py: Add support to save native, viper and asm code to .mpy files.

This commit adds support for saving and loading .mpy files that contain
native code (native, viper and inline-asm).  A lot of the ground work was
already done for this in the form of removing pointers from generated
native code.  The changes here are mainly to link in qstr values to the
native code, and change the format of .mpy files to contain native code
blocks (possibly mixed with bytecode).

A top-level summary:

- @micropython.native, @micropython.viper and @micropython.asm_thumb/
  asm_xtensa are now allowed in .py files when compiling to .mpy, and they
  work transparently to the user.

- Entire .py files can be compiled to native via mpy-cross -X emit=native
  and for the most part the generated .mpy files should work the same as
  their bytecode version.

- The .mpy file format is changed to 1) specify in the header if the file
  contains native code and if so the architecture (eg x86, ARMV7M, Xtensa);
  2) for each function block the kind of code is specified (bytecode,
  native, viper, asm).

- When native code is loaded from a .mpy file the native code must be
  modified (in place) to link qstr values in, just like bytecode (see
  py/persistentcode.c:arch_link_qstr() function).

In addition, this now defines a public, native ABI for dynamically loadable
native code generated by other languages, like C.

1 files changed, 11 insertions, 5 deletions

diff --git a/py/asmarm.c b/py/asmarm.c
index 3610f838e..f2221f8a9 100644
--- a/py/asmarm.c
+++ b/py/asmarm.c
@@ -197,7 +197,16 @@ void asm_arm_mov_reg_reg(asm_arm_t *as, uint reg_dest, uint reg_src) {
     emit_al(as, asm_arm_op_mov_reg(reg_dest, reg_src));
 }
 
-void asm_arm_mov_reg_i32(asm_arm_t *as, uint rd, int imm) {
+size_t asm_arm_mov_reg_i32(asm_arm_t *as, uint rd, int imm) {
+    // Insert immediate into code and jump over it
+    emit_al(as, 0x59f0000 | (rd << 12)); // ldr rd, [pc]
+    emit_al(as, 0xa000000); // b pc
+    size_t loc = mp_asm_base_get_code_pos(&as->base);
+    emit(as, imm);
+    return loc;
+}
+
+void asm_arm_mov_reg_i32_optimised(asm_arm_t *as, uint rd, int imm) {
     // TODO: There are more variants of immediate values
     if ((imm & 0xFF) == imm) {
         emit_al(as, asm_arm_op_mov_imm(rd, imm));
@@ -205,10 +214,7 @@ void asm_arm_mov_reg_i32(asm_arm_t *as, uint rd, int imm) {
         // mvn is "move not", not "move negative"
         emit_al(as, asm_arm_op_mvn_imm(rd, ~imm));
     } else {
-        //Insert immediate into code and jump over it
-        emit_al(as, 0x59f0000 | (rd << 12)); // ldr rd, [pc]
-        emit_al(as, 0xa000000); // b pc
-        emit(as, imm);
+        asm_arm_mov_reg_i32(as, rd, imm);
     }
 }