1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
14 use rustc::middle::region::{CodeExtent, CodeExtentData};
15 use rustc::ty::{self, Ty};
17 use rustc::util::nodemap::NodeMap;
21 use syntax::symbol::keywords;
24 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
28 pub struct Builder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
29 hir: Cx<'a, 'gcx, 'tcx>,
35 /// the current set of scopes, updated as we traverse;
36 /// see the `scope` module for more details
37 scopes: Vec<scope::Scope<'tcx>>,
39 /// the current set of breakables; see the `scope` module for more
41 breakable_scopes: Vec<scope::BreakableScope<'tcx>>,
43 /// the vector of all scopes that we have created thus far;
44 /// we track this for debuginfo later
45 visibility_scopes: IndexVec<VisibilityScope, VisibilityScopeData>,
46 visibility_scope: VisibilityScope,
48 /// Maps node ids of variable bindings to the `Local`s created for them.
49 var_indices: NodeMap<Local>,
50 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
51 unit_temp: Option<Lvalue<'tcx>>,
53 /// cached block with the RESUME terminator; this is created
54 /// when first set of cleanups are built.
55 cached_resume_block: Option<BasicBlock>,
56 /// cached block with the RETURN terminator
57 cached_return_block: Option<BasicBlock>,
61 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
64 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
65 pub struct ScopeId(u32);
67 impl Idx for ScopeId {
68 fn new(index: usize) -> ScopeId {
69 assert!(index < (u32::MAX as usize));
73 fn index(self) -> usize {
78 ///////////////////////////////////////////////////////////////////////////
79 /// The `BlockAnd` "monad" packages up the new basic block along with a
80 /// produced value (sometimes just unit, of course). The `unpack!`
81 /// macro (and methods below) makes working with `BlockAnd` much more
84 #[must_use] // if you don't use one of these results, you're leaving a dangling edge
85 pub struct BlockAnd<T>(BasicBlock, T);
87 trait BlockAndExtension {
88 fn and<T>(self, v: T) -> BlockAnd<T>;
89 fn unit(self) -> BlockAnd<()>;
92 impl BlockAndExtension for BasicBlock {
93 fn and<T>(self, v: T) -> BlockAnd<T> {
97 fn unit(self) -> BlockAnd<()> {
102 /// Update a block pointer and return the value.
103 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
104 macro_rules! unpack {
105 ($x:ident = $c:expr) => {
107 let BlockAnd(b, v) = $c;
115 let BlockAnd(b, ()) = $c;
121 ///////////////////////////////////////////////////////////////////////////
122 /// the main entry point for building MIR for a function
124 pub fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>,
129 body: &'gcx hir::Body)
131 where A: Iterator<Item=(Ty<'gcx>, Option<&'gcx hir::Pat>)>
133 let arguments: Vec<_> = arguments.collect();
136 let span = tcx.hir.span(fn_id);
137 let mut builder = Builder::new(hir, span, arguments.len(), return_ty);
139 let call_site_extent =
140 tcx.intern_code_extent(
141 CodeExtentData::CallSiteScope { fn_id: fn_id, body_id: body.value.id });
143 tcx.intern_code_extent(
144 CodeExtentData::ParameterScope { fn_id: fn_id, body_id: body.value.id });
145 let mut block = START_BLOCK;
146 unpack!(block = builder.in_scope(call_site_extent, block, |builder| {
147 unpack!(block = builder.in_scope(arg_extent, block, |builder| {
148 builder.args_and_body(block, &arguments, arg_extent, &body.value)
150 // Attribute epilogue to function's closing brace
151 let fn_end = Span { lo: span.hi, ..span };
152 let source_info = builder.source_info(fn_end);
153 let return_block = builder.return_block();
154 builder.cfg.terminate(block, source_info,
155 TerminatorKind::Goto { target: return_block });
156 builder.cfg.terminate(return_block, source_info,
157 TerminatorKind::Return);
160 assert_eq!(block, builder.return_block());
162 let mut spread_arg = None;
163 if abi == Abi::RustCall {
164 // RustCall pseudo-ABI untuples the last argument.
165 spread_arg = Some(Local::new(arguments.len()));
168 // Gather the upvars of a closure, if any.
