benchtests: Move bench.py to benchtests/scripts/

It makes much more sense to have all benchmarking-related scripts in a
single place away from everything else.

benchtests/scripts/bench.py

@@ -0,0 +1,299 @@
+#!/usr/bin/python
+# Copyright (C) 2014 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) %(func)s (%(func_args)s)
+
+struct args
+{
+%(args)s
+};
+
+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 BENCH_FUNC(i, j) ({%(getret)s CALL_BENCH_FUNC (i, j);})
+#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.
+    if directives['ret']:
+        print('static %s volatile ret;' % directives['ret'])
+        getret = 'ret = '
+    else:
+        getret = ''
+
+    print(EPILOGUE % {'getret': getret, 'func': func})
+
+
+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;' % (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},' % v for v in vals]
+
+        # Members for the variants structure list that we will
+        # print later.
+        variants.append('  {"%s(%s)", %d, in%d},' % (func, 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': ''
+    }
+
+    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:]))