rust/src/librustc/middle/trans/adt.rs

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// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
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use core::libc::c_ulonglong;
use core::option::{Option, Some, None};
use core::vec;
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use lib::llvm::{ValueRef, TypeRef, True, False};
use middle::trans::_match;
use middle::trans::build::*;
use middle::trans::common::*;
use middle::trans::machine;
use middle::trans::type_of;
use middle::ty;
use syntax::ast;
use util::ppaux::ty_to_str;
// XXX: should this be done with boxed traits instead of ML-style?
pub enum Repr {
Unit(int),
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CEnum(int, int), /* discriminant range */
Univariant(Struct, Destructor),
General(~[Struct])
}
enum Destructor {
DtorPresent,
DtorAbsent,
NoDtor
}
struct Struct {
size: u64,
align: u64,
fields: ~[ty::t]
}
pub fn represent_node(bcx: block, node: ast::node_id)
-> Repr {
represent_type(bcx.ccx(), node_id_type(bcx, node))
}
pub fn represent_type(cx: @CrateContext, t: ty::t) -> Repr {
debug!("Representing: %s", ty_to_str(cx.tcx, t));
// XXX: cache this
match ty::get(t).sty {
ty::ty_tup(ref elems) => {
Univariant(mk_struct(cx, *elems), NoDtor)
}
ty::ty_rec(ref fields) => {
// XXX: Are these in the right order?
Univariant(mk_struct(cx, fields.map(|f| f.mt.ty)), DtorAbsent)
}
ty::ty_struct(def_id, ref substs) => {
let fields = ty::lookup_struct_fields(cx.tcx, def_id);
let dt = ty::ty_dtor(cx.tcx, def_id).is_present();
Univariant(mk_struct(cx, fields.map(|field| {
ty::lookup_field_type(cx.tcx, def_id, field.id, substs)
})), if dt { DtorPresent } else { DtorAbsent })
}
ty::ty_enum(def_id, ref substs) => {
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struct Case { discr: int, tys: ~[ty::t] };
let cases = do ty::enum_variants(cx.tcx, def_id).map |vi| {
let arg_tys = do vi.args.map |&raw_ty| {
ty::subst(cx.tcx, substs, raw_ty)
};
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Case { discr: vi.disr_val, tys: arg_tys }
};
if cases.len() == 0 {
// Uninhabitable; represent as unit
Univariant(mk_struct(cx, ~[]), NoDtor)
} else if cases.len() == 1 && cases[0].tys.len() == 0 {
Unit(cases[0].discr)
} else if cases.len() == 1 {
// struct, tuple, newtype, etc.
assert cases[0].discr == 0;
Univariant(mk_struct(cx, cases[0].tys), NoDtor)
} else if cases.all(|c| c.tys.len() == 0) {
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let discrs = cases.map(|c| c.discr);
CEnum(discrs.min(), discrs.max())
} else {
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if !cases.alli(|i,c| c.discr == (i as int)) {
cx.sess.bug(fmt!("non-C-like enum %s with specified \
discriminants",
ty::item_path_str(cx.tcx, def_id)))
}
General(cases.map(|c| mk_struct(cx, c.tys)))
}
}
_ => cx.sess.bug(~"adt::represent_type called on non-ADT type")
}
}
fn mk_struct(cx: @CrateContext, tys: &[ty::t]) -> Struct {
let lltys = tys.map(|&ty| type_of::sizing_type_of(cx, ty));
let llty_rec = T_struct(lltys);
Struct {
size: machine::llsize_of_alloc(cx, llty_rec) /*bad*/as u64,
align: machine::llalign_of_min(cx, llty_rec) /*bad*/as u64,
fields: vec::from_slice(tys)
}
}
pub fn sizing_fields_of(cx: @CrateContext, r: &Repr) -> ~[TypeRef] {
generic_fields_of(cx, r, true)
}
pub fn fields_of(cx: @CrateContext, r: &Repr) -> ~[TypeRef] {
generic_fields_of(cx, r, false)
}
fn generic_fields_of(cx: @CrateContext, r: &Repr, sizing: bool)
-> ~[TypeRef] {
match *r {
Unit(*) => ~[],
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CEnum(*) => ~[T_enum_discrim(cx)],
Univariant(ref st, dt) => {
let f = if sizing {
st.fields.map(|&ty| type_of::sizing_type_of(cx, ty))
} else {
st.fields.map(|&ty| type_of::type_of(cx, ty))
};
match dt {
NoDtor => f,
DtorAbsent => ~[T_struct(f)],
DtorPresent => ~[T_struct(f), T_i8()]
}
}
General(ref sts) => {
~[T_enum_discrim(cx),
T_array(T_i8(), sts.map(|st| st.size).max() /*bad*/as uint)]
}
}
}
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fn load_discr(bcx: block, scrutinee: ValueRef, min: int, max: int)
-> ValueRef {
let ptr = GEPi(bcx, scrutinee, [0, 0]);
if max + 1 == min {
// i.e., if the range is everything. The lo==hi case would be
// rejected by the LLVM verifier (it would mean either an
// empty set, which is impossible, or the entire range of the
// type, which is pointless).
