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stor-layout.c (update_alignment_for_field): New function.

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* stor-layout.c (update_alignment_for_field): New function.
	(place_union_field): Use it.
	(place_field): Likewise.
	* gcc.dg/empty1.C: New test.

From-SVN: r57697
This commit is contained in:
Mark Mitchell 2002-10-01 18:44:49 +00:00 committed by Mark Mitchell
parent b4c20e524c
commit 0645ba8f0b
4 changed files with 124 additions and 122 deletions
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6
gcc/ChangeLog
View File

@ -1,3 +1,9 @@
2002-10-01 Mark Mitchell <mark@codesourcery.com>
* stor-layout.c (update_alignment_for_field): New function.
(place_union_field): Use it.
(place_field): Likewise.
2002-10-01 Nathan Sidwell <nathan@codesourcery.com>
* gcc.c (cc1_options): Add space on -auxbase-strip.

228
gcc/stor-layout.c
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@ -60,6 +60,9 @@ static int reference_types_internal = 0;
static void finalize_record_size PARAMS ((record_layout_info));
static void finalize_type_size PARAMS ((tree));
static void place_union_field PARAMS ((record_layout_info, tree));
static unsigned int update_alignment_for_field
PARAMS ((record_layout_info, tree,
unsigned int));
extern void debug_rli PARAMS ((record_layout_info));
/* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
@ -644,130 +647,23 @@ rli_size_so_far (rli)
return bit_from_pos (rli->offset, rli->bitpos);
}
/* Called from place_field to handle unions. */
/* 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. */
static void
place_union_field (rli, field)
record_layout_info rli;
tree field;
{
unsigned int desired_align;
layout_decl (field, 0);
DECL_FIELD_OFFSET (field) = size_zero_node;
DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
desired_align = DECL_ALIGN (field);
#ifdef BIGGEST_FIELD_ALIGNMENT
/* Some targets (i.e. i386) limit union field alignment
to a lower boundary than alignment of variables unless
it was overridden by attribute aligned. */
if (! DECL_USER_ALIGN (field))
desired_align =
MIN (desired_align, (unsigned) BIGGEST_FIELD_ALIGNMENT);
#endif
#ifdef ADJUST_FIELD_ALIGN
if (! DECL_USER_ALIGN (field))
desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
#endif
TYPE_USER_ALIGN (rli->t) |= DECL_USER_ALIGN (field);
/* Union must be at least as aligned as any field requires. */
rli->record_align = MAX (rli->record_align, desired_align);
rli->unpadded_align = MAX (rli->unpadded_align, desired_align);
#ifdef PCC_BITFIELD_TYPE_MATTERS
/* On the m88000, a bit field of declare type `int' forces the
entire union to have `int' alignment. */
if (PCC_BITFIELD_TYPE_MATTERS && DECL_BIT_FIELD_TYPE (field))
{
unsigned int type_align = TYPE_ALIGN (TREE_TYPE (field));
#ifdef ADJUST_FIELD_ALIGN
if (! TYPE_USER_ALIGN (TREE_TYPE (field)))
type_align = ADJUST_FIELD_ALIGN (field, type_align);
#endif
rli->record_align = MAX (rli->record_align, type_align);
rli->unpadded_align = MAX (rli->unpadded_align, type_align);
TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (TREE_TYPE (field));
}
#endif
/* We assume the union's size will be a multiple of a byte so we don't
bother with BITPOS. */
if (TREE_CODE (rli->t) == UNION_TYPE)
rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
rli->offset = fold (build (COND_EXPR, sizetype,
DECL_QUALIFIER (field),
DECL_SIZE_UNIT (field), rli->offset));
}
/* RLI contains information about the layout of a RECORD_TYPE. FIELD
is a FIELD_DECL to be added after those fields already present in
T. (FIELD is not actually added to the TYPE_FIELDS list here;
callers that desire that behavior must manually perform that step.) */
void
place_field (rli, field)
static unsigned int
update_alignment_for_field (rli, field, known_align)
record_layout_info rli;
tree field;
unsigned int known_align;
{
/* The alignment required for FIELD. */
unsigned int desired_align;
/* The alignment FIELD would have if we just dropped it into the
record as it presently stands. */
unsigned int known_align;
unsigned int actual_align;
unsigned int user_align;
/* The type of this field. */
tree type = TREE_TYPE (field);
if (TREE_CODE (field) == ERROR_MARK || TREE_CODE (type) == ERROR_MARK)
return;
/* If FIELD is static, then treat it like a separate variable, not
really like a structure field. If it is a FUNCTION_DECL, it's a
method. In both cases, all we do is lay out the decl, and we do
it *after* the record is laid out. */
if (TREE_CODE (field) == VAR_DECL)
{
rli->pending_statics = tree_cons (NULL_TREE, field,
rli->pending_statics);
return;
}
/* Enumerators and enum types which are local to this class need not
be laid out. Likewise for initialized constant fields. */
else if (TREE_CODE (field) != FIELD_DECL)
return;
/* Unions are laid out very differently than records, so split
that code off to another function. */
else if (TREE_CODE (rli->t) != RECORD_TYPE)
{
place_union_field (rli, field);
return;
}
/* Work out the known alignment so far. Note that A & (-A) is the
value of the least-significant bit in A that is one. */
if (! integer_zerop (rli->bitpos))
