src/librustc_mir/util/pretty.rs - third_party/rust - Git at Google

 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
 use rustc::hir::def::CtorKind;
 use rustc::mir::*;
 use rustc::mir::visit::Visitor;
 use rustc::ty::{self, TyCtxt};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::indexed_vec::Idx;
 use std::fmt::Display;
 use std::fmt::Write as _;
 use std::fs;
 use std::io::{self, Write};
 use std::path::{Path, PathBuf};
 use super::graphviz::write_mir_fn_graphviz;
 use crate::transform::MirSource;

 const INDENT: &str = "    ";
 /// Alignment for lining up comments following MIR statements
 pub(crate) const ALIGN: usize = 40;

 /// An indication of where we are in the control flow graph. Used for printing
 /// extra information in `dump_mir`
 pub enum PassWhere {
     /// We have not started dumping the control flow graph, but we are about to.
     BeforeCFG,

     /// We just finished dumping the control flow graph. This is right before EOF
     AfterCFG,

     /// We are about to start dumping the given basic block.
     BeforeBlock(BasicBlock),

     /// We are just about to dump the given statement or terminator.
     BeforeLocation(Location),

     /// We just dumped the given statement or terminator.
     AfterLocation(Location),

     /// We just dumped the terminator for a block but not the closing `}`.
     AfterTerminator(BasicBlock),
 }

 /// If the session is properly configured, dumps a human-readable
 /// representation of the mir into:
 ///
 /// ```text
 /// rustc.node<node_id>.<pass_num>.<pass_name>.<disambiguator>
 /// ```
 ///
 /// Output from this function is controlled by passing `-Z dump-mir=<filter>`,
 /// where `<filter>` takes the following forms:
 ///
 /// - `all` -- dump MIR for all fns, all passes, all everything
 /// - a filter defined by a set of substrings combined with `&` and `|`
 ///   (`&` has higher precedence). At least one of the `|`-separated groups
 ///   must match; an `|`-separated group matches if all of its `&`-separated
 ///   substrings are matched.
 ///
 /// Example:
 ///
 /// - `nll` == match if `nll` appears in the name
 /// - `foo & nll` == match if `foo` and `nll` both appear in the name
 /// - `foo & nll | typeck` == match if `foo` and `nll` both appear in the name
 ///   or `typeck` appears in the name.
 /// - `foo & nll | bar & typeck` == match if `foo` and `nll` both appear in the name
 ///   or `typeck` and `bar` both appear in the name.
 pub fn dump_mir<'a, 'gcx, 'tcx, F>(
     tcx: TyCtxt<'a, 'gcx, 'tcx>,
     pass_num: Option<&dyn Display>,
     pass_name: &str,
     disambiguator: &dyn Display,
     source: MirSource<'tcx>,
     mir: &Mir<'tcx>,
     extra_data: F,
 ) where
     F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
 {
     if !dump_enabled(tcx, pass_name, source) {
         return;
     }

     let node_path = ty::print::with_forced_impl_filename_line(|| {
         // see notes on #41697 below
         tcx.def_path_str(source.def_id())
     });
     dump_matched_mir_node(
         tcx,
         pass_num,
         pass_name,
         &node_path,
         disambiguator,
         source,
         mir,
         extra_data,
     );
 }

 pub fn dump_enabled<'a, 'gcx, 'tcx>(
     tcx: TyCtxt<'a, 'gcx, 'tcx>,
     pass_name: &str,
     source: MirSource<'tcx>,
 ) -> bool {
     let filters = match tcx.sess.opts.debugging_opts.dump_mir {
         None => return false,
         Some(ref filters) => filters,
     };
     let node_path = ty::print::with_forced_impl_filename_line(|| {
         // see notes on #41697 below
         tcx.def_path_str(source.def_id())
     });
     filters.split('|').any(|or_filter| {
         or_filter.split('&').all(|and_filter| {
             and_filter == "all" || pass_name.contains(and_filter) || node_path.contains(and_filter)
         })
     })
 }

 // #41697 -- we use `with_forced_impl_filename_line()` because
 // `def_path_str()` would otherwise trigger `type_of`, and this can
 // run while we are already attempting to evaluate `type_of`.

 fn dump_matched_mir_node<'a, 'gcx, 'tcx, F>(
     tcx: TyCtxt<'a, 'gcx, 'tcx>,
     pass_num: Option<&dyn Display>,
     pass_name: &str,
     node_path: &str,
     disambiguator: &dyn Display,
     source: MirSource<'tcx>,
     mir: &Mir<'tcx>,
     mut extra_data: F,
 ) where
     F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
 {
     let _: io::Result<()> = try {
         let mut file = create_dump_file(tcx, "mir", pass_num, pass_name, disambiguator, source)?;
         writeln!(file, "// MIR for `{}`", node_path)?;
         writeln!(file, "// source = {:?}", source)?;
         writeln!(file, "// pass_name = {}", pass_name)?;
         writeln!(file, "// disambiguator = {}", disambiguator)?;
         if let Some(ref layout) = mir.generator_layout {
             writeln!(file, "// generator_layout = {:?}", layout)?;
         }
         writeln!(file, "")?;
         extra_data(PassWhere::BeforeCFG, &mut file)?;
         write_user_type_annotations(mir, &mut file)?;
         write_mir_fn(tcx, source, mir, &mut extra_data, &mut file)?;
         extra_data(PassWhere::AfterCFG, &mut file)?;
     };

     if tcx.sess.opts.debugging_opts.dump_mir_graphviz {
         let _: io::Result<()> = try {
             let mut file =
                 create_dump_file(tcx, "dot", pass_num, pass_name, disambiguator, source)?;
             write_mir_fn_graphviz(tcx, source.def_id(), mir, &mut file)?;
         };
     }
 }

