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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;
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use hair::LintLevel;
use rustc::hir;
use rustc::hir::def_id::{DefId, LocalDefId};
use rustc::middle::region;
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use rustc::mir::*;
use rustc::mir::visit::{MutVisitor, TyContext};
use rustc::ty::{self, Ty, TyCtxt};
use rustc::ty::subst::Substs;
use rustc::util::nodemap::NodeMap;
use rustc_const_eval::pattern::{BindingMode, PatternKind};
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 transform::MirSource;
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 {
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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(),
};
tcx.infer_ctxt().enter(|infcx| {
let cx = Cx::new(&infcx, id);
let mut mir = if cx.tables().tainted_by_errors {
build::construct_error(cx, body_id)
} else if let hir::BodyOwnerKind::Fn = cx.body_owner_kind {
// 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;
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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((liberated_closure_env_ty(tcx, id, body_id), None))
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}
ty::TyGenerator(..) => {
let gen_ty = tcx.body_tables(body_id).node_id_to_type(fn_hir_id);
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Some((gen_ty, None))
}
_ => None,
};
// FIXME: safety in closures
let safety = match fn_sig.unsafety {
hir::Unsafety::Normal => Safety::Safe,
hir::Unsafety::Unsafe => Safety::FnUnsafe,
};
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);
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let (yield_ty, return_ty) = if body.is_generator {
let gen_sig = match ty.sty {
ty::TyGenerator(gen_def_id, gen_substs, ..) =>
gen_substs.generator_sig(gen_def_id, tcx),
_ =>
span_bug!(tcx.hir.span(id), "generator w/o generator type: {:?}", ty),
};
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(Some(gen_sig.yield_ty), gen_sig.return_ty)
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} else {
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(None, fn_sig.output())
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};
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build::construct_fn(cx, id, arguments, safety, 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,
MirSource::item(def_id), &mir, |_, _| Ok(()) );
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>, _: TyContext) {
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 = 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,
MirSource::item(tcx.hir.local_def_id(ctor_id)),
&mir, |_, _| Ok(()) );
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
fn liberated_closure_env_ty<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, '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, closure_substs) = match closure_ty.sty {
ty::TyClosure(closure_def_id, closure_substs) => (closure_def_id, closure_substs),
_ => bug!("closure expr does not have closure type: {:?}", closure_ty)
};
let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs).unwrap();
tcx.liberate_late_bound_regions(closure_def_id, &closure_env_ty)
}
struct Builder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
hir: Cx<'a, 'gcx, 'tcx>,
cfg: CFG<'tcx>,
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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>>,
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/// The current unsafe block in scope, even if it is hidden by
/// a PushUnsafeBlock
unpushed_unsafe: Safety,
/// The number of `push_unsafe_block` levels in scope
push_unsafe_count: usize,
/// the current set of breakables; see the `scope` module for more
/// details
breakable_scopes: Vec<scope::BreakableScope<'tcx>>,
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/// the vector of all scopes that we have created thus far;
/// we track this for debuginfo later
visibility_scopes: IndexVec<VisibilityScope, VisibilityScopeData>,
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visibility_scope_info: IndexVec<VisibilityScope, VisibilityScopeInfo>,
visibility_scope: VisibilityScope,
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/// Maps node ids of variable bindings to the `Local`s created for them.
var_indices: NodeMap<Local>,
local_decls: IndexVec<Local, LocalDecl<'tcx>>,
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unit_temp: Option<Place<'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>,
/// cached block with the UNREACHABLE terminator
cached_unreachable_block: Option<BasicBlock>,
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}
struct CFG<'tcx> {
basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
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}
newtype_index!(ScopeId);
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///////////////////////////////////////////////////////////////////////////
/// 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.
