diff options
Diffstat (limited to 'gcc/stor-layout.c')
| -rw-r--r-- | gcc/stor-layout.c | 113 |
1 files changed, 92 insertions, 21 deletions
diff --git a/gcc/stor-layout.c b/gcc/stor-layout.c index 41d316543e7..cffb81c7f62 100644 --- a/gcc/stor-layout.c +++ b/gcc/stor-layout.c @@ -634,9 +634,9 @@ rli_size_so_far (record_layout_info rli) } /* FIELD is about to be added to RLI->T. The alignment (in bits) of - the next available location is given by KNOWN_ALIGN. Update the - variable alignment fields in RLI, and return the alignment to give - the FIELD. */ + the next available location within the record is given by KNOWN_ALIGN. + Update the variable alignment fields in RLI, and return the alignment + to give the FIELD. */ unsigned int update_alignment_for_field (record_layout_info rli, tree field, @@ -682,6 +682,18 @@ update_alignment_for_field (record_layout_info rli, tree field, type_align = MIN (type_align, maximum_field_alignment); rli->record_align = MAX (rli->record_align, type_align); rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type)); + /* If we start a new run, make sure we start it properly aligned. */ + if ((!rli->prev_field + || integer_zerop (DECL_SIZE (field)) + || integer_zerop (DECL_SIZE (rli->prev_field)) + || !host_integerp (DECL_SIZE (rli->prev_field), 0) + || !host_integerp (TYPE_SIZE (type), 0) + || !simple_cst_equal (TYPE_SIZE (type), + TYPE_SIZE (TREE_TYPE (rli->prev_field))) + || (rli->remaining_in_alignment + < tree_low_cst (DECL_SIZE (field), 0))) + && desired_align < type_align) + desired_align = type_align; } } #ifdef PCC_BITFIELD_TYPE_MATTERS @@ -820,7 +832,7 @@ place_field (record_layout_info rli, tree field) known_align = (tree_low_cst (rli->bitpos, 1) & - tree_low_cst (rli->bitpos, 1)); else if (integer_zerop (rli->offset)) - known_align = BIGGEST_ALIGNMENT; + known_align = 0; else if (host_integerp (rli->offset, 1)) known_align = (BITS_PER_UNIT * (tree_low_cst (rli->offset, 1) @@ -829,6 +841,8 @@ place_field (record_layout_info rli, tree field) known_align = rli->offset_align; desired_align = update_alignment_for_field (rli, field, known_align); + if (known_align == 0) + known_align = MAX (BIGGEST_ALIGNMENT, rli->record_align); if (warn_packed && DECL_PACKED (field)) { @@ -1001,18 +1015,30 @@ place_field (record_layout_info rli, tree field) if (rli->remaining_in_alignment < bitsize) { - /* out of bits; bump up to next 'word'. */ - rli->offset = DECL_FIELD_OFFSET (rli->prev_field); - rli->bitpos - = size_binop (PLUS_EXPR, TYPE_SIZE (type), - DECL_FIELD_BIT_OFFSET (rli->prev_field)); - rli->prev_field = field; - rli->remaining_in_alignment - = tree_low_cst (TYPE_SIZE (type), 0); + /* If PREV_FIELD is packed, and we haven't lumped + non-packed bitfields with it, treat this as if PREV_FIELD + was not a bitfield. This avoids anomalies where a packed + bitfield with long long base type can take up more + space than a same-size bitfield with base type short. */ + if (rli->prev_packed) + rli->prev_field = prev_saved = NULL; + else + { + /* out of bits; bump up to next 'word'. */ + rli->offset = DECL_FIELD_OFFSET (rli->prev_field); + rli->bitpos + = size_binop (PLUS_EXPR, TYPE_SIZE (type), + DECL_FIELD_BIT_OFFSET (rli->prev_field)); + rli->prev_field = field; + rli->remaining_in_alignment + = tree_low_cst (TYPE_SIZE (type), 0) - bitsize; + } } - - rli->remaining_in_alignment -= bitsize; + else + rli->remaining_in_alignment -= bitsize; } + else if (rli->prev_packed) + rli->prev_field = prev_saved = NULL; else { /* End of a run: if leaving a run of bitfields of the same type @@ -1028,9 +1054,14 @@ place_field (record_layout_info rli, tree field) { tree type_size = TYPE_SIZE (TREE_TYPE (rli->prev_field)); - rli->bitpos - = size_binop (PLUS_EXPR, type_size, - DECL_FIELD_BIT_OFFSET (rli->prev_field)); + /* If the desired alignment is greater or equal to TYPE_SIZE, + we have already adjusted rli->bitpos / rli->offset above. + */ + if ((unsigned HOST_WIDE_INT) tree_low_cst (type_size, 0) + > desired_align) + rli->bitpos + = size_binop (PLUS_EXPR, type_size, + DECL_FIELD_BIT_OFFSET (rli->prev_field)); } else /* We "use up" size zero fields; the code below should behave @@ -1044,6 +1075,7 @@ place_field (record_layout_info rli, tree field) rli->prev_field = NULL; } + rli->prev_packed = 0; normalize_rli (rli); } @@ -1116,20 +1148,59 @@ place_field (record_layout_info rli, tree field) actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1) & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)); else if (integer_zerop (DECL_FIELD_OFFSET (field))) - actual_align = BIGGEST_ALIGNMENT; + actual_align = MAX (BIGGEST_ALIGNMENT, rli->record_align); else if (host_integerp (DECL_FIELD_OFFSET (field), 1)) actual_align = (BITS_PER_UNIT * (tree_low_cst (DECL_FIELD_OFFSET (field), 1) & - tree_low_cst (DECL_FIELD_OFFSET (field), 1))); else actual_align = DECL_OFFSET_ALIGN (field); + /* ACTUAL_ALIGN is still the actual alignment *within the record* . + store / extract bit field operations will check the alignment of the + record against the mode of bit fields. */ if (known_align != actual_align) layout_decl (field, actual_align); - /* Only the MS bitfields use this. */ - if (rli->prev_field == NULL && DECL_BIT_FIELD_TYPE(field)) - rli->prev_field = field; + if (DECL_BIT_FIELD_TYPE (field)) + { + unsigned int type_align = TYPE_ALIGN (type); + + /* Only the MS bitfields use this. We used to also put any kind of + packed bit fields into prev_field, but that makes no sense, because + an 8 bit packed bit field shouldn't impose more restriction on + following fields than a char field, and the alignment requirements + are also not fulfilled. + There is no sane value to set rli->remaining_in_alignment to when + a packed bitfield in prev_field is unaligned. */ + if (maximum_field_alignment != 0) + type_align = MIN (type_align, maximum_field_alignment); + gcc_assert (rli->prev_field + || actual_align >= type_align || DECL_PACKED (field) + || integer_zerop (DECL_SIZE (field)) + || !targetm.ms_bitfield_layout_p (rli->t)); + if (rli->prev_field == NULL && actual_align >= type_align + && !integer_zerop (DECL_SIZE (field))) + { + rli->prev_field = field; + /* rli->remaining_in_alignment has not been set if the bitfield + has size zero, or if it is a packed bitfield. */ + rli->remaining_in_alignment + = (tree_low_cst (TYPE_SIZE (TREE_TYPE (field)), 0) + - tree_low_cst (DECL_SIZE (field), 0)); + rli->prev_packed = DECL_PACKED (field); + + } + else if (rli->prev_field && DECL_PACKED (field)) + { + HOST_WIDE_INT bitsize = tree_low_cst (DECL_SIZE (field), 0); + + if (rli->remaining_in_alignment < bitsize) + rli->prev_field = NULL; + else + rli->remaining_in_alignment -= bitsize; + } + } /* Now add size of this field to the size of the record. If the size is not constant, treat the field as being a multiple of bytes and just |