169 let upvar_decls: Vec<_> = tcx.with_freevars(fn_id, |freevars| {
170 freevars.iter().map(|fv| {
171 let var_id = tcx.hir.as_local_node_id(fv.def.def_id()).unwrap();
172 let by_ref = hir.tables().upvar_capture(ty::UpvarId {
174 closure_expr_id: fn_id
175 }).map_or(false, |capture| match capture {
176 ty::UpvarCapture::ByValue => false,
177 ty::UpvarCapture::ByRef(..) => true
179 let mut decl = UpvarDecl {
180 debug_name: keywords::Invalid.name(),
183 if let Some(hir::map::NodeLocal(pat)) = tcx.hir.find(var_id) {
184 if let hir::PatKind::Binding(_, _, ref ident, _) = pat.node {
185 decl.debug_name = ident.node;
192 let mut mir = builder.finish(upvar_decls, return_ty);
193 mir.spread_arg = spread_arg;
197 pub fn construct_const<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>,
198 body_id: hir::BodyId)
201 let ast_expr = &tcx.hir.body(body_id).value;
202 let ty = hir.tables().expr_ty_adjusted(ast_expr);
203 let owner_id = tcx.hir.body_owner(body_id);
204 let span = tcx.hir.span(owner_id);
205 let mut builder = Builder::new(hir, span, 0, ty);
207 let region_maps = tcx.region_maps();
208 let extent = region_maps.temporary_scope(tcx, ast_expr.id)
209 .unwrap_or(tcx.item_extent(owner_id));
210 let mut block = START_BLOCK;
211 let _ = builder.in_scope(extent, block, |builder| {
212 let expr = builder.hir.mirror(ast_expr);
213 unpack!(block = builder.into(&Lvalue::Local(RETURN_POINTER), block, expr));
215 let source_info = builder.source_info(span);
216 let return_block = builder.return_block();
217 builder.cfg.terminate(block, source_info,
218 TerminatorKind::Goto { target: return_block });
219 builder.cfg.terminate(return_block, source_info,
220 TerminatorKind::Return);
225 builder.finish(vec![], ty)
228 pub fn construct_error<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>,
229 body_id: hir::BodyId)
231 let span = hir.tcx().hir.span(hir.tcx().hir.body_owner(body_id));
232 let ty = hir.tcx().types.err;
233 let mut builder = Builder::new(hir, span, 0, ty);
234 let source_info = builder.source_info(span);
235 builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
236 builder.finish(vec![], ty)
239 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
240 fn new(hir: Cx<'a, 'gcx, 'tcx>,
244 -> Builder<'a, 'gcx, 'tcx> {
245 let mut builder = Builder {
247 cfg: CFG { basic_blocks: IndexVec::new() },
249 arg_count: arg_count,
251 visibility_scopes: IndexVec::new(),
252 visibility_scope: ARGUMENT_VISIBILITY_SCOPE,
253 breakable_scopes: vec![],
254 local_decls: IndexVec::from_elem_n(LocalDecl::new_return_pointer(return_ty,
256 var_indices: NodeMap(),
258 cached_resume_block: None,
259 cached_return_block: None
262 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
263 assert_eq!(builder.new_visibility_scope(span), ARGUMENT_VISIBILITY_SCOPE);
264 builder.visibility_scopes[ARGUMENT_VISIBILITY_SCOPE].parent_scope = None;
270 upvar_decls: Vec<UpvarDecl>,
273 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
274 if block.terminator.is_none() {
275 span_bug!(self.fn_span, "no terminator on block {:?}", index);
279 Mir::new(self.cfg.basic_blocks,
280 self.visibility_scopes,
290 fn args_and_body(&mut self,
291 mut block: BasicBlock,
292 arguments: &[(Ty<'gcx>, Option<&'gcx hir::Pat>)],
293 argument_extent: CodeExtent<'tcx>,
294 ast_body: &'gcx hir::Expr)
297 // Allocate locals for the function arguments
298 for &(ty, pattern) in arguments.iter() {
299 // If this is a simple binding pattern, give the local a nice name for debuginfo.
301 if let Some(pat) = pattern {
302 if let hir::PatKind::Binding(_, _, ref ident, _) = pat.node {
303 name = Some(ident.node);
307 self.local_decls.push(LocalDecl {
308 mutability: Mutability::Not,
310 source_info: SourceInfo {
311 scope: ARGUMENT_VISIBILITY_SCOPE,
312 span: pattern.map_or(self.fn_span, |pat| pat.span)
315 is_user_variable: false,
319 let mut scope = None;
320 // Bind the argument patterns
321 for (index, &(ty, pattern)) in arguments.iter().enumerate() {
322 // Function arguments always get the first Local indices after the return pointer
323 let lvalue = Lvalue::Local(Local::new(index + 1));
325 if let Some(pattern) = pattern {
326 let pattern = Pattern::from_hir(self.hir.tcx(), self.hir.tables(), pattern);
327 scope = self.declare_bindings(scope, ast_body.span, &pattern);
328 unpack!(block = self.lvalue_into_pattern(block, pattern, &lvalue));
331 // Make sure we drop (parts of) the argument even when not matched on.
332 self.schedule_drop(pattern.as_ref().map_or(ast_body.span, |pat| pat.span),
333 argument_extent, &lvalue, ty);
337 // Enter the argument pattern bindings visibility scope, if it exists.
338 if let Some(visibility_scope) = scope {
339 self.visibility_scope = visibility_scope;
342 let body = self.hir.mirror(ast_body);
343 self.into(&Lvalue::Local(RETURN_POINTER), block, body)
346 fn get_unit_temp(&mut self) -> Lvalue<'tcx> {
347 match self.unit_temp {
348 Some(ref tmp) => tmp.clone(),
350 let ty = self.hir.unit_ty();
351 let fn_span = self.fn_span;
352 let tmp = self.temp(ty, fn_span);
353 self.unit_temp = Some(tmp.clone());
359 fn return_block(&mut self) -> BasicBlock {
360 match self.cached_return_block {
363 let rb = self.cfg.start_new_block();
364 self.cached_return_block = Some(rb);
371 ///////////////////////////////////////////////////////////////////////////
372 // Builder methods are broken up into modules, depending on what kind
373 // of thing is being translated. Note that they use the `unpack` macro
374 // above extensively.