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rust/src/librustc_trans/trans/expr.rs

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// Copyright 2012-2014 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.
//! # Translation of Expressions
//!
//! Public entry points:
//!
//! - `trans_into(bcx, expr, dest) -> bcx`: evaluates an expression,
//! storing the result into `dest`. This is the preferred form, if you
//! can manage it.
//!
//! - `trans(bcx, expr) -> DatumBlock`: evaluates an expression, yielding
//! `Datum` with the result. You can then store the datum, inspect
//! the value, etc. This may introduce temporaries if the datum is a
//! structural type.
//!
//! - `trans_to_lvalue(bcx, expr, "...") -> DatumBlock`: evaluates an
//! expression and ensures that the result has a cleanup associated with it,
//! creating a temporary stack slot if necessary.
//!
//! - `trans_local_var -> Datum`: looks up a local variable or upvar.
//!
//! See doc.rs for more comments.
#![allow(non_camel_case_types)]
pub use self::cast_kind::*;
pub use self::Dest::*;
use self::lazy_binop_ty::*;
use back::abi;
use llvm::{self, ValueRef};
use middle::def;
use middle::mem_categorization::Typer;
use middle::subst::{self, Substs};
use trans::{_match, adt, asm, base, callee, closure, consts, controlflow};
use trans::base::*;
use trans::build::*;
use trans::cleanup::{self, CleanupMethods};
use trans::common::*;
use trans::datum::*;
use trans::debuginfo::{self, DebugLoc, ToDebugLoc};
use trans::glue;
use trans::machine;
use trans::meth;
use trans::monomorphize;
use trans::inline;
use trans::tvec;
use trans::type_of;
use middle::ty::{struct_fields, tup_fields};
use middle::ty::{AdjustDerefRef, AdjustReifyFnPointer, AutoUnsafe};
use middle::ty::{AutoPtr};
use middle::ty::{self, Ty};
use middle::ty::MethodCall;
use util::common::indenter;
use util::ppaux::Repr;
use trans::machine::{llsize_of, llsize_of_alloc};
use trans::type_::Type;
use syntax::{ast, ast_util, codemap};
use syntax::ptr::P;
use syntax::parse::token;
use std::rc::Rc;
use std::iter::repeat;
// Destinations
// These are passed around by the code generating functions to track the
// destination of a computation's value.
#[derive(Copy, PartialEq)]
pub enum Dest {
SaveIn(ValueRef),
Ignore,
}
impl Dest {
pub fn to_string(&self, ccx: &CrateContext) -> String {
match *self {
SaveIn(v) => format!("SaveIn({})", ccx.tn().val_to_string(v)),
Ignore => "Ignore".to_string()
}
}
}
/// This function is equivalent to `trans(bcx, expr).store_to_dest(dest)` but it may generate
/// better optimized LLVM code.
pub fn trans_into<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
dest: Dest)
-> Block<'blk, 'tcx> {
let mut bcx = bcx;
if bcx.tcx().adjustments.borrow().contains_key(&expr.id) {
// use trans, which may be less efficient but
// which will perform the adjustments:
let datum = unpack_datum!(bcx, trans(bcx, expr));
return datum.store_to_dest(bcx, dest, expr.id)
}
debug!("trans_into() expr={}", expr.repr(bcx.tcx()));
let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
expr.id,
expr.span,
false);
bcx.fcx.push_ast_cleanup_scope(cleanup_debug_loc);
debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
let kind = ty::expr_kind(bcx.tcx(), expr);
bcx = match kind {
ty::LvalueExpr | ty::RvalueDatumExpr => {
trans_unadjusted(bcx, expr).store_to_dest(dest, expr.id)
}
ty::RvalueDpsExpr => {
trans_rvalue_dps_unadjusted(bcx, expr, dest)
}
ty::RvalueStmtExpr => {
trans_rvalue_stmt_unadjusted(bcx, expr)
}
};
bcx.fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id)
}
/// Translates an expression, returning a datum (and new block) encapsulating the result. When
/// possible, it is preferred to use `trans_into`, as that may avoid creating a temporary on the
/// stack.
pub fn trans<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr)
-> DatumBlock<'blk, 'tcx, Expr> {
debug!("trans(expr={})", bcx.expr_to_string(expr));
let mut bcx = bcx;
let fcx = bcx.fcx;
let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
expr.id,
expr.span,
false);
fcx.push_ast_cleanup_scope(cleanup_debug_loc);
let datum = unpack_datum!(bcx, trans_unadjusted(bcx, expr));
let datum = unpack_datum!(bcx, apply_adjustments(bcx, expr, datum));
bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id);
return DatumBlock::new(bcx, datum);
}
pub fn get_len(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
GEPi(bcx, fat_ptr, &[0, abi::FAT_PTR_EXTRA])
}
pub fn get_dataptr(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
GEPi(bcx, fat_ptr, &[0, abi::FAT_PTR_ADDR])
}
/// Helper for trans that apply adjustments from `expr` to `datum`, which should be the unadjusted
/// translation of `expr`.
fn apply_adjustments<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
datum: Datum<'tcx, Expr>)
-> DatumBlock<'blk, 'tcx, Expr> {
let mut bcx = bcx;
let mut datum = datum;
let adjustment = match bcx.tcx().adjustments.borrow().get(&expr.id).cloned() {
None => {
return DatumBlock::new(bcx, datum);
}
Some(adj) => { adj }
};
debug!("unadjusted datum for expr {}: {}, adjustment={}",
expr.repr(bcx.tcx()),
datum.to_string(bcx.ccx()),
adjustment.repr(bcx.tcx()));
match adjustment {
AdjustReifyFnPointer(_def_id) => {
// FIXME(#19925) once fn item types are
// zero-sized, we'll need to do something here
}
AdjustDerefRef(ref adj) => {
let (autoderefs, use_autoref) = match adj.autoref {
// Extracting a value from a box counts as a deref, but if we are
// just converting Box<[T, ..n]> to Box<[T]> we aren't really doing
// a deref (and wouldn't if we could treat Box like a normal struct).
Some(ty::AutoUnsizeUniq(..)) => (adj.autoderefs - 1, true),
// We are a bit paranoid about adjustments and thus might have a re-
// borrow here which merely derefs and then refs again (it might have
// a different region or mutability, but we don't care here. It might
// also be just in case we need to unsize. But if there are no nested
// adjustments then it should be a no-op).
Some(ty::AutoPtr(_, _, None)) |
Some(ty::AutoUnsafe(_, None)) if adj.autoderefs == 1 => {
match datum.ty.sty {
// Don't skip a conversion from Box<T> to &T, etc.
ty::ty_rptr(..) => {
let method_call = MethodCall::autoderef(expr.id, adj.autoderefs-1);
let method = bcx.tcx().method_map.borrow().get(&method_call).is_some();
if method {
// Don't skip an overloaded deref.
(adj.autoderefs, true)
} else {
(adj.autoderefs - 1, false)
}
}
_ => (adj.autoderefs, true),
}
}
_ => (adj.autoderefs, true)
};
if autoderefs > 0 {
// Schedule cleanup.
let lval = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "auto_deref", expr.id));
datum = unpack_datum!(
bcx, deref_multiple(bcx, expr, lval.to_expr_datum(), autoderefs));
}
// (You might think there is a more elegant way to do this than a
// use_autoref bool, but then you remember that the borrow checker exists).
if let (true, &Some(ref a)) = (use_autoref, &adj.autoref) {
datum = unpack_datum!(bcx, apply_autoref(a,
bcx,
expr,
datum));
}
}
}
debug!("after adjustments, datum={}", datum.to_string(bcx.ccx()));
return DatumBlock::new(bcx, datum);
fn apply_autoref<'blk, 'tcx>(autoref: &ty::AutoRef<'tcx>,
bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
datum: Datum<'tcx, Expr>)
-> DatumBlock<'blk, 'tcx, Expr> {
let mut bcx = bcx;
let mut datum = datum;
let datum = match autoref {
&AutoPtr(_, _, ref a) | &AutoUnsafe(_, ref a) => {
debug!(" AutoPtr");
match a {
&Some(box ref a) => {
datum = unpack_datum!(bcx, apply_autoref(a, bcx, expr, datum));
}
&None => {}
}
unpack_datum!(bcx, ref_ptr(bcx, expr, datum))
}
&ty::AutoUnsize(ref k) => {
debug!(" AutoUnsize");
unpack_datum!(bcx, unsize_expr(bcx, expr, datum, k))
}
&ty::AutoUnsizeUniq(ty::UnsizeLength(len)) => {
debug!(" AutoUnsizeUniq(UnsizeLength)");
unpack_datum!(bcx, unsize_unique_vec(bcx, expr, datum, len))
}
&ty::AutoUnsizeUniq(ref k) => {
debug!(" AutoUnsizeUniq");
unpack_datum!(bcx, unsize_unique_expr(bcx, expr, datum, k))
}
};
DatumBlock::new(bcx, datum)
}
fn ref_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
datum: Datum<'tcx, Expr>)
-> DatumBlock<'blk, 'tcx, Expr> {
debug!("ref_ptr(expr={}, datum={})",
expr.repr(bcx.tcx()),
datum.to_string(bcx.ccx()));
if !type_is_sized(bcx.tcx(), datum.ty) {
debug!("Taking address of unsized type {}",
bcx.ty_to_string(datum.ty));
ref_fat_ptr(bcx, expr, datum)
} else {
debug!("Taking address of sized type {}",
bcx.ty_to_string(datum.ty));
auto_ref(bcx, datum, expr)
}
}
// Retrieve the information we are losing (making dynamic) in an unsizing
// adjustment.
