diff options
Diffstat (limited to 'compiler/rustc_mir_build/src/build/custom')
| -rw-r--r-- | compiler/rustc_mir_build/src/build/custom/mod.rs | 155 | ||||
| -rw-r--r-- | compiler/rustc_mir_build/src/build/custom/parse.rs | 256 | ||||
| -rw-r--r-- | compiler/rustc_mir_build/src/build/custom/parse/instruction.rs | 105 |
3 files changed, 516 insertions, 0 deletions
diff --git a/compiler/rustc_mir_build/src/build/custom/mod.rs b/compiler/rustc_mir_build/src/build/custom/mod.rs new file mode 100644 index 000000000..eb021f477 --- /dev/null +++ b/compiler/rustc_mir_build/src/build/custom/mod.rs @@ -0,0 +1,155 @@ +//! Provides the implementation of the `custom_mir` attribute. +//! +//! Up until MIR building, this attribute has absolutely no effect. The `mir!` macro is a normal +//! decl macro that expands like any other, and the code goes through parsing, name resolution and +//! type checking like all other code. In MIR building we finally detect whether this attribute is +//! present, and if so we branch off into this module, which implements the attribute by +//! implementing a custom lowering from THIR to MIR. +//! +//! The result of this lowering is returned "normally" from the `mir_built` query, with the only +//! notable difference being that the `injected` field in the body is set. Various components of the +//! MIR pipeline, like borrowck and the pass manager will then consult this field (via +//! `body.should_skip()`) to skip the parts of the MIR pipeline that precede the MIR phase the user +//! specified. +//! +//! This file defines the general framework for the custom parsing. The parsing for all the +//! "top-level" constructs can be found in the `parse` submodule, while the parsing for statements, +//! terminators, and everything below can be found in the `parse::instruction` submodule. +//! + +use rustc_ast::Attribute; +use rustc_data_structures::fx::FxHashMap; +use rustc_hir::def_id::DefId; +use rustc_index::vec::IndexVec; +use rustc_middle::{ + mir::*, + thir::*, + ty::{Ty, TyCtxt}, +}; +use rustc_span::Span; + +mod parse; + +pub(super) fn build_custom_mir<'tcx>( + tcx: TyCtxt<'tcx>, + did: DefId, + thir: &Thir<'tcx>, + expr: ExprId, + params: &IndexVec<ParamId, Param<'tcx>>, + return_ty: Ty<'tcx>, + return_ty_span: Span, + span: Span, + attr: &Attribute, +) -> Body<'tcx> { + let mut body = Body { + basic_blocks: BasicBlocks::new(IndexVec::new()), + source: MirSource::item(did), + phase: MirPhase::Built, + source_scopes: IndexVec::new(), + generator: None, + local_decls: LocalDecls::new(), + user_type_annotations: IndexVec::new(), + arg_count: params.len(), + spread_arg: None, + var_debug_info: Vec::new(), + span, + required_consts: Vec::new(), + is_polymorphic: false, + tainted_by_errors: None, + injection_phase: None, + pass_count: 0, + }; + + body.local_decls.push(LocalDecl::new(return_ty, return_ty_span)); + body.basic_blocks_mut().push(BasicBlockData::new(None)); + body.source_scopes.push(SourceScopeData { + span, + parent_scope: None, + inlined: None, + inlined_parent_scope: None, + local_data: ClearCrossCrate::Clear, + }); + body.injection_phase = Some(parse_attribute(attr)); + + let mut pctxt = ParseCtxt { + tcx, + thir, + source_scope: OUTERMOST_SOURCE_SCOPE, + body: &mut body, + local_map: FxHashMap::default(), + block_map: FxHashMap::default(), + }; + + let res = (|| { + pctxt.parse_args(¶ms)?; + pctxt.parse_body(expr) + })(); + if let Err(err) = res { + tcx.sess.diagnostic().span_fatal( + err.span, + format!