py: Combine 3 comprehension opcodes (list/dict/set) into 1.

With the previous patch combining 3 emit functions into 1, it now makes
sense to also combine the corresponding VM opcodes, which is what this
patch does.  This eliminates 2 opcodes which simplifies the VM and reduces
code size, in bytes: bare-arm:44, minimal:64, unix(NDEBUG,x86-64):272,
stmhal:92, esp8266:200.  Profiling (with a simple script that creates many
list/dict/set comprehensions) shows no measurable change in performance.

py/bc0.h

@@ -82,13 +82,11 @@
 
 #define MP_BC_BUILD_TUPLE        (0x50) // uint
 #define MP_BC_BUILD_LIST         (0x51) // uint
-#define MP_BC_LIST_APPEND        (0x52) // uint
 #define MP_BC_BUILD_MAP          (0x53) // uint
 #define MP_BC_STORE_MAP          (0x54)
-#define MP_BC_MAP_ADD            (0x55) // uint
 #define MP_BC_BUILD_SET          (0x56) // uint
-#define MP_BC_SET_ADD            (0x57) // uint
 #define MP_BC_BUILD_SLICE        (0x58) // uint
+#define MP_BC_STORE_COMP         (0x57) // uint
 #define MP_BC_UNPACK_SEQUENCE    (0x59) // uint
 #define MP_BC_UNPACK_EX          (0x5a) // uint
 

py/emitbc.c

@@ -862,21 +862,21 @@ void mp_emit_bc_build_slice(emit_t *emit, mp_uint_t n_args) {
 #endif
 
 void mp_emit_bc_store_comp(emit_t *emit, scope_kind_t kind, mp_uint_t collection_stack_index) {
+    int t;
     int n;
-    byte opcode;
     if (kind == SCOPE_LIST_COMP) {
-        n = -1;
+        n = 0;
-        opcode = MP_BC_LIST_APPEND;
+        t = 0;
-    } else if (MICROPY_PY_BUILTINS_SET && kind == SCOPE_SET_COMP) {
+    } else if (!MICROPY_PY_BUILTINS_SET || kind == SCOPE_DICT_COMP) {
-        n = -1;
+        n = 1;
-        opcode = MP_BC_SET_ADD;
+        t = 1;
-    } else {
+    } else if (MICROPY_PY_BUILTINS_SET) {
-        // scope == SCOPE_DICT_COMP
+        n = 0;
-        n = -2;
+        t = 2;
-        opcode = MP_BC_MAP_ADD;
     }
-    emit_bc_pre(emit, n);
+    emit_bc_pre(emit, -1 - n);
-    emit_write_bytecode_byte_uint(emit, opcode, collection_stack_index);
+    // the lower 2 bits of the opcode argument indicate the collection type
+    emit_write_bytecode_byte_uint(emit, MP_BC_STORE_COMP, ((collection_stack_index + n) << 2) | t);
 }
 
 void mp_emit_bc_unpack_sequence(emit_t *emit, mp_uint_t n_args) {

py/showbc.c

@@ -409,11 +409,6 @@ const byte *mp_bytecode_print_str(const byte *ip) {
             printf("BUILD_LIST " UINT_FMT, unum);
             break;
 
-        case MP_BC_LIST_APPEND:
-            DECODE_UINT;
-            printf("LIST_APPEND " UINT_FMT, unum);
-            break;
-
         case MP_BC_BUILD_MAP:
             DECODE_UINT;
             printf("BUILD_MAP " UINT_FMT, unum);
@@ -423,21 +418,11 @@ const byte *mp_bytecode_print_str(const byte *ip) {
             printf("STORE_MAP");
             break;
 
-        case MP_BC_MAP_ADD:
-            DECODE_UINT;
-            printf("MAP_ADD " UINT_FMT, unum);
-            break;
-
         case MP_BC_BUILD_SET:
             DECODE_UINT;
             printf("BUILD_SET " UINT_FMT, unum);
             break;
 
-        case MP_BC_SET_ADD:
-            DECODE_UINT;
-            printf("SET_ADD " UINT_FMT, unum);
-            break;
-
 #if MICROPY_PY_BUILTINS_SLICE
         case MP_BC_BUILD_SLICE:
             DECODE_UINT;
@@ -445,6 +430,11 @@ const byte *mp_bytecode_print_str(const byte *ip) {
             break;
 #endif
 
+        case MP_BC_STORE_COMP:
+            DECODE_UINT;
+            printf("STORE_COMP " UINT_FMT, unum);
+            break;
+
         case MP_BC_UNPACK_SEQUENCE:
             DECODE_UINT;
             printf("UNPACK_SEQUENCE " UINT_FMT, unum);

py/vm.c

@@ -777,15 +777,6 @@ unwind_jump:;
                     DISPATCH();
                 }
 
