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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.
use hair::cx::Cx;
use rustc::middle::region::CodeExtent;
use rustc::middle::ty::{FnOutput, Ty};
use rustc::mir::repr::*;
use rustc_data_structures::fnv::FnvHashMap;
use rustc_front::hir;
use syntax::ast;
use syntax::codemap::Span;
pub struct Builder<'a, 'tcx: 'a> {
hir: Cx<'a, 'tcx>,
cfg: CFG<'tcx>,
scopes: Vec<scope::Scope<'tcx>>,
loop_scopes: Vec<scope::LoopScope>,
var_decls: Vec<VarDecl<'tcx>>,
var_indices: FnvHashMap<ast::NodeId, u32>,
temp_decls: Vec<TempDecl<'tcx>>,
unit_temp: Option<Lvalue<'tcx>>,
}
struct CFG<'tcx> {
basic_blocks: Vec<BasicBlockData<'tcx>>,
}
///////////////////////////////////////////////////////////////////////////
/// The `BlockAnd` "monad" packages up the new basic block along with a
/// produced value (sometimes just unit, of course). The `unpack!`
/// macro (and methods below) makes working with `BlockAnd` much more
/// convenient.
#[must_use] // if you don't use one of these results, you're leaving a dangling edge
pub struct BlockAnd<T>(BasicBlock, T);
trait BlockAndExtension {
fn and<T>(self, v: T) -> BlockAnd<T>;
fn unit(self) -> BlockAnd<()>;
}
impl BlockAndExtension for BasicBlock {
fn and<T>(self, v: T) -> BlockAnd<T> {
BlockAnd(self, v)
}
fn unit(self) -> BlockAnd<()> {
BlockAnd(self, ())
}
}
/// Update a block pointer and return the value.
/// Use it like `let x = unpack!(block = self.foo(block, foo))`.
macro_rules! unpack {
($x:ident = $c:expr) => {
{
let BlockAnd(b, v) = $c;
$x = b;
v
}
};
($c:expr) => {
{
let BlockAnd(b, ()) = $c;
b
}
};
}
///////////////////////////////////////////////////////////////////////////
/// the main entry point for building MIR for a function
pub fn construct<'a,'tcx>(hir: Cx<'a,'tcx>,
span: Span,
implicit_arguments: Vec<Ty<'tcx>>,
explicit_arguments: Vec<(Ty<'tcx>, &'tcx hir::Pat)>,
argument_extent: CodeExtent,
return_ty: FnOutput<'tcx>,
ast_block: &'tcx hir::Block)
-> Mir<'tcx> {
let cfg = CFG { basic_blocks: vec![] };
let mut builder = Builder {
hir: hir,
cfg: cfg,
scopes: vec![],
loop_scopes: vec![],
temp_decls: vec![],
var_decls: vec![],
var_indices: FnvHashMap(),
unit_temp: None,
};
assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
assert_eq!(builder.cfg.start_new_block(), END_BLOCK);
let mut block = START_BLOCK;
let arg_decls = unpack!(block = builder.args_and_body(block,
implicit_arguments,
explicit_arguments,
argument_extent,
ast_block));
builder.cfg.terminate(block, Terminator::Goto { target: END_BLOCK });
builder.cfg.terminate(END_BLOCK, Terminator::Return);
Mir {
basic_blocks: builder.cfg.basic_blocks,
var_decls: builder.var_decls,
arg_decls: arg_decls,
temp_decls: builder.temp_decls,
return_ty: return_ty,
span: span
}
}
impl<'a,'tcx> Builder<'a,'tcx> {
fn args_and_body(&mut self,
mut block: BasicBlock,
implicit_arguments: Vec<Ty<'tcx>>,
explicit_arguments: Vec<(Ty<'tcx>, &'tcx hir::Pat)>,
argument_extent: CodeExtent,
ast_block: &'tcx hir::Block)
-> BlockAnd<Vec<ArgDecl<'tcx>>>
{
self.in_scope(argument_extent, block, |this| {
// to start, translate the argument patterns and collect the argument types.
let implicits = implicit_arguments.into_iter().map(|ty| (ty, None));
let explicits = explicit_arguments.into_iter().map(|(ty, pat)| (ty, Some(pat)));
let arg_decls =
implicits
.chain(explicits)
.enumerate()
.map(|(index, (ty, pattern))| {
if let Some(pattern) = pattern {
let lvalue = Lvalue::Arg(index as u32);
let pattern = this.hir.irrefutable_pat(pattern);
unpack!(block = this.lvalue_into_pattern(block,
argument_extent,
pattern,
&lvalue));
}
ArgDecl { ty: ty }
})
.collect();
// start the first basic block and translate the body
unpack!(block = this.ast_block(&Lvalue::ReturnPointer, block, ast_block));
block.and(arg_decls)
})
}
fn get_unit_temp(&mut self) -> Lvalue<'tcx> {
match self.unit_temp {
Some(ref tmp) => tmp.clone(),
None => {
let ty = self.hir.unit_ty();
let tmp = self.temp(ty);
self.unit_temp = Some(tmp.clone());
tmp
}
}
}
}
///////////////////////////////////////////////////////////////////////////
// Builder methods are broken up into modules, depending on what kind
// of thing is being translated. Note that they use the `unpack` macro
// above extensively.
mod block;
mod cfg;
mod expr;
mod into;
mod matches;
mod misc;
mod scope;
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