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Fix struct layout some more
Anonymous sub-sub-members weren't handled correctly. Bit-fields neither: this implements PCC layout for now. It temporarily disables MS-compatible bit-field layout.
This commit is contained in:
Michael Matz
parent
ddecb0e685
commit
78c7096162
155
tccgen.c
155
tccgen.c
@ -3239,7 +3239,9 @@ static Sym * find_field (CType *type, int v)
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Sym *s = type->ref;
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v |= SYM_FIELD;
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while ((s = s->next) != NULL) {
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if ((s->v & SYM_FIELD) && (s->v & ~SYM_FIELD) >= SYM_FIRST_ANOM) {
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if ((s->v & SYM_FIELD) &&
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(s->type.t & VT_BTYPE) == VT_STRUCT &&
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(s->v & ~SYM_FIELD) >= SYM_FIRST_ANOM) {
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Sym *ret = find_field (&s->type, v);
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if (ret)
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return ret;
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@ -3250,44 +3252,131 @@ static Sym * find_field (CType *type, int v)
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return s;
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}
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static void struct_add_offset (Sym *s, int offset)
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{
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while ((s = s->next) != NULL) {
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if ((s->v & SYM_FIELD) &&
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(s->type.t & VT_BTYPE) == VT_STRUCT &&
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(s->v & ~SYM_FIELD) >= SYM_FIRST_ANOM) {
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struct_add_offset(s->type.ref, offset);
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} else
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s->c += offset;
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}
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}
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static void struct_layout(CType *type, AttributeDef *ad)
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{
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int align, maxalign, offset, c;
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int align, maxalign, offset, c, bit_pos;
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Sym *f;
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if (ad->a.aligned)
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maxalign = ad->a.aligned;
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else
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maxalign = 1;
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offset = 0;
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c = 0;
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for (f = type->ref->next; f; f = f->next) {
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int extra_bytes = f->c;
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int bit_pos;
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int size = type_size(&f->type, &align);
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if (f->type.t & VT_BITFIELD)
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bit_pos = (f->type.t >> VT_STRUCT_SHIFT) & 0x3f;
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else
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bit_pos = 0;
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if (f->r) {
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align = f->r;
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} else if (ad->a.packed) {
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align = 1;
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for (f = type->ref->next; f; f = f->next) {
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int extra_bytes = 0;
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int typealign, bit_size;
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int size = type_size(&f->type, &typealign);
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int pcc = !tcc_state->ms_bitfields;
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if (f->type.t & VT_BITFIELD) {
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bit_size = (f->type.t >> (VT_STRUCT_SHIFT + 6)) & 0x3f;
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/* without ms-bitfields, allocate the
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* minimum number of bytes necessary,
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* adding single bytes as needed */
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if (!tcc_state->ms_bitfields) {
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if (bit_pos == 0)
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/* minimum bytes for new bitfield */
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size = (bit_size + 7) / 8;
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else {
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/* enough spare bits already allocated? */
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int add_size = (bit_pos - 1) % 8 + 1 + bit_size;
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if (add_size > 8) /* doesn't fit */
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extra_bytes = (add_size - 1) / 8;
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}
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if (extra_bytes) c += extra_bytes;
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else if (bit_pos == 0) {
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}
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} else
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bit_size = -1;
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if (bit_size == 0 && pcc) {
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/* Zero-width bit-fields in PCC mode aren't affected
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by any packing (attribute or pragma). */
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align = typealign;
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} else if (f->r > 1) {
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align = f->r;
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} else if (ad->a.packed || f->r == 1) {
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align = 1;
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typealign = 1;
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} else {
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align = typealign;
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}
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/*if (extra_bytes) c += extra_bytes;
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else*/ if (bit_size < 0) {
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int addbytes = (bit_pos + 7) >> 3;
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if (type->ref->type.t == TOK_STRUCT) {
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c = (c + align - 1) & -align;
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c = (c + addbytes + align - 1) & -align;
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offset = c;
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if (size > 0)
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c += size;
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} else {
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offset = 0;
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if (addbytes > c)
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c = addbytes;
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if (size > c)
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c = size;
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}
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if (align > maxalign)
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maxalign = align;
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bit_pos = 0;
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} else {
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/* A bit-field. Layout is more complicated. There are two
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options TCC implements: PCC compatible and MS compatible
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(PCC compatible is what GCC uses for almost all targets). */
