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Add support for ECMA switch statements. These are like LISP cond in that they

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evaluate the case label each time.
Still to do is to optimize so that TABLESWITCH and LOOKUPSWITCH are created
when possible.


git-svn-id: svn://10.0.0.236/trunk@9296 18797224-902f-48f8-a5cc-f745e15eee43
This commit is contained in:
norris%netscape.com 1998-09-04 00:45:21 +00:00
parent 6e086b553a
commit bc2d3f5307
5 changed files with 144 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

64
mozilla/js/ref/jsemit.c
View File

@ -668,6 +668,11 @@ js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn)
JSParseNode **table;
jsbytecode *pc;
JSBool hasDefault = JS_FALSE;
JSBool isEcmaSwitch = cx->version == JSVERSION_DEFAULT ||
cx->version >= JSVERSION_1_4;
ptrdiff_t defaultOpPc = -1;
switchop = isEcmaSwitch ? JSOP_CONDSWITCH : JSOP_TABLESWITCH;
/* Emit code for the discriminant first. */
if (!js_EmitTree(cx, cg, pn->pn_kid1))
@ -677,7 +682,6 @@ js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn)
top = CG_OFFSET(cg);
js_PushStatement(&cg->treeContext, &stmtInfo, STMT_SWITCH, top);
switchop = JSOP_TABLESWITCH;
pn2 = pn->pn_kid2;
ncases = pn2->pn_count;
@ -696,6 +700,8 @@ js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn)
continue;
}
PR_ASSERT(pn3->pn_type == TOK_CASE);
if (switchop == JSOP_CONDSWITCH)
continue;
if (!cg2.base) {
if (!js_InitCodeGenerator(cx, &cg2, cg->filename,
pn3->pn_pos.begin.lineno,
@ -716,18 +722,19 @@ js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn)
return JS_FALSE;
/*
* The GC must not run during this case expression evaluation.
* It won't if it runs only from the branch callback (because
* the only branches possible in a case expression come from ?:
* expressions, and those generate downward branches, while the
* The GC must not run during this case expression
* evaluation. It won't if it runs only from the
* branch callback (because the only branches possible
* in a case expression come from ?: expressions,
* and those generate downward branches, while the
* branch callback runs only for upward branches).
* XXX - but function calls are possible!
*/
ok = js_Execute(cx, cx->fp->scopeChain, script, NULL, cx->fp,
JS_FALSE, &pn3->pn_val);
ok = js_Execute(cx, cx->fp->scopeChain, script, NULL,
cx->fp, JS_FALSE, &pn3->pn_val);
js_DestroyScript(cx, script);
if (!ok)
return JS_FALSE;
if (!JSVAL_IS_NUMBER(pn3->pn_val) &&
!JSVAL_IS_STRING(pn3->pn_val) &&
!JSVAL_IS_BOOLEAN(pn3->pn_val)) {
@ -741,7 +748,7 @@ js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn)
return JS_FALSE;
}
if (switchop == JSOP_LOOKUPSWITCH)
if (switchop != JSOP_TABLESWITCH)
continue;
if (!JSVAL_IS_INT(pn3->pn_val)) {
switchop = JSOP_LOOKUPSWITCH;
@ -757,7 +764,7 @@ js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn)
if (high < i)
high = i;
}
if (cg2.base)
if (switchop != JSOP_CONDSWITCH && cg2.base)
js_ResetCodeGenerator(cx, &cg2);
if (switchop == JSOP_TABLESWITCH) {
tablen = (uint32)(high - low + 1);
@ -788,8 +795,34 @@ js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn)
if (js_EmitN(cx, cg, switchop, switchsize) < 0)
return JS_FALSE;
if (switchop == JSOP_CONDSWITCH) {
/* Emit code for evaluating cases and jumping to case statements. */
if (!js_SetJumpOffset(cx, cg, CG_CODE(cg, top),
CG_OFFSET(cg) - top))
return JS_FALSE;
for (pn3 = pn2->pn_head; pn3; pn3 = pn3->pn_next) {
if (pn3->pn_type == TOK_DEFAULT)
continue;
pn4 = pn3->pn_left;
if (!js_EmitTree(cx, cg, pn4))
return JS_FALSE;
pn3->pn_offset = js_Emit3(cx, cg, JSOP_CASE, 0, 0);
if (pn3->pn_offset < 0)
return JS_FALSE;
pn3->pn_offset;
}
/* Emit default even if no explicit default statement. */
defaultOpPc = js_Emit3(cx, cg, JSOP_DEFAULT, 0, 0);
if (defaultOpPc < 0)
return JS_FALSE;
}
/* Emit code for each case's statements, copying pn_offset up to pn3. */
for (pn3 = pn2->pn_head; pn3; pn3 = pn3->pn_next) {
if (switchop == JSOP_CONDSWITCH && pn3->pn_type != TOK_DEFAULT) {
pn3->pn_val = INT_TO_JSVAL(pn3->pn_offset - top);
CHECK_AND_SET_JUMP_OFFSET_AT(cx, cg, pn3->pn_offset);
}
pn4 = pn3->pn_right;
if (!js_EmitTree(cx, cg, pn4))
return JS_FALSE;
@ -805,8 +838,15 @@ js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn)
/* Set the default offset (to end of switch if no default). */
pc = CG_CODE(cg, top);
if (!js_SetJumpOffset(cx, cg, pc, off))
return JS_FALSE;
if (switchop != JSOP_CONDSWITCH) {
if (!js_SetJumpOffset(cx, cg, pc, off))
return JS_FALSE;
}
if (defaultOpPc != -1) {
if (!js_SetJumpOffset(cx, cg, CG_CODE(cg, defaultOpPc),
off - (defaultOpPc - top)))
return JS_FALSE;
}
pc += 2;
/* Set the SRC_SWITCH note's offset operand to tell end of switch. */

