tests/run-natmodtests.py: Autodetect the test target architecture.

This commit lets the natmod tests runner to automatically detect the
architecture of the test target.  This allows to avoid to explicitly
pass the architecture name to the runner in test scripts.

However, the ability to manually specify a target was not removed but it
was made optional.  This way the user is able to override the
architecture name if needed (like if one wants to test an armv6 MPY on
an armv7 board).

Signed-off-by: Alessandro Gatti <a.gatti@frob.it>

ports/qemu/README.md

@@ -105,9 +105,7 @@ can also be tested with this command (this is currently supported only for the
     $ make test_natmod
 
 The same remarks about manually running the tests apply for native modules, but
-`run-natmodtests.py` should be run instead of `run-tests.py`.  In this case you
-also have to explicitly pass the architecture you are running native modules to
-`run-natmodtests.py` ("--arch rv32imc" for the `VIRT_RV32` board).
+`run-natmodtests.py` should be run instead of `run-tests.py`.
 
 Extra make options
 ------------------

ports/qemu/boards/VIRT_RV32/mpconfigboard.mk

@@ -9,5 +9,3 @@ LDSCRIPT = mcu/rv32/virt.ld
 SRC_BOARD_O += shared/runtime/gchelper_native.o shared/runtime/gchelper_rv32i.o
 
 MPY_CROSS_FLAGS += -march=rv32imc
-
-RUN_NATMODTESTS_ARGS = --arch rv32imc

tests/run-natmodtests.py

@@ -28,6 +28,23 @@ TEST_MAPPINGS = {
     "re": "re/re_$(ARCH).mpy",
 }
 
+# Supported architectures for native mpy modules
+AVAILABLE_ARCHS = (
+    "x86",
+    "x64",
+    "armv6",
+    "armv6m",
+    "armv7m",
+    "armv7em",
+    "armv7emsp",
+    "armv7emdp",
+    "xtensa",
+    "xtensawin",
+    "rv32imc",
+)
+
+ARCH_MAPPINGS = {"armv7em": "armv7m"}
+
 # Code to allow a target MicroPython to import an .mpy from RAM
 injected_import_hook_code = """\
 import sys, io, vfs
@@ -96,14 +113,33 @@ class TargetPyboard:
             return b"", er
 
 
-def run_tests(target_truth, target, args, stats):
+def detect_architecture(target):
+    with open("./feature_check/target_info.py", "rb") as f:
+        target_info_data = f.read()
+        result_out, error = target.run_script(target_info_data)
+        if error is not None:
+            return None, None, error
+        info = result_out.split(b" ")
+        if len(info) < 2:
+            return None, None, "unexpected target info: {}".format(info)
+        platform = info[0].strip().decode()
+        arch = info[1].strip().decode()
+        if arch not in AVAILABLE_ARCHS:
+            if arch == "None":
+                return None, None, "the target does not support dynamic modules"
+            else:
+                return None, None, "{} is not a supported architecture".format(arch)
+        return platform, arch, None
+
+
+def run_tests(target_truth, target, args, stats, resolved_arch):
     for test_file in args.files:
         # Find supported test
         test_file_basename = os.path.basename(test_file)
         for k, v in TEST_MAPPINGS.items():
             if test_file_basename.startswith(k):
                 test_module = k
-                test_mpy = v.replace("$(ARCH)", args.arch)
+                test_mpy = v.replace("$(ARCH)", resolved_arch)
                 break
         else:
             print("----  {} - no matching mpy".format(test_file))
@@ -174,7 +210,7 @@ def main():
         "-d", "--device", default="/dev/ttyACM0", help="the device for pyboard.py"
     )
     cmd_parser.add_argument(
-        "-a", "--arch", default="x64", help="native architecture of the target"
+        "-a", "--arch", choices=AVAILABLE_ARCHS, help="override native architecture of the target"
     )
     cmd_parser.add_argument("files", nargs="*", help="input test files")
     args = cmd_parser.parse_args()
@@ -186,8 +222,22 @@ def main():
     else:
         target = TargetSubprocess([MICROPYTHON])
 
+    if hasattr(args, "arch") and args.arch is not None:
+        target_arch = args.arch
+        target_platform = None
+    else:
+        target_platform, target_arch, error = detect_architecture(target)
+        if error:
+            print("Cannot run tests: {}".format(error))
+            sys.exit(1)
+    target_arch = ARCH_MAPPINGS.get(target_arch, target_arch)
+
+    if target_platform:
+        print("platform={} ".format(target_platform), end="")
+    print("arch={}".format(target_arch))
+
     stats = {"total": 0, "pass": 0, "fail": 0, "skip": 0}
-    run_tests(target_truth, target, args, stats)
+    run_tests(target_truth, target, args, stats, target_arch)
 
     target.close()
     target_truth.close()