vm: cut vmentrytable size

This also adds a bit of code everywhere we DISPATCH(), but the net is
+232 bytes free on Feather M0 Adalogger.

Key assumption: All of the offsets in mp_execute_bytecode fit in 16 bits;
it is not clear whether the compiler will verify this assumption (e.g.,
by warning that a constant will be truncated)

2 files changed, 81 insertions, 79 deletions

diff --git a/py/vm.c b/py/vm.c
index 13a9980aa..c7b50b81c 100644
--- a/py/vm.c
+++ b/py/vm.c
@@ -132,7 +132,7 @@ mp_vm_return_kind_t PLACE_IN_ITCM(mp_execute_bytecode)(mp_code_state_t *code_sta
     #define DISPATCH() do { \
         TRACE(ip); \
         MARK_EXC_IP_GLOBAL(); \
-        goto *entry_table[*ip++]; \
+        goto *(void*)((char*)&&entry_MP_BC_LOAD_CONST_FALSE + entry_table[*ip++]); \
     } while (0)
     #define DISPATCH_WITH_PEND_EXC_CHECK() goto pending_exception_check
     #define ENTRY(op) entry_##op
diff --git a/py/vmentrytable.h b/py/vmentrytable.h
index e01199eee..8d9f00ad8 100644
--- a/py/vmentrytable.h
+++ b/py/vmentrytable.h
@@ -31,88 +31,90 @@
 
 #include "supervisor/linker.h"
 
-static const void *const PLACE_IN_DTCM_DATA(entry_table[256]) = {
-    [0 ... 255] = &&entry_default,
-    [MP_BC_LOAD_CONST_FALSE] = &&entry_MP_BC_LOAD_CONST_FALSE,
-    [MP_BC_LOAD_CONST_NONE] = &&entry_MP_BC_LOAD_CONST_NONE,
-    [MP_BC_LOAD_CONST_TRUE] = &&entry_MP_BC_LOAD_CONST_TRUE,
-    [MP_BC_LOAD_CONST_SMALL_INT] = &&entry_MP_BC_LOAD_CONST_SMALL_INT,
-    [MP_BC_LOAD_CONST_STRING] = &&entry_MP_BC_LOAD_CONST_STRING,
-    [MP_BC_LOAD_CONST_OBJ] = &&entry_MP_BC_LOAD_CONST_OBJ,
-    [MP_BC_LOAD_NULL] = &&entry_MP_BC_LOAD_NULL,
-    [MP_BC_LOAD_FAST_N] = &&entry_MP_BC_LOAD_FAST_N,
-    [MP_BC_LOAD_DEREF] = &&entry_MP_BC_LOAD_DEREF,
-    [MP_BC_LOAD_NAME] = &&entry_MP_BC_LOAD_NAME,
-    [MP_BC_LOAD_GLOBAL] = &&entry_MP_BC_LOAD_GLOBAL,
-    [MP_BC_LOAD_ATTR] = &&entry_MP_BC_LOAD_ATTR,
-    [MP_BC_LOAD_METHOD] = &&entry_MP_BC_LOAD_METHOD,
-    [MP_BC_LOAD_SUPER_METHOD] = &&entry_MP_BC_LOAD_SUPER_METHOD,
-    [MP_BC_LOAD_BUILD_CLASS] = &&entry_MP_BC_LOAD_BUILD_CLASS,
-    [MP_BC_LOAD_SUBSCR] = &&entry_MP_BC_LOAD_SUBSCR,
-    [MP_BC_STORE_FAST_N] = &&entry_MP_BC_STORE_FAST_N,
-    [MP_BC_STORE_DEREF] = &&entry_MP_BC_STORE_DEREF,
-    [MP_BC_STORE_NAME] = &&entry_MP_BC_STORE_NAME,
-    [MP_BC_STORE_GLOBAL] = &&entry_MP_BC_STORE_GLOBAL,
