Skip to content

Commit

Permalink
Implement short-circuit evaluation for && and ||
Browse files Browse the repository at this point in the history 
PUBLISHED_FROM=4589803544e77d2ea40c107e9e98bbe760a14fad
  • Loading branch information
@dimonomid @cesantabot
dimonomid authored and cesantabot committed May 23, 2017
1 parent 3603a08 commit 2ac4ac9
Show file tree
Hide file tree
Showing 6 changed files with 200 additions and 122 deletions.
157 changes: 96 additions & 61 deletions mjs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3324,35 +3324,37 @@ extern "C" {
#endif /* __cplusplus */

enum mjs_opcode {
OP_NOP, /* ( -- ) */
OP_DROP, /* ( a -- ) */
OP_DUP, /* ( a -- a a ) */
OP_SWAP, /* ( a b -- b a ) */
OP_JMP, /* ( -- ) */
OP_JMP_TRUE, /* ( -- ) */
OP_JMP_FALSE, /* ( -- ) */
OP_FIND_SCOPE, /* ( a -- a b ) */
OP_PUSH_SCOPE, /* ( -- a ) */
OP_PUSH_STR, /* ( -- a ) */
OP_PUSH_TRUE, /* ( -- a ) */
OP_PUSH_FALSE, /* ( -- a ) */
OP_PUSH_INT, /* ( -- a ) */
OP_PUSH_DBL, /* ( -- a ) */
OP_PUSH_NULL, /* ( -- a ) */
OP_PUSH_UNDEF, /* ( -- a ) */
OP_PUSH_OBJ, /* ( -- a ) */
OP_PUSH_ARRAY, /* ( -- a ) */
OP_PUSH_FUNC, /* ( -- a ) */
OP_PUSH_THIS, /* ( -- a ) */
OP_GET, /* ( key obj -- obj[key] ) */
OP_CREATE, /* ( key obj -- ) */
OP_EXPR, /* ( ... -- a ) */
OP_APPEND, /* ( a b -- ) */
OP_SET_ARG, /* ( a -- a ) */
OP_NEW_SCOPE, /* ( -- ) */
OP_DEL_SCOPE, /* ( -- ) */
OP_CALL, /* ( func param1 param2 ... num_params -- result ) */
OP_RETURN, /* ( -- ) */
OP_NOP, /* ( -- ) */
OP_DROP, /* ( a -- ) */
OP_DUP, /* ( a -- a a ) */
OP_SWAP, /* ( a b -- b a ) */
OP_JMP, /* ( -- ) */
OP_JMP_TRUE, /* ( -- ) */
OP_JMP_NEUTRAL_TRUE, /* ( -- ) */
OP_JMP_FALSE, /* ( -- ) */
OP_JMP_NEUTRAL_FALSE, /* ( -- ) */
OP_FIND_SCOPE, /* ( a -- a b ) */
OP_PUSH_SCOPE, /* ( -- a ) */
OP_PUSH_STR, /* ( -- a ) */
OP_PUSH_TRUE, /* ( -- a ) */
OP_PUSH_FALSE, /* ( -- a ) */
OP_PUSH_INT, /* ( -- a ) */
OP_PUSH_DBL, /* ( -- a ) */
OP_PUSH_NULL, /* ( -- a ) */
OP_PUSH_UNDEF, /* ( -- a ) */
OP_PUSH_OBJ, /* ( -- a ) */
OP_PUSH_ARRAY, /* ( -- a ) */
OP_PUSH_FUNC, /* ( -- a ) */
OP_PUSH_THIS, /* ( -- a ) */
OP_GET, /* ( key obj -- obj[key] ) */
OP_CREATE, /* ( key obj -- ) */
OP_EXPR, /* ( ... -- a ) */
OP_APPEND, /* ( a b -- ) */
OP_SET_ARG, /* ( a -- a ) */
OP_NEW_SCOPE, /* ( -- ) */
OP_DEL_SCOPE, /* ( -- ) */
OP_CALL, /* ( func param1 param2 ... num_params -- result ) */
OP_RETURN, /* ( -- ) */
OP_LOOP, /* ( -- ) Push break & continue addresses to loop_labels */
OP_BREAK, /* ( -- ) */
OP_CONTINUE, /* ( -- ) */
Expand Down Expand Up @@ -7442,18 +7444,12 @@ static void exec_expr(struct mjs *mjs, int op) {
}
break;
}
case TOK_LOGICAL_AND: {
mjs_val_t b = mjs_pop(mjs);
mjs_val_t a = mjs_pop(mjs);
mjs_push(mjs, mjs_is_truthy(mjs, a) ? b : a);
break;
}
case TOK_LOGICAL_OR: {
mjs_val_t b = mjs_pop(mjs);
mjs_val_t a = mjs_pop(mjs);
mjs_push(mjs, mjs_is_truthy(mjs, a) ? a : b);
break;
}
/*
* NOTE: TOK_LOGICAL_AND and TOK_LOGICAL_OR don't need to be here, because
* they are just naturally handled by the short-circuit evaluation.
* See PARSE_LTR_BINOP() macro in mjs_parser.c.
*/

