py/modsys: Add architecture flags to MicroPython metadata.

This commit adds the currently supported architecture flags value as the
upper part of "sys.implementation._mpy".

This had the side effect of perturbing quite a bit of testing
infrastructure and invalidating documentation related to MPY files.  To
make the test suite run successfully and keep the documentation in sync
the following changes have been made:

* The target info feature check file now isolates eventual architecture
  flags and adds them as a separate field
* The test runner now picks up the new architecture flags field, reports
  it to STDOUT if needed and stores it for future uses
* Relevant test files for MPY files import code had to be updated to
  mask out the architecture flags bits in order to perform correctly
* MPY file format documentation was updated to show how to mask off and
  properly display the architecture flags information.

This works out of the box if the flag bits can fit in a smallint value
once merged with the MPY file header value.

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

7 files changed, 27 insertions, 12 deletions

diff --git a/docs/reference/mpyfiles.rst b/docs/reference/mpyfiles.rst
index 9687f5e46..58e45e158 100644
--- a/docs/reference/mpyfiles.rst
+++ b/docs/reference/mpyfiles.rst
@@ -58,12 +58,14 @@ If importing an .mpy file fails then try the following:
     sys_mpy = sys.implementation._mpy
     arch = [None, 'x86', 'x64',
         'armv6', 'armv6m', 'armv7m', 'armv7em', 'armv7emsp', 'armv7emdp',
-        'xtensa', 'xtensawin', 'rv32imc', 'rv64imc'][sys_mpy >> 10]
+        'xtensa', 'xtensawin', 'rv32imc', 'rv64imc'][(sys_mpy >> 10) & 0x0F]
     print('mpy version:', sys_mpy & 0xff)
     print('mpy sub-version:', sys_mpy >> 8 & 3)
     print('mpy flags:', end='')
     if arch:
         print(' -march=' + arch, end='')
+    if (sys_mpy >> 16) != 0:
+        print(' -march-flags=' + (sys_mpy >> 16), end='')
     print()
 
 * Check the validity of the .mpy file by inspecting the first two bytes of
diff --git a/py/asmrv32.h b/py/asmrv32.h
index 4456e6119..6f709daa1 100644
--- a/py/asmrv32.h
+++ b/py/asmrv32.h
@@ -709,11 +709,11 @@ static inline void asm_rv32_opcode_xori(asm_rv32_t *state, mp_uint_t rd, mp_uint
     asm_rv32_emit_word_opcode(state, RV32_ENCODE_TYPE_I(0x13, 0x04, rd, rs, immediate));
 }
 
+#define MICROPY_RV32_EXTENSIONS \
+    (MICROPY_EMIT_RV32_ZBA ? RV32_EXT_ZBA : 0)
+
 static inline uint8_t asm_rv32_allowed_extensions(void) {
-    uint8_t extensions = 0;
-    #if MICROPY_EMIT_RV32_ZBA
-    extensions |= RV32_EXT_ZBA;
-    #endif
+    uint8_t extensions = MICROPY_RV32_EXTENSIONS;
     #if MICROPY_DYNAMIC_COMPILER
     if (mp_dynamic_compiler.backend_options != NULL) {
         extensions |= ((asm_rv32_backend_options_t *)mp_dynamic_compiler.backend_options)->allowed_extensions;
diff --git a/py/modsys.c b/py/modsys.c
index ef6273fc8..3dae92681 100644
--- a/py/modsys.c
+++ b/py/modsys.c
@@ -85,8 +85,16 @@ static const MP_DEFINE_STR_OBJ(mp_sys_implementation_machine_obj, MICROPY_BANNER
     MP_ROM_PTR(&mp_sys_implementation_machine_obj)
 
