diff options
| author | Mike Pall <mike> | 2011-03-03 17:29:09 +0100 |
|---|---|---|
| committer | Mike Pall <mike> | 2011-03-03 17:29:09 +0100 |
| commit | f29a9d4341c64fa47c735bdf6ae1f379b6b6464c (patch) | |
| tree | 78582e47199e76dad6309ddd540d070e3f4c16d2 /src/lj_opt_narrow.c | |
| parent | 1cb58fb7bb3cfe455426246599cac32ad5ec57ee (diff) | |
| download | luajit2-f29a9d4341c64fa47c735bdf6ae1f379b6b6464c.tar.gz | |
Fix narrowing of POW.
Diffstat (limited to 'src/lj_opt_narrow.c')
| -rw-r--r-- | src/lj_opt_narrow.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/src/lj_opt_narrow.c b/src/lj_opt_narrow.c index 71062493..0a2bb6cd 100644 --- a/src/lj_opt_narrow.c +++ b/src/lj_opt_narrow.c @@ -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)) lj_trace_err(J, LJ_TRERR_BADTYPE); n = numV(vc); - /* Limit narrowing for pow to small exponents (or for two constants). */ - if ((tref_isk(rc) && tref_isint(rc) && tref_isk(rb)) || - ((J->flags & JIT_F_OPT_NARROW) && - (numisint(n) && n >= -65536.0 && n <= 65536.0))) { - TRef tmp; + /* Narrowing must be unconditional to preserve (-x)^i semantics. */ + if (numisint(n)) { + int checkrange = 0; + /* Split pow is faster for bigger exponents. But do this only for (+k)^i. */ + 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_isstr(rc)) rc = emitir(IRTG(IR_STRTO, IRT_NUM), rc, 0); /* Guarded conversion to integer! */ rc = emitir(IRTGI(IR_CONV), rc, IRCONV_INT_NUM|IRCONV_CHECK); } - if (!tref_isk(rc)) { /* Range guard: -65536 <= i <= 65536 */ - tmp = emitir(IRTI(IR_ADD), rc, lj_ir_kint(J, 65536-2147483647-1)); - emitir(IRTGI(IR_LE), tmp, lj_ir_kint(J, 2*65536-2147483647-1)); + if (checkrange && !tref_isk(rc)) { /* Range guard: -65536 <= i <= 65536 */ + TRef tmp = emitir(IRTI(IR_ADD), rc, lj_ir_kint(J, 65536)); + emitir(IRTGI(IR_ULE), tmp, lj_ir_kint(J, 2*65536)); } return emitir(IRTN(IR_POW), rb, rc); } +split_pow: /* FOLD covers most cases, but some are easier to do here. */ if (tref_isk(rb) && tvispone(ir_knum(IR(tref_ref(rb))))) return rb; /* 1 ^ x ==> 1 */ |