Load(bcx, ptr)
} else {
// llvm::ConstantRange can deal with ranges that wrap around,
// so an overflow on (max + 1) is fine.
LoadRangeAssert(bcx, ptr, min as c_ulonglong,
(max + 1) as c_ulonglong,
/* signed: */ True)
}
}
pub fn trans_switch(bcx: block, r: &Repr, scrutinee: ValueRef) ->
(_match::branch_kind, Option<ValueRef>) {
match *r {
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CEnum(min, max) => {
(_match::switch, Some(load_discr(bcx, scrutinee, min, max)))
}
Unit(*) | Univariant(*) => {
(_match::single, None)
}
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General(ref cases) => {
(_match::switch, Some(load_discr(bcx, scrutinee, 0,
(cases.len() - 1) as int)))
}
}
}
pub fn trans_case(bcx: block, r: &Repr, discr: int) -> _match::opt_result {
match *r {
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CEnum(*) => {
_match::single_result(rslt(bcx, C_int(bcx.ccx(), discr)))
}
Unit(*) | Univariant(*)=> {
bcx.ccx().sess.bug(~"no cases for univariants or structs")
}
General(*) => {
_match::single_result(rslt(bcx, C_int(bcx.ccx(), discr)))
}
}
}
pub fn trans_set_discr(bcx: block, r: &Repr, val: ValueRef, discr: int) {
match *r {
Unit(the_discr) => {
assert discr == the_discr;
}
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CEnum(min, max) => {
assert min <= discr && discr <= max;
Store(bcx, C_int(bcx.ccx(), discr), GEPi(bcx, val, [0, 0]))
}
Univariant(_, DtorPresent) => {
assert discr == 0;
Store(bcx, C_u8(1), GEPi(bcx, val, [0, 1]))
}
Univariant(*) => {
assert discr == 0;
}
General(*) => {
Store(bcx, C_int(bcx.ccx(), discr), GEPi(bcx, val, [0, 0]))
}
}
}
pub fn num_args(r: &Repr, discr: int) -> uint {
match *r {
Unit(*) | CEnum(*) => 0,
Univariant(ref st, _dt) => { assert discr == 0; st.fields.len() }
General(ref cases) => cases[discr as uint].fields.len()
}
}
pub fn trans_GEP(bcx: block, r: &Repr, val: ValueRef, discr: int, ix: uint)
-> ValueRef {
// Note: if this ever needs to generate conditionals (e.g., if we
// decide to do some kind of cdr-coding-like non-unique repr
// someday), it'll need to return a possibly-new bcx as well.