24
mozilla/js/ref/jsinterp.c
View File

@ -1126,6 +1126,11 @@ js_Interpret(JSContext *cx, jsval *result)
fp->rval = POP();
goto out;
#if JS_HAS_SWITCH_STATEMENT
case JSOP_DEFAULT:
POP();
/* fall through */
#endif
case JSOP_GOTO:
len = GET_JUMP_OFFSET(pc);
CHECK_BRANCH(len);
@ -1662,6 +1667,20 @@ js_Interpret(JSContext *cx, jsval *result)
case JSOP_NEW_NE:
NEW_EQUALITY_OP(!=, JS_TRUE);
break;
#if JS_HAS_SWITCH_STATEMENT
case JSOP_CASE:
NEW_EQUALITY_OP(==, JS_FALSE);
POP();
if (cond) {
len = GET_JUMP_OFFSET(pc);
CHECK_BRANCH(len);
} else {
PUSH(lval);
}
break;
#endif
#endif /* !JS_BUG_FALLIBLE_EQOPS */
case JSOP_LT:
@ -2306,6 +2325,11 @@ js_Interpret(JSContext *cx, jsval *result)
}
#undef SEARCH_PAIRS
break;
case JSOP_CONDSWITCH:
len = GET_JUMP_OFFSET(pc);
goto advance_pc;
#endif /* JS_HAS_SWITCH_STATEMENT */
#if JS_HAS_LEXICAL_CLOSURE

71
mozilla/js/ref/jsopcode.c
View File

@ -192,7 +192,7 @@ js_Disassemble1(JSContext *cx, JSScript *script, jsbytecode *pc, uintN loc,
pc2 += JUMP_OFFSET_LEN;
npairs = (uintN) GET_ATOM_INDEX(pc2);
pc2 += ATOM_INDEX_LEN;
fprintf(fp, " defaultOffset %d npairs %u", off, npairs);
fprintf(fp, " offset %d npairs %u", off, npairs);
while (npairs) {
atom = GET_ATOM(cx, script, pc2);
pc2 += ATOM_INDEX_LEN;
@ -567,13 +567,14 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb);
static JSBool
DecompileSwitch(SprintStack *ss, TableEntry *table, uintN tableLength,
jsbytecode *pc, ptrdiff_t switchLength, ptrdiff_t defaultOffset)
jsbytecode *pc, ptrdiff_t switchLength,
ptrdiff_t defaultOffset, JSBool isCondSwitch)
{
JSContext *cx;
JSPrinter *jp;
char *lval, *rval;
uintN i;
ptrdiff_t diff, off, off2;
ptrdiff_t diff, off, off2, caseExprOff;
jsval key;
JSString *str;
@ -593,6 +594,8 @@ DecompileSwitch(SprintStack *ss, TableEntry *table, uintN tableLength,
return JS_FALSE;
jp->indent -= 4;
}
caseExprOff = 1 + JUMP_OFFSET_LEN + ATOM_INDEX_LEN +
tableLength * (ATOM_INDEX_LEN + JUMP_OFFSET_LEN);
for (i = 0; i < tableLength; i++) {
off = table[i].offset;
if (i + 1 < tableLength)
@ -600,18 +603,28 @@ DecompileSwitch(SprintStack *ss, TableEntry *table, uintN tableLength,
else
off2 = switchLength;
key = table[i].key;
str = js_ValueToString(cx, key);
if (!str)
return JS_FALSE;
jp->indent += 2;
if (JSVAL_IS_STRING(key)) {
rval = QuoteString(&ss->sprinter, str, '"');
if (!rval)
if (isCondSwitch) {
uint32 caseLen = js_CodeSpec[JSOP_CASE].length;
ptrdiff_t caseOff = JSVAL_TO_INT(key);
jp->indent += 2;
if (!Decompile(ss, pc + caseExprOff,
caseOff - caseExprOff + caseLen))
return JS_FALSE;
} else {
rval = JS_GetStringBytes(str);
}
js_printf(jp, "\tcase %s:\n", rval);
caseExprOff = caseOff + caseLen;
} else {
str = js_ValueToString(cx, key);
if (!str)
return JS_FALSE;
jp->indent += 2;
if (JSVAL_IS_STRING(key)) {
rval = QuoteString(&ss->sprinter, str, '"');
if (!rval)
return JS_FALSE;
} else {
rval = JS_GetStringBytes(str);
}
js_printf(jp, "\tcase %s:\n", rval);
}
jp->indent += 2;
if (off <= defaultOffset && defaultOffset < off2) {
diff = defaultOffset - off;
@ -1580,7 +1593,8 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb)
}
js_qsort(table, (size_t)j, sizeof *table, CompareOffsets, NULL);
ok = DecompileSwitch(ss, table, (uintN)j, pc, len, off);
ok = DecompileSwitch(ss, table, (uintN)j, pc, len, off,
JS_FALSE);
JS_free(cx, table);
if (!ok)
return ok;
@ -1589,6 +1603,7 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb)
}
case JSOP_LOOKUPSWITCH:
case JSOP_CONDSWITCH:
{
jsbytecode *pc2 = pc;
ptrdiff_t off, off2;
@ -1614,14 +1629,38 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb)
table[i].key = ATOM_KEY(atom);
table[i].offset = off2;
}
if (op == JSOP_CONDSWITCH) {
/*
* Find offset of default code by finding the default
* instruction and adding its offset.
*/
jsbytecode *pc3;
ok = DecompileSwitch(ss, table, (uintN)npairs, pc, len, off);
off = JSVAL_TO_INT(table[npairs-1].key) +
js_CodeSpec[JSOP_CASE].length;
pc3 = pc + off;
off += GET_JUMP_OFFSET(pc3);
}
ok = DecompileSwitch(ss, table, (uintN)npairs, pc, len, off,
op == JSOP_CONDSWITCH);
JS_free(cx, table);
if (!ok)
return ok;
todo = -2;
break;
}
case JSOP_CASE:
{
lval = POP_STR();
if (!lval)
return JS_FALSE;
js_printf(jp, "\tcase %s:\n", lval);
todo = -2;
break;
}
#endif /* JS_HAS_SWITCH_STATEMENT */
#if !JS_BUG_FALLIBLE_EQOPS

