py: Split RAISE_VARARGS opcode into 3 separate ones.

From the beginning of this project the RAISE_VARARGS opcode was named and
implemented following CPython, where it has an argument (to the opcode)
counting how many args the raise takes:

    raise # 0 args (re-raise previous exception)
    raise exc # 1 arg
    raise exc from exc2 # 2 args (chained raise)

In the bytecode this operation therefore takes 2 bytes, one for
RAISE_VARARGS and one for the number of args.

This patch splits this opcode into 3, where each is now a single byte.
This reduces bytecode size by 1 byte for each use of raise.  Every byte
counts!  It also has the benefit of reducing code size (on all ports except
nanbox).

1 files changed, 3 insertions, 8 deletions

diff --git a/py/emitbc.c b/py/emitbc.c
index 83fcbae415..a8d57d27b0 100644
--- a/py/emitbc.c
+++ b/py/emitbc.c
@@ -193,13 +193,6 @@ STATIC void emit_write_bytecode_byte(emit_t *emit, int stack_adj, byte b1) {
     c[0] = b1;
 }
 
-STATIC void emit_write_bytecode_byte_byte(emit_t* emit, int stack_adj, byte b1, byte b2) {
-    mp_emit_bc_adjust_stack_size(emit, stack_adj);
-    byte *c = emit_get_cur_to_write_bytecode(emit, 2);
-    c[0] = b1;
-    c[1] = b2;
-}
-
 // Similar to emit_write_bytecode_uint(), just some extra handling to encode sign
 STATIC void emit_write_bytecode_byte_int(emit_t *emit, int stack_adj, byte b1, mp_int_t num) {
     emit_write_bytecode_byte(emit, stack_adj, b1);
@@ -848,8 +841,10 @@ void mp_emit_bc_return_value(emit_t *emit) {
 }
 
 void mp_emit_bc_raise_varargs(emit_t *emit, mp_uint_t n_args) {
+    MP_STATIC_ASSERT(MP_BC_RAISE_LAST + 1 == MP_BC_RAISE_OBJ);
+    MP_STATIC_ASSERT(MP_BC_RAISE_LAST + 2 == MP_BC_RAISE_FROM);
     assert(n_args <= 2);
-    emit_write_bytecode_byte_byte(emit, -n_args, MP_BC_RAISE_VARARGS, n_args);
+    emit_write_bytecode_byte(emit, -n_args, MP_BC_RAISE_LAST + n_args);
 }
 
 void mp_emit_bc_yield(emit_t *emit, int kind) {