tests: Add framework for comparative benchmarking.

Motivation is optimizing handling of various constructs as well as
understanding which constructs are more efficient in MicroPython.
More info: http://forum.micropython.org/viewtopic.php?f=3&t=77

Results are wildly unexpected. For example, "optimization" of range
iteration into while loop makes it twice as slow. Generally, the more
bytecodes, the slower the code.

tests/bench/bench.py

+import time
+
+
+ITERS = 20000000
+
+def run(f):
+    t = time.time()
+    f(ITERS)
+    t = time.time() - t
+    print(t)

tests/bench/loop_count-1-range.py

+import bench
+
+def test(num):
+    for i in range(num):
+        pass
+
+bench.run(test)

tests/bench/loop_count-2-range_iter.py

+import bench
+
+def test(num):
+    for i in iter(range(num)):
+        pass
+
+bench.run(test)

tests/bench/loop_count-3-while_up.py

+import bench
+
+def test(num):
+    i = 0
+    while i < num:
+        i += 1
+
+bench.run(test)

tests/bench/loop_count-4-while_down_gt.py

+import bench
+
+def test(num):
+    while num > 0:
+        num -= 1
+
+bench.run(test)

tests/bench/loop_count-5-while_down_ne.py

+import bench
+
+def test(num):
+    while num != 0:
+        num -= 1
+
+bench.run(test)

tests/bench/var-1-constant.py

+import bench
+
+def test(num):
+    i = 0
+    while i < 20000000:
+        i += 1
+
+bench.run(test)

tests/bench/var-2-global.py

+import bench
+
+ITERS = 20000000
+
+def test(num):
+    i = 0
+    while i < ITERS:
+        i += 1
+
+bench.run(test)

tests/bench/var-3-local.py

+import bench
+
+
+def test(num):
+    ITERS = 20000000
+    i = 0
+    while i < ITERS:
+        i += 1
+
+bench.run(test)

tests/bench/var-4-arg.py

+import bench
+
+
+def test(num):
+    i = 0
+    while i < num:
+        i += 1
+
+bench.run(lambda n:test(20000000))

tests/run-bench-tests

+#! /usr/bin/env python3
+
+import os
+import subprocess
+import sys
+import argparse
+import re
+from glob import glob
+from collections import defaultdict
+
+# Tests require at least CPython 3.3. If your default python3 executable
+# is of lower version, you can point MICROPY_CPYTHON3 environment var
+# to the correct executable.
+if os.name == 'nt':
+    CPYTHON3 = os.getenv('MICROPY_CPYTHON3', 'python3.exe')
+    MICROPYTHON = os.getenv('MICROPY_MICROPYTHON', '../windows/micropython.exe')
+else:
+    CPYTHON3 = os.getenv('MICROPY_CPYTHON3', 'python3')
+    MICROPYTHON = os.getenv('MICROPY_MICROPYTHON', '../unix/micropython')
+
+def run_tests(pyb, test_dict):
+    test_count = 0
+    testcase_count = 0
+
+    for base_test, tests in test_dict.items():
+        print(base_test + ":")
+        for test_file in tests:
+
+            # run Micro Python
+            if pyb is None:
+                # run on PC
+                try:
+                    output_mupy = subprocess.check_output([MICROPYTHON, '-X', 'emit=bytecode', test_file[0]])
+                except subprocess.CalledProcessError:
+                    output_mupy = b'CRASH'
+            else:
+                # run on pyboard
+                pyb.enter_raw_repl()
+                try:
+                    output_mupy = pyb.execfile(test_file).replace(b'\r\n', b'\n')
+                except pyboard.PyboardError:
+                    output_mupy = b'CRASH'
+
+            output_mupy = float(output_mupy.strip())
+            test_file[1] = output_mupy
+            testcase_count += 1
+
+        test_count += 1
+        baseline = None
+        for t in tests:
+            if baseline is None:
+                baseline = t[1]
+            print("    %.3fs (%+06.2f%%) %s" % (t[1], (t[1] * 100 / baseline) - 100, t[0]))
+
+    print("{} tests performed ({} individual testcases)".format(test_count, testcase_count))
+
+    # all tests succeeded
+    return True
+
+def main():
+    cmd_parser = argparse.ArgumentParser(description='Run tests for Micro Python.')
+    cmd_parser.add_argument('--pyboard', action='store_true', help='run the tests on the pyboard')
+    cmd_parser.add_argument('files', nargs='*', help='input test files')
+    args = cmd_parser.parse_args()
+
+    # Note pyboard support is copied over from run-tests, not testes, and likely needs revamping
+    if args.pyboard:
+        import pyboard
+        pyb = pyboard.Pyboard('/dev/ttyACM0')
+        pyb.enter_raw_repl()
+    else:
+        pyb = None
+
+    if len(args.files) == 0:
+        if pyb is None:
+            # run PC tests
+            test_dirs = ('bench',)
+        else:
+            # run pyboard tests
+            test_dirs = ('basics', 'float', 'pyb')
+        tests = sorted(test_file for test_files in (glob('{}/*.py'.format(dir)) for dir in test_dirs) for test_file in test_files)
+    else:
+        # tests explicitly given
+        tests = sorted(args.files)
+
+    test_dict = defaultdict(lambda: [])
+    for t in tests:
+        m = re.match(r"(.+?)-(.+)\.py", t)
+        if not m:
+            continue
+        test_dict[m.group(1)].append([t, None])
+
+    if not run_tests(pyb, test_dict):
+        sys.exit(1)
+
+if __name__ == "__main__":
+    main()