// When making a dtor, we need to do different things depending on the
// ownership of the object.. mk_ty is a function for turning `unadjusted_ty`
// into a type to be destructed. If we want to end up with a Box pointer,
// then mk_ty should make a Box pointer (T -> Box<T>), if we want a
// borrowed reference then it should be T -> &T.
fn unsized_info<'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
kind: &ty::UnsizeKind<'tcx>,
id: ast::NodeId,
unadjusted_ty: Ty<'tcx>,
mk_ty: F) -> ValueRef where
F: FnOnce(Ty<'tcx>) -> Ty<'tcx>,
{
// FIXME(#19596) workaround: `|t| t` causes monomorphization recursion
fn identity<T>(t: T) -> T { t }
debug!("unsized_info(kind={:?}, id={}, unadjusted_ty={})",
kind, id, unadjusted_ty.repr(bcx.tcx()));
match kind {
&ty::UnsizeLength(len) => C_uint(bcx.ccx(), len),
&ty::UnsizeStruct(box ref k, tp_index) => match unadjusted_ty.sty {
ty::ty_struct(_, ref substs) => {
let ty_substs = substs.types.get_slice(subst::TypeSpace);
// The dtor for a field treats it like a value, so mk_ty
// should just be the identity function.
unsized_info(bcx, k, id, ty_substs[tp_index], identity)
}
_ => bcx.sess().bug(&format!("UnsizeStruct with bad sty: {}",
bcx.ty_to_string(unadjusted_ty))[])
},
&ty::UnsizeVtable(ty::TyTrait { ref principal, .. }, _) => {
// Note that we preserve binding levels here:
let substs = principal.0.substs.with_self_ty(unadjusted_ty).erase_regions();
let substs = bcx.tcx().mk_substs(substs);
let trait_ref =
ty::Binder(Rc::new(ty::TraitRef { def_id: principal.def_id(),
substs: substs }));
let trait_ref = bcx.monomorphize(&trait_ref);
let box_ty = mk_ty(unadjusted_ty);
PointerCast(bcx,
meth::get_vtable(bcx, box_ty, trait_ref),
Type::vtable_ptr(bcx.ccx()))
}
}
}
fn unsize_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
datum: Datum<'tcx, Expr>,
k: &ty::UnsizeKind<'tcx>)
-> DatumBlock<'blk, 'tcx, Expr> {
let tcx = bcx.tcx();
let datum_ty = datum.ty;
let unsized_ty = ty::unsize_ty(tcx, datum_ty, k, expr.span);
debug!("unsized_ty={}", unsized_ty.repr(bcx.tcx()));
let dest_ty = ty::mk_open(tcx, unsized_ty);
debug!("dest_ty={}", unsized_ty.repr(bcx.tcx()));
// Closures for extracting and manipulating the data and payload parts of
// the fat pointer.
let info = |bcx, _val| unsized_info(bcx,
k,
expr.id,
datum_ty,
|t| ty::mk_rptr(tcx,
tcx.mk_region(ty::ReStatic),
ty::mt{
ty: t,
mutbl: ast::MutImmutable
}));
match *k {
ty::UnsizeStruct(..) =>
into_fat_ptr(bcx, expr, datum, dest_ty, |bcx, val| {
PointerCast(bcx, val, type_of::type_of(bcx.ccx(), unsized_ty).ptr_to())
}, info),
ty::UnsizeLength(..) =>
into_fat_ptr(bcx, expr, datum, dest_ty, |bcx, val| {
GEPi(bcx, val, &[0, 0])
}, info),
ty::UnsizeVtable(..) =>
into_fat_ptr(bcx, expr, datum, dest_ty, |_bcx, val| {
PointerCast(bcx, val, Type::i8p(bcx.ccx()))
}, info),
}
}
fn ref_fat_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
datum: Datum<'tcx, Expr>)
-> DatumBlock<'blk, 'tcx, Expr> {
let tcx = bcx.tcx();
let dest_ty = ty::close_type(tcx, datum.ty);
let base = |bcx, val| Load(bcx, get_dataptr(bcx, val));
let len = |bcx, val| Load(bcx, get_len(bcx, val));
into_fat_ptr(bcx, expr, datum, dest_ty, base, len)
}
fn into_fat_ptr<'blk, 'tcx, F, G>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
datum: Datum<'tcx, Expr>,
dest_ty: Ty<'tcx>,
base: F,
info: G)
-> DatumBlock<'blk, 'tcx, Expr> where
F: FnOnce(Block<'blk, 'tcx>, ValueRef) -> ValueRef,
G: FnOnce(Block<'blk, 'tcx>, ValueRef) -> ValueRef,
{
let mut bcx = bcx;
// Arrange cleanup
let lval = unpack_datum!(bcx,
datum.to_lvalue_datum(bcx, "into_fat_ptr", expr.id));
let base = base(bcx, lval.val);
let info = info(bcx, lval.val);
let scratch = rvalue_scratch_datum(bcx, dest_ty, "__fat_ptr");
Store(bcx, base, get_dataptr(bcx, scratch.val));
Store(bcx, info, get_len(bcx, scratch.val));
DatumBlock::new(bcx, scratch.to_expr_datum())
}
fn unsize_unique_vec<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
datum: Datum<'tcx, Expr>,
len: uint)
-> DatumBlock<'blk, 'tcx, Expr> {
let mut bcx = bcx;
let tcx = bcx.tcx();
let datum_ty = datum.ty;
debug!("unsize_unique_vec expr.id={} datum_ty={} len={}",
expr.id, datum_ty.repr(tcx), len);
// We do not arrange cleanup ourselves; if we already are an
// L-value, then cleanup will have already been scheduled (and
// the `datum.store_to` call below will emit code to zero the
// drop flag when moving out of the L-value). If we are an R-value,
// then we do not need to schedule cleanup.
let ll_len = C_uint(bcx.ccx(), len);
let unit_ty = ty::sequence_element_type(tcx, ty::type_content(datum_ty));
let vec_ty = ty::mk_uniq(tcx, ty::mk_vec(tcx, unit_ty, None));
let scratch = rvalue_scratch_datum(bcx, vec_ty, "__unsize_unique");
let base = get_dataptr(bcx, scratch.val);
let base = PointerCast(bcx,
base,
type_of::type_of(bcx.ccx(), datum_ty).ptr_to());
bcx = datum.store_to(bcx, base);
Store(bcx, ll_len, get_len(bcx, scratch.val));
DatumBlock::new(bcx, scratch.to_expr_datum())
}
fn unsize_unique_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
datum: Datum<'tcx, Expr>,
k: &ty::UnsizeKind<'tcx>)
-> DatumBlock<'blk, 'tcx, Expr> {
let mut bcx = bcx;
let tcx = bcx.tcx();
let datum_ty = datum.ty;
let unboxed_ty = match datum_ty.sty {
ty::ty_uniq(t) => t,
_ => bcx.sess().bug(&format!("Expected ty_uniq, found {}",
bcx.ty_to_string(datum_ty))[])
};
let result_ty = ty::mk_uniq(tcx, ty::unsize_ty(tcx, unboxed_ty, k, expr.span));
// We do not arrange cleanup ourselves; if we already are an
// L-value, then cleanup will have already been scheduled (and
// the `datum.store_to` call below will emit code to zero the
// drop flag when moving out of the L-value). If we are an R-value,
// then we do not need to schedule cleanup.
let scratch = rvalue_scratch_datum(bcx, result_ty, "__uniq_fat_ptr");
let llbox_ty = type_of::type_of(bcx.ccx(), datum_ty);
let base = PointerCast(bcx, get_dataptr(bcx, scratch.val), llbox_ty.ptr_to());
bcx = datum.store_to(bcx, base);
let info = unsized_info(bcx, k, expr.id, unboxed_ty, |t| ty::mk_uniq(tcx, t));
Store(bcx, info, get_len(bcx, scratch.val));
DatumBlock::new(bcx, scratch.to_expr_datum())
}
}
/// Translates an expression in "lvalue" mode -- meaning that it returns a reference to the memory
/// that the expr represents.
///
/// If this expression is an rvalue, this implies introducing a temporary. In other words,
/// something like `x().f` is translated into roughly the equivalent of
///
/// { tmp = x(); tmp.f }
pub fn trans_to_lvalue<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
name: &str)
-> DatumBlock<'blk, 'tcx, Lvalue> {
let mut bcx = bcx;
let datum = unpack_datum!(bcx, trans(bcx, expr));
return datum.to_lvalue_datum(bcx, name, expr.id);
}
/// A version of `trans` that ignores adjustments. You almost certainly do not want to call this
/// directly.
fn trans_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr)
-> DatumBlock<'blk, 'tcx, Expr> {
let mut bcx = bcx;
debug!("trans_unadjusted(expr={})", bcx.expr_to_string(expr));
let _indenter = indenter();
debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
return match ty::expr_kind(bcx.tcx(), expr) {
ty::LvalueExpr | ty::RvalueDatumExpr => {
let datum = unpack_datum!(bcx, {
trans_datum_unadjusted(bcx, expr)
});
DatumBlock {bcx: bcx, datum: datum}
}
ty::RvalueStmtExpr => {
bcx = trans_rvalue_stmt_unadjusted(bcx, expr);
nil(bcx, expr_ty(bcx, expr))
}
ty::RvalueDpsExpr => {
let ty = expr_ty(bcx, expr);
if type_is_zero_size(bcx.ccx(), ty) {
bcx = trans_rvalue_dps_unadjusted(bcx, expr, Ignore);
nil(bcx, ty)
} else {
let scratch = rvalue_scratch_datum(bcx, ty, "");
bcx = trans_rvalue_dps_unadjusted(
bcx, expr, SaveIn(scratch.val));
// Note: this is not obviously a good idea. It causes
// immediate values to be loaded immediately after a
// return from a call or other similar expression,
// which in turn leads to alloca's having shorter
// lifetimes and hence larger stack frames. However,
// in turn it can lead to more register pressure.
