mirror of
https://github.com/lua/lua
synced 2025-02-07 08:44:01 +03:00
Code reorganization for opcodes OP_FORPREP and OP_FORLOOP
Parts of the code for opcodes OP_FORPREP and OP_FORLOOP were moved to functions outside the interpreter loop.
This commit is contained in:
Roberto Ierusalimschy
parent
508a705c1c
commit
81f2401c6d
191
lvm.c
191
lvm.c
@ -80,6 +80,21 @@
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#endif
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/*
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** Try to convert a value from string to a number value.
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** If the value is not a string or is a string not representing
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** a valid numeral (or if coercions from strings to numbers
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** are disabled via macro 'cvt2num'), do not modify 'result'
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** and return 0.
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*/
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static int l_strton (const TValue *obj, TValue *result) {
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lua_assert(obj != result);
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if (!cvt2num(obj)) /* is object not a string? */
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return 0;
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else
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return (luaO_str2num(svalue(obj), result) == vslen(obj) + 1);
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}
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/*
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** Try to convert a value to a float. The float case is already handled
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@ -91,8 +106,7 @@ int luaV_tonumber_ (const TValue *obj, lua_Number *n) {
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*n = cast_num(ivalue(obj));
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return 1;
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}
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else if (cvt2num(obj) && /* string coercible to number? */
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luaO_str2num(svalue(obj), &v) == vslen(obj) + 1) {
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else if (l_strton(obj, &v)) { /* string coercible to number? */
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*n = nvalue(&v); /* convert result of 'luaO_str2num' to a float */
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return 1;
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}
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@ -111,7 +125,7 @@ int luaV_flttointeger (lua_Number n, lua_Integer *p, int mode) {
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lua_Number f = l_floor(n);
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if (n != f) { /* not an integral value? */
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if (mode == 0) return 0; /* fails if mode demands integral value */
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else if (mode > 1) /* needs ceil? */
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else if (mode == 2) /* needs ceil? */
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f += 1; /* convert floor to ceil (remember: n != f) */
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}
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return lua_numbertointeger(f, p);
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@ -140,27 +154,27 @@ int luaV_tointegerns (const TValue *obj, lua_Integer *p, int mode) {
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*/
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int luaV_tointeger (const TValue *obj, lua_Integer *p, int mode) {
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TValue v;
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if (cvt2num(obj) && luaO_str2num(svalue(obj), &v) == vslen(obj) + 1)
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obj = &v; /* change string to its corresponding number */
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if (l_strton(obj, &v)) /* does 'obj' point to a numerical string? */
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obj = &v; /* change it to point to its corresponding number */
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return luaV_tointegerns(obj, p, mode);
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}
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/*
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** Try to convert a 'for' limit to an integer, preserving the semantics
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** of the loop. (The following explanation assumes a positive step;
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** it is valid for negative steps mutatis mutandis.)
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** Return true if the loop must not run.
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** of the loop. Return true if the loop must not run; otherwise, '*p'
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** gets the integer limit.
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** (The following explanation assumes a positive step; it is valid for
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** negative steps mutatis mutandis.)
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** If the limit is an integer or can be converted to an integer,
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** rounding down, that is the limit.
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** Otherwise, check whether the limit can be converted to a float. If
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** the float is too large, clip it to LUA_MAXINTEGER. If the float
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** is too negative, the loop should not run, because any initial
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** integer value is greater than such limit; so, it returns true to
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** signal that.
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** (For this latter case, no integer limit would be correct; even a
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** limit of LUA_MININTEGER would run the loop once for an initial
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** value equal to LUA_MININTEGER.)
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** integer value is greater than such limit; so, the function returns
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** true to signal that. (For this latter case, no integer limit would be
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** correct; even a limit of LUA_MININTEGER would run the loop once for
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** an initial value equal to LUA_MININTEGER.)
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*/
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static int forlimit (lua_State *L, lua_Integer init, const TValue *lim,
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lua_Integer *p, lua_Integer step) {
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@ -183,6 +197,91 @@ static int forlimit (lua_State *L, lua_Integer init, const TValue *lim,
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}
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/*
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** Prepare a numerical for loop (opcode OP_FORPREP).
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** Return true to skip the loop. Otherwise,
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** after preparation, stack will be as follows:
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** ra : internal index (safe copy of the control variable)
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** ra + 1 : loop counter (integer loops) or limit (float loops)
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** ra + 2 : step
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** ra + 3 : control variable
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*/
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static int forprep (lua_State *L, StkId ra) {
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TValue *pinit = s2v(ra);
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TValue *plimit = s2v(ra + 1);
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TValue *pstep = s2v(ra + 2);
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if (ttisinteger(pinit) && ttisinteger(pstep)) { /* integer loop? */
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lua_Integer init = ivalue(pinit);
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lua_Integer step = ivalue(pstep);
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lua_Integer limit;
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if (step == 0)
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luaG_runerror(L, "'for' step is zero");
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setivalue(s2v(ra + 3), init); /* control variable */
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if (forlimit(L, init, plimit, &limit, step))
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return 1; /* skip the loop */
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else { /* prepare loop counter */
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lua_Unsigned count;
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if (step > 0) { /* ascending loop? */
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count = l_castS2U(limit) - l_castS2U(init);
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if (step != 1) /* avoid division in the too common case */
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count /= l_castS2U(step);
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}
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else { /* step < 0; descending loop */
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count = l_castS2U(init) - l_castS2U(limit);
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/* 'step+1' avoids negating 'mininteger' */
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count /= l_castS2U(-(step + 1)) + 1u;
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}
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/* store the counter in place of the limit (which won't be
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needed anymore */
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setivalue(plimit, l_castU2S(count));
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}
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}
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else { /* try making all values floats */
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lua_Number init; lua_Number limit; lua_Number step;
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if (unlikely(!tonumber(plimit, &limit)))
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luaG_forerror(L, plimit, "limit");
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if (unlikely(!tonumber(pstep, &step)))
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luaG_forerror(L, pstep, "step");
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if (unlikely(!tonumber(pinit, &init)))
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luaG_forerror(L, pinit, "initial value");
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if (step == 0)
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luaG_runerror(L, "'for' step is zero");
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if (luai_numlt(0, step) ? luai_numlt(limit, init)
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: luai_numlt(init, limit))
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return 1; /* skip the loop */
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else {
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/* make sure internal values are all floats */
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setfltvalue(plimit, limit);
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setfltvalue(pstep, step);
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setfltvalue(s2v(ra), init); /* internal index */
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setfltvalue(s2v(ra + 3), init); /* control variable */
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}
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}
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return 0;
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}
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/*
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** Execute a step of a float numerical for loop, returning
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** true iff the loop must continue. (The integer case is
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** written online with opcode OP_FORLOOP, for performance.)