-                ENTRY(MP_BC_LIST_APPEND): {
-                    MARK_EXC_IP_SELECTIVE();
-                    DECODE_UINT;
-                    // I think it's guaranteed by the compiler that sp[unum] is a list
-                    mp_obj_list_append(sp[-unum], sp[0]);
-                    sp--;
-                    DISPATCH();
-                }
-
                 ENTRY(MP_BC_BUILD_MAP): {
                     MARK_EXC_IP_SELECTIVE();
                     DECODE_UINT;
@@ -799,15 +790,6 @@ unwind_jump:;
                     mp_obj_dict_store(sp[0], sp[2], sp[1]);
                     DISPATCH();
 
-                ENTRY(MP_BC_MAP_ADD): {
-                    MARK_EXC_IP_SELECTIVE();
-                    DECODE_UINT;
-                    // I think it's guaranteed by the compiler that sp[-unum - 1] is a map
-                    mp_obj_dict_store(sp[-unum - 1], sp[0], sp[-1]);
-                    sp -= 2;
-                    DISPATCH();
-                }
-
 #if MICROPY_PY_BUILTINS_SET
                 ENTRY(MP_BC_BUILD_SET): {
                     MARK_EXC_IP_SELECTIVE();
@@ -816,15 +798,6 @@ unwind_jump:;
                     SET_TOP(mp_obj_new_set(unum, sp));
                     DISPATCH();
                 }
-
-                ENTRY(MP_BC_SET_ADD): {
-                    MARK_EXC_IP_SELECTIVE();
-                    DECODE_UINT;
-                    // I think it's guaranteed by the compiler that sp[-unum] is a set
-                    mp_obj_set_store(sp[-unum], sp[0]);
-                    sp--;
-                    DISPATCH();
-                }
 #endif
 
 #if MICROPY_PY_BUILTINS_SLICE
@@ -845,6 +818,25 @@ unwind_jump:;
                 }
 #endif
 
+                ENTRY(MP_BC_STORE_COMP): {
+                    MARK_EXC_IP_SELECTIVE();
+                    DECODE_UINT;
+                    mp_obj_t obj = sp[-(unum >> 2)];
+                    if ((unum & 3) == 0) {
+                        mp_obj_list_append(obj, sp[0]);
+                        sp--;
+                    } else if (!MICROPY_PY_BUILTINS_SET || (unum & 3) == 1) {
+                        mp_obj_dict_store(obj, sp[0], sp[-1]);
+                        sp -= 2;
+                    #if MICROPY_PY_BUILTINS_SET
+                    } else {
+                        mp_obj_set_store(obj, sp[0]);
+                        sp--;
+                    #endif
+                    }
+                    DISPATCH();
+                }
+
                 ENTRY(MP_BC_UNPACK_SEQUENCE): {
                     MARK_EXC_IP_SELECTIVE();
                     DECODE_UINT;

py/vmentrytable.h

@@ -78,17 +78,15 @@ static const void *const entry_table[256] = {
     [MP_BC_POP_EXCEPT] = &&entry_MP_BC_POP_EXCEPT,
     [MP_BC_BUILD_TUPLE] = &&entry_MP_BC_BUILD_TUPLE,
     [MP_BC_BUILD_LIST] = &&entry_MP_BC_BUILD_LIST,
-    [MP_BC_LIST_APPEND] = &&entry_MP_BC_LIST_APPEND,
     [MP_BC_BUILD_MAP] = &&entry_MP_BC_BUILD_MAP,
     [MP_BC_STORE_MAP] = &&entry_MP_BC_STORE_MAP,
-    [MP_BC_MAP_ADD] = &&entry_MP_BC_MAP_ADD,
     #if MICROPY_PY_BUILTINS_SET
     [MP_BC_BUILD_SET] = &&entry_MP_BC_BUILD_SET,
-    [MP_BC_SET_ADD] = &&entry_MP_BC_SET_ADD,
     #endif
     #if MICROPY_PY_BUILTINS_SLICE
     [MP_BC_BUILD_SLICE] = &&entry_MP_BC_BUILD_SLICE,
     #endif
+    [MP_BC_STORE_COMP] = &&entry_MP_BC_STORE_COMP,
     [MP_BC_UNPACK_SEQUENCE] = &&entry_MP_BC_UNPACK_SEQUENCE,
     [MP_BC_UNPACK_EX] = &&entry_MP_BC_UNPACK_EX,
     [MP_BC_MAKE_FUNCTION] = &&entry_MP_BC_MAKE_FUNCTION,