// Still, in practice it seems to increase
// performance, since we have fewer problems with
// morestack churn.
let scratch = unpack_datum!(
bcx, scratch.to_appropriate_datum(bcx));
DatumBlock::new(bcx, scratch.to_expr_datum())
}
}
};
fn nil<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, ty: Ty<'tcx>)
-> DatumBlock<'blk, 'tcx, Expr> {
let llval = C_undef(type_of::type_of(bcx.ccx(), ty));
let datum = immediate_rvalue(llval, ty);
DatumBlock::new(bcx, datum.to_expr_datum())
}
}
fn trans_datum_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr)
-> DatumBlock<'blk, 'tcx, Expr> {
let mut bcx = bcx;
let fcx = bcx.fcx;
let _icx = push_ctxt("trans_datum_unadjusted");
match expr.node {
ast::ExprParen(ref e) => {
trans(bcx, &**e)
}
ast::ExprPath(_) | ast::ExprQPath(_) => {
trans_def(bcx, expr, bcx.def(expr.id))
}
ast::ExprField(ref base, ident) => {
trans_rec_field(bcx, &**base, ident.node)
}
ast::ExprTupField(ref base, idx) => {
trans_rec_tup_field(bcx, &**base, idx.node)
}
ast::ExprIndex(ref base, ref idx) => {
trans_index(bcx, expr, &**base, &**idx, MethodCall::expr(expr.id))
}
ast::ExprBox(_, ref contents) => {
// Special case for `Box<T>`
let box_ty = expr_ty(bcx, expr);
let contents_ty = expr_ty(bcx, &**contents);
match box_ty.sty {
ty::ty_uniq(..) => {
trans_uniq_expr(bcx, box_ty, &**contents, contents_ty)
}
_ => bcx.sess().span_bug(expr.span,
"expected unique box")
}
}
ast::ExprLit(ref lit) => trans_immediate_lit(bcx, expr, &**lit),
ast::ExprBinary(op, ref lhs, ref rhs) => {
trans_binary(bcx, expr, op, &**lhs, &**rhs)
}
ast::ExprUnary(op, ref x) => {
trans_unary(bcx, expr, op, &**x)
}
ast::ExprAddrOf(_, ref x) => {
match x.node {
ast::ExprRepeat(..) | ast::ExprVec(..) => {
// Special case for slices.
let cleanup_debug_loc =
debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
x.id,
x.span,
false);
fcx.push_ast_cleanup_scope(cleanup_debug_loc);
let datum = unpack_datum!(
bcx, tvec::trans_slice_vec(bcx, expr, &**x));
bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, x.id);
DatumBlock::new(bcx, datum)
}
_ => {
trans_addr_of(bcx, expr, &**x)
}
}
}
ast::ExprCast(ref val, _) => {
// Datum output mode means this is a scalar cast:
trans_imm_cast(bcx, &**val, expr.id)
}
_ => {
bcx.tcx().sess.span_bug(
expr.span,
&format!("trans_rvalue_datum_unadjusted reached \
fall-through case: {:?}",
expr.node)[]);
}
}
}
fn trans_field<'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
base: &ast::Expr,
get_idx: F)
-> DatumBlock<'blk, 'tcx, Expr> where
F: FnOnce(&'blk ty::ctxt<'tcx>, &[ty::field<'tcx>]) -> uint,
{
let mut bcx = bcx;
let _icx = push_ctxt("trans_rec_field");
let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, base, "field"));
let bare_ty = ty::unopen_type(base_datum.ty);
let repr = adt::represent_type(bcx.ccx(), bare_ty);
with_field_tys(bcx.tcx(), bare_ty, None, move |discr, field_tys| {
let ix = get_idx(bcx.tcx(), field_tys);
let d = base_datum.get_element(
bcx,
field_tys[ix].mt.ty,
|srcval| adt::trans_field_ptr(bcx, &*repr, srcval, discr, ix));
if type_is_sized(bcx.tcx(), d.ty) {
DatumBlock { datum: d.to_expr_datum(), bcx: bcx }
} else {
let scratch = rvalue_scratch_datum(bcx, ty::mk_open(bcx.tcx(), d.ty), "");
Store(bcx, d.val, get_dataptr(bcx, scratch.val));
let info = Load(bcx, get_len(bcx, base_datum.val));
Store(bcx, info, get_len(bcx, scratch.val));
DatumBlock::new(bcx, scratch.to_expr_datum())
}
})
}
/// Translates `base.field`.
fn trans_rec_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
base: &ast::Expr,
field: ast::Ident)
-> DatumBlock<'blk, 'tcx, Expr> {
trans_field(bcx, base, |tcx, field_tys| ty::field_idx_strict(tcx, field.name, field_tys))
}
/// Translates `base.<idx>`.
fn trans_rec_tup_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
base: &ast::Expr,
idx: uint)
-> DatumBlock<'blk, 'tcx, Expr> {
trans_field(bcx, base, |_, _| idx)
}
fn trans_index<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
index_expr: &ast::Expr,
base: &ast::Expr,
idx: &ast::Expr,
method_call: MethodCall)
-> DatumBlock<'blk, 'tcx, Expr> {
//! Translates `base[idx]`.
let _icx = push_ctxt("trans_index");
let ccx = bcx.ccx();
let mut bcx = bcx;
// Check for overloaded index.
let method_ty = ccx.tcx()
.method_map
.borrow()
.get(&method_call)
.map(|method| method.ty);
let elt_datum = match method_ty {
Some(method_ty) => {
let method_ty = monomorphize_type(bcx, method_ty);
let base_datum = unpack_datum!(bcx, trans(bcx, base));
// Translate index expression.
let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
let ref_ty = // invoked methods have LB regions instantiated:
ty::assert_no_late_bound_regions(
bcx.tcx(), &ty::ty_fn_ret(method_ty)).unwrap();
let elt_ty = match ty::deref(ref_ty, true) {
None => {
bcx.tcx().sess.span_bug(index_expr.span,
"index method didn't return a \
dereferenceable type?!")
}
Some(elt_tm) => elt_tm.ty,
};
// Overloaded. Evaluate `trans_overloaded_op`, which will
// invoke the user's index() method, which basically yields
// a `&T` pointer. We can then proceed down the normal
// path (below) to dereference that `&T`.
let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_index_elt");
unpack_result!(bcx,
trans_overloaded_op(bcx,
index_expr,
method_call,
base_datum,
vec![(ix_datum, idx.id)],
Some(SaveIn(scratch.val)),
true));
let datum = scratch.to_expr_datum();
if type_is_sized(bcx.tcx(), elt_ty) {
Datum::new(datum.to_llscalarish(bcx), elt_ty, LvalueExpr)
} else {
Datum::new(datum.val, ty::mk_open(bcx.tcx(), elt_ty), LvalueExpr)
}
}
None => {
let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx,
base,
"index"));
// Translate index expression and cast to a suitable LLVM integer.
// Rust is less strict than LLVM in this regard.
let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
let ix_val = ix_datum.to_llscalarish(bcx);
let ix_size = machine::llbitsize_of_real(bcx.ccx(),
val_ty(ix_val));
let int_size = machine::llbitsize_of_real(bcx.ccx(),
ccx.int_type());
let ix_val = {
if ix_size < int_size {
if ty::type_is_signed(expr_ty(bcx, idx)) {
SExt(bcx, ix_val, ccx.int_type())
} else { ZExt(bcx, ix_val, ccx.int_type()) }
} else if ix_size > int_size {
Trunc(bcx, ix_val, ccx.int_type())
} else {
ix_val
}
};
let vt =
tvec::vec_types(bcx,
ty::sequence_element_type(bcx.tcx(),
base_datum.ty));
let (base, len) = base_datum.get_vec_base_and_len(bcx);
debug!("trans_index: base {}", bcx.val_to_string(base));
debug!("trans_index: len {}", bcx.val_to_string(len));
let bounds_check = ICmp(bcx, llvm::IntUGE, ix_val, len);
let expect = ccx.get_intrinsic(&("llvm.expect.i1"));
let expected = Call(bcx,
expect,
&[bounds_check, C_bool(ccx, false)],
None,
index_expr.debug_loc());
bcx = with_cond(bcx, expected, |bcx| {
controlflow::trans_fail_bounds_check(bcx,
index_expr.span,
ix_val,
len)
});
let elt = InBoundsGEP(bcx, base, &[ix_val]);
let elt = PointerCast(bcx, elt, vt.llunit_ty.ptr_to());
Datum::new(elt, vt.unit_ty, LvalueExpr)
}
};
DatumBlock::new(bcx, elt_datum)
}
fn trans_def<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
ref_expr: &ast::Expr,
def: def::Def)
-> DatumBlock<'blk, 'tcx, Expr> {
//! Translates a reference to a path.
let _icx = push_ctxt("trans_def_lvalue");
match def {
def::DefFn(..) | def::DefStaticMethod(..) | def::DefMethod(..) |
def::DefStruct(_) | def::DefVariant(..) => {
let datum = trans_def_fn_unadjusted(bcx.ccx(), ref_expr, def,
bcx.fcx.param_substs);
DatumBlock::new(bcx, datum.to_expr_datum())
}
def::DefStatic(did, _) => {
// There are two things that may happen here:
// 1) If the static item is defined in this crate, it will be
// translated using `get_item_val`, and we return a pointer to
// the result.
// 2) If the static item is defined in another crate then we add
// (or reuse) a declaration of an external global, and return a
// pointer to that.
let const_ty = expr_ty(bcx, ref_expr);
fn get_val<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, did: ast::DefId,
const_ty: Ty<'tcx>) -> ValueRef {
// For external constants, we don't inline.
if did.krate == ast::LOCAL_CRATE {
// Case 1.