/* clang-format off */
case TOK_MINUS_ASSIGN: op_assign(mjs, TOK_MINUS); break;
case TOK_PLUS_ASSIGN: op_assign(mjs, TOK_PLUS); break;
Expand Down Expand Up @@ -7665,6 +7661,27 @@ MJS_PRIVATE mjs_err_t mjs_execute(struct mjs *mjs, size_t off, mjs_val_t *res) {
}
break;
}
/*
* OP_JMP_NEUTRAL_... ops are like as OP_JMP_..., but they are completely
* stack-neutral: they just check the TOS, and increment instruction
* pointer if the TOS is truthy/falsy.
*/
case OP_JMP_NEUTRAL_TRUE: {
int llen, n = cs_varint_decode(&code[i + 1], &llen);
i += llen;
if (mjs_is_truthy(mjs, vtop(&mjs->stack))) {
i += n;
}
break;
}
case OP_JMP_NEUTRAL_FALSE: {
int llen, n = cs_varint_decode(&code[i + 1], &llen);
i += llen;
if (!mjs_is_truthy(mjs, vtop(&mjs->stack))) {
i += n;
}
break;
}
case OP_FIND_SCOPE: {
mjs_val_t key = vtop(&mjs->stack);
mjs_push(mjs, mjs_find_scope(mjs, key));
Expand Down Expand Up @@ -10573,17 +10590,34 @@ static void emit_op(struct pstate *pstate, int tok) {

// Intentionally left as macro rather than a function, to let the
// compiler to inline calls and mimimize runtime stack usage.
#define PARSE_LTR_BINOP(p, f1, f2, ops, prev_op) \
do { \
mjs_err_t res = MJS_OK; \
if ((res = f1(p, TOK_EOF)) != MJS_OK) return res; \
if (prev_op != TOK_EOF) emit_op(p, prev_op); \
if (findtok(ops, p->tok.tok) != TOK_EOF) { \
int op = p->tok.tok; \
pnext1(p); \
if ((res = f2(p, op)) != MJS_OK) return res; \
} \
return res; \
#define PARSE_LTR_BINOP(p, f1, f2, ops, prev_op) \
do { \
mjs_err_t res = MJS_OK; \
if ((res = f1(p, TOK_EOF)) != MJS_OK) return res; \
if (prev_op != TOK_EOF) emit_op(p, prev_op); \
if (findtok(ops, p->tok.tok) != TOK_EOF) { \
int op = p->tok.tok; \
size_t off_if = 0; \
/* For AND/OR, implement short-circuit evaluation */ \
if (ops[0] == TOK_LOGICAL_AND || ops[0] == TOK_LOGICAL_OR) { \
emit_byte(p, ops[0] == TOK_LOGICAL_AND ? OP_JMP_NEUTRAL_FALSE \
: OP_JMP_NEUTRAL_TRUE); \
off_if = p->cur_idx; \
emit_init_offset(p); \
/* No need to emit TOK_LOGICAL_AND and TOK_LOGICAL_OR: */ \
/* Just drop the first value, and evaluate the second one. */ \
emit_byte(p, OP_DROP); \
op = TOK_EOF; \
} \
pnext1(p); \
if ((res = f2(p, op)) != MJS_OK) return res; \
\
if (off_if != 0) { \
mjs_bcode_insert_offset(p, p->mjs, off_if, \
p->cur_idx - off_if - MJS_INIT_OFFSET_SIZE); \
} \
} \
return res; \
} while (0)

#define PARSE_RTL_BINOP(p, f1, f2, ops, prev_op) \
Expand Down Expand Up @@ -12436,14 +12470,13 @@ void mjs_fprintf(mjs_val_t v, struct mjs *mjs, FILE *fp) {