 /// Returns the path to the filename where we should dump a given MIR.
 /// Also used by other bits of code (e.g., NLL inference) that dump
 /// graphviz data or other things.
 fn dump_path(
     tcx: TyCtxt<'_, '_, '_>,
     extension: &str,
     pass_num: Option<&dyn Display>,
     pass_name: &str,
     disambiguator: &dyn Display,
     source: MirSource<'tcx>,
 ) -> PathBuf {
     let promotion_id = match source.promoted {
         Some(id) => format!("-{:?}", id),
         None => String::new(),
     };

     let pass_num = if tcx.sess.opts.debugging_opts.dump_mir_exclude_pass_number {
         String::new()
     } else {
         match pass_num {
             None => ".-------".to_string(),
             Some(pass_num) => format!(".{}", pass_num),
         }
     };

     let mut file_path = PathBuf::new();
     file_path.push(Path::new(&tcx.sess.opts.debugging_opts.dump_mir_dir));

     let item_name = tcx
         .def_path(source.def_id())
         .to_filename_friendly_no_crate();
     // All drop shims have the same DefId, so we have to add the type
     // to get unique file names.
     let shim_disambiguator = match source.instance {
         ty::InstanceDef::DropGlue(_, Some(ty)) => {
             // Unfortunately, pretty-printed typed are not very filename-friendly.
             // We dome some filtering.
             let mut s = ".".to_owned();
             s.extend(ty.to_string()
                 .chars()
                 .filter_map(|c| match c {
                     ' ' => None,
                     ':' | '<' | '>' => Some('_'),
                     c => Some(c)
                 }));
             s
         }
         _ => String::new(),
     };

     let file_name = format!(
         "rustc.{}{}{}{}.{}.{}.{}",
         item_name,
         shim_disambiguator,
         promotion_id,
         pass_num,
         pass_name,
         disambiguator,
         extension,
     );

     file_path.push(&file_name);

     file_path
 }

 /// Attempts to open a file where we should dump a given MIR or other
 /// bit of MIR-related data. Used by `mir-dump`, but also by other
 /// bits of code (e.g., NLL inference) that dump graphviz data or
 /// other things, and hence takes the extension as an argument.
 pub(crate) fn create_dump_file(
     tcx: TyCtxt<'_, '_, '_>,
     extension: &str,
     pass_num: Option<&dyn Display>,
     pass_name: &str,
     disambiguator: &dyn Display,
     source: MirSource<'tcx>,
 ) -> io::Result<fs::File> {
     let file_path = dump_path(tcx, extension, pass_num, pass_name, disambiguator, source);
     if let Some(parent) = file_path.parent() {
         fs::create_dir_all(parent)?;
     }
     fs::File::create(&file_path)
 }

 /// Write out a human-readable textual representation for the given MIR.
 pub fn write_mir_pretty<'a, 'gcx, 'tcx>(
     tcx: TyCtxt<'a, 'gcx, 'tcx>,
     single: Option<DefId>,
     w: &mut dyn Write,
 ) -> io::Result<()> {
     writeln!(
         w,
         "// WARNING: This output format is intended for human consumers only"
     )?;
     writeln!(
         w,
         "// and is subject to change without notice. Knock yourself out."
     )?;

     let mut first = true;
     for def_id in dump_mir_def_ids(tcx, single) {
         let mir = &tcx.optimized_mir(def_id);

         if first {
             first = false;
         } else {
             // Put empty lines between all items
             writeln!(w, "")?;
         }

         write_mir_fn(tcx, MirSource::item(def_id), mir, &mut |_, _| Ok(()), w)?;

         for (i, mir) in mir.promoted.iter_enumerated() {
             writeln!(w, "")?;
             let src = MirSource {
                 instance: ty::InstanceDef::Item(def_id),
                 promoted: Some(i),
             };
             write_mir_fn(tcx, src, mir, &mut |_, _| Ok(()), w)?;
         }
     }
     Ok(())
 }

 pub fn write_mir_fn<'a, 'gcx, 'tcx, F>(
     tcx: TyCtxt<'a, 'gcx, 'tcx>,
     src: MirSource<'tcx>,
     mir: &Mir<'tcx>,
     extra_data: &mut F,
     w: &mut dyn Write,
 ) -> io::Result<()>
 where
     F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
 {
     write_mir_intro(tcx, src, mir, w)?;
     for block in mir.basic_blocks().indices() {
         extra_data(PassWhere::BeforeBlock(block), w)?;
         write_basic_block(tcx, block, mir, extra_data, w)?;
         if block.index() + 1 != mir.basic_blocks().len() {
             writeln!(w, "")?;
         }
     }

     writeln!(w, "}}")?;
     Ok(())
 }

 /// Write out a human-readable textual representation for the given basic block.
 pub fn write_basic_block<'cx, 'gcx, 'tcx, F>(
     tcx: TyCtxt<'cx, 'gcx, 'tcx>,
     block: BasicBlock,
     mir: &Mir<'tcx>,
     extra_data: &mut F,
     w: &mut dyn Write,
 ) -> io::Result<()>
 where
     F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
 {
     let data = &mir[block];

     // Basic block label at the top.
     let cleanup_text = if data.is_cleanup { " // cleanup" } else { "" };
     let lbl = format!("{}{:?}: {{", INDENT, block);
     writeln!(w, "{0:1$}{2}", lbl, ALIGN, cleanup_text)?;

     // List of statements in the middle.
     let mut current_location = Location {
         block: block,
         statement_index: 0,
     };
     for statement in &data.statements {
         extra_data(PassWhere::BeforeLocation(current_location), w)?;
         let indented_mir = format!("{0}{0}{1:?};", INDENT, statement);
         writeln!(
             w,
             "{:A$} // {:?}: {}",
             indented_mir,
             current_location,
             comment(tcx, statement.source_info),
             A = ALIGN,
         )?;

         write_extra(tcx, w, |visitor| {
             visitor.visit_statement(current_location.block, statement, current_location);
         })?;

         extra_data(PassWhere::AfterLocation(current_location), w)?;

         current_location.statement_index += 1;
     }

     // Terminator at the bottom.
     extra_data(PassWhere::BeforeLocation(current_location), w)?;
     let indented_terminator = format!("{0}{0}{1:?};", INDENT, data.terminator().kind);
     writeln!(
         w,
         "{:A$} // {:?}: {}",
         indented_terminator,
         current_location,
         comment(tcx, data.terminator().source_info),
         A = ALIGN,
     )?;

     write_extra(tcx, w, |visitor| {
         visitor.visit_terminator(current_location.block, data.terminator(), current_location);
     })?;

     extra_data(PassWhere::AfterLocation(current_location), w)?;
     extra_data(PassWhere::AfterTerminator(block), w)?;

     writeln!(w, "{}}}", INDENT)
 }

 /// After we print the main statement, we sometimes dump extra
 /// information. There's often a lot of little things "nuzzled up" in
 /// a statement.
 fn write_extra<'cx, 'gcx, 'tcx, F>(
     tcx: TyCtxt<'cx, 'gcx, 'tcx>,
     write: &mut dyn Write,
     mut visit_op: F,
 ) -> io::Result<()>
 where
     F: FnMut(&mut ExtraComments<'cx, 'gcx, 'tcx>),
 {
     let mut extra_comments = ExtraComments {
         _tcx: tcx,
         comments: vec![],
     };
     visit_op(&mut extra_comments);
     for comment in extra_comments.comments {
         writeln!(write, "{:A$} // {}", "", comment, A = ALIGN)?;
     }
     Ok(())
 }

 struct ExtraComments<'cx, 'gcx: 'tcx, 'tcx: 'cx> {
     _tcx: TyCtxt<'cx, 'gcx, 'tcx>, // don't need it now, but bet we will soon
     comments: Vec<String>,
 }

 impl<'cx, 'gcx, 'tcx> ExtraComments<'cx, 'gcx, 'tcx> {
     fn push(&mut self, lines: &str) {
         for line in lines.split('\n') {
             self.comments.push(line.to_string());
         }
     }
 }

 impl<'cx, 'gcx, 'tcx> Visitor<'tcx> for ExtraComments<'cx, 'gcx, 'tcx> {
     fn visit_constant(&mut self, constant: &Constant<'tcx>, location: Location) {
         self.super_constant(constant, location);
         let Constant { span, ty, user_ty, literal } = constant;
         self.push("mir::Constant");
         self.push(&format!("+ span: {:?}", span));
         self.push(&format!("+ ty: {:?}", ty));
         if let Some(user_ty) = user_ty {
             self.push(&format!("+ user_ty: {:?}", user_ty));
         }
         self.push(&format!("+ literal: {:?}", literal));
     }

     fn visit_const(&mut self, constant: &&'tcx ty::Const<'tcx>, _: Location) {
         self.super_const(constant);
         let ty::Const { ty, val, .. } = constant;
         self.push("ty::Const");
         self.push(&format!("+ ty: {:?}", ty));
         self.push(&format!("+ val: {:?}", val));
     }

     fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
         self.super_rvalue(rvalue, location);
         match rvalue {
             Rvalue::Aggregate(kind, _) => match **kind {
                 AggregateKind::Closure(def_id, substs) => {
                     self.push("closure");
                     self.push(&format!("+ def_id: {:?}", def_id));
                     self.push(&format!("+ substs: {:#?}", substs));
                 }

                 AggregateKind::Generator(def_id, substs, movability) => {
                     self.push("generator");
                     self.push(&format!("+ def_id: {:?}", def_id));
                     self.push(&format!("+ substs: {:#?}", substs));
                     self.push(&format!("+ movability: {:?}", movability));
                 }

                 AggregateKind::Adt(_, _, _, Some(user_ty), _) => {
                     self.push("adt");
                     self.push(&format!("+ user_ty: {:?}", user_ty));
                 }

                 _ => {}
             },

             _ => {}
         }
     }
 }

 fn comment(tcx: TyCtxt<'_, '_, '_>, SourceInfo { span, scope }: SourceInfo) -> String {
     format!(
         "scope {} at {}",
         scope.index(),
         tcx.sess.source_map().span_to_string(span)
     )
 }

 /// Prints user-defined variables in a scope tree.
 ///
 /// Returns the total number of variables printed.
 fn write_scope_tree(
     tcx: TyCtxt<'_, '_, '_>,
     mir: &Mir<'_>,
     scope_tree: &FxHashMap<SourceScope, Vec<SourceScope>>,
     w: &mut dyn Write,
     parent: SourceScope,
     depth: usize,
 ) -> io::Result<()> {
     let indent = depth * INDENT.len();

     let children = match scope_tree.get(&parent) {
         Some(children) => children,
         None => return Ok(()),
     };

     for &child in children {
         let data = &mir.source_scopes[child];
         assert_eq!(data.parent_scope, Some(parent));
         writeln!(w, "{0:1$}scope {2} {{", "", indent, child.index())?;

         // User variable types (including the user's name in a comment).
         for local in mir.vars_iter() {
             let var = &mir.local_decls[local];
             let (name, source_info) = if var.source_info.scope == child {
                 (var.name.unwrap(), var.source_info)
             } else {
                 // Not a variable or not declared in this scope.
                 continue;
             };

             let mut_str = if var.mutability == Mutability::Mut {
                 "mut "
             } else {
                 ""
             };

             let indent = indent + INDENT.len();
             let mut indented_var = format!(
                 "{0:1$}let {2}{3:?}: {4:?}",
                 INDENT,
                 indent,
                 mut_str,
                 local,
                 var.ty
             );
             for user_ty in var.user_ty.projections() {
                 write!(indented_var, " as {:?}", user_ty).unwrap();
             }
             indented_var.push_str(";");
             writeln!(
                 w,
                 "{0:1$} // \"{2}\" in {3}",
                 indented_var,
                 ALIGN,
                 name,
                 comment(tcx, source_info)
             )?;
         }

         write_scope_tree(tcx, mir, scope_tree, w, child, depth + 1)?;

         writeln!(w, "{0:1$}}}", "", depth * INDENT.len())?;
     }

     Ok(())
 }

 /// Write out a human-readable textual representation of the MIR's `fn` type and the types of its
 /// local variables (both user-defined bindings and compiler temporaries).
 pub fn write_mir_intro<'a, 'gcx, 'tcx>(
     tcx: TyCtxt<'a, 'gcx, 'tcx>,
     src: MirSource<'tcx>,
     mir: &Mir<'_>,
     w: &mut dyn Write,
 ) -> io::Result<()> {
     write_mir_sig(tcx, src, mir, w)?;
     writeln!(w, "{{")?;

     // construct a scope tree and write it out
     let mut scope_tree: FxHashMap<SourceScope, Vec<SourceScope>> = Default::default();
     for (index, scope_data) in mir.source_scopes.iter().enumerate() {
         if let Some(parent) = scope_data.parent_scope {
             scope_tree
                 .entry(parent)
                 .or_default()
                 .push(SourceScope::new(index));
         } else {
             // Only the argument scope has no parent, because it's the root.
             assert_eq!(index, OUTERMOST_SOURCE_SCOPE.index());
         }
     }

     // Print return place
     let indented_retptr = format!("{}let mut {:?}: {};",
                                   INDENT,
                                   RETURN_PLACE,
                                   mir.local_decls[RETURN_PLACE].ty);
     writeln!(w, "{0:1$} // return place",
              indented_retptr,
              ALIGN)?;

     write_scope_tree(tcx, mir, &scope_tree, w, OUTERMOST_SOURCE_SCOPE, 1)?;

     write_temp_decls(mir, w)?;

     // Add an empty line before the first block is printed.
     writeln!(w, "")?;

     Ok(())
 }

 fn write_mir_sig(
     tcx: TyCtxt<'_, '_, '_>,
     src: MirSource<'tcx>,
     mir: &Mir<'_>,
     w: &mut dyn Write,
 ) -> io::Result<()> {
     use rustc::hir::def::Def;

     trace!("write_mir_sig: {:?}", src.instance);
     let descr = tcx.describe_def(src.def_id());
     let is_function = match descr {
         Some(Def::Fn(_)) | Some(Def::Method(_)) | Some(Def::Variant(..)) |
         Some(Def::StructCtor(_, CtorKind::Fn)) => true,
         _ => tcx.is_closure(src.def_id()),
     };
     match (descr, src.promoted) {
         (_, Some(i)) => write!(w, "{:?} in ", i)?,
         (Some(Def::StructCtor(..)), _) => write!(w, "struct ")?,
         (Some(Def::Const(_)), _)
         | (Some(Def::AssociatedConst(_)), _) => write!(w, "const ")?,
         (Some(Def::Static(_, /*is_mutbl*/false)), _) => write!(w, "static ")?,
         (Some(Def::Static(_, /*is_mutbl*/true)), _) => write!(w, "static mut ")?,
         (_, _) if is_function => write!(w, "fn ")?,
         (None, _) => {}, // things like anon const, not an item
         _ => bug!("Unexpected def description {:?}", descr),
     }

     ty::print::with_forced_impl_filename_line(|| {
         // see notes on #41697 elsewhere
         write!(w, " {}", tcx.def_path_str(src.def_id()))
     })?;

     if src.promoted.is_none() && is_function {
         write!(w, "(")?;

         // fn argument types.
         for (i, arg) in mir.args_iter().enumerate() {
             if i != 0 {
                 write!(w, ", ")?;
             }
             write!(w, "{:?}: {}", Place::Base(PlaceBase::Local(arg)), mir.local_decls[arg].ty)?;
         }

         write!(w, ") -> {}", mir.return_ty())?;
     } else {
         assert_eq!(mir.arg_count, 0);
         write!(w, ": {} =", mir.return_ty())?;
     }

     if let Some(yield_ty) = mir.yield_ty {
         writeln!(w)?;
         writeln!(w, "yields {}", yield_ty)?;
     }

     write!(w, " ")?;
     // Next thing that gets printed is the opening {

     Ok(())
 }

 fn write_temp_decls(mir: &Mir<'_>, w: &mut dyn Write) -> io::Result<()> {
     // Compiler-introduced temporary types.
     for temp in mir.temps_iter() {
         writeln!(
             w,
             "{}let {}{:?}: {};",
             INDENT,
             if mir.local_decls[temp].mutability == Mutability::Mut {"mut "} else {""},
             temp,
             mir.local_decls[temp].ty
         )?;
     }

     Ok(())
 }

 fn write_user_type_annotations(mir: &Mir<'_>, w: &mut dyn Write) -> io::Result<()> {
     if !mir.user_type_annotations.is_empty() {
         writeln!(w, "| User Type Annotations")?;
     }
     for (index, annotation) in mir.user_type_annotations.iter_enumerated() {
         writeln!(w, "| {:?}: {:?} at {:?}", index.index(), annotation.user_ty, annotation.span)?;
     }
     if !mir.user_type_annotations.is_empty() {
         writeln!(w, "|")?;
     }
     Ok(())
 }

 pub fn dump_mir_def_ids(tcx: TyCtxt<'_, '_, '_>, single: Option<DefId>) -> Vec<DefId> {
     if let Some(i) = single {
         vec![i]
     } else {
         tcx.mir_keys(LOCAL_CRATE).iter().cloned().collect()
     }
 }
	use rustc::hir::def_id::{DefId, LOCAL_CRATE};
	use rustc::hir::def::CtorKind;
	use rustc::mir::*;
	use rustc::mir::visit::Visitor;
	use rustc::ty::{self, TyCtxt};
	use rustc_data_structures::fx::FxHashMap;
	use rustc_data_structures::indexed_vec::Idx;
	use std::fmt::Display;
	use std::fmt::Write as _;
	use std::fs;
	use std::io::{self, Write};
	use std::path::{Path, PathBuf};
	use super::graphviz::write_mir_fn_graphviz;
	use crate::transform::MirSource;

	const INDENT: &str = " ";
	/// Alignment for lining up comments following MIR statements
	pub(crate) const ALIGN: usize = 40;

	/// An indication of where we are in the control flow graph. Used for printing
	/// extra information in `dump_mir`
	pub enum PassWhere {
	/// We have not started dumping the control flow graph, but we are about to.
	BeforeCFG,

	/// We just finished dumping the control flow graph. This is right before EOF
	AfterCFG,

	/// We are about to start dumping the given basic block.
	BeforeBlock(BasicBlock),

	/// We are just about to dump the given statement or terminator.
	BeforeLocation(Location),

	/// We just dumped the given statement or terminator.
	AfterLocation(Location),

	/// We just dumped the terminator for a block but not the closing `}`.
	AfterTerminator(BasicBlock),
	}

	/// If the session is properly configured, dumps a human-readable
	/// representation of the mir into:
	///
	/// ```text
	/// rustc.node<node_id>.<pass_num>.<pass_name>.<disambiguator>
	/// ```
	///
	/// Output from this function is controlled by passing `-Z dump-mir=<filter>`,
	/// where `<filter>` takes the following forms:
	///
	/// - `all` -- dump MIR for all fns, all passes, all everything
	/// - a filter defined by a set of substrings combined with `&` and `\|`
	/// (`&` has higher precedence). At least one of the `\|`-separated groups
	/// must match; an `\|`-separated group matches if all of its `&`-separated
	/// substrings are matched.
	///
	/// Example:
	///
	/// - `nll` == match if `nll` appears in the name
	/// - `foo & nll` == match if `foo` and `nll` both appear in the name
	/// - `foo & nll \| typeck` == match if `foo` and `nll` both appear in the name
	/// or `typeck` appears in the name.
	/// - `foo & nll \| bar & typeck` == match if `foo` and `nll` both appear in the name
	/// or `typeck` and `bar` both appear in the name.
	pub fn dump_mir<'a, 'gcx, 'tcx, F>(
	tcx: TyCtxt<'a, 'gcx, 'tcx>,
	pass_num: Option<&dyn Display>,
	pass_name: &str,
	disambiguator: &dyn Display,
	source: MirSource<'tcx>,
	mir: &Mir<'tcx>,
	extra_data: F,
	) where
	F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
	{
	if !dump_enabled(tcx, pass_name, source) {
	return;
	}

	let node_path = ty::print::with_forced_impl_filename_line(\|\| {
	// see notes on #41697 below
	tcx.def_path_str(source.def_id())
	});
	dump_matched_mir_node(
	tcx,
	pass_num,
	pass_name,
	&node_path,
	disambiguator,
	source,
	mir,
	extra_data,
	);
	}

	pub fn dump_enabled<'a, 'gcx, 'tcx>(
	tcx: TyCtxt<'a, 'gcx, 'tcx>,
	pass_name: &str,
	source: MirSource<'tcx>,
	) -> bool {
	let filters = match tcx.sess.opts.debugging_opts.dump_mir {
	None => return false,
	Some(ref filters) => filters,
	};
	let node_path = ty::print::with_forced_impl_filename_line(\|\| {
	// see notes on #41697 below
	tcx.def_path_str(source.def_id())
	});
	filters.split('\|').any(\|or_filter\| {
	or_filter.split('&').all(\|and_filter\| {
	and_filter == "all" \|\| pass_name.contains(and_filter) \|\| node_path.contains(and_filter)
	})
	})
	}

	// #41697 -- we use `with_forced_impl_filename_line()` because
	// `def_path_str()` would otherwise trigger `type_of`, and this can
	// run while we are already attempting to evaluate `type_of`.

	fn dump_matched_mir_node<'a, 'gcx, 'tcx, F>(
	tcx: TyCtxt<'a, 'gcx, 'tcx>,
	pass_num: Option<&dyn Display>,
	pass_name: &str,
	node_path: &str,
	disambiguator: &dyn Display,
	source: MirSource<'tcx>,
	mir: &Mir<'tcx>,
	mut extra_data: F,
	) where
	F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
	{
	let _: io::Result<()> = try {
	let mut file = create_dump_file(tcx, "mir", pass_num, pass_name, disambiguator, source)?;
	writeln!(file, "// MIR for `{}`", node_path)?;
	writeln!(file, "// source = {:?}", source)?;
	writeln!(file, "// pass_name = {}", pass_name)?;
	writeln!(file, "// disambiguator = {}", disambiguator)?;
	if let Some(ref layout) = mir.generator_layout {
	writeln!(file, "// generator_layout = {:?}", layout)?;
	}
	writeln!(file, "")?;
	extra_data(PassWhere::BeforeCFG, &mut file)?;
	write_user_type_annotations(mir, &mut file)?;
	write_mir_fn(tcx, source, mir, &mut extra_data, &mut file)?;
	extra_data(PassWhere::AfterCFG, &mut file)?;
	};

	if tcx.sess.opts.debugging_opts.dump_mir_graphviz {
	let _: io::Result<()> = try {
	let mut file =
	create_dump_file(tcx, "dot", pass_num, pass_name, disambiguator, source)?;
	write_mir_fn_graphviz(tcx, source.def_id(), mir, &mut file)?;
	};
	}
	}

	/// Returns the path to the filename where we should dump a given MIR.
	/// Also used by other bits of code (e.g., NLL inference) that dump
	/// graphviz data or other things.
	fn dump_path(
	tcx: TyCtxt<'_, '_, '_>,
	extension: &str,
	pass_num: Option<&dyn Display>,
	pass_name: &str,
	disambiguator: &dyn Display,
	source: MirSource<'tcx>,
	) -> PathBuf {
	let promotion_id = match source.promoted {
	Some(id) => format!("-{:?}", id),
	None => String::new(),
	};

	let pass_num = if tcx.sess.opts.debugging_opts.dump_mir_exclude_pass_number {
	String::new()
	} else {
	match pass_num {
	None => ".-------".to_string(),
	Some(pass_num) => format!(".{}", pass_num),
	}
	};

	let mut file_path = PathBuf::new();
	file_path.push(Path::new(&tcx.sess.opts.debugging_opts.dump_mir_dir));

	let item_name = tcx
	.def_path(source.def_id())
	.to_filename_friendly_no_crate();
	// All drop shims have the same DefId, so we have to add the type
	// to get unique file names.
	let shim_disambiguator = match source.instance {
	ty::InstanceDef::DropGlue(_, Some(ty)) => {
	// Unfortunately, pretty-printed typed are not very filename-friendly.
	// We dome some filtering.
	let mut s = ".".to_owned();
	s.extend(ty.to_string()
	.chars()
	.filter_map(\|c\| match c {
	' ' => None,
	':' \| '<' \| '>' => Some('_'),
	c => Some(c)
	}));
	s
	}
	_ => String::new(),
	};

	let file_name = format!(
	"rustc.{}{}{}{}.{}.{}.{}",
	item_name,
	shim_disambiguator,
	promotion_id,
	pass_num,
	pass_name,
	disambiguator,
	extension,
	);

	file_path.push(&file_name);

	file_path
	}

	/// Attempts to open a file where we should dump a given MIR or other
	/// bit of MIR-related data. Used by `mir-dump`, but also by other
	/// bits of code (e.g., NLL inference) that dump graphviz data or
	/// other things, and hence takes the extension as an argument.
	pub(crate) fn create_dump_file(
	tcx: TyCtxt<'_, '_, '_>,
	extension: &str,
	pass_num: Option<&dyn Display>,
	pass_name: &str,
	disambiguator: &dyn Display,
	source: MirSource<'tcx>,
	) -> io::Result<fs::File> {
	let file_path = dump_path(tcx, extension, pass_num, pass_name, disambiguator, source);
	if let Some(parent) = file_path.parent() {
	fs::create_dir_all(parent)?;
	}
	fs::File::create(&file_path)
	}

	/// Write out a human-readable textual representation for the given MIR.
	pub fn write_mir_pretty<'a, 'gcx, 'tcx>(
	tcx: TyCtxt<'a, 'gcx, 'tcx>,
	single: Option<DefId>,
	w: &mut dyn Write,
	) -> io::Result<()> {
	writeln!(
	w,
	"// WARNING: This output format is intended for human consumers only"
	)?;
	writeln!(
	w,
	"// and is subject to change without notice. Knock yourself out."
	)?;

	let mut first = true;
	for def_id in dump_mir_def_ids(tcx, single) {
	let mir = &tcx.optimized_mir(def_id);

	if first {
	first = false;
	} else {
	// Put empty lines between all items
	writeln!(w, "")?;
	}

	write_mir_fn(tcx, MirSource::item(def_id), mir, &mut \|_, _\| Ok(()), w)?;

	for (i, mir) in mir.promoted.iter_enumerated() {
	writeln!(w, "")?;
	let src = MirSource {
	instance: ty::InstanceDef::Item(def_id),
	promoted: Some(i),
	};
	write_mir_fn(tcx, src, mir, &mut \|_, _\| Ok(()), w)?;
	}
	}
	Ok(())
	}

	pub fn write_mir_fn<'a, 'gcx, 'tcx, F>(
	tcx: TyCtxt<'a, 'gcx, 'tcx>,
	src: MirSource<'tcx>,
	mir: &Mir<'tcx>,
	extra_data: &mut F,
	w: &mut dyn Write,
	) -> io::Result<()>
	where
	F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
	{
	write_mir_intro(tcx, src, mir, w)?;
	for block in mir.basic_blocks().indices() {
	extra_data(PassWhere::BeforeBlock(block), w)?;
	write_basic_block(tcx, block, mir, extra_data, w)?;
	if block.index() + 1 != mir.basic_blocks().len() {
	writeln!(w, "")?;
	}
	}

	writeln!(w, "}}")?;
	Ok(())
	}

	/// Write out a human-readable textual representation for the given basic block.
	pub fn write_basic_block<'cx, 'gcx, 'tcx, F>(
	tcx: TyCtxt<'cx, 'gcx, 'tcx>,
	block: BasicBlock,
	mir: &Mir<'tcx>,
	extra_data: &mut F,
	w: &mut dyn Write,
	) -> io::Result<()>
	where
	F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
	{
	let data = &mir[block];

	// Basic block label at the top.
	let cleanup_text = if data.is_cleanup { " // cleanup" } else { "" };
	let lbl = format!("{}{:?}: {{", INDENT, block);
	writeln!(w, "{0:1$}{2}", lbl, ALIGN, cleanup_text)?;

	// List of statements in the middle.
	let mut current_location = Location {
	block: block,
	statement_index: 0,
	};
	for statement in &data.statements {
	extra_data(PassWhere::BeforeLocation(current_location), w)?;
	let indented_mir = format!("{0}{0}{1:?};", INDENT, statement);
	writeln!(
	w,
	"{:A$} // {:?}: {}",
	indented_mir,
	current_location,
	comment(tcx, statement.source_info),
	A = ALIGN,
	)?;

	write_extra(tcx, w, \|visitor\| {
	visitor.visit_statement(current_location.block, statement, current_location);
	})?;

	extra_data(PassWhere::AfterLocation(current_location), w)?;

	current_location.statement_index += 1;
	}

	// Terminator at the bottom.
	extra_data(PassWhere::BeforeLocation(current_location), w)?;
	let indented_terminator = format!("{0}{0}{1:?};", INDENT, data.terminator().kind);
	writeln!(
	w,
	"{:A$} // {:?}: {}",
	indented_terminator,
	current_location,
	comment(tcx, data.terminator().source_info),
	A = ALIGN,
	)?;

	write_extra(tcx, w, \|visitor\| {
	visitor.visit_terminator(current_location.block, data.terminator(), current_location);
	})?;

	extra_data(PassWhere::AfterLocation(current_location), w)?;
	extra_data(PassWhere::AfterTerminator(block), w)?;

	writeln!(w, "{}}}", INDENT)
	}

	/// After we print the main statement, we sometimes dump extra
	/// information. There's often a lot of little things "nuzzled up" in
	/// a statement.
	fn write_extra<'cx, 'gcx, 'tcx, F>(
	tcx: TyCtxt<'cx, 'gcx, 'tcx>,
	write: &mut dyn Write,
	mut visit_op: F,
	) -> io::Result<()>
	where
	F: FnMut(&mut ExtraComments<'cx, 'gcx, 'tcx>),
	{
	let mut extra_comments = ExtraComments {
	_tcx: tcx,
	comments: vec![],
	};
	visit_op(&mut extra_comments);
	for comment in extra_comments.comments {
	writeln!(write, "{:A$} // {}", "", comment, A = ALIGN)?;
	}
	Ok(())
	}

	struct ExtraComments<'cx, 'gcx: 'tcx, 'tcx: 'cx> {
	_tcx: TyCtxt<'cx, 'gcx, 'tcx>, // don't need it now, but bet we will soon
	comments: Vec<String>,
	}

	impl<'cx, 'gcx, 'tcx> ExtraComments<'cx, 'gcx, 'tcx> {
	fn push(&mut self, lines: &str) {
	for line in lines.split('\n') {
	self.comments.push(line.to_string());
	}
	}
	}

	impl<'cx, 'gcx, 'tcx> Visitor<'tcx> for ExtraComments<'cx, 'gcx, 'tcx> {
	fn visit_constant(&mut self, constant: &Constant<'tcx>, location: Location) {
	self.super_constant(constant, location);
	let Constant { span, ty, user_ty, literal } = constant;
	self.push("mir::Constant");
	self.push(&format!("+ span: {:?}", span));
	self.push(&format!("+ ty: {:?}", ty));
	if let Some(user_ty) = user_ty {
	self.push(&format!("+ user_ty: {:?}", user_ty));
	}
	self.push(&format!("+ literal: {:?}", literal));
	}

	fn visit_const(&mut self, constant: &&'tcx ty::Const<'tcx>, _: Location) {
	self.super_const(constant);
	let ty::Const { ty, val, .. } = constant;
	self.push("ty::Const");
	self.push(&format!("+ ty: {:?}", ty));
	self.push(&format!("+ val: {:?}", val));
	}

	fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
	self.super_rvalue(rvalue, location);
	match rvalue {
	Rvalue::Aggregate(kind, _) => match **kind {
	AggregateKind::Closure(def_id, substs) => {
	self.push("closure");
	self.push(&format!("+ def_id: {:?}", def_id));
	self.push(&format!("+ substs: {:#?}", substs));
	}

	AggregateKind::Generator(def_id, substs, movability) => {
	self.push("generator");
	self.push(&format!("+ def_id: {:?}", def_id));
	self.push(&format!("+ substs: {:#?}", substs));
	self.push(&format!("+ movability: {:?}", movability));
	}

	AggregateKind::Adt(_, _, _, Some(user_ty), _) => {
	self.push("adt");
	self.push(&format!("+ user_ty: {:?}", user_ty));
	}

	_ => {}
	},

	_ => {}
	}
	}
	}

	fn comment(tcx: TyCtxt<'_, '_, '_>, SourceInfo { span, scope }: SourceInfo) -> String {
	format!(
	"scope {} at {}",
	scope.index(),
	tcx.sess.source_map().span_to_string(span)
	)
	}

	/// Prints user-defined variables in a scope tree.
	///
	/// Returns the total number of variables printed.
	fn write_scope_tree(
	tcx: TyCtxt<'_, '_, '_>,
	mir: &Mir<'_>,
	scope_tree: &FxHashMap<SourceScope, Vec<SourceScope>>,
	w: &mut dyn Write,
	parent: SourceScope,
	depth: usize,
	) -> io::Result<()> {
	let indent = depth * INDENT.len();

	let children = match scope_tree.get(&parent) {
	Some(children) => children,
	None => return Ok(()),
	};

	for &child in children {
	let data = &mir.source_scopes[child];
	assert_eq!(data.parent_scope, Some(parent));
	writeln!(w, "{0:1$}scope {2} {{", "", indent, child.index())?;