// The LLVM global has the type of its initializer,
// which may not be equal to the enum's type for
// non-C-like enums.
let val = base::get_item_val(bcx.ccx(), did.node);
let pty = type_of::type_of(bcx.ccx(), const_ty).ptr_to();
PointerCast(bcx, val, pty)
} else {
// Case 2.
base::get_extern_const(bcx.ccx(), did, const_ty)
}
}
let val = get_val(bcx, did, const_ty);
DatumBlock::new(bcx, Datum::new(val, const_ty, LvalueExpr))
}
def::DefConst(did) => {
// First, inline any external constants into the local crate so we
// can be sure to get the LLVM value corresponding to it.
let did = inline::maybe_instantiate_inline(bcx.ccx(), did);
if did.krate != ast::LOCAL_CRATE {
bcx.tcx().sess.span_bug(ref_expr.span,
"cross crate constant could not \
be inlined");
}
let val = base::get_item_val(bcx.ccx(), did.node);
// Next, we need to crate a ByRef rvalue datum to return. We can't
// use the normal .to_ref_datum() function because the type of
// `val` is not actually the same as `const_ty`.
//
// To get around this, we make a custom alloca slot with the
// appropriate type (const_ty), and then we cast it to a pointer of
// typeof(val), store the value, and then hand this slot over to
// the datum infrastructure.
let const_ty = expr_ty(bcx, ref_expr);
let llty = type_of::type_of(bcx.ccx(), const_ty);
let slot = alloca(bcx, llty, "const");
let pty = Type::from_ref(unsafe { llvm::LLVMTypeOf(val) }).ptr_to();
Store(bcx, val, PointerCast(bcx, slot, pty));
let datum = Datum::new(slot, const_ty, Rvalue::new(ByRef));
DatumBlock::new(bcx, datum.to_expr_datum())
}
_ => {
DatumBlock::new(bcx, trans_local_var(bcx, def).to_expr_datum())
}
}
}
fn trans_rvalue_stmt_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr)
-> Block<'blk, 'tcx> {
let mut bcx = bcx;
let _icx = push_ctxt("trans_rvalue_stmt");
if bcx.unreachable.get() {
return bcx;
}
debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
match expr.node {
ast::ExprParen(ref e) => {
trans_into(bcx, &**e, Ignore)
}
ast::ExprBreak(label_opt) => {
controlflow::trans_break(bcx, expr, label_opt)
}
ast::ExprAgain(label_opt) => {
controlflow::trans_cont(bcx, expr, label_opt)
}
ast::ExprRet(ref ex) => {
// Check to see if the return expression itself is reachable.
// This can occur when the inner expression contains a return
let reachable = if let Some(ref cfg) = bcx.fcx.cfg {
cfg.node_is_reachable(expr.id)
} else {
true
};
if reachable {
controlflow::trans_ret(bcx, expr, ex.as_ref().map(|e| &**e))
} else {
// If it's not reachable, just translate the inner expression
// directly. This avoids having to manage a return slot when
// it won't actually be used anyway.
if let &Some(ref x) = ex {
bcx = trans_into(bcx, &**x, Ignore);
}
// Mark the end of the block as unreachable. Once we get to
// a return expression, there's no more we should be doing
// after this.
Unreachable(bcx);
bcx
}
}
ast::ExprWhile(ref cond, ref body, _) => {
controlflow::trans_while(bcx, expr, &**cond, &**body)
}
ast::ExprLoop(ref body, _) => {
controlflow::trans_loop(bcx, expr, &**body)
}
ast::ExprAssign(ref dst, ref src) => {
let src_datum = unpack_datum!(bcx, trans(bcx, &**src));
let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &**dst, "assign"));
if type_needs_drop(bcx.tcx(), dst_datum.ty) {
// If there are destructors involved, make sure we
// are copying from an rvalue, since that cannot possible
// alias an lvalue. We are concerned about code like:
//
// a = a
//
// but also
//
// a = a.b
//
// where e.g. a : Option<Foo> and a.b :
// Option<Foo>. In that case, freeing `a` before the
// assignment may also free `a.b`!
//
// We could avoid this intermediary with some analysis
// to determine whether `dst` may possibly own `src`.
debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
let src_datum = unpack_datum!(
bcx, src_datum.to_rvalue_datum(bcx, "ExprAssign"));
bcx = glue::drop_ty(bcx,
dst_datum.val,
dst_datum.ty,
expr.debug_loc());
src_datum.store_to(bcx, dst_datum.val)
} else {
src_datum.store_to(bcx, dst_datum.val)
}
}
ast::ExprAssignOp(op, ref dst, ref src) => {
trans_assign_op(bcx, expr, op, &**dst, &**src)
}
ast::ExprInlineAsm(ref a) => {
asm::trans_inline_asm(bcx, a)
}
_ => {
bcx.tcx().sess.span_bug(
expr.span,
&format!("trans_rvalue_stmt_unadjusted reached \
fall-through case: {:?}",
expr.node)[]);
}
}
}
fn trans_rvalue_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
dest: Dest)
-> Block<'blk, 'tcx> {
let _icx = push_ctxt("trans_rvalue_dps_unadjusted");
let mut bcx = bcx;
let tcx = bcx.tcx();
debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
match expr.node {
ast::ExprParen(ref e) => {
trans_into(bcx, &**e, dest)
}
ast::ExprPath(_) | ast::ExprQPath(_) => {
trans_def_dps_unadjusted(bcx, expr, bcx.def(expr.id), dest)
}
ast::ExprIf(ref cond, ref thn, ref els) => {
controlflow::trans_if(bcx, expr.id, &**cond, &**thn, els.as_ref().map(|e| &**e), dest)
}
ast::ExprMatch(ref discr, ref arms, _) => {
_match::trans_match(bcx, expr, &**discr, &arms[], dest)
}
ast::ExprBlock(ref blk) => {
controlflow::trans_block(bcx, &**blk, dest)
}
ast::ExprStruct(_, ref fields, ref base) => {
trans_struct(bcx,
&fields[],
base.as_ref().map(|e| &**e),
expr.span,
expr.id,
node_id_type(bcx, expr.id),
dest)
}
ast::ExprRange(ref start, ref end) => {
// FIXME it is just not right that we are synthesising ast nodes in
// trans. Shudder.
fn make_field(field_name: &str, expr: P<ast::Expr>) -> ast::Field {
ast::Field {
ident: codemap::dummy_spanned(token::str_to_ident(field_name)),
expr: expr,
span: codemap::DUMMY_SP,
}
}
// A range just desugars into a struct.
// Note that the type of the start and end may not be the same, but
// they should only differ in their lifetime, which should not matter
// in trans.
let (did, fields, ty_params) = match (start, end) {
(&Some(ref start), &Some(ref end)) => {
// Desugar to Range
let fields = vec![make_field("start", start.clone()),
make_field("end", end.clone())];
(tcx.lang_items.range_struct(), fields, vec![node_id_type(bcx, start.id)])
}
(&Some(ref start), &None) => {
// Desugar to RangeFrom
let fields = vec![make_field("start", start.clone())];
(tcx.lang_items.range_from_struct(), fields, vec![node_id_type(bcx, start.id)])
}
(&None, &Some(ref end)) => {
// Desugar to RangeTo
let fields = vec![make_field("end", end.clone())];
(tcx.lang_items.range_to_struct(), fields, vec![node_id_type(bcx, end.id)])
}
_ => {
// Desugar to RangeFull
(tcx.lang_items.range_full_struct(), vec![], vec![])
}
};
if let Some(did) = did {
let substs = Substs::new_type(ty_params, vec![]);
trans_struct(bcx,
&fields,
None,
expr.span,
expr.id,
ty::mk_struct(tcx, did, tcx.mk_substs(substs)),
dest)
} else {
tcx.sess.span_bug(expr.span,
"No lang item for ranges (how did we get this far?)")
}
}
ast::ExprTup(ref args) => {
let numbered_fields: Vec<(uint, &ast::Expr)> =
args.iter().enumerate().map(|(i, arg)| (i, &**arg)).collect();
trans_adt(bcx,
expr_ty(bcx, expr),
0,
&numbered_fields[],
None,
dest,
expr.debug_loc())
}
ast::ExprLit(ref lit) => {
match lit.node {
ast::LitStr(ref s, _) => {
tvec::trans_lit_str(bcx, expr, (*s).clone(), dest)
}
_ => {
bcx.tcx()
.sess
.span_bug(expr.span,
"trans_rvalue_dps_unadjusted shouldn't be \
translating this type of literal")
}
}
}
ast::ExprVec(..) | ast::ExprRepeat(..) => {
tvec::trans_fixed_vstore(bcx, expr, dest)
}
ast::ExprClosure(_, ref decl, ref body) => {
closure::trans_closure_expr(bcx, &**decl, &**body, expr.id, dest)
}
ast::ExprCall(ref f, ref args) => {
if bcx.tcx().is_method_call(expr.id) {
trans_overloaded_call(bcx,
expr,
&**f,
&args[],
Some(dest))
} else {
callee::trans_call(bcx,
expr,
&**f,
callee::ArgExprs(&args[]),
dest)
}
}
ast::ExprMethodCall(_, _, ref args) => {
callee::trans_method_call(bcx,
expr,
&*args[0],
callee::ArgExprs(&args[]),
dest)
}
ast::ExprBinary(op, ref lhs, ref rhs) => {
// if not overloaded, would be RvalueDatumExpr
let lhs = unpack_datum!(bcx, trans(bcx, &**lhs));
let rhs_datum = unpack_datum!(bcx, trans(bcx, &**rhs));
trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id), lhs,
vec![(rhs_datum, rhs.id)], Some(dest),
!ast_util::is_by_value_binop(op.node)).bcx
}
ast::ExprUnary(op, ref subexpr) => {
// if not overloaded, would be RvalueDatumExpr
let arg = unpack_datum!(bcx, trans(bcx, &**subexpr));
trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id),
arg, Vec::new(), Some(dest), !ast_util::is_by_value_unop(op)).bcx
}
ast::ExprIndex(ref base, ref idx) => {
// if not overloaded, would be RvalueDatumExpr
let base = unpack_datum!(bcx, trans(bcx, &**base));
let idx_datum = unpack_datum!(bcx, trans(bcx, &**idx));
trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id), base,
vec![(idx_datum, idx.id)], Some(dest), true).bcx
}
ast::ExprCast(ref val, _) => {
// DPS output mode means this is a trait cast:
if ty::type_is_trait(node_id_type(bcx, expr.id)) {
let trait_ref =
bcx.tcx().object_cast_map.borrow()
.get(&expr.id)
.map(|t| (*t).clone())
.unwrap();
let trait_ref = bcx.monomorphize(&trait_ref);
let datum = unpack_datum!(bcx, trans(bcx, &**val));
meth::trans_trait_cast(bcx, datum, expr.id,
trait_ref, dest)
} else {
bcx.tcx().sess.span_bug(expr.span,
"expr_cast of non-trait");
}
}
ast::ExprAssignOp(op, ref dst, ref src) => {
trans_assign_op(bcx, expr, op, &**dst, &**src)
}
_ => {
bcx.tcx().sess.span_bug(
expr.span,
&format!("trans_rvalue_dps_unadjusted reached fall-through \
case: {:?}",
expr.node)[]);
}
}
}
fn trans_def_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
ref_expr: &ast::Expr,
def: def::Def,
dest: Dest)
-> Block<'blk, 'tcx> {
let _icx = push_ctxt("trans_def_dps_unadjusted");
let lldest = match dest {
SaveIn(lldest) => lldest,
Ignore => { return bcx; }
};
match def {
def::DefVariant(tid, vid, _) => {
let variant_info = ty::enum_variant_with_id(bcx.tcx(), tid, vid);
if variant_info.args.len() > 0 {
// N-ary variant.