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*/
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static int floatforloop (StkId ra) {
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lua_Number step = fltvalue(s2v(ra + 2));
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lua_Number limit = fltvalue(s2v(ra + 1));
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lua_Number idx = fltvalue(s2v(ra)); /* internal index */
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idx = luai_numadd(L, idx, step); /* increment index */
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if (luai_numlt(0, step) ? luai_numle(idx, limit)
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: luai_numle(limit, idx)) {
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chgfltvalue(s2v(ra), idx); /* update internal index */
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setfltvalue(s2v(ra + 3), idx); /* and control variable */
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return 1; /* jump back */
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}
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else
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return 0; /* finish the loop */
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}
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/*
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** Finish the table access 'val = t[key]'.
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** if 'slot' is NULL, 't' is not a table; otherwise, 'slot' points to
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@ -1631,73 +1730,15 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
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pc -= GETARG_Bx(i); /* jump back */
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}
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}
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else { /* floating loop */
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lua_Number step = fltvalue(s2v(ra + 2));
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lua_Number limit = fltvalue(s2v(ra + 1));
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lua_Number idx = fltvalue(s2v(ra));
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idx = luai_numadd(L, idx, step); /* increment index */
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if (luai_numlt(0, step) ? luai_numle(idx, limit)
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: luai_numle(limit, idx)) {
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chgfltvalue(s2v(ra), idx); /* update internal index */
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setfltvalue(s2v(ra + 3), idx); /* and control variable */
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pc -= GETARG_Bx(i); /* jump back */
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}
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}
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else if (floatforloop(ra)) /* float loop */
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pc -= GETARG_Bx(i); /* jump back */
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updatetrap(ci); /* allows a signal to break the loop */
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vmbreak;
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}
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vmcase(OP_FORPREP) {
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TValue *pinit = s2v(ra);
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TValue *plimit = s2v(ra + 1);
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TValue *pstep = s2v(ra + 2);
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savestate(L, ci); /* in case of errors */
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if (ttisinteger(pinit) && ttisinteger(pstep)) { /* integer loop? */
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lua_Integer init = ivalue(pinit);
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lua_Integer step = ivalue(pstep);
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lua_Integer limit;
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if (step == 0)
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luaG_runerror(L, "'for' step is zero");
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setivalue(s2v(ra + 3), init); /* control variable */
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if (forlimit(L, init, plimit, &limit, step))
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pc += GETARG_Bx(i) + 1; /* skip the loop */
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else { /* prepare loop counter */
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lua_Unsigned count;
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if (step > 0) { /* ascending loop? */
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count = l_castS2U(limit) - l_castS2U(init);
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if (step != 1) /* avoid division in the too common case */
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count /= l_castS2U(step);
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}
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else { /* step < 0; descending loop */
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count = l_castS2U(init) - l_castS2U(limit);
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/* 'step+1' avoids negating 'mininteger' */
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count /= l_castS2U(-(step + 1)) + 1u;
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}
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/* store the counter in place of the limit (which won't be
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needed anymore */
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setivalue(plimit, l_castU2S(count));
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}
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}
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else { /* try making all values floats */
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lua_Number init; lua_Number limit; lua_Number step;
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if (unlikely(!tonumber(plimit, &limit)))
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luaG_forerror(L, plimit, "limit");
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if (unlikely(!tonumber(pstep, &step)))
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luaG_forerror(L, pstep, "step");
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if (unlikely(!tonumber(pinit, &init)))
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luaG_forerror(L, pinit, "initial value");
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if (step == 0)
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luaG_runerror(L, "'for' step is zero");
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if (luai_numlt(0, step) ? luai_numlt(limit, init)
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: luai_numlt(init, limit))
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pc += GETARG_Bx(i) + 1; /* skip the loop */
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else {
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/* make sure internal values are all float */
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setfltvalue(plimit, limit);
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setfltvalue(pstep, step);
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setfltvalue(s2v(ra), init); /* internal index */
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setfltvalue(s2v(ra + 3), init); /* control variable */
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}
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}
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if (forprep(L, ra))
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pc += GETARG_Bx(i) + 1; /* skip the loop */
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vmbreak;
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}
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vmcase(OP_TFORPREP) {
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