py: Remove mp_load_const_bytes and instead load precreated bytes object.

Previous to this patch each time a bytes object was referenced a new
instance (with the same data) was created.  With this patch a single
bytes object is created in the compiler and is loaded directly at execute
time as a true constant (similar to loading bignum and float objects).
This saves on allocating RAM and means that bytes objects can now be
used when the memory manager is locked (eg in interrupts).

The MP_BC_LOAD_CONST_BYTES bytecode was removed as part of this.

Generated bytecode is slightly larger due to storing a pointer to the
bytes object instead of the qstr identifier.

Code size is reduced by about 60 bytes on Thumb2 architectures.

1 files changed, 3 insertions, 6 deletions

diff --git a/py/emitcpy.c b/py/emitcpy.c
index dc96c529fb..3bdec1716d 100644
--- a/py/emitcpy.c
+++ b/py/emitcpy.c
@@ -176,7 +176,7 @@ STATIC void emit_cpy_load_const_small_int(emit_t *emit, mp_int_t arg) {
     }
 }
 
-STATIC void print_quoted_str(qstr qst, bool bytes) {
+STATIC void print_quoted_str(qstr qst) {
     const char *str = qstr_str(qst);
     int len = strlen(str);
     bool has_single_quote = false;
@@ -188,9 +188,6 @@ STATIC void print_quoted_str(qstr qst, bool bytes) {
             has_double_quote = true;
         }
     }
-    if (bytes) {
-        printf("b");
-    }
     int quote_char = '\'';
     if (has_single_quote && !has_double_quote) {
         quote_char = '"';
@@ -213,11 +210,11 @@ STATIC void print_quoted_str(qstr qst, bool bytes) {
     printf("%c", quote_char);
 }
 
-STATIC void emit_cpy_load_const_str(emit_t *emit, qstr qst, bool bytes) {
+STATIC void emit_cpy_load_const_str(emit_t *emit, qstr qst) {
     emit_pre(emit, 1, 3);
     if (emit->pass == MP_PASS_EMIT) {
         printf("LOAD_CONST ");
-        print_quoted_str(qst, bytes);
+        print_quoted_str(qst);
         printf("\n");
     }
 }