 #if MICROPY_PERSISTENT_CODE_LOAD
+// Note: Adding architecture flags to _mpy will break if the flags information
+//       takes up more bits than what is available in a small-int value.
+#if MICROPY_EMIT_RV32
+#include "py/asmrv32.h"
+#define MPY_FILE_ARCH_FLAGS (MICROPY_RV32_EXTENSIONS << 16)
+#else
+#define MPY_FILE_ARCH_FLAGS (0)
+#endif
 #define SYS_IMPLEMENTATION_ELEMS__MPY \
-    , MP_ROM_INT(MPY_FILE_HEADER_INT)
+    , MP_ROM_INT(MPY_FILE_HEADER_INT | MPY_FILE_ARCH_FLAGS)
 #else
 #define SYS_IMPLEMENTATION_ELEMS__MPY
 #endif
diff --git a/tests/feature_check/target_info.py b/tests/feature_check/target_info.py
index 35a995a15..e95530023 100644
--- a/tests/feature_check/target_info.py
+++ b/tests/feature_check/target_info.py
@@ -20,7 +20,8 @@ arch = [
     "xtensawin",
     "rv32imc",
     "rv64imc",
-][sys_mpy >> 10]
+][(sys_mpy >> 10) & 0x0F]
+arch_flags = sys_mpy >> 16
 build = getattr(sys.implementation, "_build", "unknown")
 thread = getattr(sys.implementation, "_thread", None)
 
@@ -35,4 +36,4 @@ try:
 except NameError:
     float_prec = 0
 
-print(platform, arch, build, thread, float_prec, len("α") == 1)
+print(platform, arch, arch_flags, build, thread, float_prec, len("α") == 1)
diff --git a/tests/micropython/import_mpy_native.py b/tests/micropython/import_mpy_native.py
index 7a9bb8edd..b7908b5a6 100644
--- a/tests/micropython/import_mpy_native.py
+++ b/tests/micropython/import_mpy_native.py
@@ -54,11 +54,11 @@ class UserFS:
 
 # these are the test .mpy files
 small_int_bits = 30
-valid_header = bytes([77, 6, mpy_arch, small_int_bits])
+valid_header = bytes([77, 6, (mpy_arch & 0x3F), small_int_bits])
 # fmt: off
 user_files = {
     # bad architecture (mpy_arch needed for sub-version)
-    '/mod0.mpy': bytes([77, 6, 0xfc | mpy_arch, small_int_bits]),
+    '/mod0.mpy': bytes([77, 6, 0xfc | (mpy_arch & 3), small_int_bits]),
 
     # test loading of viper and asm
     '/mod1.mpy': valid_header + (
diff --git a/tests/micropython/import_mpy_native_gc.py b/tests/micropython/import_mpy_native_gc.py
index 851eb3922..997e052fd 100644
--- a/tests/micropython/import_mpy_native_gc.py
+++ b/tests/micropython/import_mpy_native_gc.py
@@ -67,7 +67,7 @@ for arch in (0x1406, 0x1806, 0x1C06, 0x2006):
     features0_file_contents[arch] = features0_file_contents[0x1006]
 
 # Check that a .mpy exists for the target (ignore sub-version in lookup).
-sys_implementation_mpy = sys.implementation._mpy & ~(3 << 8)
+sys_implementation_mpy = (sys.implementation._mpy & ~(3 << 8)) & 0xFFFF
 if sys_implementation_mpy not in features0_file_contents:
     print("SKIP")
     raise SystemExit
diff --git a/tests/run-tests.py b/tests/run-tests.py
index b55bd8e49..f184203a8 100755
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -387,7 +387,9 @@ def detect_test_platform(pyb, args):
     output = run_feature_check(pyb, args, "target_info.py")
     if output.endswith(b"CRASH"):
         raise ValueError("cannot detect platform: {}".format(output))
-    platform, arch, build, thread, float_prec, unicode = str(output, "ascii").strip().split()
+    platform, arch, arch_flags, build, thread, float_prec, unicode = (
+        str(output, "ascii").strip().split()
+    )
     if arch == "None":
         arch = None
     inlineasm_arch = detect_inline_asm_arch(pyb, args)
@@ -400,6 +402,7 @@ def detect_test_platform(pyb, args):
     args.arch = arch
     if arch and not args.mpy_cross_flags:
         args.mpy_cross_flags = "-march=" + arch
+    args.arch_flags = arch_flags
     args.inlineasm_arch = inlineasm_arch
     args.build = build
     args.thread = thread
@@ -410,6 +413,7 @@ def detect_test_platform(pyb, args):
     print("platform={}".format(platform), end="")
     if arch:
         print(" arch={}".format(arch), end="")
+        print(" arch_flags={}".format(arch_flags), end="")
     if inlineasm_arch:
         print(" inlineasm={}".format(inlineasm_arch), end="")
     if thread: