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Changes in opcodes for generic 'for'

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Again, as the control variable is read only, the code doesn't need
to keep an internal copy of it.
This commit is contained in:
Roberto Ierusalimschy
2022-12-22 13:52:53 -03:00
parent 873588dc5f
commit 7d4c7ae2af
3 changed files with 38 additions and 29 deletions
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40
lvm.c
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@@ -1806,26 +1806,38 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
vmbreak;
}
vmcase(OP_TFORPREP) {
/* before: 'ra' has the iterator function, 'ra + 1' has the state,
'ra + 2' has the initial value for the control variable, and
'ra + 3' has the closing variable. This opcode then swaps the
control and the closing variables and marks the closing variable
as to-be-closed.
*/
StkId ra = RA(i);
/* create to-be-closed upvalue (if needed) */
halfProtect(luaF_newtbcupval(L, ra + 3));
pc += GETARG_Bx(i);
i = *(pc++); /* go to next instruction */
TValue temp; /* to swap control and closing variables */
setobj(L, &temp, s2v(ra + 3));
setobjs2s(L, ra + 3, ra + 2);
setobj2s(L, ra + 2, &temp);
/* create to-be-closed upvalue (if closing var. is not nil) */
halfProtect(luaF_newtbcupval(L, ra + 2));
pc += GETARG_Bx(i); /* go to end of the loop */
i = *(pc++); /* fetch next instruction */
lua_assert(GET_OPCODE(i) == OP_TFORCALL && ra == RA(i));
goto l_tforcall;
}
vmcase(OP_TFORCALL) {
l_tforcall: {
StkId ra = RA(i);
/* 'ra' has the iterator function, 'ra + 1' has the state,
'ra + 2' has the control variable, and 'ra + 3' has the
to-be-closed variable. The call will use the stack after
these values (starting at 'ra + 4')
'ra + 2' has the closing variable, and 'ra + 3' has the control
variable. The call will use the stack starting at 'ra + 3',
so that it preserves the first three values, and the first
return will be the new value for the control variable.
*/
/* push function, state, and control variable */
memcpy(ra + 4, ra, 3 * sizeof(*ra));
L->top.p = ra + 4 + 3;
ProtectNT(luaD_call(L, ra + 4, GETARG_C(i))); /* do the call */
StkId ra = RA(i);
setobjs2s(L, ra + 5, ra + 3); /* copy the control variable */
setobjs2s(L, ra + 4, ra + 1); /* copy state */
setobjs2s(L, ra + 3, ra); /* copy function */
L->top.p = ra + 3 + 3;
ProtectNT(luaD_call(L, ra + 3, GETARG_C(i))); /* do the call */
updatestack(ci); /* stack may have changed */
i = *(pc++); /* go to next instruction */
lua_assert(GET_OPCODE(i) == OP_TFORLOOP && ra == RA(i));
@@ -1834,10 +1846,8 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
vmcase(OP_TFORLOOP) {
l_tforloop: {
StkId ra = RA(i);
if (!ttisnil(s2v(ra + 4))) { /* continue loop? */
setobjs2s(L, ra + 2, ra + 4); /* save control variable */
if (!ttisnil(s2v(ra + 3))) /* continue loop? */
pc -= GETARG_Bx(i); /* jump back */
}
vmbreak;
}}
vmcase(OP_SETLIST) {