MJS_PRIVATE const char *opcodetostr(uint8_t opcode) {
static const char *names[] = {
"NOP", "DROP", "DUP", "SWAP", "JMP",
"JMP_TRUE", "JMP_FALSE", "FIND_SCOPE", "PUSH_SCOPE", "PUSH_STR",
"PUSH_TRUE", "PUSH_FALSE", "PUSH_INT", "PUSH_DBL", "PUSH_NULL",
"PUSH_UNDEF", "PUSH_OBJ", "PUSH_ARRAY", "PUSH_FUNC", "PUSH_THIS",
"GET", "CREATE", "EXPR", "APPEND", "SET_ARG",
"NEW_SCOPE", "DEL_SCOPE", "CALL", "RETURN", "LOOP",
"BREAK", "CONTINUE", "SETRETVAL", "EXIT", "BCODE_HDR",
"ARGS", "FOR_IN_NEXT",
"NOP", "DROP", "DUP", "SWAP", "JMP", "JMP_TRUE", "JMP_NEUTRAL_TRUE",
"JMP_FALSE", "JMP_NEUTRAL_FALSE", "FIND_SCOPE", "PUSH_SCOPE", "PUSH_STR",
"PUSH_TRUE", "PUSH_FALSE", "PUSH_INT", "PUSH_DBL", "PUSH_NULL",
"PUSH_UNDEF", "PUSH_OBJ", "PUSH_ARRAY", "PUSH_FUNC", "PUSH_THIS", "GET",
"CREATE", "EXPR", "APPEND", "SET_ARG", "NEW_SCOPE", "DEL_SCOPE", "CALL",
"RETURN", "LOOP", "BREAK", "CONTINUE", "SETRETVAL", "EXIT", "BCODE_HDR",
"ARGS", "FOR_IN_NEXT",
};
const char *name = "UNKNOWN OPCODE";
assert(ARRAY_SIZE(names) == OP_MAX);
Expand Down Expand Up @@ -12485,7 +12518,9 @@ MJS_PRIVATE size_t mjs_disasm_single(const uint8_t *code, size_t i, FILE *fp) {
}
case OP_JMP:
case OP_JMP_TRUE:
case OP_JMP_FALSE: {
case OP_JMP_NEUTRAL_TRUE:
case OP_JMP_FALSE:
case OP_JMP_NEUTRAL_FALSE: {
int llen, n = cs_varint_decode(&code[i + 1], &llen);
fprintf(fp, "\t%u",
(unsigned) i + n + llen +
Expand Down
60 changes: 31 additions & 29 deletions mjs/src/mjs_bcode.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,35 +15,37 @@ extern "C" {
#endif /* __cplusplus */