("Could not parse {}, found: {:?}", err.expected, err.item_description), + ) + } + + body +} + +fn parse_attribute(attr: &Attribute) -> MirPhase { + let meta_items = attr.meta_item_list().unwrap(); + let mut dialect: Option<String> = None; + let mut phase: Option<String> = None; + + for nested in meta_items { + let name = nested.name_or_empty(); + let value = nested.value_str().unwrap().as_str().to_string(); + match name.as_str() { + "dialect" => { + assert!(dialect.is_none()); + dialect = Some(value); + } + "phase" => { + assert!(phase.is_none()); + phase = Some(value); + } + other => { + panic!("Unexpected key {}", other); + } + } + } + + let Some(dialect) = dialect else { + assert!(phase.is_none()); + return MirPhase::Built; + }; + + MirPhase::parse(dialect, phase) +} + +struct ParseCtxt<'tcx, 'body> { + tcx: TyCtxt<'tcx>, + thir: &'body Thir<'tcx>, + source_scope: SourceScope, + + body: &'body mut Body<'tcx>, + local_map: FxHashMap<LocalVarId, Local>, + block_map: FxHashMap<LocalVarId, BasicBlock>, +} + +struct ParseError { + span: Span, + item_description: String, + expected: String, +} + +impl<'tcx, 'body> ParseCtxt<'tcx, 'body> { + fn expr_error(&self, expr: ExprId, expected: &'static str) -> ParseError { + let expr = &self.thir[expr]; + ParseError { + span: expr.span, + item_description: format!("{:?}", expr.kind), + expected: expected.to_string(), + } + } +} + +type PResult<T> = Result<T, ParseError>; diff --git a/compiler/rustc_mir_build/src/build/custom/parse.rs b/compiler/rustc_mir_build/src/build/custom/parse.rs new file mode 100644 index 000000000..d72770e70 --- /dev/null +++ b/compiler/rustc_mir_build/src/build/custom/parse.rs @@ -0,0 +1,256 @@ +use rustc_index::vec::IndexVec; +use rustc_middle::{mir::*, thir::*, ty::Ty}; +use rustc_span::Span; + +use super::{PResult, ParseCtxt, ParseError}; + +mod instruction; + +/// Helper macro for parsing custom MIR. +/// +/// Example usage looks something like: +/// ```rust,ignore (incomplete example) +/// parse_by_kind!( +/// self, // : &ParseCtxt +/// expr_id, // what you're matching against +/// "assignment", // the thing you're trying to parse +/// @call("mir_assign", args) => { args[0] }, // match invocations of the `mir_assign` special function +/// ExprKind::Assign { lhs, .. } => { lhs }, // match thir assignment expressions +/// // no need for fallthrough case - reasonable error is automatically generated +/// ) +/// ``` +macro_rules! parse_by_kind { + ( + $self:ident, + $expr_id:expr, + $expr_name:pat, + $expected:literal, + $( + @call($name:literal, $args:ident) => $call_expr:expr, + )* + $( + $pat:pat => $expr:expr, + )* + ) => {{ + let expr_id = $self.preparse($expr_id); + let expr = &$self.thir[expr_id]; + debug!("Trying to parse {:?} as {}", expr.kind, $expected); + let $expr_name = expr; + match &expr.kind { + $( + ExprKind::Call { ty, fun: _, args: $args, .. } if { + match ty.kind() { + ty::FnDef(did, _) => { + $self.tcx.is_diagnostic_item(rustc_span::Symbol::intern($name), *did) + } + _ => false, + } + } => $call_expr, + )* + $( + $pat => $expr, + )* + #[allow(unreachable_patterns)] + _ => return Err($self.expr_error(expr_id, $expected)) + } + }}; +} +pub(crate) use parse_by_kind; + +impl<'tcx, 'body> ParseCtxt<'tcx, 'body> { + /// Expressions should only ever be matched on after preparsing them. This removes extra scopes + /// we don't care about. + fn preparse(&self, expr_id: ExprId) -> ExprId { + let expr = &self.thir[expr_id]; + match expr.kind { + ExprKind::Scope { value, .. } => self.preparse(value), + _ => expr_id, + } + } + + fn statement_as_expr(&self, stmt_id: StmtId) -> PResult<ExprId> { + match &self.thir[stmt_id].kind { + StmtKind::Expr { expr, .. } => Ok(*expr), + kind @ StmtKind::Let { pattern, .. } => { + return Err(ParseError { + span: pattern.span, + item_description: format!