-    [MP_BC_STORE_ATTR] = &&entry_MP_BC_STORE_ATTR,
-    [MP_BC_STORE_SUBSCR] = &&entry_MP_BC_STORE_SUBSCR,
-    [MP_BC_DELETE_FAST] = &&entry_MP_BC_DELETE_FAST,
-    [MP_BC_DELETE_DEREF] = &&entry_MP_BC_DELETE_DEREF,
-    [MP_BC_DELETE_NAME] = &&entry_MP_BC_DELETE_NAME,
-    [MP_BC_DELETE_GLOBAL] = &&entry_MP_BC_DELETE_GLOBAL,
-    [MP_BC_DUP_TOP] = &&entry_MP_BC_DUP_TOP,
-    [MP_BC_DUP_TOP_TWO] = &&entry_MP_BC_DUP_TOP_TWO,
-    [MP_BC_POP_TOP] = &&entry_MP_BC_POP_TOP,
-    [MP_BC_ROT_TWO] = &&entry_MP_BC_ROT_TWO,
-    [MP_BC_ROT_THREE] = &&entry_MP_BC_ROT_THREE,
-    [MP_BC_JUMP] = &&entry_MP_BC_JUMP,
-    [MP_BC_POP_JUMP_IF_TRUE] = &&entry_MP_BC_POP_JUMP_IF_TRUE,
-    [MP_BC_POP_JUMP_IF_FALSE] = &&entry_MP_BC_POP_JUMP_IF_FALSE,
-    [MP_BC_JUMP_IF_TRUE_OR_POP] = &&entry_MP_BC_JUMP_IF_TRUE_OR_POP,
-    [MP_BC_JUMP_IF_FALSE_OR_POP] = &&entry_MP_BC_JUMP_IF_FALSE_OR_POP,
-    [MP_BC_SETUP_WITH] = &&entry_MP_BC_SETUP_WITH,
-    [MP_BC_WITH_CLEANUP] = &&entry_MP_BC_WITH_CLEANUP,
-    [MP_BC_UNWIND_JUMP] = &&entry_MP_BC_UNWIND_JUMP,
-    [MP_BC_SETUP_EXCEPT] = &&entry_MP_BC_SETUP_EXCEPT,
-    [MP_BC_SETUP_FINALLY] = &&entry_MP_BC_SETUP_FINALLY,
-    [MP_BC_END_FINALLY] = &&entry_MP_BC_END_FINALLY,
-    [MP_BC_GET_ITER] = &&entry_MP_BC_GET_ITER,
-    [MP_BC_GET_ITER_STACK] = &&entry_MP_BC_GET_ITER_STACK,
-    [MP_BC_FOR_ITER] = &&entry_MP_BC_FOR_ITER,
-    [MP_BC_POP_BLOCK] = &&entry_MP_BC_POP_BLOCK,
-    [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_BUILD_MAP] = &&entry_MP_BC_BUILD_MAP,
-    [MP_BC_STORE_MAP] = &&entry_MP_BC_STORE_MAP,
+#define COMPUTE_ENTRY(x) ((char*)(x) - (char*)&&entry_MP_BC_LOAD_CONST_FALSE)
+
+static int16_t const PLACE_IN_DTCM_DATA(entry_table[256]) = {
+    [0 ... 255] = COMPUTE_ENTRY(&&entry_default),
+    [MP_BC_LOAD_CONST_FALSE] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_CONST_FALSE),
+    [MP_BC_LOAD_CONST_NONE] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_CONST_NONE),
+    [MP_BC_LOAD_CONST_TRUE] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_CONST_TRUE),
+    [MP_BC_LOAD_CONST_SMALL_INT] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_CONST_SMALL_INT),
+    [MP_BC_LOAD_CONST_STRING] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_CONST_STRING),
+    [MP_BC_LOAD_CONST_OBJ] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_CONST_OBJ),