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if (!bit_pos) {
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if (type->ref->type.t == TOK_STRUCT) {
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/* Don't align c here. That's only to be done
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in certain cases. */
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offset = c;
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} else {
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offset = 0;
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}
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}
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if (pcc) {
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/* In PCC layout a non-packed bit-field is placed adjacent
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to the preceding bit-fields, except if it would overflow
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its container (depending on base type) or it's a zero-width
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bit-field. Packed non-zero-width bit-fields always are
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placed adjacent. */
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if (typealign != 1 &&
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(bit_pos + bit_size > size * 8 ||
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bit_size == 0)) {
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c = (c + ((bit_pos + 7) >> 3) + typealign - 1) & -typealign;
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offset = c;
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bit_pos = 0;
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}
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/* In PCC layout named bit-fields influence the alignment
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of the containing struct using the base types alignment,
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except for packed fields or zero-width fields. */
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if (bit_size > 0) {
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if (align > maxalign)
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maxalign = align;
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if (typealign > maxalign)
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maxalign = typealign;
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}
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} else {
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tcc_error("ms bit-field layout not implemented");
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}
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f->type.t = (f->type.t & ~(0x3f << VT_STRUCT_SHIFT))
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| (bit_pos << VT_STRUCT_SHIFT);
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bit_pos += bit_size;
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if (bit_pos >= size * 8) {
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c += size;
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bit_pos -= size * 8;
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}
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}
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#if 0
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printf("set field %s offset=%d",
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get_tok_str(f->v & ~SYM_FIELD, NULL), offset);
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printf("set field %s offset=%d c=%d",
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get_tok_str(f->v & ~SYM_FIELD, NULL), offset, c);
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if (f->type.t & VT_BITFIELD) {
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printf(" pos=%d size=%d",
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(f->type.t >> VT_STRUCT_SHIFT) & 0x3f,
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@ -3325,9 +3414,7 @@ static void struct_layout(CType *type, AttributeDef *ad)
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}
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*pps = NULL;
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}
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ass = f->type.ref;
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while ((ass = ass->next) != NULL)
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ass->c += offset;
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struct_add_offset(f->type.ref, offset);
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f->c = 0;
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} else {
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f->c = offset;
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@ -3336,7 +3423,7 @@ static void struct_layout(CType *type, AttributeDef *ad)
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f->r = 0;
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}
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/* store size and alignment */
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type->ref->c = (c + maxalign - 1) & -maxalign;
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type->ref->c = (c + ((bit_pos + 7) >> 3) + maxalign - 1) & -maxalign;
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type->ref->r = maxalign;
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}
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@ -3515,11 +3602,6 @@ static void struct_decl(CType *type, AttributeDef *ad, int u)
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} else if (bit_size == bsize) {
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/* no need for bit fields */
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bit_pos = 0;
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} else if (bit_size == 0) {
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/* XXX: what to do if only padding in a
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structure ? */
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/* zero size: means to pad */
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bit_pos = 0;
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} else {
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/* if type change, union, or will overrun
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* allignment slot, start at a newly
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@ -3531,20 +3613,6 @@ static void struct_decl(CType *type, AttributeDef *ad, int u)
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type1.t |= VT_BITFIELD |
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(bit_pos << VT_STRUCT_SHIFT) |
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(bit_size << (VT_STRUCT_SHIFT + 6));
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/* without ms-bitfields, allocate the
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* minimum number of bytes necessary,
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* adding single bytes as needed */
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if (!tcc_state->ms_bitfields) {
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if (bit_pos == 0)
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/* minimum bytes for new bitfield */
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size = (bit_size + 7) / 8;
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else {
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/* enough spare bits already allocated? */
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int add_size = (bit_pos - 1) % 8 + 1 + bit_size;
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if (add_size > 8) /* doesn't fit */
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extra_bytes = (add_size - 1) / 8;
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}
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}
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bit_pos += bit_size;
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}
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prevbt = bt;
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@ -3561,6 +3629,11 @@ static void struct_decl(CType *type, AttributeDef *ad, int u)
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anonymous member of struct type. */
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v = anon_sym++;
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}
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if (v == 0 && bit_size >= 0) {
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/* Need to remember anon bit-fields as well.
