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September 22, 2017 07:20
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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 build; | |
use hair::cx::Cx; | |
use rustc::hir; | |
use rustc::hir::def_id::DefId; | |
use rustc::middle::region; | |
use rustc::mir::*; | |
use rustc::mir::transform::MirSource; | |
use rustc::mir::visit::{MutVisitor, Lookup}; | |
use rustc::ty::{self, Ty, TyCtxt}; | |
use rustc::ty::subst::Substs; | |
use rustc::util::nodemap::NodeMap; | |
use rustc_data_structures::indexed_vec::{IndexVec, Idx}; | |
use shim; | |
use std::mem; | |
use std::u32; | |
use syntax::abi::Abi; | |
use syntax::ast; | |
use syntax::symbol::keywords; | |
use syntax_pos::Span; | |
use util as mir_util; | |
/// Construct the MIR for a given def-id. | |
pub fn mir_build<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Mir<'tcx> { | |
let id = tcx.hir.as_local_node_id(def_id).unwrap(); | |
let unsupported = || { | |
span_bug!(tcx.hir.span(id), "can't build MIR for {:?}", def_id); | |
}; | |
// Figure out what primary body this item has. | |
let body_id = match tcx.hir.get(id) { | |
hir::map::NodeItem(item) => { | |
match item.node { | |
hir::ItemConst(_, body) | | |
hir::ItemStatic(_, _, body) | | |
hir::ItemFn(.., body) => body, | |
_ => unsupported() | |
} | |
} | |
hir::map::NodeTraitItem(item) => { | |
match item.node { | |
hir::TraitItemKind::Const(_, Some(body)) | | |
hir::TraitItemKind::Method(_, | |
hir::TraitMethod::Provided(body)) => body, | |
_ => unsupported() | |
} | |
} | |
hir::map::NodeImplItem(item) => { | |
match item.node { | |
hir::ImplItemKind::Const(_, body) | | |
hir::ImplItemKind::Method(_, body) => body, | |
_ => unsupported() | |
} | |
} | |
hir::map::NodeExpr(expr) => { | |
// FIXME(eddyb) Closures should have separate | |
// function definition IDs and expression IDs. | |
// Type-checking should not let closures get | |
// this far in a constant position. | |
// Assume that everything other than closures | |
// is a constant "initializer" expression. | |
match expr.node { | |
hir::ExprClosure(_, _, body, _, _) => body, | |
_ => hir::BodyId { node_id: expr.id } | |
} | |
} | |
hir::map::NodeVariant(variant) => | |
return create_constructor_shim(tcx, id, &variant.node.data), | |
hir::map::NodeStructCtor(ctor) => | |
return create_constructor_shim(tcx, id, ctor), | |
_ => unsupported() | |
}; | |
let src = MirSource::from_node(tcx, id); | |
tcx.infer_ctxt().enter(|infcx| { | |
let cx = Cx::new(&infcx, src); | |
let mut mir = if cx.tables().tainted_by_errors { | |
build::construct_error(cx, body_id) | |
} else if let MirSource::Fn(id) = src { | |
// fetch the fully liberated fn signature (that is, all bound | |
// types/lifetimes replaced) | |
let fn_hir_id = tcx.hir.node_to_hir_id(id); | |
let fn_sig = cx.tables().liberated_fn_sigs()[fn_hir_id].clone(); | |
let ty = tcx.type_of(tcx.hir.local_def_id(id)); | |
let mut abi = fn_sig.abi; | |
let implicit_argument = match ty.sty { | |
ty::TyClosure(..) => { | |
// HACK(eddyb) Avoid having RustCall on closures, | |
// as it adds unnecessary (and wrong) auto-tupling. | |
abi = Abi::Rust; | |
Some((closure_self_ty(tcx, id, body_id), None)) | |
} | |
ty::TyGenerator(..) => { | |
let gen_ty = tcx.body_tables(body_id).node_id_to_type(fn_hir_id); | |
Some((gen_ty, None)) | |
} | |
_ => None, | |
}; | |
let body = tcx.hir.body(body_id); | |
let explicit_arguments = | |
body.arguments | |