let llfn = callee::trans_fn_ref(bcx.ccx(), vid,
ExprId(ref_expr.id),
bcx.fcx.param_substs).val;
Store(bcx, llfn, lldest);
return bcx;
} else {
// Nullary variant.
let ty = expr_ty(bcx, ref_expr);
let repr = adt::represent_type(bcx.ccx(), ty);
adt::trans_set_discr(bcx, &*repr, lldest,
variant_info.disr_val);
return bcx;
}
}
def::DefStruct(_) => {
let ty = expr_ty(bcx, ref_expr);
match ty.sty {
ty::ty_struct(did, _) if ty::has_dtor(bcx.tcx(), did) => {
let repr = adt::represent_type(bcx.ccx(), ty);
adt::trans_set_discr(bcx, &*repr, lldest, 0);
}
_ => {}
}
bcx
}
_ => {
bcx.tcx().sess.span_bug(ref_expr.span, &format!(
"Non-DPS def {:?} referened by {}",
def, bcx.node_id_to_string(ref_expr.id))[]);
}
}
}
pub fn trans_def_fn_unadjusted<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
ref_expr: &ast::Expr,
def: def::Def,
param_substs: &subst::Substs<'tcx>)
-> Datum<'tcx, Rvalue> {
let _icx = push_ctxt("trans_def_datum_unadjusted");
match def {
def::DefFn(did, _) |
def::DefStruct(did) | def::DefVariant(_, did, _) |
def::DefStaticMethod(did, def::FromImpl(_)) |
def::DefMethod(did, _, def::FromImpl(_)) => {
callee::trans_fn_ref(ccx, did, ExprId(ref_expr.id), param_substs)
}
def::DefStaticMethod(impl_did, def::FromTrait(trait_did)) |
def::DefMethod(impl_did, _, def::FromTrait(trait_did)) => {
meth::trans_static_method_callee(ccx, impl_did,
trait_did, ref_expr.id,
param_substs)
}
_ => {
ccx.tcx().sess.span_bug(ref_expr.span, &format!(
"trans_def_fn_unadjusted invoked on: {:?} for {}",
def,
ref_expr.repr(ccx.tcx()))[]);
}
}
}
/// Translates a reference to a local variable or argument. This always results in an lvalue datum.
pub fn trans_local_var<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
def: def::Def)
-> Datum<'tcx, Lvalue> {
let _icx = push_ctxt("trans_local_var");
match def {
def::DefUpvar(nid, _) => {
// Can't move upvars, so this is never a ZeroMemLastUse.
let local_ty = node_id_type(bcx, nid);
match bcx.fcx.llupvars.borrow().get(&nid) {
Some(&val) => Datum::new(val, local_ty, Lvalue),
None => {
bcx.sess().bug(&format!(
"trans_local_var: no llval for upvar {} found",
nid)[]);
}
}
}
def::DefLocal(nid) => {
let datum = match bcx.fcx.lllocals.borrow().get(&nid) {
Some(&v) => v,
None => {
bcx.sess().bug(&format!(
"trans_local_var: no datum for local/arg {} found",
nid)[]);
}
};
debug!("take_local(nid={}, v={}, ty={})",
nid, bcx.val_to_string(datum.val), bcx.ty_to_string(datum.ty));
datum
}
_ => {
bcx.sess().unimpl(&format!(
"unsupported def type in trans_local_var: {:?}",
def)[]);
}
}
}
/// Helper for enumerating the field types of structs, enums, or records. The optional node ID here
/// is the node ID of the path identifying the enum variant in use. If none, this cannot possibly
/// an enum variant (so, if it is and `node_id_opt` is none, this function panics).
pub fn with_field_tys<'tcx, R, F>(tcx: &ty::ctxt<'tcx>,
ty: Ty<'tcx>,
node_id_opt: Option<ast::NodeId>,
op: F)
-> R where
F: FnOnce(ty::Disr, &[ty::field<'tcx>]) -> R,
{
match ty.sty {
ty::ty_struct(did, substs) => {
let fields = struct_fields(tcx, did, substs);
let fields = monomorphize::normalize_associated_type(tcx, &fields);
op(0, &fields[])
}
ty::ty_tup(ref v) => {
op(0, &tup_fields(&v[])[])
}
ty::ty_enum(_, substs) => {
// We want the *variant* ID here, not the enum ID.
match node_id_opt {
None => {
tcx.sess.bug(&format!(
"cannot get field types from the enum type {} \
without a node ID",
ty.repr(tcx))[]);
}
Some(node_id) => {
let def = tcx.def_map.borrow()[node_id].clone();
match def {
def::DefVariant(enum_id, variant_id, _) => {
let variant_info = ty::enum_variant_with_id(
tcx, enum_id, variant_id);
let fields = struct_fields(tcx, variant_id, substs);
let fields = monomorphize::normalize_associated_type(tcx, &fields);
op(variant_info.disr_val, &fields[])
}
_ => {
tcx.sess.bug("resolve didn't map this expr to a \
variant ID")
}
}
}
}
}
_ => {
tcx.sess.bug(&format!(
"cannot get field types from the type {}",
ty.repr(tcx))[]);
}
}
}
fn trans_struct<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
fields: &[ast::Field],
base: Option<&ast::Expr>,
expr_span: codemap::Span,
expr_id: ast::NodeId,
ty: Ty<'tcx>,
dest: Dest) -> Block<'blk, 'tcx> {
let _icx = push_ctxt("trans_rec");
let tcx = bcx.tcx();
with_field_tys(tcx, ty, Some(expr_id), |discr, field_tys| {
let mut need_base: Vec<bool> = repeat(true).take(field_tys.len()).collect();
let numbered_fields = fields.iter().map(|field| {
let opt_pos =
field_tys.iter().position(|field_ty|
field_ty.name == field.ident.node.name);
let result = match opt_pos {
Some(i) => {
need_base[i] = false;
(i, &*field.expr)
}
None => {
tcx.sess.span_bug(field.span,
"Couldn't find field in struct type")
}
};
result
}).collect::<Vec<_>>();
let optbase = match base {
Some(base_expr) => {
let mut leftovers = Vec::new();
for (i, b) in need_base.iter().enumerate() {
if *b {
leftovers.push((i, field_tys[i].mt.ty));
}
}
Some(StructBaseInfo {expr: base_expr,
fields: leftovers })
}
None => {
if need_base.iter().any(|b| *b) {
tcx.sess.span_bug(expr_span, "missing fields and no base expr")
}
None
}
};
trans_adt(bcx,
ty,
discr,
&numbered_fields,
optbase,
dest,
DebugLoc::At(expr_id, expr_span))
})
}
/// Information that `trans_adt` needs in order to fill in the fields
/// of a struct copied from a base struct (e.g., from an expression
/// like `Foo { a: b, ..base }`.
///
/// Note that `fields` may be empty; the base expression must always be
/// evaluated for side-effects.
pub struct StructBaseInfo<'a, 'tcx> {
/// The base expression; will be evaluated after all explicit fields.
expr: &'a ast::Expr,
/// The indices of fields to copy paired with their types.
fields: Vec<(uint, Ty<'tcx>)>
}
/// Constructs an ADT instance:
///
/// - `fields` should be a list of field indices paired with the
/// expression to store into that field. The initializers will be
/// evaluated in the order specified by `fields`.