+    [MP_BC_LOAD_NULL] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_NULL),
+    [MP_BC_LOAD_FAST_N] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_FAST_N),
+    [MP_BC_LOAD_DEREF] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_DEREF),
+    [MP_BC_LOAD_NAME] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_NAME),
+    [MP_BC_LOAD_GLOBAL] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_GLOBAL),
+    [MP_BC_LOAD_ATTR] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_ATTR),
+    [MP_BC_LOAD_METHOD] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_METHOD),
+    [MP_BC_LOAD_SUPER_METHOD] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_SUPER_METHOD),
+    [MP_BC_LOAD_BUILD_CLASS] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_BUILD_CLASS),
+    [MP_BC_LOAD_SUBSCR] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_SUBSCR),
+    [MP_BC_STORE_FAST_N] = COMPUTE_ENTRY(&&entry_MP_BC_STORE_FAST_N),
+    [MP_BC_STORE_DEREF] = COMPUTE_ENTRY(&&entry_MP_BC_STORE_DEREF),
+    [MP_BC_STORE_NAME] = COMPUTE_ENTRY(&&entry_MP_BC_STORE_NAME),
+    [MP_BC_STORE_GLOBAL] = COMPUTE_ENTRY(&&entry_MP_BC_STORE_GLOBAL),
+    [MP_BC_STORE_ATTR] = COMPUTE_ENTRY(&&entry_MP_BC_STORE_ATTR),
+    [MP_BC_STORE_SUBSCR] = COMPUTE_ENTRY(&&entry_MP_BC_STORE_SUBSCR),
+    [MP_BC_DELETE_FAST] = COMPUTE_ENTRY(&&entry_MP_BC_DELETE_FAST),
+    [MP_BC_DELETE_DEREF] = COMPUTE_ENTRY(&&entry_MP_BC_DELETE_DEREF),
+    [MP_BC_DELETE_NAME] = COMPUTE_ENTRY(&&entry_MP_BC_DELETE_NAME),
+    [MP_BC_DELETE_GLOBAL] = COMPUTE_ENTRY(&&entry_MP_BC_DELETE_GLOBAL),
+    [MP_BC_DUP_TOP] = COMPUTE_ENTRY(&&entry_MP_BC_DUP_TOP),
+    [MP_BC_DUP_TOP_TWO] = COMPUTE_ENTRY(&&entry_MP_BC_DUP_TOP_TWO),
+    [MP_BC_POP_TOP] = COMPUTE_ENTRY(&&entry_MP_BC_POP_TOP),
+    [MP_BC_ROT_TWO] = COMPUTE_ENTRY(&&entry_MP_BC_ROT_TWO),
+    [MP_BC_ROT_THREE] = COMPUTE_ENTRY(&&entry_MP_BC_ROT_THREE),
+    [MP_BC_JUMP] = COMPUTE_ENTRY(&&entry_MP_BC_JUMP),
+    [MP_BC_POP_JUMP_IF_TRUE] = COMPUTE_ENTRY(&&entry_MP_BC_POP_JUMP_IF_TRUE),
+    [MP_BC_POP_JUMP_IF_FALSE] = COMPUTE_ENTRY(&&entry_MP_BC_POP_JUMP_IF_FALSE),
+    [MP_BC_JUMP_IF_TRUE_OR_POP] = COMPUTE_ENTRY(&&entry_MP_BC_JUMP_IF_TRUE_OR_POP),
+    [MP_BC_JUMP_IF_FALSE_OR_POP] = COMPUTE_ENTRY(&&entry_MP_BC_JUMP_IF_FALSE_OR_POP),
+    [MP_BC_SETUP_WITH] = COMPUTE_ENTRY(&&entry_MP_BC_SETUP_WITH),
