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class.c (check_bitfield_decl): Remove restriction on really long bitfields.

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* class.c (check_bitfield_decl): Remove restriction on really long
	bitfields.
	(layout_class_type): Implement new ABI handling of bitfields
	longer than their types.

From-SVN: r32625
This commit is contained in:
Mark Mitchell 2000-03-19 00:59:51 +00:00 committed by Mark Mitchell
parent 7145ef21d8
commit 01955e9613
3 changed files with 81 additions and 20 deletions
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7
gcc/cp/ChangeLog
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@ -1,3 +1,10 @@
2000-03-18 Mark Mitchell <mark@codesourcery.com>
* class.c (check_bitfield_decl): Remove restriction on really long
bitfields.
(layout_class_type): Implement new ABI handling of bitfields
longer than their types.
2000-03-18 Martin v. Löwis <loewis@informatik.hu-berlin.de>
* parse.y (extdefs): Call ggc_collect.

87
gcc/cp/class.c
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@ -3658,17 +3658,6 @@ check_bitfield_decl (field)
DECL_INITIAL (field) = NULL;
cp_error_at ("zero width for bit-field `%D'", field);
}
else if (0 < compare_tree_int (w,
TYPE_PRECISION
(long_long_unsigned_type_node)))
{
/* The backend will dump if you try to use something too
big; avoid that. */
DECL_INITIAL (field) = NULL;
sorry ("bit-fields larger than %d bits",
TYPE_PRECISION (long_long_unsigned_type_node));
cp_error_at (" in declaration of `%D'", field);
}
else if (compare_tree_int (w, TYPE_PRECISION (type)) > 0
&& TREE_CODE (type) != ENUMERAL_TYPE
&& TREE_CODE (type) != BOOLEAN_TYPE)
@ -4168,8 +4157,10 @@ dfs_search_base_offsets (binfo, data)
non-static data member of the type indicated by RLI. BINFO is the
binfo corresponding to the base subobject, or, if this is a
non-static data-member, a dummy BINFO for the type of the data
member. V maps offsets to types already located at those offsets.
This function determines the position of the DECL. */
member. BINFO may be NULL if checks to see if the field overlaps
an existing field with the same type are not required. V maps
offsets to types already located at those offsets. This function
determines the position of the DECL. */
static void
layout_nonempty_base_or_field (rli, decl, binfo, v)
@ -4192,7 +4183,8 @@ layout_nonempty_base_or_field (rli, decl, binfo, v)
BINFO_OFFSET. */
offset = size_int (CEIL (TREE_INT_CST_LOW (DECL_FIELD_BITPOS (decl)),
BITS_PER_UNIT));
propagate_binfo_offsets (binfo, offset);
if (binfo)
propagate_binfo_offsets (binfo, offset);
/* We have to check to see whether or not there is already
something of the same type at the offset we're about to use.
@ -4209,10 +4201,10 @@ layout_nonempty_base_or_field (rli, decl, binfo, v)
empty class, have non-zero size, any overlap can happen only
with a direct or indirect base-class -- it can't happen with
a data member. */
if (flag_new_abi && dfs_walk (binfo,
dfs_search_base_offsets,
dfs_skip_vbases,
v))
if (binfo && flag_new_abi && dfs_walk (binfo,
dfs_search_base_offsets,
dfs_skip_vbases,
v))
{
/* Undo the propogate_binfo_offsets call. */
offset = convert (sizetype,
@ -4930,6 +4922,8 @@ layout_class_type (t, empty_p, has_virtual_p,
field = TREE_CHAIN (field))
{
tree binfo;
tree type;
tree padding;
/* We still pass things that aren't non-static data members to
the back-end, in case it wants to do something with them. */
@ -4939,11 +4933,64 @@ layout_class_type (t, empty_p, has_virtual_p,
continue;
}
type = TREE_TYPE (field);
/* If this field is a bit-field whose width is greater than its
type, then there are some special rules for allocating it
under the new ABI. Under the old ABI, there were no special
rules, but the back-end can't handle bitfields longer than a
`long long', so we use the same mechanism. */
if (DECL_C_BIT_FIELD (field)
&& ((flag_new_abi
&& INT_CST_LT (TYPE_SIZE (type), DECL_SIZE (field)))
|| (!flag_new_abi
&& compare_tree_int (DECL_SIZE (field),
TYPE_PRECISION
(long_long_unsigned_type_node)) > 0)))
{
integer_type_kind itk;
tree integer_type;
/* We must allocate the bits as if suitably aligned for the
longest integer type that fits in this many bits. type
of the field. Then, we are supposed to use the left over
bits as additional padding. */
for (itk = itk_char; itk != itk_none; ++itk)
if (INT_CST_LT (DECL_SIZE (field),
TYPE_SIZE (integer_types[itk])))
break;
/* ITK now indicates a type that is too large for the
field. We have to back up by one to find the largest
type that fits. */
integer_type = integer_types[itk - 1];
padding = size_diffop (DECL_SIZE (field),
TYPE_SIZE (integer_type));
DECL_SIZE (field) = TYPE_SIZE (integer_type);
DECL_ALIGN (field) = TYPE_ALIGN (integer_type);
}
else
padding = NULL_TREE;
/* Create a dummy BINFO corresponding to this field. */
binfo = make_binfo (size_zero_node, TREE_TYPE (field),
NULL_TREE, NULL_TREE);
binfo = make_binfo (size_zero_node, type, NULL_TREE, NULL_TREE);
unshare_base_binfos (binfo);
layout_nonempty_base_or_field (rli, field, binfo, v);
/* If we needed additional padding after this field, add it
now. */
if (padding)
{
tree padding_field;
padding_field = build_decl (FIELD_DECL,
NULL_TREE,
char_type_node);
DECL_BIT_FIELD (padding_field) = 1;
DECL_SIZE (padding_field) = padding;
DECL_ALIGN (padding_field) = 1;
layout_nonempty_base_or_field (rli, padding_field, NULL_TREE, v);
}
}
/* Clean up. */

7
gcc/testsuite/g++.old-deja/g++.other/bitfld5.C Normal file
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@ -0,0 +1,7 @@
// Build don't link:
// Special g++ Options: -w
struct S
{
int i : 1756;
};