	// User variable types (including the user's name in a comment).
	for local in mir.vars_iter() {
	let var = &mir.local_decls[local];
	let (name, source_info) = if var.source_info.scope == child {
	(var.name.unwrap(), var.source_info)
	} else {
	// Not a variable or not declared in this scope.
	continue;
	};

	let mut_str = if var.mutability == Mutability::Mut {
	"mut "
	} else {
	""
	};

	let indent = indent + INDENT.len();
	let mut indented_var = format!(
	"{0:1$}let {2}{3:?}: {4:?}",
	INDENT,
	indent,
	mut_str,
	local,
	var.ty
	);
	for user_ty in var.user_ty.projections() {
	write!(indented_var, " as {:?}", user_ty).unwrap();
	}
	indented_var.push_str(";");
	writeln!(
	w,
	"{0:1$} // \"{2}\" in {3}",
	indented_var,
	ALIGN,
	name,
	comment(tcx, source_info)
	)?;
	}

	write_scope_tree(tcx, mir, scope_tree, w, child, depth + 1)?;

	writeln!(w, "{0:1$}}}", "", depth * INDENT.len())?;
	}

	Ok(())
	}

	/// Write out a human-readable textual representation of the MIR's `fn` type and the types of its
	/// local variables (both user-defined bindings and compiler temporaries).
	pub fn write_mir_intro<'a, 'gcx, 'tcx>(
	tcx: TyCtxt<'a, 'gcx, 'tcx>,
	src: MirSource<'tcx>,
	mir: &Mir<'_>,
	w: &mut dyn Write,
	) -> io::Result<()> {
	write_mir_sig(tcx, src, mir, w)?;
	writeln!(w, "{{")?;

	// construct a scope tree and write it out
	let mut scope_tree: FxHashMap<SourceScope, Vec<SourceScope>> = Default::default();
	for (index, scope_data) in mir.source_scopes.iter().enumerate() {
	if let Some(parent) = scope_data.parent_scope {
	scope_tree
	.entry(parent)
	.or_default()
	.push(SourceScope::new(index));
	} else {
	// Only the argument scope has no parent, because it's the root.
	assert_eq!(index, OUTERMOST_SOURCE_SCOPE.index());
	}
	}

	// Print return place
	let indented_retptr = format!("{}let mut {:?}: {};",
	INDENT,
	RETURN_PLACE,
	mir.local_decls[RETURN_PLACE].ty);
	writeln!(w, "{0:1$} // return place",
	indented_retptr,
	ALIGN)?;

	write_scope_tree(tcx, mir, &scope_tree, w, OUTERMOST_SOURCE_SCOPE, 1)?;

	write_temp_decls(mir, w)?;

	// Add an empty line before the first block is printed.
	writeln!(w, "")?;

	Ok(())
	}

	fn write_mir_sig(
	tcx: TyCtxt<'_, '_, '_>,
	src: MirSource<'tcx>,
	mir: &Mir<'_>,
	w: &mut dyn Write,
	) -> io::Result<()> {
	use rustc::hir::def::Def;

	trace!("write_mir_sig: {:?}", src.instance);
	let descr = tcx.describe_def(src.def_id());
	let is_function = match descr {
	Some(Def::Fn(_)) \| Some(Def::Method(_)) \| Some(Def::Variant(..)) \|
	Some(Def::StructCtor(_, CtorKind::Fn)) => true,
	_ => tcx.is_closure(src.def_id()),
	};
	match (descr, src.promoted) {
	(_, Some(i)) => write!(w, "{:?} in ", i)?,
	(Some(Def::StructCtor(..)), _) => write!(w, "struct ")?,
	(Some(Def::Const(_)), _)
	\| (Some(Def::AssociatedConst(_)), _) => write!(w, "const ")?,
	(Some(Def::Static(_, /is_mutbl/false)), _) => write!(w, "static ")?,
	(Some(Def::Static(_, /is_mutbl/true)), _) => write!(w, "static mut ")?,
	(_, _) if is_function => write!(w, "fn ")?,
	(None, _) => {}, // things like anon const, not an item
	_ => bug!("Unexpected def description {:?}", descr),
	}

	ty::print::with_forced_impl_filename_line(\|\| {
	// see notes on #41697 elsewhere
	write!(w, " {}", tcx.def_path_str(src.def_id()))
	})?;

	if src.promoted.is_none() && is_function {
	write!(w, "(")?;

	// fn argument types.
	for (i, arg) in mir.args_iter().enumerate() {
	if i != 0 {
	write!(w, ", ")?;
	}
	write!(w, "{:?}: {}", Place::Base(PlaceBase::Local(arg)), mir.local_decls[arg].ty)?;
	}

	write!(w, ") -> {}", mir.return_ty())?;
	} else {
	assert_eq!(mir.arg_count, 0);
	write!(w, ": {} =", mir.return_ty())?;
	}

	if let Some(yield_ty) = mir.yield_ty {
	writeln!(w)?;
	writeln!(w, "yields {}", yield_ty)?;
	}

	write!(w, " ")?;
	// Next thing that gets printed is the opening {

	Ok(())
	}

	fn write_temp_decls(mir: &Mir<'_>, w: &mut dyn Write) -> io::Result<()> {
	// Compiler-introduced temporary types.
	for temp in mir.temps_iter() {
	writeln!(
	w,
	"{}let {}{:?}: {};",
	INDENT,
	if mir.local_decls[temp].mutability == Mutability::Mut {"mut "} else {""},
	temp,
	mir.local_decls[temp].ty
	)?;
	}

	Ok(())
	}

	fn write_user_type_annotations(mir: &Mir<'_>, w: &mut dyn Write) -> io::Result<()> {
	if !mir.user_type_annotations.is_empty() {
	writeln!(w, "\| User Type Annotations")?;
	}
	for (index, annotation) in mir.user_type_annotations.iter_enumerated() {
	writeln!(w, "\| {:?}: {:?} at {:?}", index.index(), annotation.user_ty, annotation.span)?;
	}
	if !mir.user_type_annotations.is_empty() {
	writeln!(w, "\|")?;
	}
	Ok(())
	}

	pub fn dump_mir_def_ids(tcx: TyCtxt<'_, '_, '_>, single: Option<DefId>) -> Vec<DefId> {
	if let Some(i) = single {
	vec![i]
	} else {
	tcx.mir_keys(LOCAL_CRATE).iter().cloned().collect()
	}
	}