("{:?}", kind), + expected: "expression".to_string(), + }); + } + } + } + + pub fn parse_args(&mut self, params: &IndexVec<ParamId, Param<'tcx>>) -> PResult<()> { + for param in params.iter() { + let (var, span) = { + let pat = param.pat.as_ref().unwrap(); + match &pat.kind { + PatKind::Binding { var, .. } => (*var, pat.span), + _ => { + return Err(ParseError { + span: pat.span, + item_description: format!("{:?}", pat.kind), + expected: "local".to_string(), + }); + } + } + }; + let decl = LocalDecl::new(param.ty, span); + let local = self.body.local_decls.push(decl); + self.local_map.insert(var, local); + } + + Ok(()) + } + + /// Bodies are of the form: + /// + /// ```text + /// { + /// let bb1: BasicBlock; + /// let bb2: BasicBlock; + /// { + /// let RET: _; + /// let local1; + /// let local2; + /// + /// { + /// { // entry block + /// statement1; + /// terminator1 + /// }; + /// + /// bb1 = { + /// statement2; + /// terminator2 + /// }; + /// + /// bb2 = { + /// statement3; + /// terminator3 + /// } + /// + /// RET + /// } + /// } + /// } + /// ``` + /// + /// This allows us to easily parse the basic blocks declarations, local declarations, and + /// basic block definitions in order. + pub fn parse_body(&mut self, expr_id: ExprId) -> PResult<()> { + let body = parse_by_kind!(self, expr_id, _, "whole body", + ExprKind::Block { block } => self.thir[*block].expr.unwrap(), + ); + let (block_decls, rest) = parse_by_kind!(self, body, _, "body with block decls", + ExprKind::Block { block } => { + let block = &self.thir[*block]; + (&block.stmts, block.expr.unwrap()) + }, + ); + self.parse_block_decls(block_decls.iter().copied())?; + + let (local_decls, rest) = parse_by_kind!(self, rest, _, "body with local decls", + ExprKind::Block { block } => { + let block = &self.thir[*block]; + (&block.stmts, block.expr.unwrap()) + }, + ); + self.parse_local_decls(local_decls.iter().copied())?; + + let block_defs = parse_by_kind!(self, rest, _, "body with block defs", + ExprKind::Block { block } => &self.thir[*block].stmts, + ); + for (i, block_def) in block_defs.iter().enumerate() { + let block = self.parse_block_def(self.statement_as_expr(*block_def)?)?; + self.body.basic_blocks_mut()[BasicBlock::from_usize(i)] = block; + } + + Ok(()) + } + + fn parse_block_decls(&mut self, stmts: impl Iterator<Item = StmtId>) -> PResult<()> { + for stmt in stmts { + let (var, _, _) = self.parse_let_statement(stmt)?; + let data = BasicBlockData::new(None); + let block = self.body.basic_blocks_mut().push(data); + self.block_map.insert(var, block); + } + + Ok(()) + } + + fn parse_local_decls(&mut self, mut stmts: impl Iterator<Item = StmtId>) -> PResult<()> { + let (ret_var, ..) = self.parse_let_statement(stmts.next().unwrap())?; + self.local_map.insert(ret_var, Local::from_u32(0)); + + for stmt in stmts { + let (var, ty, span) = self.parse_let_statement(stmt)?; + let decl = LocalDecl::new(ty, span); + let local = self.body.local_decls.push(decl); + self.local_map.insert(var, local); + } + + Ok(()) + } + + fn