip(directives['args'], itertools.count()):

        if arg[0] == '<' and arg[-1] == '>':

            pos = arg.rfind('*')

            if pos == -1:

                die('Output argument must be a pointer type')

            outargs.append('static %s out%d __attribute__((used));' % (arg[1:pos], i))

            func_args.append(' &out%d' % i)

        else:

            arg_struct.append('  %s volatile arg%d;' % (arg, i))

            func_args.append('variants[v].in[i].arg%d' % i)

    print(STRUCT_TEMPLATE % {'args' : '\n'.join(arg_struct), 'func': func,

                             'func_args': ', '.join(func_args)})

    # Now print the values.

    variants = []

    for (k, vals), i in zip(all_vals.items(), itertools.count()):

        out = ['  {%s, 0},' % v for v in vals]

        # Members for the variants structure list that we will

        # print later.

        variants.append('  {"%s", %d, in%d},' % (k, len(vals), i))

        print(ARGS_TEMPLATE % {'argnum': i, 'num_args': len(vals),

                               'args': '\n'.join(out)})

    # Print the variants and the last set of macros.

    print(VARIANTS_TEMPLATE % {'num_variants': len(all_vals),

                               'variants': '\n'.join(variants)})

    return outargs

def _process_directive(d_name, d_val):

    """Process a directive.

    Evaluate the directive name and value passed and return the

    processed value. This is a helper function for parse_file.

    Args:

      d_name: Name of the directive

      d_val: The string value to process

    Returns:

      The processed value, which may be the string as it is or an object

      that describes the directive.

    """

    # Process the directive values if necessary.  name and ret don't

    # need any processing.

    if d_name.startswith('include'):

        d_val = d_val.split(',')

    elif d_name == 'args':

        d_val = d_val.split(':')

    # Return the values.

    return d_val

def parse_file(func):

    """Parse an input file

    Given a function name, open and parse an input file for the function

    and get the necessary parameters for the generated code and the list

    of inputs.

    Args:

      func: The function name

    Returns:

      A tuple of two elements, one a dictionary of directives and the

      other a dictionary of all input values.

    """

    all_vals = {}

    # Valid directives.

    directives = {

            'name': '',

            'args': [],

            'includes': [],

            'include-sources': [],

            'ret': '',

            'init': ''

    }

    try:

        with open('%s-inputs' % func) as f:

            for line in f:

                # Look for directives and parse it if found.

                if line.startswith('##'):

                    try:

                        d_name, d_val = line[2:].split(':', 1)

                        d_name = d_name.strip()

                        d_val = d_val.strip()

                        directives[d_name] = _process_directive(d_name, d_val)

                    except (IndexError, KeyError):

                        die('Invalid directive: %s' % line[2:])

                # Skip blank lines and comments.

                line = line.split('#', 1)[0].rstrip()

                if not line:

                    continue

                # Otherwise, we're an input.  Add to the appropriate

                # input set.

                cur_name = directives['name']

                all_vals.setdefault(cur_name, [])

                all_vals[cur_name].append(line)

    except IOError as ex:

        die("Failed to open input file (%s): %s" % (ex.filename, ex.strerror))

    return directives, all_vals

def die(msg):

    """Exit with an error

    Prints an error message to the standard error stream and exits with

    a non-zero status.

    Args:

      msg: The error message to print to standard error

    """

    print('%s\n' % msg, file=sys.stderr)

    sys.exit(os.EX_DATAERR)

def main(args):

    """Main function

    Use the first command line argument as function name and parse its

    input file to generate C source that calls the function repeatedly

    for the input.

    Args:

      args: The command line arguments with the program name dropped

    Returns:

      os.EX_USAGE on error and os.EX_OK on success.

    """

    if len(args) != 1:

        print('Usage: %s <function>' % sys.argv[0])

        return os.EX_USAGE

    directives, all_vals = parse_file(args[0])

    gen_source(args[0], directives, all_vals)

    return os.EX_OK

if __name__ == '__main__':

    sys.exit(main(sys.argv[1:]))