.iter() | |
.enumerate() | |
.map(|(index, arg)| { | |
(fn_sig.inputs()[index], Some(&*arg.pat)) | |
}); | |
let arguments = implicit_argument.into_iter().chain(explicit_arguments); | |
let (yield_ty, return_ty) = if body.is_generator { | |
let gen_sig = cx.tables().generator_sigs()[fn_hir_id].clone().unwrap(); | |
(Some(gen_sig.yield_ty), gen_sig.return_ty) | |
} else { | |
(None, fn_sig.output()) | |
}; | |
build::construct_fn(cx, id, arguments, abi, return_ty, yield_ty, body) | |
} else { | |
build::construct_const(cx, body_id) | |
}; | |
// Convert the Mir to global types. | |
let mut globalizer = GlobalizeMir { | |
tcx, | |
span: mir.span | |
}; | |
globalizer.visit_mir(&mut mir); | |
let mir = unsafe { | |
mem::transmute::<Mir, Mir<'tcx>>(mir) | |
}; | |
mir_util::dump_mir(tcx, None, "mir_map", &0, src, &mir); | |
mir | |
}) | |
} | |
/// A pass to lift all the types and substitutions in a Mir | |
/// to the global tcx. Sadly, we don't have a "folder" that | |
/// can change 'tcx so we have to transmute afterwards. | |
struct GlobalizeMir<'a, 'gcx: 'a> { | |
tcx: TyCtxt<'a, 'gcx, 'gcx>, | |
span: Span | |
} | |
impl<'a, 'gcx: 'tcx, 'tcx> MutVisitor<'tcx> for GlobalizeMir<'a, 'gcx> { | |
fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: Lookup) { | |
if let Some(lifted) = self.tcx.lift(ty) { | |
*ty = lifted; | |
} else { | |
span_bug!(self.span, | |
"found type `{:?}` with inference types/regions in MIR", | |
ty); | |
} | |
} | |
fn visit_region(&mut self, region: &mut ty::Region<'tcx>, _: Location) { | |
if let Some(lifted) = self.tcx.lift(region) { | |
*region = lifted; | |
} else { | |
span_bug!(self.span, | |
"found region `{:?}` with inference types/regions in MIR", | |
region); | |
} | |
} | |
fn visit_const(&mut self, constant: &mut &'tcx ty::Const<'tcx>, _: Location) { | |
if let Some(lifted) = self.tcx.lift(constant) { | |
*constant = lifted; | |
} else { | |
span_bug!(self.span, | |
"found constant `{:?}` with inference types/regions in MIR", | |
constant); | |
} | |
} | |
fn visit_substs(&mut self, substs: &mut &'tcx Substs<'tcx>, _: Location) { | |
if let Some(lifted) = self.tcx.lift(substs) { | |
*substs = lifted; | |
} else { | |
span_bug!(self.span, | |
"found substs `{:?}` with inference types/regions in MIR", | |
substs); | |
} | |
} | |
} | |
fn create_constructor_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, | |
ctor_id: ast::NodeId, | |
v: &'tcx hir::VariantData) | |
-> Mir<'tcx> | |
{ | |
let span = tcx.hir.span(ctor_id); | |
if let hir::VariantData::Tuple(ref fields, ctor_id) = *v { | |
tcx.infer_ctxt().enter(|infcx| { | |
let (mut mir, src) = | |
shim::build_adt_ctor(&infcx, ctor_id, fields, span); | |
// Convert the Mir to global types. | |
let tcx = infcx.tcx.global_tcx(); | |
let mut globalizer = GlobalizeMir { | |
tcx, | |
span: mir.span | |
}; | |
globalizer.visit_mir(&mut mir); | |
let mir = unsafe { | |
mem::transmute::<Mir, Mir<'tcx>>(mir) | |
}; | |
mir_util::dump_mir(tcx, None, "mir_map", &0, src, &mir); | |
mir | |
}) | |
} else { | |
span_bug!(span, "attempting to create MIR for non-tuple variant {:?}", v); | |
} | |
} | |
/////////////////////////////////////////////////////////////////////////// | |
// BuildMir -- walks a crate, looking for fn items and methods to build MIR from | |
pub fn closure_self_ty<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, | |
closure_expr_id: ast::NodeId, | |
body_id: hir::BodyId) | |
-> Ty<'tcx> { | |