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They influence layout. */
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v = anon_sym++;
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}
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if (v) {
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ss = sym_push(v | SYM_FIELD, &type1, alignoverride, extra_bytes);
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*ps = ss;
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@ -1026,10 +1026,67 @@ struct aligntest4 {
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double a[0];
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};
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struct __attribute__((aligned(16))) aligntest5
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{
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int i;
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};
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struct aligntest6
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{
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int i;
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} __attribute__((aligned(16)));
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struct aligntest7
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{
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int i;
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};
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struct aligntest5 altest5[2];
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struct aligntest6 altest6[2];
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int pad1;
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/* altest7 is correctly aligned to 16 bytes also with TCC,
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but __alignof__ returns the wrong result (4) because we
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can't store the alignment yet when specified on symbols
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directly (it's stored in the type so we'd need to make
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a copy of it).
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struct aligntest7 altest7[2] __attribute__((aligned(16)));*/
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struct Large {
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unsigned long flags;
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union {
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void *u1;
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int *u2;
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};
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struct {
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union {
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unsigned long index;
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void *freelist;
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};
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union {
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unsigned long counters;
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struct {
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int bla;
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};
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};
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};
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union {
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struct {
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long u3;
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long u4;
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};
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void *u5;
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struct {
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unsigned long compound_head;
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unsigned int compound_dtor;
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unsigned int compound_order;
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};
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};
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} __attribute__((aligned(2 * sizeof(long))));
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void struct_test()
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{
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struct1 *s;
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union union2 u;
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struct Large ls;
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printf("struct:\n");
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printf("sizes: %d %d %d %d\n",
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@ -1037,6 +1094,7 @@ void struct_test()
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sizeof(struct struct2),
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sizeof(union union1),
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sizeof(union union2));
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printf("offsets: %d\n", (int)((char*)&st1.u.v1 - (char*)&st1));
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st1.f1 = 1;
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st1.f2 = 2;
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st1.f3 = 3;
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@ -1065,10 +1123,27 @@ void struct_test()
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sizeof(struct aligntest3), __alignof__(struct aligntest3));
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printf("aligntest4 sizeof=%d alignof=%d\n",
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sizeof(struct aligntest4), __alignof__(struct aligntest4));
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printf("aligntest5 sizeof=%d alignof=%d\n",
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sizeof(struct aligntest5), __alignof__(struct aligntest5));
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printf("aligntest6 sizeof=%d alignof=%d\n",
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sizeof(struct aligntest6), __alignof__(struct aligntest6));
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printf("aligntest7 sizeof=%d alignof=%d\n",
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sizeof(struct aligntest7), __alignof__(struct aligntest7));
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printf("altest5 sizeof=%d alignof=%d\n",
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sizeof(altest5), __alignof__(altest5));
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printf("altest6 sizeof=%d alignof=%d\n",
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sizeof(altest6), __alignof__(altest6));
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/*printf("altest7 sizeof=%d alignof=%d\n",
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sizeof(altest7), __alignof__(altest7));*/
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/* empty structures (GCC extension) */
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printf("sizeof(struct empty) = %d\n", sizeof(struct empty));
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printf("alignof(struct empty) = %d\n", __alignof__(struct empty));
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printf("Large: sizeof=%d\n", sizeof(ls));
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memset(&ls, 0, sizeof(ls));
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ls.compound_head = 42;
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printf("Large: offsetof(compound_head)=%d\n", (int)((char*)&ls.compound_head - (char*)&ls));
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}
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/* XXX: depend on endianness */
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@ -3547,11 +3622,22 @@ typedef struct Spacked3_s {
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int c;
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} __attribute__((__packed__)) Spacked3;
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Spacked3 spacked3;
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struct gate_struct64 {
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unsigned short offset_low;
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unsigned short segment;
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unsigned ist : 3, zero0 : 5, type : 5, dpl : 2, p : 1;
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unsigned short offset_middle;
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unsigned offset_high;
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unsigned zero1;
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} __attribute__((packed));
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typedef struct gate_struct64 gate_desc;
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gate_desc a_gate_desc;
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void attrib_test(void)
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{
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printf("attr: %d %d %d %d\n", sizeof(struct Spacked),
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sizeof(spacked), sizeof(Spacked2), sizeof(spacked2));
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printf("attr: %d %d\n", sizeof(Spacked3), sizeof(spacked3));
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printf("attr: %d %d\n", sizeof(gate_desc), sizeof(a_gate_desc));
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}
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extern __attribute__((__unused__)) char * __attribute__((__unused__)) *
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strange_attrib_placement (void);
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