///
/// - `optbase` contains information on the base struct (if any) from
/// which remaining fields are copied; see comments on `StructBaseInfo`.
pub fn trans_adt<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
ty: Ty<'tcx>,
discr: ty::Disr,
fields: &[(uint, &ast::Expr)],
optbase: Option<StructBaseInfo<'a, 'tcx>>,
dest: Dest,
debug_location: DebugLoc)
-> Block<'blk, 'tcx> {
let _icx = push_ctxt("trans_adt");
let fcx = bcx.fcx;
let repr = adt::represent_type(bcx.ccx(), ty);
debug_location.apply(bcx.fcx);
// If we don't care about the result, just make a
// temporary stack slot
let addr = match dest {
SaveIn(pos) => pos,
Ignore => alloc_ty(bcx, ty, "temp"),
};
// This scope holds intermediates that must be cleaned should
// panic occur before the ADT as a whole is ready.
let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
// First we trans the base, if we have one, to the dest
if let Some(base) = optbase {
assert_eq!(discr, 0);
match ty::expr_kind(bcx.tcx(), &*base.expr) {
ty::RvalueDpsExpr | ty::RvalueDatumExpr if !type_needs_drop(bcx.tcx(), ty) => {
bcx = trans_into(bcx, &*base.expr, SaveIn(addr));
},
ty::RvalueStmtExpr => bcx.tcx().sess.bug("unexpected expr kind for struct base expr"),
_ => {
let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &*base.expr, "base"));
for &(i, t) in &base.fields {
let datum = base_datum.get_element(
bcx, t, |srcval| adt::trans_field_ptr(bcx, &*repr, srcval, discr, i));
assert!(type_is_sized(bcx.tcx(), datum.ty));
let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
bcx = datum.store_to(bcx, dest);
}
}
}
}
debug_location.apply(bcx.fcx);
if ty::type_is_simd(bcx.tcx(), ty) {
// This is the constructor of a SIMD type, such types are
// always primitive machine types and so do not have a
// destructor or require any clean-up.
let llty = type_of::type_of(bcx.ccx(), ty);
// keep a vector as a register, and running through the field
// `insertelement`ing them directly into that register
// (i.e. avoid GEPi and `store`s to an alloca) .
let mut vec_val = C_undef(llty);
for &(i, ref e) in fields {
let block_datum = trans(bcx, &**e);
bcx = block_datum.bcx;
let position = C_uint(bcx.ccx(), i);
let value = block_datum.datum.to_llscalarish(bcx);
vec_val = InsertElement(bcx, vec_val, value, position);
}
Store(bcx, vec_val, addr);
} else {
// Now, we just overwrite the fields we've explicitly specified
for &(i, ref e) in fields {
let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
let e_ty = expr_ty_adjusted(bcx, &**e);
bcx = trans_into(bcx, &**e, SaveIn(dest));
let scope = cleanup::CustomScope(custom_cleanup_scope);
fcx.schedule_lifetime_end(scope, dest);
fcx.schedule_drop_mem(scope, dest, e_ty);
}
}
adt::trans_set_discr(bcx, &*repr, addr, discr);
fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
// If we don't care about the result drop the temporary we made
match dest {
SaveIn(_) => bcx,
Ignore => {
bcx = glue::drop_ty(bcx, addr, ty, debug_location);
base::call_lifetime_end(bcx, addr);
bcx
}
}
}
fn trans_immediate_lit<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
lit: &ast::Lit)
-> DatumBlock<'blk, 'tcx, Expr> {
// must not be a string constant, that is a RvalueDpsExpr
let _icx = push_ctxt("trans_immediate_lit");
let ty = expr_ty(bcx, expr);
let v = consts::const_lit(bcx.ccx(), expr, lit);
immediate_rvalue_bcx(bcx, v, ty).to_expr_datumblock()
}
fn trans_unary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
op: ast::UnOp,
sub_expr: &ast::Expr)
-> DatumBlock<'blk, 'tcx, Expr> {
let ccx = bcx.ccx();
let mut bcx = bcx;
let _icx = push_ctxt("trans_unary_datum");
let method_call = MethodCall::expr(expr.id);
// The only overloaded operator that is translated to a datum
// is an overloaded deref, since it is always yields a `&T`.
// Otherwise, we should be in the RvalueDpsExpr path.
assert!(
op == ast::UnDeref ||
!ccx.tcx().method_map.borrow().contains_key(&method_call));
let un_ty = expr_ty(bcx, expr);
let debug_loc = expr.debug_loc();
match op {
ast::UnNot => {
let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
let llresult = Not(bcx, datum.to_llscalarish(bcx), debug_loc);
immediate_rvalue_bcx(bcx, llresult, un_ty).to_expr_datumblock()
}
ast::UnNeg => {
let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
let val = datum.to_llscalarish(bcx);
let llneg = {
if ty::type_is_fp(un_ty) {
FNeg(bcx, val, debug_loc)
} else {
Neg(bcx, val, debug_loc)
}
};
immediate_rvalue_bcx(bcx, llneg, un_ty).to_expr_datumblock()
}
ast::UnUniq => {
trans_uniq_expr(bcx, un_ty, sub_expr, expr_ty(bcx, sub_expr))
}
ast::UnDeref => {
let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
deref_once(bcx, expr, datum, method_call)
}
}
}
fn trans_uniq_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
box_ty: Ty<'tcx>,
contents: &ast::Expr,
contents_ty: Ty<'tcx>)
-> DatumBlock<'blk, 'tcx, Expr> {
let _icx = push_ctxt("trans_uniq_expr");
let fcx = bcx.fcx;
assert!(type_is_sized(bcx.tcx(), contents_ty));
let llty = type_of::type_of(bcx.ccx(), contents_ty);
let size = llsize_of(bcx.ccx(), llty);
let align = C_uint(bcx.ccx(), type_of::align_of(bcx.ccx(), contents_ty));
let llty_ptr = llty.ptr_to();
let Result { bcx, val } = malloc_raw_dyn(bcx, llty_ptr, box_ty, size, align);
// Unique boxes do not allocate for zero-size types. The standard library
// may assume that `free` is never called on the pointer returned for
// `Box<ZeroSizeType>`.
let bcx = if llsize_of_alloc(bcx.ccx(), llty) == 0 {
trans_into(bcx, contents, SaveIn(val))
} else {
let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
fcx.schedule_free_value(cleanup::CustomScope(custom_cleanup_scope),
val, cleanup::HeapExchange, contents_ty);
let bcx = trans_into(bcx, contents, SaveIn(val));
fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
bcx
};
immediate_rvalue_bcx(bcx, val, box_ty).to_expr_datumblock()
}
fn trans_addr_of<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
subexpr: &ast::Expr)
-> DatumBlock<'blk, 'tcx, Expr> {
let _icx = push_ctxt("trans_addr_of");
let mut bcx = bcx;
let sub_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, subexpr, "addr_of"));
match sub_datum.ty.sty {
ty::ty_open(_) => {
// Opened DST value, close to a fat pointer
debug!("Closing fat pointer {}", bcx.ty_to_string(sub_datum.ty));
let scratch = rvalue_scratch_datum(bcx,
ty::close_type(bcx.tcx(), sub_datum.ty),
"fat_addr_of");
let base = Load(bcx, get_dataptr(bcx, sub_datum.val));
Store(bcx, base, get_dataptr(bcx, scratch.val));
let len = Load(bcx, get_len(bcx, sub_datum.val));
Store(bcx, len, get_len(bcx, scratch.val));
DatumBlock::new(bcx, scratch.to_expr_datum())
}
_ => {
// Sized value, ref to a thin pointer
let ty = expr_ty(bcx, expr);
immediate_rvalue_bcx(bcx, sub_datum.val, ty).to_expr_datumblock()
}
}
}
// Important to get types for both lhs and rhs, because one might be _|_
// and the other not.