let closure_expr_hir_id = tcx.hir.node_to_hir_id(closure_expr_id); | |
let closure_ty = tcx.body_tables(body_id).node_id_to_type(closure_expr_hir_id); | |
let closure_def_id = tcx.hir.local_def_id(closure_expr_id); | |
let region = ty::ReFree(ty::FreeRegion { | |
scope: closure_def_id, | |
bound_region: ty::BoundRegion::BrEnv, | |
}); | |
let region = tcx.mk_region(region); | |
match tcx.closure_kind(closure_def_id) { | |
ty::ClosureKind::Fn => | |
tcx.mk_ref(region, | |
ty::TypeAndMut { ty: closure_ty, | |
mutbl: hir::MutImmutable }), | |
ty::ClosureKind::FnMut => | |
tcx.mk_ref(region, | |
ty::TypeAndMut { ty: closure_ty, | |
mutbl: hir::MutMutable }), | |
ty::ClosureKind::FnOnce => | |
closure_ty | |
} | |
} | |
struct Builder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> { | |
hir: Cx<'a, 'gcx, 'tcx>, | |
cfg: CFG<'tcx>, | |
fn_span: Span, | |
arg_count: usize, | |
/// the current set of scopes, updated as we traverse; | |
/// see the `scope` module for more details | |
scopes: Vec<scope::Scope<'tcx>>, | |
/// the current set of breakables; see the `scope` module for more | |
/// details | |
breakable_scopes: Vec<scope::BreakableScope<'tcx>>, | |
/// the vector of all scopes that we have created thus far; | |
/// we track this for debuginfo later | |
visibility_scopes: IndexVec<VisibilityScope, VisibilityScopeData>, | |
visibility_scope: VisibilityScope, | |
/// Maps node ids of variable bindings to the `Local`s created for them. | |
var_indices: NodeMap<Local>, | |
local_decls: IndexVec<Local, LocalDecl<'tcx>>, | |
unit_temp: Option<Lvalue<'tcx>>, | |
/// cached block with the RESUME terminator; this is created | |
/// when first set of cleanups are built. | |
cached_resume_block: Option<BasicBlock>, | |
/// cached block with the RETURN terminator | |
cached_return_block: Option<BasicBlock>, | |
} | |
struct CFG<'tcx> { | |
basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>, | |
} | |
#[derive(Copy, Clone, Debug, PartialEq, Eq)] | |
pub struct ScopeId(u32); | |
impl Idx for ScopeId { | |
fn new(index: usize) -> ScopeId { | |
assert!(index < (u32::MAX as usize)); | |
ScopeId(index as u32) | |
} | |
fn index(self) -> usize { | |
self.0 as usize | |
} | |
} | |
/////////////////////////////////////////////////////////////////////////// | |
/// 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 | |
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 | |
fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>, | |
fn_id: ast::NodeId, | |
arguments: A, | |
abi: Abi, | |
return_ty: Ty<'gcx>, | |
yield_ty: Option<Ty<'gcx>>, | |
body: &'gcx hir::Body) | |
-> Mir<'tcx> | |
where A: Iterator<Item=(Ty<'gcx>, Option<&'gcx hir::Pat>)> | |
{ | |
let arguments: Vec<_> = arguments.collect(); | |
let tcx = hir.tcx(); | |
let span = tcx.hir.span(fn_id); | |
let mut builder = Builder::new(hir.clone(), | |
span, | |
arguments.len(), | |
return_ty); | |
let call_site_scope = region::Scope::CallSite(body.value.hir_id.local_id); | |
let arg_scope = region::Scope::Arguments(body.value.hir_id.local_id); | |
let mut block = START_BLOCK; | |
let source_info = builder.source_info(span); | |
unpack!(block = builder.in_scope((call_site_scope, source_info), block, |builder| { | |
unpack!(block = builder.in_scope((arg_scope, source_info), block, |builder| { | |
builder.args_and_body(block, &arguments, arg_scope, &body.value) | |
})); | |
// CODE ADDED START | |
// We cannot unwind into FFI. Therefore generate an extra "Abort" landing pad. | |
