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| author | Charles M. Hannum <root@ihack.net> | 1999-03-26 14:52:14 -0700 |
|---|---|---|
| committer | Jeff Law <law@gcc.gnu.org> | 1999-03-26 14:52:14 -0700 |
| commit | 97ea717682ff2c82773a482c9dc9d467810c03ef (patch) | |
| tree | 78a476e1fb06efb51cbc4e1ab6e07cdd1af05727 /gcc | |
| parent | 2d490c9e5d6c47fffb395c10115aed5e4082ddbe (diff) | |
| download | gcc-97ea717682ff2c82773a482c9dc9d467810c03ef.zip gcc-97ea717682ff2c82773a482c9dc9d467810c03ef.tar.gz gcc-97ea717682ff2c82773a482c9dc9d467810c03ef.tar.bz2 | |
fold-const.c (fold_truthop): Mask the lhs and rhs after merging adjacent bitfield references.
* fold-const.c (fold_truthop): Mask the lhs and rhs after merging
adjacent bitfield references.
From-SVN: r26004
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 3 | ||||
| -rw-r--r-- | gcc/fold-const.c | 32 |
2 files changed, 25 insertions, 10 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 1935236..0e9486c 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -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): Mask the lhs and rhs after merging + adjacent bitfield references. + * fold-const.c (fold_truthop): Verify that the lhs and rhs are in the same bit position when optimizing bitfield references which have the same mask. diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 78d7e41..93a0ae0 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -3956,20 +3956,32 @@ fold_truthop (code, truth_type, lhs, rhs) /* There is still another way we can do something: If both pairs of fields being compared are adjacent, we may be able to make a wider - field containing them both. */ + field containing them both. + + Note that we still must mask the lhs/rhs expressions. Furthermore, + the mask must be shifted to account for the shift done by + make_bit_field_ref. */ if ((ll_bitsize + ll_bitpos == rl_bitpos && lr_bitsize + lr_bitpos == rr_bitpos) || (ll_bitpos == rl_bitpos + rl_bitsize && lr_bitpos == rr_bitpos + rr_bitsize)) - return build (wanted_code, truth_type, - make_bit_field_ref (ll_inner, type, - ll_bitsize + rl_bitsize, - MIN (ll_bitpos, rl_bitpos), - ll_unsignedp), - make_bit_field_ref (lr_inner, type, - lr_bitsize + rr_bitsize, - MIN (lr_bitpos, rr_bitpos), - lr_unsignedp)); + { + lhs = make_bit_field_ref (ll_inner, type, ll_bitsize + rl_bitsize, + MIN (ll_bitpos, rl_bitpos), ll_unsignedp); + ll_mask = const_binop (RSHIFT_EXPR, ll_mask, + size_int (MIN (xll_bitpos, xrl_bitpos)), 0); + if (! all_ones_mask_p (ll_mask, ll_bitsize + rl_bitsize)) + lhs = build (BIT_AND_EXPR, type, lhs, ll_mask); + + rhs = make_bit_field_ref (lr_inner, type, lr_bitsize + rr_bitsize, + MIN (lr_bitpos, rr_bitpos), lr_unsignedp); + lr_mask = const_binop (RSHIFT_EXPR, lr_mask, + size_int (MIN (xlr_bitpos, xrr_bitpos)), 0); + if (! all_ones_mask_p (lr_mask, lr_bitsize + rr_bitsize)) + rhs = build (BIT_AND_EXPR, type, rhs, lr_mask); + + return build (wanted_code, truth_type, lhs, rhs); + } return 0; } |