type *decl_type_for_bitfield(decl *d)
{
assert(!type_is(d->ref, type_func));
if(d->bits.var.field_width){
const unsigned bits = const_fold_val_i(d->bits.var.field_width);
const int is_signed = type_is_signed(d->ref);
unsigned bytes = bits / CHAR_BIT;
/* need to add on a byte for any leftovers */
if(bits % CHAR_BIT)
bytes++;
return type_nav_MAX_FOR(cc1_type_nav, bytes, is_signed);
}else{
return d->ref;
}
}
static void impl_overlay_mem_reg(
out_ctx *octx,
unsigned memsz, unsigned nregs,
struct vreg regs[], int mem2reg,
const out_val *ptr)
{
const unsigned pws = platform_word_size();
struct vreg *cur_reg = regs;
unsigned reg_i = 0;
if(memsz == 0){
out_val_release(octx, ptr);
return;
}
UCC_ASSERT(
nregs * pws >= memsz,
"not enough registers for memory overlay");
out_comment(octx,
"overlay, %s2%s(%u)",
mem2reg ? "mem" : "reg",
mem2reg ? "reg" : "mem",
memsz);
if(!mem2reg){
/* reserve all registers so we don't accidentally wipe before the spill */
for(reg_i = 0; reg_i < nregs; reg_i++)
v_reserve_reg(octx, ®s[reg_i]);
}
for(;; cur_reg++, reg_i++){
/* read/write whatever size is required */
type *this_ty;
unsigned this_sz;
if(cur_reg->is_float){
UCC_ASSERT(memsz >= 4, "float for memsz %u?", memsz);
this_ty = type_nav_btype(
cc1_type_nav,
memsz > 4 ? type_double : type_float);
}else{
this_ty = type_nav_MAX_FOR(cc1_type_nav, memsz);
}
this_sz = type_size(this_ty, NULL);
UCC_ASSERT(this_sz <= memsz, "reading/writing too much memory");
ptr = out_change_type(octx, ptr, type_ptr_to(this_ty));
out_val_retain(octx, ptr);
if(mem2reg){
const out_val *fetched;
/* can use impl_deref, as we have a register already,
* and know that the memory is an lvalue and not a bitfield
*
* this means we can load straight into the desired register
*/
fetched = impl_deref(octx, ptr, cur_reg);
UCC_ASSERT(reg_i < nregs, "reg oob");
if(fetched->type != V_REG || !vreg_eq(&fetched->bits.regoff.reg, cur_reg)){
/* move to register */
v_freeup_reg(octx, cur_reg);
fetched = v_to_reg_given(octx, fetched, cur_reg);
}
out_flush_volatile(octx, fetched);
v_reserve_reg(octx, cur_reg); /* prevent changes */
}else{
const out_val *vreg = v_new_reg(octx, NULL, this_ty, cur_reg);
out_store(octx, ptr, vreg);
}
memsz -= this_sz;
/* early termination */
if(memsz == 0)
break;
/* increment our memory pointer */
ptr = out_change_type(
octx,
ptr,
type_ptr_to(type_nav_btype(cc1_type_nav, type_uchar)));
ptr = out_op(octx, op_plus,
ptr,
out_new_l(
octx,
type_nav_btype(cc1_type_nav, type_intptr_t),
pws));
}
out_val_release(octx, ptr);
/* done, unreserve all registers */
for(reg_i = 0; reg_i < nregs; reg_i++)
v_unreserve_reg(octx, ®s[reg_i]);
}