12
mozilla/js/ref/jsopcode.def
View File

@ -195,9 +195,17 @@ OPDEF(JSOP_INSTANCEOF,112,js_instanceof_str,js_instanceof_str,1,2,1,6,JOF_BYTE)
OPDEF(JSOP_DEBUGGER, 113,"debugger", NULL, 1, 0, 0, 0, JOF_BYTE)
/* gosub/retsub for finally handling */
OPDEF(JSOP_GOSUB, 114,"gosub", NULL, 3, 0, 1, 0, JOF_JUMP)
OPDEF(JSOP_GOSUB, 114,"gosub", NULL, 3, 0, 1, 0, JOF_JUMP)
OPDEF(JSOP_RETSUB, 115,"retsub", NULL, 1, 1, 0, 0, JOF_BYTE)
/* more exception handling ops */
OPDEF(JSOP_EXCEPTION, 116,"exception", NULL, 1, 0, 1, 0, JOF_BYTE)
OPDEF(JSOP_SETSP, 117,"setsp", NULL, 3, 0, 0, 0, JOF_UINT16)
OPDEF(JSOP_SETSP, 117,"setsp", NULL, 3, 0, 0, 0, JOF_UINT16)
/*
* ECMA-compliant switch statement ops.
* "switch" is essentially "nop" and "default" is essentially "pop" + "goto".
*/
OPDEF(JSOP_CONDSWITCH,118,"switch", NULL, -1, 0, 0, 0, JOF_LOOKUPSWITCH)
OPDEF(JSOP_CASE, 119,"case", NULL, 3, 1, 0, 0, JOF_JUMP)
OPDEF(JSOP_DEFAULT, 120,"default", NULL, 3, 1, 0, 0, JOF_JUMP)

5
mozilla/js/ref/jsopcode.h
View File

@ -47,8 +47,9 @@ typedef enum JSOp {
#define JOF_UINT16 3 /* unsigned 16-bit immediate operand */
#define JOF_TABLESWITCH 4 /* table switch */
#define JOF_LOOKUPSWITCH 5 /* lookup switch */
#define JOF_QARG 6 /* quickened get/set function argument ops */
#define JOF_QVAR 7 /* quickened get/set local variable ops */
#define JOF_CONDSWITCH 6 /* cond switch */
#define JOF_QARG 7 /* quickened get/set function argument ops */
#define JOF_QVAR 8 /* quickened get/set local variable ops */
#define JOF_TYPEMASK 0x000f /* mask for above immediate types */
#define JOF_NAME 0x0010 /* name operation */
#define JOF_PROP 0x0020 /* obj.prop operation */