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fold-const.c (fold_truthop): Optimize bitfield references with different masks as long as their size and bit...

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* fold-const.c (fold_truthop): Optimize bitfield references with
        different masks as long as their size and bit position are the same.

From-SVN: r26006
This commit is contained in:
Charles M. Hannum 1999-03-26 15:46:33 -07:00 committed by Jeff Law
parent bd910dcf7a
commit 11a86c5688
2 changed files with 14 additions and 12 deletions
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gcc/ChangeLog
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@ -65,6 +65,9 @@ Fri Mar 26 10:43:47 1999 Nick Clifton <nickc@cygnus.com>
Fri Mar 26 01:59:15 1999 "Charles M. Hannum" <root@ihack.net>
* fold-const.c (fold_truthop): Optimize bitfield references with
different masks as long as their size and bit position are the same.
* fold-const.c (fold_truthop): Build a type for both the lhs and
rhs and use it appropriately.

23
gcc/fold-const.c
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@ -3934,25 +3934,24 @@ fold_truthop (code, truth_type, lhs, rhs)
size_int (xrr_bitpos), 0);
/* Make a mask that corresponds to both fields being compared.
Do this for both items being compared. If the masks agree,
and the bits being compared are in the same position, and the
types agree, then we can do this by masking both and comparing
the masked results. */
Do this for both items being compared. If the operands are the
same size and the bits being compared are in the same position
then we can do this by masking both and comparing the masked
results. */
ll_mask = const_binop (BIT_IOR_EXPR, ll_mask, rl_mask, 0);
lr_mask = const_binop (BIT_IOR_EXPR, lr_mask, rr_mask, 0);
if (operand_equal_p (ll_mask, lr_mask, 0)
&& lnbitsize == rnbitsize && xll_bitpos == xlr_bitpos
&& lntype == rntype)
if (lnbitsize == rnbitsize && xll_bitpos == xlr_bitpos)
{
lhs = make_bit_field_ref (ll_inner, lntype, lnbitsize, lnbitpos,
ll_unsignedp || rl_unsignedp);
if (! all_ones_mask_p (ll_mask, lnbitsize))
lhs = build (BIT_AND_EXPR, lntype, lhs, ll_mask);
rhs = make_bit_field_ref (lr_inner, rntype, rnbitsize, rnbitpos,
lr_unsignedp || rr_unsignedp);
if (! all_ones_mask_p (ll_mask, lnbitsize))
{
lhs = build (BIT_AND_EXPR, lntype, lhs, ll_mask);
rhs = build (BIT_AND_EXPR, rntype, rhs, ll_mask);
}
if (! all_ones_mask_p (lr_mask, rnbitsize))
rhs = build (BIT_AND_EXPR, rntype, rhs, lr_mask);
return build (wanted_code, truth_type, lhs, rhs);
}