enum mjs_opcode {
OP_NOP, /* ( -- ) */
OP_DROP, /* ( a -- ) */
OP_DUP, /* ( a -- a a ) */
OP_SWAP, /* ( a b -- b a ) */
OP_JMP, /* ( -- ) */
OP_JMP_TRUE, /* ( -- ) */
OP_JMP_FALSE, /* ( -- ) */
OP_FIND_SCOPE, /* ( a -- a b ) */
OP_PUSH_SCOPE, /* ( -- a ) */
OP_PUSH_STR, /* ( -- a ) */
OP_PUSH_TRUE, /* ( -- a ) */
OP_PUSH_FALSE, /* ( -- a ) */
OP_PUSH_INT, /* ( -- a ) */
OP_PUSH_DBL, /* ( -- a ) */
OP_PUSH_NULL, /* ( -- a ) */
OP_PUSH_UNDEF, /* ( -- a ) */
OP_PUSH_OBJ, /* ( -- a ) */
OP_PUSH_ARRAY, /* ( -- a ) */
OP_PUSH_FUNC, /* ( -- a ) */
OP_PUSH_THIS, /* ( -- a ) */
OP_GET, /* ( key obj -- obj[key] ) */
OP_CREATE, /* ( key obj -- ) */
OP_EXPR, /* ( ... -- a ) */
OP_APPEND, /* ( a b -- ) */
OP_SET_ARG, /* ( a -- a ) */
OP_NEW_SCOPE, /* ( -- ) */
OP_DEL_SCOPE, /* ( -- ) */
OP_CALL, /* ( func param1 param2 ... num_params -- result ) */
OP_RETURN, /* ( -- ) */
OP_NOP, /* ( -- ) */
OP_DROP, /* ( a -- ) */
OP_DUP, /* ( a -- a a ) */
OP_SWAP, /* ( a b -- b a ) */
OP_JMP, /* ( -- ) */
OP_JMP_TRUE, /* ( -- ) */
OP_JMP_NEUTRAL_TRUE, /* ( -- ) */
OP_JMP_FALSE, /* ( -- ) */
OP_JMP_NEUTRAL_FALSE, /* ( -- ) */
OP_FIND_SCOPE, /* ( a -- a b ) */
OP_PUSH_SCOPE, /* ( -- a ) */
OP_PUSH_STR, /* ( -- a ) */
OP_PUSH_TRUE, /* ( -- a ) */
OP_PUSH_FALSE, /* ( -- a ) */
OP_PUSH_INT, /* ( -- a ) */
OP_PUSH_DBL, /* ( -- a ) */
OP_PUSH_NULL, /* ( -- a ) */
OP_PUSH_UNDEF, /* ( -- a ) */
OP_PUSH_OBJ, /* ( -- a ) */
OP_PUSH_ARRAY, /* ( -- a ) */
OP_PUSH_FUNC, /* ( -- a ) */
OP_PUSH_THIS, /* ( -- a ) */
OP_GET, /* ( key obj -- obj[key] ) */
OP_CREATE, /* ( key obj -- ) */
OP_EXPR, /* ( ... -- a ) */
OP_APPEND, /* ( a b -- ) */
OP_SET_ARG, /* ( a -- a ) */
OP_NEW_SCOPE, /* ( -- ) */
OP_DEL_SCOPE, /* ( -- ) */
OP_CALL, /* ( func param1 param2 ... num_params -- result ) */
OP_RETURN, /* ( -- ) */
OP_LOOP, /* ( -- ) Push break & continue addresses to loop_labels */
OP_BREAK, /* ( -- ) */
OP_CONTINUE, /* ( -- ) */
Expand Down
39 changes: 27 additions & 12 deletions mjs/src/mjs_exec.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -355,18 +355,12 @@ static void exec_expr(struct mjs *mjs, int op) {
}
break;
}
case TOK_LOGICAL_AND: {
mjs_val_t b = mjs_pop(mjs);
mjs_val_t a = mjs_pop(mjs);
mjs_push(mjs, mjs_is_truthy(mjs, a) ? b : a);
break;
}
case TOK_LOGICAL_OR: {
mjs_val_t b = mjs_pop(mjs);
mjs_val_t a = mjs_pop(mjs);
mjs_push(mjs, mjs_is_truthy(mjs, a) ? a : b);
break;
}
/*
* NOTE: TOK_LOGICAL_AND and TOK_LOGICAL_OR don't need to be here, because
* they are just naturally handled by the short-circuit evaluation.
* See PARSE_LTR_BINOP() macro in mjs_parser.c.
*/

/* clang-format off */
case TOK_MINUS_ASSIGN: op_assign(mjs, TOK_MINUS); break;
case TOK_PLUS_ASSIGN: op_assign(mjs, TOK_PLUS); break;
Expand Down Expand Up @@ -578,6 +572,27 @@ MJS_PRIVATE mjs_err_t mjs_execute(struct mjs *mjs, size_t off, mjs_val_t *res) {
}
break;
}
/*
* OP_JMP_NEUTRAL_... ops are like as OP_JMP_..., but they are completely
* stack-neutral: they just check the TOS, and increment instruction
* pointer if the TOS is truthy/falsy.
*/
case OP_JMP_NEUTRAL_TRUE: {
int llen, n = cs_varint_decode(&code[i + 1], &llen);
i += llen;
if (mjs_is_truthy(mjs, vtop(&mjs->stack))) {
i += n;
}
break;
}
case OP_JMP_NEUTRAL_FALSE: {
int llen, n = cs_varint_decode(&code[i + 1], &llen);
i += llen;
if (!mjs_is_truthy(mjs, vtop(&mjs->stack))) {
i += n;
}
break;
}
case OP_FIND_SCOPE: {
mjs_val_t key = vtop(&mjs->stack);
mjs_push(mjs, mjs_find_scope(mjs, key));
Expand Down
39 changes: 28 additions & 11 deletions mjs/src/mjs_parser.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -72,17 +72,34 @@ static void emit_op(struct pstate *pstate, int tok) {