+    [MP_BC_WITH_CLEANUP] = COMPUTE_ENTRY(&&entry_MP_BC_WITH_CLEANUP),
+    [MP_BC_UNWIND_JUMP] = COMPUTE_ENTRY(&&entry_MP_BC_UNWIND_JUMP),
+    [MP_BC_SETUP_EXCEPT] = COMPUTE_ENTRY(&&entry_MP_BC_SETUP_EXCEPT),
+    [MP_BC_SETUP_FINALLY] = COMPUTE_ENTRY(&&entry_MP_BC_SETUP_FINALLY),
+    [MP_BC_END_FINALLY] = COMPUTE_ENTRY(&&entry_MP_BC_END_FINALLY),
+    [MP_BC_GET_ITER] = COMPUTE_ENTRY(&&entry_MP_BC_GET_ITER),
+    [MP_BC_GET_ITER_STACK] = COMPUTE_ENTRY(&&entry_MP_BC_GET_ITER_STACK),
+    [MP_BC_FOR_ITER] = COMPUTE_ENTRY(&&entry_MP_BC_FOR_ITER),
+    [MP_BC_POP_BLOCK] = COMPUTE_ENTRY(&&entry_MP_BC_POP_BLOCK),
+    [MP_BC_POP_EXCEPT] = COMPUTE_ENTRY(&&entry_MP_BC_POP_EXCEPT),
+    [MP_BC_BUILD_TUPLE] = COMPUTE_ENTRY(&&entry_MP_BC_BUILD_TUPLE),
+    [MP_BC_BUILD_LIST] = COMPUTE_ENTRY(&&entry_MP_BC_BUILD_LIST),
+    [MP_BC_BUILD_MAP] = COMPUTE_ENTRY(&&entry_MP_BC_BUILD_MAP),
+    [MP_BC_STORE_MAP] = COMPUTE_ENTRY(&&entry_MP_BC_STORE_MAP),
     #if MICROPY_PY_BUILTINS_SET
-    [MP_BC_BUILD_SET] = &&entry_MP_BC_BUILD_SET,
+    [MP_BC_BUILD_SET] = COMPUTE_ENTRY(&&entry_MP_BC_BUILD_SET),
     #endif
     #if MICROPY_PY_BUILTINS_SLICE
-    [MP_BC_BUILD_SLICE] = &&entry_MP_BC_BUILD_SLICE,
+    [MP_BC_BUILD_SLICE] = COMPUTE_ENTRY(&&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,
-    [MP_BC_MAKE_FUNCTION_DEFARGS] = &&entry_MP_BC_MAKE_FUNCTION_DEFARGS,
-    [MP_BC_MAKE_CLOSURE] = &&entry_MP_BC_MAKE_CLOSURE,
-    [MP_BC_MAKE_CLOSURE_DEFARGS] = &&entry_MP_BC_MAKE_CLOSURE_DEFARGS,
-    [MP_BC_CALL_FUNCTION] = &&entry_MP_BC_CALL_FUNCTION,
-    [MP_BC_CALL_FUNCTION_VAR_KW] = &&entry_MP_BC_CALL_FUNCTION_VAR_KW,
-    [MP_BC_CALL_METHOD] = &&entry_MP_BC_CALL_METHOD,
-    [MP_BC_CALL_METHOD_VAR_KW] = &&entry_MP_BC_CALL_METHOD_VAR_KW,
-    [MP_BC_RETURN_VALUE] = &&entry_MP_BC_RETURN_VALUE,
-    [MP_BC_RAISE_VARARGS] = &&entry_MP_BC_RAISE_VARARGS,
-    [MP_BC_YIELD_VALUE] = &&entry_MP_BC_YIELD_VALUE,
-    [MP_BC_YIELD_FROM] = &&entry_MP_BC_YIELD_FROM,
-    [MP_BC_IMPORT_NAME] = &&entry_MP_BC_IMPORT_NAME,
-    [MP_BC_IMPORT_FROM] = &&entry_MP_BC_IMPORT_FROM,
-    [MP_BC_IMPORT_STAR] = &&entry_MP_BC_IMPORT_STAR,
-    [MP_BC_LOAD_CONST_SMALL_INT_MULTI ... MP_BC_LOAD_CONST_SMALL_INT_MULTI + 63] = &&entry_MP_BC_LOAD_CONST_SMALL_INT_MULTI,
-    [MP_BC_LOAD_FAST_MULTI ... MP_BC_LOAD_FAST_MULTI + 15] = &&entry_MP_BC_LOAD_FAST_MULTI,
