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Fix narrowing of POW.

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This commit is contained in:
Mike Pall 2011-03-03 17:29:09 +01:00
parent 1cb58fb7bb
commit f29a9d4341
1 changed files with 12 additions and 8 deletions
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20
src/lj_opt_narrow.c
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@ -413,23 +413,27 @@ TRef lj_opt_narrow_pow(jit_State *J, TRef rb, TRef rc, TValue *vc)
if (tvisstr(vc) && !lj_str_tonum(strV(vc), vc)) if (tvisstr(vc) && !lj_str_tonum(strV(vc), vc))
lj_trace_err(J, LJ_TRERR_BADTYPE); lj_trace_err(J, LJ_TRERR_BADTYPE);
n = numV(vc); n = numV(vc);
/* Limit narrowing for pow to small exponents (or for two constants). */ /* Narrowing must be unconditional to preserve (-x)^i semantics. */
if ((tref_isk(rc) && tref_isint(rc) && tref_isk(rb)) || if (numisint(n)) {
((J->flags & JIT_F_OPT_NARROW) && int checkrange = 0;
(numisint(n) && n >= -65536.0 && n <= 65536.0))) { /* Split pow is faster for bigger exponents. But do this only for (+k)^i. */
TRef tmp; if (tref_isk(rb) && (int32_t)ir_knum(IR(tref_ref(rb)))->u32.hi >= 0) {
if (!(n >= -65536.0 && n <= 65536.0)) goto split_pow;
checkrange = 1;
}
if (!tref_isinteger(rc)) { if (!tref_isinteger(rc)) {
if (tref_isstr(rc)) if (tref_isstr(rc))
rc = emitir(IRTG(IR_STRTO, IRT_NUM), rc, 0); rc = emitir(IRTG(IR_STRTO, IRT_NUM), rc, 0);
/* Guarded conversion to integer! */ /* Guarded conversion to integer! */
rc = emitir(IRTGI(IR_CONV), rc, IRCONV_INT_NUM|IRCONV_CHECK); rc = emitir(IRTGI(IR_CONV), rc, IRCONV_INT_NUM|IRCONV_CHECK);
} }
if (!tref_isk(rc)) { /* Range guard: -65536 <= i <= 65536 */ if (checkrange && !tref_isk(rc)) { /* Range guard: -65536 <= i <= 65536 */
tmp = emitir(IRTI(IR_ADD), rc, lj_ir_kint(J, 65536-2147483647-1)); TRef tmp = emitir(IRTI(IR_ADD), rc, lj_ir_kint(J, 65536));
emitir(IRTGI(IR_LE), tmp, lj_ir_kint(J, 2*65536-2147483647-1)); emitir(IRTGI(IR_ULE), tmp, lj_ir_kint(J, 2*65536));
} }
return emitir(IRTN(IR_POW), rb, rc); return emitir(IRTN(IR_POW), rb, rc);
} }
split_pow:
/* FOLD covers most cases, but some are easier to do here. */ /* FOLD covers most cases, but some are easier to do here. */
if (tref_isk(rb) && tvispone(ir_knum(IR(tref_ref(rb))))) if (tref_isk(rb) && tvispone(ir_knum(IR(tref_ref(rb)))))
return rb; /* 1 ^ x ==> 1 */ return rb; /* 1 ^ x ==> 1 */