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Add FOLD rule to turn i << 1 into i + i.

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Mike Pall 2010-12-06 13:26:58 +01:00
parent a5bdae8f23
commit f6c4e8d3d7
1 changed files with 5 additions and 0 deletions
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5
src/lj_opt_fold.c
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@ -859,6 +859,11 @@ LJFOLDF(simplify_shift_ik)
int32_t k = (fright->i & mask);
if (k == 0) /* i o 0 ==> i */
return LEFTFOLD;
if (k == 1 && fins->o == IR_BSHL) { /* i << 1 ==> i + i */
fins->o = IR_ADD;
fins->op2 = fins->op1;
return RETRYFOLD;
}
if (k != fright->i) { /* i o k ==> i o (k & mask) */
fins->op2 = (IRRef1)lj_ir_kint(J, k);
return RETRYFOLD;