mpy-cross/main: Add support for RV32 Zba opcodes.

This commit adds a new command line switch to inform the RV32 emitter to
use Zba opcodes in its output.

A new implementation-specific option was introduced, called
"-march-flags", that will contain a list of additional
architecture-specific flags to pass to the chosen native emitter
implementation.

At the moment only the RV32 emitter can make use of this command line
facility: if the architecture flags string equals to "zba"
(case-sensitive), then the native emitter will emit Zba opcodes if it
has a chance to do so.

At the moment there is no check on whether additional architecture flags
using to build a MPY file are compatible with the target the output code
is run on, so use this with caution.

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

1 files changed, 33 insertions, 0 deletions

diff --git a/mpy-cross/main.c b/mpy-cross/main.c
index 63a74d084..9dcad3c5d 100644
--- a/mpy-cross/main.c
+++ b/mpy-cross/main.c
@@ -40,6 +40,12 @@
 #include "ports/windows/fmode.h"
 #endif
 
+#if MICROPY_EMIT_NATIVE && MICROPY_EMIT_RV32
+#include "py/asmrv32.h"
+
+static asm_rv32_backend_options_t rv32_options = { 0 };
+#endif
+
 // Command line options, with their defaults
 static uint emit_opt = MP_EMIT_OPT_NONE;
 mp_uint_t mp_verbose_flag = 0;
@@ -132,6 +138,8 @@ static int usage(char **argv) {
         "-march=<arch> : set architecture for native emitter;\n"
         "                x86, x64, armv6, armv6m, armv7m, armv7em, armv7emsp,\n"
         "                armv7emdp, xtensa, xtensawin, rv32imc, rv64imc, host, debug\n"
+        "-march-flags=<flags> : set architecture-specific flags (OUTPUT FILE MAY NOT WORK ON ALL TARGETS!)\n"
+        "                       supported flags for rv32imc: zba\n"
         "\n"
         "Implementation specific options:\n", argv[0]
         );
@@ -237,11 +245,13 @@ MP_NOINLINE int main_(int argc, char **argv) {
     // don't support native emitter unless -march is specified
     mp_dynamic_compiler.native_arch = MP_NATIVE_ARCH_NONE;
     mp_dynamic_compiler.nlr_buf_num_regs = 0;
+    mp_dynamic_compiler.backend_options = NULL;
 
     const char *input_file = NULL;
     const char *output_file = NULL;
     const char *source_file = NULL;
     bool option_parsing_active = true;
+    const char *arch_flags = NULL;
 
     // parse main options
     for (int a = 1; a < argc; a++) {
@@ -343,6 +353,8 @@ MP_NOINLINE int main_(int argc, char **argv) {
                 } else {
                     return usage(argv);
                 }
+            } else if (strncmp(argv[a], "-march-flags=", sizeof("-march-flags=") - 1) == 0) {
+                arch_flags = argv[a] + sizeof("-march-flags=") - 1;
             } else if (strcmp(argv[a], "--") == 0) {
                 option_parsing_active = false;
             } else {
@@ -357,6 +369,27 @@ MP_NOINLINE int main_(int argc, char **argv) {
         }
     }
 
+    if (arch_flags && mp_dynamic_compiler.native_arch != MP_NATIVE_ARCH_NONE) {
+        bool processed = false;
+        #if MICROPY_EMIT_NATIVE && MICROPY_EMIT_RV32
+        if (mp_dynamic_compiler.native_arch == MP_NATIVE_ARCH_RV32IMC) {
+            mp_dynamic_compiler.backend_options = (void *)&rv32_options;
+            if (strncmp(arch_flags, "zba", sizeof("zba") - 1) == 0) {
+                rv32_options.allowed_extensions |= RV32_EXT_ZBA;
+                processed = true;
+            }
+        }
+        #endif
+        if (!processed) {
+            mp_printf(&mp_stderr_print, "unrecognised arch flags\n");
+            exit(1);
+        }
+        mp_printf(&mp_stderr_print,
+            "WARNING: Using architecture-specific flags may create a MPY file whose code won't run on all targets!\n"
+            "         Currently there are no checks in the module file loader for whether the chosen flags used to\n"
+            "         build the MPY file are compatible with the running target.\n\n");
+    }
+
     #if MICROPY_EMIT_NATIVE
     if ((MP_STATE_VM(default_emit_opt) == MP_EMIT_OPT_NATIVE_PYTHON
          || MP_STATE_VM(default_emit_opt) == MP_EMIT_OPT_VIPER)