1 // Copyright 2016 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.
13 use rustc::mir::repr::{Local, Location, Lvalue, Mir};
14 use rustc::mir::visit::{LvalueContext, MutVisitor, Visitor};
15 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
16 use std::marker::PhantomData;
19 pub struct DefUseAnalysis<'tcx> {
20 info: IndexVec<Local, Info<'tcx>>,
21 mir_summary: MirSummary,
25 pub struct Info<'tcx> {
26 pub defs_and_uses: Vec<Use<'tcx>>,
30 pub struct Use<'tcx> {
31 pub context: LvalueContext<'tcx>,
32 pub location: Location,
35 impl<'tcx> DefUseAnalysis<'tcx> {
36 pub fn new(mir: &Mir<'tcx>) -> DefUseAnalysis<'tcx> {
38 info: IndexVec::from_elem_n(Info::new(), mir.count_locals()),
39 mir_summary: MirSummary::new(mir),
43 pub fn analyze(&mut self, mir: &Mir<'tcx>) {
44 let mut finder = DefUseFinder {
45 info: mem::replace(&mut self.info, IndexVec::new()),
46 mir_summary: self.mir_summary,
48 finder.visit_mir(mir);
49 self.info = finder.info
52 pub fn local_info(&self, local: Local) -> &Info<'tcx> {
56 pub fn local_info_mut(&mut self, local: Local) -> &mut Info<'tcx> {
60 fn mutate_defs_and_uses<F>(&self, local: Local, mir: &mut Mir<'tcx>, mut callback: F)
61 where F: for<'a> FnMut(&'a mut Lvalue<'tcx>,
64 for lvalue_use in &self.info[local].defs_and_uses {
65 MutateUseVisitor::new(local,
68 mir).visit_location(mir, lvalue_use.location)
72 /// FIXME(pcwalton): This should update the def-use chains.
73 pub fn replace_all_defs_and_uses_with(&self,
76 new_lvalue: Lvalue<'tcx>) {
77 self.mutate_defs_and_uses(local, mir, |lvalue, _, _| *lvalue = new_lvalue.clone())
81 struct DefUseFinder<'tcx> {
82 info: IndexVec<Local, Info<'tcx>>,
83 mir_summary: MirSummary,
86 impl<'tcx> DefUseFinder<'tcx> {
87 fn lvalue_mut_info(&mut self, lvalue: &Lvalue<'tcx>) -> Option<&mut Info<'tcx>> {
88 let info = &mut self.info;
89 self.mir_summary.local_index(lvalue).map(move |local| &mut info[local])
93 impl<'tcx> Visitor<'tcx> for DefUseFinder<'tcx> {
94 fn visit_lvalue(&mut self,
95 lvalue: &Lvalue<'tcx>,
96 context: LvalueContext<'tcx>,
98 if let Some(ref mut info) = self.lvalue_mut_info(lvalue) {
99 info.defs_and_uses.push(Use {
104 self.super_lvalue(lvalue, context, location)
108 impl<'tcx> Info<'tcx> {
109 fn new() -> Info<'tcx> {
111 defs_and_uses: vec![],
115 pub fn def_count(&self) -> usize {
116 self.defs_and_uses.iter().filter(|lvalue_use| lvalue_use.context.is_mutating_use()).count()
119 pub fn def_count_not_including_drop(&self) -> usize {
120 self.defs_and_uses.iter().filter(|lvalue_use| {
121 lvalue_use.context.is_mutating_use() && !lvalue_use.context.is_drop()
125 pub fn use_count(&self) -> usize {
126 self.defs_and_uses.iter().filter(|lvalue_use| {
127 lvalue_use.context.is_nonmutating_use()
132 struct MutateUseVisitor<'tcx, F> {
135 mir_summary: MirSummary,
136 phantom: PhantomData<&'tcx ()>,
139 impl<'tcx, F> MutateUseVisitor<'tcx, F> {
140 fn new(query: Local, callback: F, mir_summary: MirSummary, _: &Mir<'tcx>)
141 -> MutateUseVisitor<'tcx, F>
142 where F: for<'a> FnMut(&'a mut Lvalue<'tcx>, LvalueContext<'tcx>, Location) {
146 mir_summary: mir_summary,
147 phantom: PhantomData,
152 impl<'tcx, F> MutVisitor<'tcx> for MutateUseVisitor<'tcx, F>
153 where F: for<'a> FnMut(&'a mut Lvalue<'tcx>, LvalueContext<'tcx>, Location) {
154 fn visit_lvalue(&mut self,
155 lvalue: &mut Lvalue<'tcx>,
156 context: LvalueContext<'tcx>,
157 location: Location) {
158 if self.mir_summary.local_index(lvalue) == Some(self.query) {
159 (self.callback)(lvalue, context, location)
161 self.super_lvalue(lvalue, context, location)
165 /// A small structure that enables various metadata of the MIR to be queried
166 /// without a reference to the MIR itself.
167 #[derive(Clone, Copy)]
168 pub struct MirSummary {
175 pub fn new(mir: &Mir) -> MirSummary {
177 arg_count: mir.arg_decls.len(),
178 var_count: mir.var_decls.len(),
179 temp_count: mir.temp_decls.len(),
183 pub fn local_index<'tcx>(&self, lvalue: &Lvalue<'tcx>) -> Option<Local> {
185 Lvalue::Arg(arg) => Some(Local::new(arg.index())),
186 Lvalue::Var(var) => Some(Local::new(var.index() + self.arg_count)),
187 Lvalue::Temp(temp) => {
188 Some(Local::new(temp.index() + self.arg_count + self.var_count))
190 Lvalue::ReturnPointer => {
191 Some(Local::new(self.arg_count + self.var_count + self.temp_count))