fn trans_eager_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
binop_expr: &ast::Expr,
binop_ty: Ty<'tcx>,
op: ast::BinOp,
lhs_t: Ty<'tcx>,
lhs: ValueRef,
rhs_t: Ty<'tcx>,
rhs: ValueRef)
-> DatumBlock<'blk, 'tcx, Expr> {
let _icx = push_ctxt("trans_eager_binop");
let tcx = bcx.tcx();
let is_simd = ty::type_is_simd(tcx, lhs_t);
let intype = {
if is_simd { ty::simd_type(tcx, lhs_t) }
else { lhs_t }
};
let is_float = ty::type_is_fp(intype);
let is_signed = ty::type_is_signed(intype);
let rhs = base::cast_shift_expr_rhs(bcx, op, lhs, rhs);
let binop_debug_loc = binop_expr.debug_loc();
let mut bcx = bcx;
let val = match op.node {
ast::BiAdd => {
if is_float {
FAdd(bcx, lhs, rhs, binop_debug_loc)
} else {
Add(bcx, lhs, rhs, binop_debug_loc)
}
}
ast::BiSub => {
if is_float {
FSub(bcx, lhs, rhs, binop_debug_loc)
} else {
Sub(bcx, lhs, rhs, binop_debug_loc)
}
}
ast::BiMul => {
if is_float {
FMul(bcx, lhs, rhs, binop_debug_loc)
} else {
Mul(bcx, lhs, rhs, binop_debug_loc)
}
}
ast::BiDiv => {
if is_float {
FDiv(bcx, lhs, rhs, binop_debug_loc)
} else {
// Only zero-check integers; fp /0 is NaN
bcx = base::fail_if_zero_or_overflows(bcx, binop_expr.span,
op, lhs, rhs, rhs_t);
if is_signed {
SDiv(bcx, lhs, rhs, binop_debug_loc)
} else {
UDiv(bcx, lhs, rhs, binop_debug_loc)
}
}
}
ast::BiRem => {
if is_float {
FRem(bcx, lhs, rhs, binop_debug_loc)
} else {
// Only zero-check integers; fp %0 is NaN
bcx = base::fail_if_zero_or_overflows(bcx, binop_expr.span,
op, lhs, rhs, rhs_t);
if is_signed {
SRem(bcx, lhs, rhs, binop_debug_loc)
} else {
URem(bcx, lhs, rhs, binop_debug_loc)
}
}
}
ast::BiBitOr => Or(bcx, lhs, rhs, binop_debug_loc),
ast::BiBitAnd => And(bcx, lhs, rhs, binop_debug_loc),
ast::BiBitXor => Xor(bcx, lhs, rhs, binop_debug_loc),
ast::BiShl => Shl(bcx, lhs, rhs, binop_debug_loc),
ast::BiShr => {
if is_signed {
AShr(bcx, lhs, rhs, binop_debug_loc)
} else {
LShr(bcx, lhs, rhs, binop_debug_loc)
}
}
ast::BiEq | ast::BiNe | ast::BiLt | ast::BiGe | ast::BiLe | ast::BiGt => {
if ty::type_is_scalar(rhs_t) {
unpack_result!(bcx, base::compare_scalar_types(bcx, lhs, rhs, rhs_t, op.node))
} else if is_simd {
base::compare_simd_types(bcx, lhs, rhs, intype, ty::simd_size(tcx, lhs_t), op)
} else {
bcx.tcx().sess.span_bug(binop_expr.span, "comparison operator unsupported for type")
}
}
_ => {
bcx.tcx().sess.span_bug(binop_expr.span, "unexpected binop");
}
};
immediate_rvalue_bcx(bcx, val, binop_ty).to_expr_datumblock()
}
// refinement types would obviate the need for this
enum lazy_binop_ty {
lazy_and,
lazy_or,
}
fn trans_lazy_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
binop_expr: &ast::Expr,
op: lazy_binop_ty,
a: &ast::Expr,
b: &ast::Expr)
-> DatumBlock<'blk, 'tcx, Expr> {
let _icx = push_ctxt("trans_lazy_binop");
let binop_ty = expr_ty(bcx, binop_expr);
let fcx = bcx.fcx;
let DatumBlock {bcx: past_lhs, datum: lhs} = trans(bcx, a);
let lhs = lhs.to_llscalarish(past_lhs);
if past_lhs.unreachable.get() {
return immediate_rvalue_bcx(past_lhs, lhs, binop_ty).to_expr_datumblock();
}
let join = fcx.new_id_block("join", binop_expr.id);
let before_rhs = fcx.new_id_block("before_rhs", b.id);
match op {
lazy_and => CondBr(past_lhs, lhs, before_rhs.llbb, join.llbb, DebugLoc::None),
lazy_or => CondBr(past_lhs, lhs, join.llbb, before_rhs.llbb, DebugLoc::None)
}
let DatumBlock {bcx: past_rhs, datum: rhs} = trans(before_rhs, b);
let rhs = rhs.to_llscalarish(past_rhs);
if past_rhs.unreachable.get() {
return immediate_rvalue_bcx(join, lhs, binop_ty).to_expr_datumblock();
}
Br(past_rhs, join.llbb, DebugLoc::None);
let phi = Phi(join, Type::i1(bcx.ccx()), &[lhs, rhs],
&[past_lhs.llbb, past_rhs.llbb]);
return immediate_rvalue_bcx(join, phi, binop_ty).to_expr_datumblock();
}
fn trans_binary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
op: ast::BinOp,
lhs: &ast::Expr,
rhs: &ast::Expr)
-> DatumBlock<'blk, 'tcx, Expr> {
let _icx = push_ctxt("trans_binary");
let ccx = bcx.ccx();
// if overloaded, would be RvalueDpsExpr
assert!(!ccx.tcx().method_map.borrow().contains_key(&MethodCall::expr(expr.id)));
match op.node {
ast::BiAnd => {
trans_lazy_binop(bcx, expr, lazy_and, lhs, rhs)
}
ast::BiOr => {
trans_lazy_binop(bcx, expr, lazy_or, lhs, rhs)
}
_ => {
let mut bcx = bcx;
let lhs_datum = unpack_datum!(bcx, trans(bcx, lhs));
let rhs_datum = unpack_datum!(bcx, trans(bcx, rhs));
let binop_ty = expr_ty(bcx, expr);
debug!("trans_binary (expr {}): lhs_datum={}",
expr.id,
lhs_datum.to_string(ccx));
let lhs_ty = lhs_datum.ty;
let lhs = lhs_datum.to_llscalarish(bcx);
debug!("trans_binary (expr {}): rhs_datum={}",
expr.id,
rhs_datum.to_string(ccx));
let rhs_ty = rhs_datum.ty;
let rhs = rhs_datum.to_llscalarish(bcx);
trans_eager_binop(bcx, expr, binop_ty, op,
lhs_ty, lhs, rhs_ty, rhs)
}
}
}
fn trans_overloaded_op<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
method_call: MethodCall,
lhs: Datum<'tcx, Expr>,
rhs: Vec<(Datum<'tcx, Expr>, ast::NodeId)>,
dest: Option<Dest>,
autoref: bool)
-> Result<'blk, 'tcx> {
let method_ty = (*bcx.tcx().method_map.borrow())[method_call].ty;
callee::trans_call_inner(bcx,
Some(expr_info(expr)),
monomorphize_type(bcx, method_ty),
|bcx, arg_cleanup_scope| {
meth::trans_method_callee(bcx,
method_call,
None,
arg_cleanup_scope)
},
callee::ArgOverloadedOp(lhs, rhs, autoref),
dest)
}
fn trans_overloaded_call<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
callee: &'a ast::Expr,
args: &'a [P<ast::Expr>],
dest: Option<Dest>)
-> Block<'blk, 'tcx> {
let method_call = MethodCall::expr(expr.id);
let method_type = (*bcx.tcx()
.method_map
.borrow())[method_call]
.ty;
let mut all_args = vec!(callee);
all_args.extend(args.iter().map(|e| &**e));
unpack_result!(bcx,
callee::trans_call_inner(bcx,
Some(expr_info(expr)),
monomorphize_type(bcx,
method_type),
|bcx, arg_cleanup_scope| {
meth::trans_method_callee(
bcx,
method_call,
None,
arg_cleanup_scope)
},
callee::ArgOverloadedCall(all_args),
dest));
bcx
}
fn int_cast(bcx: Block,
lldsttype: Type,
llsrctype: Type,
llsrc: ValueRef,
signed: bool)
-> ValueRef {
let _icx = push_ctxt("int_cast");
let srcsz = llsrctype.int_width();
let dstsz = lldsttype.int_width();
return if dstsz == srcsz {
BitCast(bcx, llsrc, lldsttype)
} else if srcsz > dstsz {
TruncOrBitCast(bcx, llsrc, lldsttype)
} else if signed {
SExtOrBitCast(bcx, llsrc, lldsttype)
} else {
ZExtOrBitCast(bcx, llsrc, lldsttype)
}
}
fn float_cast(bcx: Block,
lldsttype: Type,
llsrctype: Type,
llsrc: ValueRef)
-> ValueRef {
let _icx = push_ctxt("float_cast");
let srcsz = llsrctype.float_width();
let dstsz = lldsttype.float_width();
return if dstsz > srcsz {
FPExt(bcx, llsrc, lldsttype)
} else if srcsz > dstsz {
FPTrunc(bcx, llsrc, lldsttype)
} else { llsrc };
}
#[derive(Copy, PartialEq, Debug)]
pub enum cast_kind {
cast_pointer,
cast_integral,
cast_float,
cast_enum,
cast_other,
}
pub fn cast_type_kind<'tcx>(tcx: &ty::ctxt<'tcx>, t: Ty<'tcx>) -> cast_kind {
match t.sty {
ty::ty_char => cast_integral,
ty::ty_float(..) => cast_float,
ty::ty_rptr(_, mt) | ty::ty_ptr(mt) => {
if type_is_sized(tcx, mt.ty) {
cast_pointer
} else {
cast_other
}
}
ty::ty_bare_fn(..) => cast_pointer,
ty::ty_int(..) => cast_integral,
ty::ty_uint(..) => cast_integral,
ty::ty_bool => cast_integral,
ty::ty_enum(..) => cast_enum,
_ => cast_other
}
}
fn cast_is_noop<'tcx>(t_in: Ty<'tcx>, t_out: Ty<'tcx>) -> bool {
match (ty::deref(t_in, true), ty::deref(t_out, true)) {
(Some(ty::mt{ ty: t_in, .. }), Some(ty::mt{ ty: t_out, .. })) => {
t_in == t_out
}
_ => false
}
}
fn trans_imm_cast<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
id: ast::NodeId)
-> DatumBlock<'blk, 'tcx, Expr> {
let _icx = push_ctxt("trans_cast");
let mut bcx = bcx;
let ccx = bcx.ccx();
let t_in = expr_ty(bcx, expr);
let t_out = node_id_type(bcx, id);
let k_in = cast_type_kind(bcx.tcx(), t_in);
let k_out = cast_type_kind(bcx.tcx(), t_out);
let s_in = k_in == cast_integral && ty::type_is_signed(t_in);
let ll_t_in = type_of::arg_type_of(ccx, t_in);
let ll_t_out = type_of::arg_type_of(ccx, t_out);
// Convert the value to be cast into a ValueRef, either by-ref or
// by-value as appropriate given its type:
let mut datum = unpack_datum!(bcx, trans(bcx, expr));
if cast_is_noop(datum.ty, t_out) {
datum.ty = t_out;
return DatumBlock::new(bcx, datum);
}
let newval = match (k_in, k_out) {
(cast_integral, cast_integral) => {
let llexpr = datum.to_llscalarish(bcx);
int_cast(bcx, ll_t_out, ll_t_in, llexpr, s_in)
}
(cast_float, cast_float) => {
let llexpr = datum.to_llscalarish(bcx);
float_cast(bcx, ll_t_out, ll_t_in, llexpr)
}
(cast_integral, cast_float) => {
let llexpr = datum.to_llscalarish(bcx);
if s_in {