if abi != Abi::Rust && abi != Abi::RustCall && abi != Abi::RustIntrinsic { | |
let abort_block = builder.cfg.start_new_cleanup_block(); | |
builder.cfg.terminate(abort_block, source_info, TerminatorKind::Abort); // FIXME | |
} | |
// CODE ADDED END | |
// Attribute epilogue to function's closing brace | |
let fn_end = span.with_lo(span.hi()); | |
let source_info = builder.source_info(fn_end); | |
let return_block = builder.return_block(); | |
builder.cfg.terminate(block, source_info, | |
TerminatorKind::Goto { target: return_block }); | |
builder.cfg.terminate(return_block, source_info, | |
TerminatorKind::Return); | |
return_block.unit() | |
})); | |
assert_eq!(block, builder.return_block()); | |
let mut spread_arg = None; | |
if abi == Abi::RustCall { | |
// RustCall pseudo-ABI untuples the last argument. | |
spread_arg = Some(Local::new(arguments.len())); | |
} | |
// Gather the upvars of a closure, if any. | |
let upvar_decls: Vec<_> = tcx.with_freevars(fn_id, |freevars| { | |
freevars.iter().map(|fv| { | |
let var_id = fv.var_id(); | |
let var_hir_id = tcx.hir.node_to_hir_id(var_id); | |
let closure_expr_id = tcx.hir.local_def_id(fn_id).index; | |
let capture = hir.tables().upvar_capture(ty::UpvarId { | |
var_id: var_hir_id, | |
closure_expr_id, | |
}); | |
let by_ref = match capture { | |
ty::UpvarCapture::ByValue => false, | |
ty::UpvarCapture::ByRef(..) => true | |
}; | |
let mut decl = UpvarDecl { | |
debug_name: keywords::Invalid.name(), | |
by_ref, | |
}; | |
if let Some(hir::map::NodeBinding(pat)) = tcx.hir.find(var_id) { | |
if let hir::PatKind::Binding(_, _, ref ident, _) = pat.node { | |
decl.debug_name = ident.node; | |
} | |
} | |
decl | |
}).collect() | |
}); | |
let mut mir = builder.finish(upvar_decls, return_ty, yield_ty); | |
mir.spread_arg = spread_arg; | |
mir | |
} | |
fn construct_const<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>, | |
body_id: hir::BodyId) | |
-> Mir<'tcx> { | |
let tcx = hir.tcx(); | |
let ast_expr = &tcx.hir.body(body_id).value; | |
let ty = hir.tables().expr_ty_adjusted(ast_expr); | |
let owner_id = tcx.hir.body_owner(body_id); | |
let span = tcx.hir.span(owner_id); | |
let mut builder = Builder::new(hir.clone(), span, 0, ty); | |
let mut block = START_BLOCK; | |
let expr = builder.hir.mirror(ast_expr); | |
unpack!(block = builder.into_expr(&Lvalue::Local(RETURN_POINTER), block, expr)); | |
let source_info = builder.source_info(span); | |
builder.cfg.terminate(block, source_info, TerminatorKind::Return); | |
// Constants can't `return` so a return block should not be created. | |
assert_eq!(builder.cached_return_block, None); | |
builder.finish(vec![], ty, None) | |
} | |
fn construct_error<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>, | |
body_id: hir::BodyId) | |
-> Mir<'tcx> { | |
let span = hir.tcx().hir.span(hir.tcx().hir.body_owner(body_id)); | |
let ty = hir.tcx().types.err; | |
let mut builder = Builder::new(hir, span, 0, ty); | |
let source_info = builder.source_info(span); | |
builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable); | |
builder.finish(vec![], ty, None) | |
} | |
impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> { | |
fn new(hir: Cx<'a, 'gcx, 'tcx>, | |
span: Span, | |
arg_count: usize, | |
return_ty: Ty<'tcx>) | |
-> Builder<'a, 'gcx, 'tcx> { | |
let mut builder = Builder { | |
hir, | |
cfg: CFG { basic_blocks: IndexVec::new() }, | |
fn_span: span, | |
arg_count, | |
scopes: vec![], | |