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#[must_use] // if you don't use one of these results, you're leaving a dangling edge
struct BlockAnd<T>(BasicBlock, T);
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trait BlockAndExtension {
fn and<T>(self, v: T) -> BlockAnd<T>;
fn unit(self) -> BlockAnd<()>;
}
impl BlockAndExtension for BasicBlock {
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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
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fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>,
fn_id: ast::NodeId,
arguments: A,
safety: Safety,
abi: Abi,
return_ty: Ty<'gcx>,
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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);
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let mut builder = Builder::new(hir.clone(),
span,
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arguments.len(),
safety,
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return_ty);
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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);
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let call_site_s = (call_site_scope, source_info);
unpack!(block = builder.in_scope(call_site_s, LintLevel::Inherited, block, |builder| {
let arg_scope_s = (arg_scope, source_info);
unpack!(block = builder.in_scope(arg_scope_s, LintLevel::Inherited, block, |builder| {
builder.args_and_body(block, &arguments, arg_scope, &body.value)
}));
// Attribute epilogue to function's closing brace
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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);
// Attribute any unreachable codepaths to the function's closing brace
if let Some(unreachable_block) = builder.cached_unreachable_block {
builder.cfg.terminate(unreachable_block, source_info,
TerminatorKind::Unreachable);
}
return_block.unit()
}));
assert_eq!(block, builder.return_block());
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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);
let capture = hir.tables().upvar_capture(ty::UpvarId {
var_id: var_hir_id,
closure_expr_id: LocalDefId::from_def_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,
mutability: Mutability::Not,
};
if let Some(hir::map::NodeBinding(pat)) = tcx.hir.find(var_id) {
if let hir::PatKind::Binding(_, _, ref ident, _) = pat.node {
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decl.debug_name = ident.node;
let bm = *hir.tables.pat_binding_modes()
.get(pat.hir_id)
.expect("missing binding mode");
if bm == ty::BindByValue(hir::MutMutable) {
decl.mutability = Mutability::Mut;
} else {
decl.mutability = Mutability::Not;
}
}
}
decl
}).collect()
});
let mut mir = builder.finish(upvar_decls, yield_ty);
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mir.spread_arg = spread_arg;
mir
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}
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, Safety::Safe, ty);
let mut block = START_BLOCK;
let expr = builder.hir.mirror(ast_expr);
unpack!(block = builder.into_expr(&Place::Local(RETURN_PLACE), 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![], None)
}
fn construct_error<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>,
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body_id: hir::BodyId)
-> Mir<'tcx> {
let owner_id = hir.tcx().hir.body_owner(body_id);
let span = hir.tcx().hir.span(owner_id);
let ty = hir.tcx().types.err;
let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty);
let source_info = builder.source_info(span);
builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
builder.finish(vec![], None)
}
impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
fn new(hir: Cx<'a, 'gcx, 'tcx>,
span: Span,
arg_count: usize,
safety: Safety,
return_ty: Ty<'tcx>)
-> Builder<'a, 'gcx, 'tcx> {
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let lint_level = LintLevel::Explicit(hir.root_lint_level);
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,
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visibility_scope_info: IndexVec::new(),
push_unsafe_count: 0,
unpushed_unsafe: safety,
breakable_scopes: vec![],
local_decls: IndexVec::from_elem_n(LocalDecl::new_return_place(return_ty,
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span), 1),
var_indices: NodeMap(),
unit_temp: None,
cached_resume_block: None,
cached_return_block: None,
cached_unreachable_block: None,
};
assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
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assert_eq!(
builder.new_visibility_scope(span, lint_level, Some(safety)),
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ARGUMENT_VISIBILITY_SCOPE);
builder.visibility_scopes[ARGUMENT_VISIBILITY_SCOPE].parent_scope = None;
builder
}
fn finish(self,
upvar_decls: Vec<UpvarDecl>,
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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,
ClearCrossCrate::Set(self.visibility_scope_info),
IndexVec::new(),
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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<()>
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{
// 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::Mut,
ty,
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source_info: SourceInfo {
scope: ARGUMENT_VISIBILITY_SCOPE,
span: pattern.map_or(self.fn_span, |pat| pat.span)
},
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lexical_scope: ARGUMENT_VISIBILITY_SCOPE,
name,
internal: false,
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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 place
let local = Local::new(index + 1);
let place = Place::Local(local);
if let Some(pattern) = pattern {
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let pattern = self.hir.pattern_from_hir(pattern);
match *pattern.kind {
// Don't introduce extra copies for simple bindings
PatternKind::Binding { mutability, var, mode: BindingMode::ByValue, .. } => {
self.local_decls[local].mutability = mutability;
self.var_indices.insert(var, local);
}
_ => {
scope = self.declare_bindings(scope, ast_body.span,
LintLevel::Inherited, &pattern);
unpack!(block = self.place_into_pattern(block, pattern, &place));
}
}
}
// 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, &place, 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(&Place::Local(RETURN_PLACE), block, body)
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}
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fn get_unit_temp(&mut self) -> Place<'tcx> {
match self.unit_temp {
Some(ref tmp) => tmp.clone(),
None => {
let ty = self.hir.unit_ty();
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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
}
}
}
fn unreachable_block(&mut self) -> BasicBlock {
match self.cached_unreachable_block {
Some(ub) => ub,
None => {
let ub = self.cfg.start_new_block();
self.cached_unreachable_block = Some(ub);
ub
}
}
}
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}
///////////////////////////////////////////////////////////////////////////
// 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;