known_align = (tree_low_cst (rli->bitpos, 1)
& - tree_low_cst (rli->bitpos, 1));
else if (integer_zerop (rli->offset))
known_align = BIGGEST_ALIGNMENT;
else if (host_integerp (rli->offset, 1))
known_align = (BITS_PER_UNIT
* (tree_low_cst (rli->offset, 1)
& - tree_low_cst (rli->offset, 1)));
else
known_align = rli->offset_align;
/* True if the field was explicitly aligned by the user. */
bool user_align;
/* Lay out the field so we know what alignment it needs. For a
packed field, use the alignment as specified, disregarding what
@ -785,13 +681,13 @@ place_field (rli, field)
to a lower boundary than alignment of variables unless
it was overridden by attribute aligned. */
#ifdef BIGGEST_FIELD_ALIGNMENT
if (! user_align)
if (!user_align)
desired_align
= MIN (desired_align, (unsigned) BIGGEST_FIELD_ALIGNMENT);
#endif
#ifdef ADJUST_FIELD_ALIGN
if (! user_align)
if (!user_align)
desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
#endif
@ -873,6 +769,96 @@ place_field (rli, field)
rli->unpadded_align = MAX (rli->unpadded_align, DECL_ALIGN (field));
}
TYPE_USER_ALIGN (rli->t) |= user_align;
return desired_align;
}
/* Called from place_field to handle unions. */
static void
place_union_field (rli, field)
record_layout_info rli;
tree field;
{
update_alignment_for_field (rli, field, /*known_align=*/0);
DECL_FIELD_OFFSET (field) = size_zero_node;
DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
/* We assume the union's size will be a multiple of a byte so we don't
bother with BITPOS. */
if (TREE_CODE (rli->t) == UNION_TYPE)
rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
rli->offset = fold (build (COND_EXPR, sizetype,
DECL_QUALIFIER (field),
DECL_SIZE_UNIT (field), rli->offset));
}
/* RLI contains information about the layout of a RECORD_TYPE. FIELD
is a FIELD_DECL to be added after those fields already present in
T. (FIELD is not actually added to the TYPE_FIELDS list here;
callers that desire that behavior must manually perform that step.) */
void
place_field (rli, field)
record_layout_info rli;
tree field;
{
/* The alignment required for FIELD. */
unsigned int desired_align;
/* The alignment FIELD would have if we just dropped it into the
record as it presently stands. */
unsigned int known_align;
unsigned int actual_align;
/* The type of this field. */
tree type = TREE_TYPE (field);
if (TREE_CODE (field) == ERROR_MARK || TREE_CODE (type) == ERROR_MARK)
return;
/* If FIELD is static, then treat it like a separate variable, not
really like a structure field. If it is a FUNCTION_DECL, it's a
method. In both cases, all we do is lay out the decl, and we do
it *after* the record is laid out. */
if (TREE_CODE (field) == VAR_DECL)
{
rli->pending_statics = tree_cons (NULL_TREE, field,
rli->pending_statics);
return;
}
/* Enumerators and enum types which are local to this class need not
be laid out. Likewise for initialized constant fields. */
else if (TREE_CODE (field) != FIELD_DECL)
return;
/* Unions are laid out very differently than records, so split
that code off to another function. */
else if (TREE_CODE (rli->t) != RECORD_TYPE)
{
place_union_field (rli, field);
return;
}
/* Work out the known alignment so far. Note that A & (-A) is the
value of the least-significant bit in A that is one. */
if (! integer_zerop (rli->bitpos))
known_align = (tree_low_cst (rli->bitpos, 1)
& - tree_low_cst (rli->bitpos, 1));
else if (integer_zerop (rli->offset))
known_align = BIGGEST_ALIGNMENT;
else if (host_integerp (rli->offset, 1))
known_align = (BITS_PER_UNIT
* (tree_low_cst (rli->offset, 1)
& - tree_low_cst (rli->offset, 1)));
else
known_align = rli->offset_align;
desired_align = update_alignment_for_field (rli, field, known_align);
if (warn_packed && DECL_PACKED (field))
{
if (known_align > TYPE_ALIGN (type))
@ -956,7 +942,7 @@ place_field (rli, field)
> tree_low_cst (TYPE_SIZE (type), 1) / type_align)
rli->bitpos = round_up (rli->bitpos, type_align);
user_align |= TYPE_USER_ALIGN (type);
TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
}
#endif
@ -999,7 +985,7 @@ place_field (rli, field)
/ type_align))
rli->bitpos = round_up (rli->bitpos, type_align);
user_align |= TYPE_USER_ALIGN (type);
TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
}
#endif
@ -1153,8 +1139,6 @@ place_field (rli, field)
DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
TYPE_USER_ALIGN (rli->t) |= user_align;
/* If this field ended up more aligned than we thought it would be (we
approximate this by seeing if its position changed), lay out the field
again; perhaps we can use an integral mode for it now. */

2
gcc/testsuite/ChangeLog
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@ -1,5 +1,7 @@
2002-10-01 Mark Mitchell <mark@codesourcery.com>
* gcc.dg/empty1.C: New test.
* g++.dg/tls/init-2.C: Tweak error messages.
2002-10-01 Richard Sandiford <rsandifo@redhat.com>

10
gcc/testsuite/gcc.dg/empty1.c Normal file
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@ -0,0 +1,10 @@
/* { dg-do run } */
/* { dg-options "" } */
struct S { int : 0; };
union U { int : 0; };
int main () {
if (__alignof__ (struct S) != __alignof__ (union U))
return 1;
}