// Intentionally left as macro rather than a function, to let the
// compiler to inline calls and mimimize runtime stack usage.
#define PARSE_LTR_BINOP(p, f1, f2, ops, prev_op) \
do { \
mjs_err_t res = MJS_OK; \
if ((res = f1(p, TOK_EOF)) != MJS_OK) return res; \
if (prev_op != TOK_EOF) emit_op(p, prev_op); \
if (findtok(ops, p->tok.tok) != TOK_EOF) { \
int op = p->tok.tok; \
pnext1(p); \
if ((res = f2(p, op)) != MJS_OK) return res; \
} \
return res; \
#define PARSE_LTR_BINOP(p, f1, f2, ops, prev_op) \
do { \
mjs_err_t res = MJS_OK; \
if ((res = f1(p, TOK_EOF)) != MJS_OK) return res; \
if (prev_op != TOK_EOF) emit_op(p, prev_op); \
if (findtok(ops, p->tok.tok) != TOK_EOF) { \
int op = p->tok.tok; \
size_t off_if = 0; \
/* For AND/OR, implement short-circuit evaluation */ \
if (ops[0] == TOK_LOGICAL_AND || ops[0] == TOK_LOGICAL_OR) { \
emit_byte(p, ops[0] == TOK_LOGICAL_AND ? OP_JMP_NEUTRAL_FALSE \
: OP_JMP_NEUTRAL_TRUE); \
off_if = p->cur_idx; \
emit_init_offset(p); \
/* No need to emit TOK_LOGICAL_AND and TOK_LOGICAL_OR: */ \
/* Just drop the first value, and evaluate the second one. */ \
emit_byte(p, OP_DROP); \
op = TOK_EOF; \
} \
pnext1(p); \
if ((res = f2(p, op)) != MJS_OK) return res; \
\
if (off_if != 0) { \
mjs_bcode_insert_offset(p, p->mjs, off_if, \
p->cur_idx - off_if - MJS_INIT_OFFSET_SIZE); \
} \
} \
return res; \
} while (0)

#define PARSE_RTL_BINOP(p, f1, f2, ops, prev_op) \
Expand Down
19 changes: 10 additions & 9 deletions mjs/src/mjs_util.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -79,14 +79,13 @@ void mjs_fprintf(mjs_val_t v, struct mjs *mjs, FILE *fp) {

MJS_PRIVATE const char *opcodetostr(uint8_t opcode) {
static const char *names[] = {
"NOP", "DROP", "DUP", "SWAP", "JMP",
"JMP_TRUE", "JMP_FALSE", "FIND_SCOPE", "PUSH_SCOPE", "PUSH_STR",
"PUSH_TRUE", "PUSH_FALSE", "PUSH_INT", "PUSH_DBL", "PUSH_NULL",
"PUSH_UNDEF", "PUSH_OBJ", "PUSH_ARRAY", "PUSH_FUNC", "PUSH_THIS",
"GET", "CREATE", "EXPR", "APPEND", "SET_ARG",
"NEW_SCOPE", "DEL_SCOPE", "CALL", "RETURN", "LOOP",
"BREAK", "CONTINUE", "SETRETVAL", "EXIT", "BCODE_HDR",
"ARGS", "FOR_IN_NEXT",
"NOP", "DROP", "DUP", "SWAP", "JMP", "JMP_TRUE", "JMP_NEUTRAL_TRUE",
"JMP_FALSE", "JMP_NEUTRAL_FALSE", "FIND_SCOPE", "PUSH_SCOPE", "PUSH_STR",
"PUSH_TRUE", "PUSH_FALSE", "PUSH_INT", "PUSH_DBL", "PUSH_NULL",
"PUSH_UNDEF", "PUSH_OBJ", "PUSH_ARRAY", "PUSH_FUNC", "PUSH_THIS", "GET",
"CREATE", "EXPR", "APPEND", "SET_ARG", "NEW_SCOPE", "DEL_SCOPE", "CALL",
"RETURN", "LOOP", "BREAK", "CONTINUE", "SETRETVAL", "EXIT", "BCODE_HDR",
"ARGS", "FOR_IN_NEXT",
};
const char *name = "UNKNOWN OPCODE";
assert(ARRAY_SIZE(names) == OP_MAX);
Expand Down Expand Up @@ -128,7 +127,9 @@ MJS_PRIVATE size_t mjs_disasm_single(const uint8_t *code, size_t i, FILE *fp) {
}
case OP_JMP:
case OP_JMP_TRUE:
case OP_JMP_FALSE: {
case OP_JMP_NEUTRAL_TRUE:
case OP_JMP_FALSE:
case OP_JMP_NEUTRAL_FALSE: {
int llen, n = cs_varint_decode(&code[i + 1], &llen);
fprintf(fp, "\t%u",
(unsigned) i + n + llen +
Expand Down

0 comments on commit 2ac4ac9

Please sign in to comment.