SIToFP(bcx, llexpr, ll_t_out)
} else { UIToFP(bcx, llexpr, ll_t_out) }
}
(cast_float, cast_integral) => {
let llexpr = datum.to_llscalarish(bcx);
if ty::type_is_signed(t_out) {
FPToSI(bcx, llexpr, ll_t_out)
} else { FPToUI(bcx, llexpr, ll_t_out) }
}
(cast_integral, cast_pointer) => {
let llexpr = datum.to_llscalarish(bcx);
IntToPtr(bcx, llexpr, ll_t_out)
}
(cast_pointer, cast_integral) => {
let llexpr = datum.to_llscalarish(bcx);
PtrToInt(bcx, llexpr, ll_t_out)
}
(cast_pointer, cast_pointer) => {
let llexpr = datum.to_llscalarish(bcx);
PointerCast(bcx, llexpr, ll_t_out)
}
(cast_enum, cast_integral) |
(cast_enum, cast_float) => {
let mut bcx = bcx;
let repr = adt::represent_type(ccx, t_in);
let datum = unpack_datum!(
bcx, datum.to_lvalue_datum(bcx, "trans_imm_cast", expr.id));
let llexpr_ptr = datum.to_llref();
let lldiscrim_a =
adt::trans_get_discr(bcx, &*repr, llexpr_ptr, Some(Type::i64(ccx)));
match k_out {
cast_integral => int_cast(bcx, ll_t_out,
val_ty(lldiscrim_a),
lldiscrim_a, true),
cast_float => SIToFP(bcx, lldiscrim_a, ll_t_out),
_ => {
ccx.sess().bug(&format!("translating unsupported cast: \
{} ({:?}) -> {} ({:?})",
t_in.repr(bcx.tcx()),
k_in,
t_out.repr(bcx.tcx()),
k_out)[])
}
}
}
_ => ccx.sess().bug(&format!("translating unsupported cast: \
{} ({:?}) -> {} ({:?})",
t_in.repr(bcx.tcx()),
k_in,
t_out.repr(bcx.tcx()),
k_out)[])
};
return immediate_rvalue_bcx(bcx, newval, t_out).to_expr_datumblock();
}
fn trans_assign_op<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
op: ast::BinOp,
dst: &ast::Expr,
src: &ast::Expr)
-> Block<'blk, 'tcx> {
let _icx = push_ctxt("trans_assign_op");
let mut bcx = bcx;
debug!("trans_assign_op(expr={})", bcx.expr_to_string(expr));
// User-defined operator methods cannot be used with `+=` etc right now
assert!(!bcx.tcx().method_map.borrow().contains_key(&MethodCall::expr(expr.id)));
// Evaluate LHS (destination), which should be an lvalue
let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, dst, "assign_op"));
assert!(!type_needs_drop(bcx.tcx(), dst_datum.ty));
let dst_ty = dst_datum.ty;
let dst = load_ty(bcx, dst_datum.val, dst_datum.ty);
// Evaluate RHS
let rhs_datum = unpack_datum!(bcx, trans(bcx, &*src));
let rhs_ty = rhs_datum.ty;
let rhs = rhs_datum.to_llscalarish(bcx);
// Perform computation and store the result
let result_datum = unpack_datum!(
bcx, trans_eager_binop(bcx, expr, dst_datum.ty, op,
dst_ty, dst, rhs_ty, rhs));
return result_datum.store_to(bcx, dst_datum.val);
}
fn auto_ref<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
datum: Datum<'tcx, Expr>,
expr: &ast::Expr)
-> DatumBlock<'blk, 'tcx, Expr> {
let mut bcx = bcx;
// Ensure cleanup of `datum` if not already scheduled and obtain
// a "by ref" pointer.
let lv_datum = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "autoref", expr.id));
// Compute final type. Note that we are loose with the region and
// mutability, since those things don't matter in trans.
let referent_ty = lv_datum.ty;
let ptr_ty = ty::mk_imm_rptr(bcx.tcx(), bcx.tcx().mk_region(ty::ReStatic), referent_ty);
// Get the pointer.
let llref = lv_datum.to_llref();
// Construct the resulting datum, using what was the "by ref"
// ValueRef of type `referent_ty` to be the "by value" ValueRef
// of type `&referent_ty`.
DatumBlock::new(bcx, Datum::new(llref, ptr_ty, RvalueExpr(Rvalue::new(ByValue))))
}
fn deref_multiple<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
datum: Datum<'tcx, Expr>,
times: uint)
-> DatumBlock<'blk, 'tcx, Expr> {
let mut bcx = bcx;
let mut datum = datum;
for i in 0..times {
let method_call = MethodCall::autoderef(expr.id, i);
datum = unpack_datum!(bcx, deref_once(bcx, expr, datum, method_call));
}
DatumBlock { bcx: bcx, datum: datum }
}
fn deref_once<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
datum: Datum<'tcx, Expr>,
method_call: MethodCall)
-> DatumBlock<'blk, 'tcx, Expr> {
let ccx = bcx.ccx();
debug!("deref_once(expr={}, datum={}, method_call={:?})",
expr.repr(bcx.tcx()),
datum.to_string(ccx),
method_call);
let mut bcx = bcx;
// Check for overloaded deref.
let method_ty = ccx.tcx().method_map.borrow()
.get(&method_call).map(|method| method.ty);
let datum = match method_ty {
Some(method_ty) => {
let method_ty = monomorphize_type(bcx, method_ty);
// Overloaded. Evaluate `trans_overloaded_op`, which will
// invoke the user's deref() method, which basically
// converts from the `Smaht<T>` pointer that we have into
// a `&T` pointer. We can then proceed down the normal
// path (below) to dereference that `&T`.
let datum = match method_call.adjustment {
// Always perform an AutoPtr when applying an overloaded auto-deref
ty::AutoDeref(_) => unpack_datum!(bcx, auto_ref(bcx, datum, expr)),
_ => datum
};
let ref_ty = // invoked methods have their LB regions instantiated
ty::assert_no_late_bound_regions(
ccx.tcx(), &ty::ty_fn_ret(method_ty)).unwrap();
let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_deref");
unpack_result!(bcx, trans_overloaded_op(bcx, expr, method_call,
datum, Vec::new(), Some(SaveIn(scratch.val)),
false));
scratch.to_expr_datum()
}
None => {
// Not overloaded. We already have a pointer we know how to deref.
datum
}
};
let r = match datum.ty.sty {
ty::ty_uniq(content_ty) => {
if type_is_sized(bcx.tcx(), content_ty) {
deref_owned_pointer(bcx, expr, datum, content_ty)
} else {
// A fat pointer and an opened DST value have the same
// representation just different types. Since there is no
// temporary for `*e` here (because it is unsized), we cannot
// emulate the sized object code path for running drop glue and
// free. Instead, we schedule cleanup for `e`, turning it into
// an lvalue.
let datum = unpack_datum!(
bcx, datum.to_lvalue_datum(bcx, "deref", expr.id));
let datum = Datum::new(datum.val, ty::mk_open(bcx.tcx(), content_ty), LvalueExpr);
DatumBlock::new(bcx, datum)
}
}
ty::ty_ptr(ty::mt { ty: content_ty, .. }) |
ty::ty_rptr(_, ty::mt { ty: content_ty, .. }) => {
if type_is_sized(bcx.tcx(), content_ty) {
let ptr = datum.to_llscalarish(bcx);
// Always generate an lvalue datum, even if datum.mode is
// an rvalue. This is because datum.mode is only an
// rvalue for non-owning pointers like &T or *T, in which
// case cleanup *is* scheduled elsewhere, by the true
// owner (or, in the case of *T, by the user).
DatumBlock::new(bcx, Datum::new(ptr, content_ty, LvalueExpr))
} else {
// A fat pointer and an opened DST value have the same representation
// just different types.
DatumBlock::new(bcx, Datum::new(datum.val,
ty::mk_open(bcx.tcx(), content_ty),
LvalueExpr))
}
}
_ => {
bcx.tcx().sess.span_bug(
expr.span,
&format!("deref invoked on expr of illegal type {}",
datum.ty.repr(bcx.tcx()))[]);
}
};
debug!("deref_once(expr={}, method_call={:?}, result={})",
expr.id, method_call, r.datum.to_string(ccx));
return r;
/// We microoptimize derefs of owned pointers a bit here. Basically, the idea is to make the
/// deref of an rvalue result in an rvalue. This helps to avoid intermediate stack slots in the
/// resulting LLVM. The idea here is that, if the `Box<T>` pointer is an rvalue, then we can
/// schedule a *shallow* free of the `Box<T>` pointer, and then return a ByRef rvalue into the
/// pointer. Because the free is shallow, it is legit to return an rvalue, because we know that
/// the contents are not yet scheduled to be freed. The language rules ensure that the contents
/// will be used (or moved) before the free occurs.
fn deref_owned_pointer<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
expr: &ast::Expr,
datum: Datum<'tcx, Expr>,
content_ty: Ty<'tcx>)
-> DatumBlock<'blk, 'tcx, Expr> {
match datum.kind {
RvalueExpr(Rvalue { mode: ByRef }) => {
let scope = cleanup::temporary_scope(bcx.tcx(), expr.id);
let ptr = Load(bcx, datum.val);
if !type_is_zero_size(bcx.ccx(), content_ty) {
bcx.fcx.schedule_free_value(scope, ptr, cleanup::HeapExchange, content_ty);
}
}
RvalueExpr(Rvalue { mode: ByValue }) => {
let scope = cleanup::temporary_scope(bcx.tcx(), expr.id);
if !type_is_zero_size(bcx.ccx(), content_ty) {
bcx.fcx.schedule_free_value(scope, datum.val, cleanup::HeapExchange,
content_ty);
}
}
LvalueExpr => { }
}
// If we had an rvalue in, we produce an rvalue out.
let (llptr, kind) = match datum.kind {
LvalueExpr => {
(Load(bcx, datum.val), LvalueExpr)
}
RvalueExpr(Rvalue { mode: ByRef }) => {
(Load(bcx, datum.val), RvalueExpr(Rvalue::new(ByRef)))
}
RvalueExpr(Rvalue { mode: ByValue }) => {
(datum.val, RvalueExpr(Rvalue::new(ByRef)))
}
};
let datum = Datum { ty: content_ty, val: llptr, kind: kind };
DatumBlock { bcx: bcx, datum: datum }
}
}
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