match *r {
Unit(*) | CEnum(*) => {
bcx.ccx().sess.bug(~"element access in C-like enum")
}
Univariant(ref st, dt) => {
assert discr == 0;
let val = match dt {
NoDtor => val,
DtorPresent | DtorAbsent => GEPi(bcx, val, [0, 0])
};
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struct_GEP(bcx, st, val, ix, false)
}
General(ref cases) => {
struct_GEP(bcx, &cases[discr as uint],
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GEPi(bcx, val, [0, 1]), ix, true)
}
}
}
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fn struct_GEP(bcx: block, st: &Struct, val: ValueRef, ix: uint,
needs_cast: bool) -> ValueRef {
let ccx = bcx.ccx();
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let val = if needs_cast {
let real_llty = T_struct(st.fields.map(
|&ty| type_of::type_of(ccx, ty)));
PointerCast(bcx, val, T_ptr(real_llty))
} else {
val
};
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GEPi(bcx, val, [0, ix])
}
pub fn trans_const(ccx: @CrateContext, r: &Repr, discr: int,
vals: &[ValueRef]) -> ValueRef {
match *r {
Unit(*) => {
C_struct(~[])
}
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CEnum(min, max) => {
assert vals.len() == 0;
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assert min <= discr && discr <= max;
C_int(ccx, discr)
}
Univariant(ref st, dt) => {
assert discr == 0;
let s = C_struct(build_const_struct(ccx, st, vals));
match dt {
NoDtor => s,
// The actual destructor flag doesn't need to be present.
// But add an extra struct layer for compatibility.
DtorPresent | DtorAbsent => C_struct(~[s])
}
}
General(ref cases) => {
let case = &cases[discr as uint];
let max_sz = cases.map(|s| s.size).max();
let body = build_const_struct(ccx, case, vals);
C_struct([C_int(ccx, discr),
C_packed_struct([C_struct(body)]),
padding(max_sz - case.size)])
}
}
}
fn padding(size: u64) -> ValueRef {
C_undef(T_array(T_i8(), size /*bad*/as uint))
}
fn build_const_struct(ccx: @CrateContext, st: &Struct, vals: &[ValueRef])
-> ~[ValueRef] {
assert vals.len() == st.fields.len();
let mut offset = 0;
let mut cfields = ~[];
for st.fields.eachi |i, &ty| {
let llty = type_of::sizing_type_of(ccx, ty);
let type_align = machine::llalign_of_min(ccx, llty)
/*bad*/as u64;
let val_align = machine::llalign_of_min(ccx, val_ty(vals[i]))
/*bad*/as u64;
let target_offset = roundup(offset, type_align);
offset = roundup(offset, val_align);
if (offset != target_offset) {
cfields.push(padding(target_offset - offset));
offset = target_offset;
}
assert !is_undef(vals[i]);
// If that assert fails, could change it to wrap in a struct?
cfields.push(vals[i]);
}
return cfields;
}
#[always_inline]
fn roundup(x: u64, a: u64) -> u64 { ((x + (a - 1)) / a) * a }
pub fn const_get_discrim(ccx: @CrateContext, r: &Repr, val: ValueRef)
-> int {
match *r {
Unit(discr) => discr,
CEnum(*) => const_to_int(val) as int,
Univariant(*) => 0,
General(*) => const_to_int(const_get_elt(ccx, val, [0])) as int,
}
}
pub fn const_get_element(ccx: @CrateContext, r: &Repr, val: ValueRef,
_discr: int, ix: uint) -> ValueRef {
// Not to be confused with common::const_get_elt.
match *r {
Unit(*) | CEnum(*) => ccx.sess.bug(~"element access in C-like enum \
const"),
Univariant(_, NoDtor) => const_struct_field(ccx, val, ix),
Univariant(*) => const_struct_field(ccx, const_get_elt(ccx, val,
[0]), ix),
General(*) => const_struct_field(ccx, const_get_elt(ccx, val,
[1, 0]), ix)
}
}
fn const_struct_field(ccx: @CrateContext, val: ValueRef, ix: uint)
-> ValueRef {
// Get the ix-th non-undef element of the struct.
let mut real_ix = 0; // actual position in the struct
let mut ix = ix; // logical index relative to real_ix
let mut field;
loop {
loop {
field = const_get_elt(ccx, val, [real_ix]);
if !is_undef(field) {
break;
}
real_ix = real_ix + 1;
}
if ix == 0 {
return field;
}
ix = ix - 1;
real_ix = real_ix + 1;
}
}