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Revert to trival pow() optimizations to prevent inaccuracies.

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This commit is contained in:
Mike Pall
2022-03-08 19:44:10 +01:00
parent aa0550e3f0
commit 96d6d50320
18 changed files with 45 additions and 157 deletions
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37
src/lj_opt_fold.c
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@@ -236,14 +236,10 @@ LJFOLDF(kfold_fpcall2)
return NEXTFOLD;
}
LJFOLD(POW KNUM KINT)
LJFOLD(POW KNUM KNUM)
LJFOLDF(kfold_numpow)
{
lua_Number a = knumleft;
lua_Number b = fright->o == IR_KINT ? (lua_Number)fright->i : knumright;
lua_Number y = lj_vm_foldarith(a, b, IR_POW - IR_ADD);
return lj_ir_knum(J, y);
return lj_ir_knum(J, lj_vm_foldarith(knumleft, knumright, IR_POW - IR_ADD));
}
/* Must not use kfold_kref for numbers (could be NaN). */
@@ -1113,34 +1109,17 @@ LJFOLDF(simplify_nummuldiv_negneg)
return RETRYFOLD;
}
LJFOLD(POW any KINT)
LJFOLDF(simplify_numpow_xkint)
LJFOLD(POW any KNUM)
LJFOLDF(simplify_numpow_k)
{
int32_t k = fright->i;
TRef ref = fins->op1;
if (k == 0) /* x ^ 0 ==> 1 */
if (knumright == 0) /* x ^ 0 ==> 1 */
return lj_ir_knum_one(J); /* Result must be a number, not an int. */
if (k == 1) /* x ^ 1 ==> x */
else if (knumright == 1) /* x ^ 1 ==> x */
return LEFTFOLD;
if ((uint32_t)(k+65536) > 2*65536u) /* Limit code explosion. */
else if (knumright == 2) /* x ^ 2 ==> x * x */
return emitir(IRTN(IR_MUL), fins->op1, fins->op1);
else
return NEXTFOLD;
if (k < 0) { /* x ^ (-k) ==> (1/x) ^ k. */
ref = emitir(IRTN(IR_DIV), lj_ir_knum_one(J), ref);
k = -k;
}
/* Unroll x^k for 1 <= k <= 65536. */
for (; (k & 1) == 0; k >>= 1) /* Handle leading zeros. */
ref = emitir(IRTN(IR_MUL), ref, ref);
if ((k >>= 1) != 0) { /* Handle trailing bits. */
TRef tmp = emitir(IRTN(IR_MUL), ref, ref);
for (; k != 1; k >>= 1) {
if (k & 1)
ref = emitir(IRTN(IR_MUL), ref, tmp);
tmp = emitir(IRTN(IR_MUL), tmp, tmp);
}
ref = emitir(IRTN(IR_MUL), ref, tmp);
}
return ref;
}
/* -- Simplify conversions ------------------------------------------------ */