-    [MP_BC_STORE_FAST_MULTI ... MP_BC_STORE_FAST_MULTI + 15] = &&entry_MP_BC_STORE_FAST_MULTI,
-    [MP_BC_UNARY_OP_MULTI ... MP_BC_UNARY_OP_MULTI + MP_UNARY_OP_NUM_BYTECODE - 1] = &&entry_MP_BC_UNARY_OP_MULTI,
-    [MP_BC_BINARY_OP_MULTI ... MP_BC_BINARY_OP_MULTI + MP_BINARY_OP_NUM_BYTECODE - 1] = &&entry_MP_BC_BINARY_OP_MULTI,
+    [MP_BC_STORE_COMP] = COMPUTE_ENTRY(&&entry_MP_BC_STORE_COMP),
+    [MP_BC_UNPACK_SEQUENCE] = COMPUTE_ENTRY(&&entry_MP_BC_UNPACK_SEQUENCE),
+    [MP_BC_UNPACK_EX] = COMPUTE_ENTRY(&&entry_MP_BC_UNPACK_EX),
+    [MP_BC_MAKE_FUNCTION] = COMPUTE_ENTRY(&&entry_MP_BC_MAKE_FUNCTION),
+    [MP_BC_MAKE_FUNCTION_DEFARGS] = COMPUTE_ENTRY(&&entry_MP_BC_MAKE_FUNCTION_DEFARGS),
+    [MP_BC_MAKE_CLOSURE] = COMPUTE_ENTRY(&&entry_MP_BC_MAKE_CLOSURE),
+    [MP_BC_MAKE_CLOSURE_DEFARGS] = COMPUTE_ENTRY(&&entry_MP_BC_MAKE_CLOSURE_DEFARGS),
+    [MP_BC_CALL_FUNCTION] = COMPUTE_ENTRY(&&entry_MP_BC_CALL_FUNCTION),
+    [MP_BC_CALL_FUNCTION_VAR_KW] = COMPUTE_ENTRY(&&entry_MP_BC_CALL_FUNCTION_VAR_KW),
+    [MP_BC_CALL_METHOD] = COMPUTE_ENTRY(&&entry_MP_BC_CALL_METHOD),
+    [MP_BC_CALL_METHOD_VAR_KW] = COMPUTE_ENTRY(&&entry_MP_BC_CALL_METHOD_VAR_KW),
+    [MP_BC_RETURN_VALUE] = COMPUTE_ENTRY(&&entry_MP_BC_RETURN_VALUE),
+    [MP_BC_RAISE_VARARGS] = COMPUTE_ENTRY(&&entry_MP_BC_RAISE_VARARGS),
+    [MP_BC_YIELD_VALUE] = COMPUTE_ENTRY(&&entry_MP_BC_YIELD_VALUE),
+    [MP_BC_YIELD_FROM] = COMPUTE_ENTRY(&&entry_MP_BC_YIELD_FROM),
+    [MP_BC_IMPORT_NAME] = COMPUTE_ENTRY(&&entry_MP_BC_IMPORT_NAME),
+    [MP_BC_IMPORT_FROM] = COMPUTE_ENTRY(&&entry_MP_BC_IMPORT_FROM),
+    [MP_BC_IMPORT_STAR] = COMPUTE_ENTRY(&&entry_MP_BC_IMPORT_STAR),
+    [MP_BC_LOAD_CONST_SMALL_INT_MULTI ... MP_BC_LOAD_CONST_SMALL_INT_MULTI + 63] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_CONST_SMALL_INT_MULTI),
+    [MP_BC_LOAD_FAST_MULTI ... MP_BC_LOAD_FAST_MULTI + 15] = COMPUTE_ENTRY(&&entry_MP_BC_LOAD_FAST_MULTI),
+    [MP_BC_STORE_FAST_MULTI ... MP_BC_STORE_FAST_MULTI + 15] = COMPUTE_ENTRY(&&entry_MP_BC_STORE_FAST_MULTI),
+    [MP_BC_UNARY_OP_MULTI ... MP_BC_UNARY_OP_MULTI + MP_UNARY_OP_NUM_BYTECODE - 1] = COMPUTE_ENTRY(&&entry_MP_BC_UNARY_OP_MULTI),
+    [MP_BC_BINARY_OP_MULTI ... MP_BC_BINARY_OP_MULTI + MP_BINARY_OP_NUM_BYTECODE - 1] = COMPUTE_ENTRY(&&entry_MP_BC_BINARY_OP_MULTI),
 };
 
 #ifdef __clang__