visibility_scopes: IndexVec::new(), | |
visibility_scope: ARGUMENT_VISIBILITY_SCOPE, | |
breakable_scopes: vec![], | |
local_decls: IndexVec::from_elem_n(LocalDecl::new_return_pointer(return_ty, | |
span), 1), | |
var_indices: NodeMap(), | |
unit_temp: None, | |
cached_resume_block: None, | |
cached_return_block: None | |
}; | |
assert_eq!(builder.cfg.start_new_block(), START_BLOCK); | |
assert_eq!(builder.new_visibility_scope(span), ARGUMENT_VISIBILITY_SCOPE); | |
builder.visibility_scopes[ARGUMENT_VISIBILITY_SCOPE].parent_scope = None; | |
builder | |
} | |
fn finish(self, | |
upvar_decls: Vec<UpvarDecl>, | |
return_ty: Ty<'tcx>, | |
yield_ty: Option<Ty<'tcx>>) | |
-> Mir<'tcx> { | |
for (index, block) in self.cfg.basic_blocks.iter().enumerate() { | |
if block.terminator.is_none() { | |
span_bug!(self.fn_span, "no terminator on block {:?}", index); | |
} | |
} | |
Mir::new(self.cfg.basic_blocks, | |
self.visibility_scopes, | |
IndexVec::new(), | |
return_ty, | |
yield_ty, | |
self.local_decls, | |
self.arg_count, | |
upvar_decls, | |
self.fn_span | |
) | |
} | |
fn args_and_body(&mut self, | |
mut block: BasicBlock, | |
arguments: &[(Ty<'gcx>, Option<&'gcx hir::Pat>)], | |
argument_scope: region::Scope, | |
ast_body: &'gcx hir::Expr) | |
-> BlockAnd<()> | |
{ | |
// Allocate locals for the function arguments | |
for &(ty, pattern) in arguments.iter() { | |
// If this is a simple binding pattern, give the local a nice name for debuginfo. | |
let mut name = None; | |
if let Some(pat) = pattern { | |
if let hir::PatKind::Binding(_, _, ref ident, _) = pat.node { | |
name = Some(ident.node); | |
} | |
} | |
self.local_decls.push(LocalDecl { | |
mutability: Mutability::Not, | |
ty, | |
source_info: SourceInfo { | |
scope: ARGUMENT_VISIBILITY_SCOPE, | |
span: pattern.map_or(self.fn_span, |pat| pat.span) | |
}, | |
name, | |
internal: false, | |
is_user_variable: false, | |
}); | |
} | |
let mut scope = None; | |
// Bind the argument patterns | |
for (index, &(ty, pattern)) in arguments.iter().enumerate() { | |
// Function arguments always get the first Local indices after the return pointer | |
let lvalue = Lvalue::Local(Local::new(index + 1)); | |
if let Some(pattern) = pattern { | |
let pattern = self.hir.pattern_from_hir(pattern); | |
scope = self.declare_bindings(scope, ast_body.span, &pattern); | |
unpack!(block = self.lvalue_into_pattern(block, pattern, &lvalue)); | |
} | |
// Make sure we drop (parts of) the argument even when not matched on. | |
self.schedule_drop(pattern.as_ref().map_or(ast_body.span, |pat| pat.span), | |
argument_scope, &lvalue, ty); | |
} | |
// Enter the argument pattern bindings visibility scope, if it exists. | |
if let Some(visibility_scope) = scope { | |
self.visibility_scope = visibility_scope; | |
} | |
let body = self.hir.mirror(ast_body); | |
self.into(&Lvalue::Local(RETURN_POINTER), block, body) | |
} | |
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 fn_span = self.fn_span; | |
let tmp = self.temp(ty, fn_span); | |
self.unit_temp = Some(tmp.clone()); | |
tmp | |
} | |
} | |
} | |
fn return_block(&mut self) -> BasicBlock { | |
match self.cached_return_block { | |
Some(rb) => rb, | |
None => { | |
let rb = self.cfg.start_new_block(); | |
self.cached_return_block = Some(rb); | |
rb | |
} | |
} | |
} | |
} | |
/////////////////////////////////////////////////////////////////////////// | |
// 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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