parse_let_statement(&mut self, stmt_id: StmtId) -> PResult<(LocalVarId, Ty<'tcx>, Span)> { + let pattern = match &self.thir[stmt_id].kind { + StmtKind::Let { pattern, .. } => pattern, + StmtKind::Expr { expr, .. } => { + return Err(self.expr_error(*expr, "let statement")); + } + }; + + self.parse_var(pattern) + } + + fn parse_var(&mut self, mut pat: &Pat<'tcx>) -> PResult<(LocalVarId, Ty<'tcx>, Span)> { + // Make sure we throw out any `AscribeUserType` we find + loop { + match &pat.kind { + PatKind::Binding { var, ty, .. } => break Ok((*var, *ty, pat.span)), + PatKind::AscribeUserType { subpattern, .. } => { + pat = subpattern; + } + _ => { + break Err(ParseError { + span: pat.span, + item_description: format!("{:?}", pat.kind), + expected: "local".to_string(), + }); + } + } + } + } + + fn parse_block_def(&self, expr_id: ExprId) -> PResult<BasicBlockData<'tcx>> { + let block = parse_by_kind!(self, expr_id, _, "basic block", + ExprKind::Block { block } => &self.thir[*block], + ); + + let mut data = BasicBlockData::new(None); + for stmt_id in &*block.stmts { + let stmt = self.statement_as_expr(*stmt_id)?; + let span = self.thir[stmt].span; + let statement = self.parse_statement(stmt)?; + data.statements.push(Statement { + source_info: SourceInfo { span, scope: self.source_scope }, + kind: statement, + }); + } + + let Some(trailing) = block.expr else { + return Err(self.expr_error(expr_id, "terminator")) + }; + let span = self.thir[trailing].span; + let terminator = self.parse_terminator(trailing)?; + data.terminator = Some(Terminator { + source_info: SourceInfo { span, scope: self.source_scope }, + kind: terminator, + }); + + Ok(data) + } +} diff --git a/compiler/rustc_mir_build/src/build/custom/parse/instruction.rs b/compiler/rustc_mir_build/src/build/custom/parse/instruction.rs new file mode 100644 index 000000000..03206af33 --- /dev/null +++ b/compiler/rustc_mir_build/src/build/custom/parse/instruction.rs @@ -0,0 +1,105 @@ +use rustc_middle::mir::interpret::{ConstValue, Scalar}; +use rustc_middle::{mir::*, thir::*, ty}; + +use super::{parse_by_kind, PResult, ParseCtxt}; + +impl<'tcx, 'body> ParseCtxt<'tcx, 'body> { + pub fn parse_statement(&self, expr_id: ExprId) -> PResult<StatementKind<'tcx>> { + parse_by_kind!(self, expr_id, _, "statement", + @call("mir_retag", args) => { + Ok(StatementKind::Retag(RetagKind::Default, Box::new(self.parse_place(args[0])?))) + }, + @call("mir_retag_raw", args) => { + Ok(StatementKind::Retag(RetagKind::Raw, Box::new(self.parse_place(args[0])?))) + }, + ExprKind::Assign { lhs, rhs } => { + let lhs = self.parse_place(*lhs)?; + let rhs = self.parse_rvalue(*rhs)?; + Ok(StatementKind::Assign(Box::new((lhs, rhs)))) + }, + ) + } + + pub fn parse_terminator(&self, expr_id: ExprId) -> PResult<TerminatorKind<'tcx>> { + parse_by_kind!(self, expr_id, _, "terminator", + @call("mir_return", _args) => { + Ok(TerminatorKind::Return) + }, + @call("mir_goto", args) => { + Ok(TerminatorKind::Goto { target: self.parse_block(args[0])? } ) + }, + ) + } + + fn parse_rvalue(&self, expr_id: ExprId) -> PResult<Rvalue<'tcx>> { + parse_by_kind!(self, expr_id, _, "rvalue", + ExprKind::Borrow { borrow_kind, arg } => Ok( + Rvalue::Ref(self.tcx.lifetimes.re_erased, *borrow_kind, self.parse_place(*arg)?) + ), + ExprKind::AddressOf { mutability, arg } => Ok( + Rvalue::AddressOf(*mutability, self.parse_place(*arg)?) + ), + _ => self.parse_operand(expr_id).map(Rvalue::Use), + ) + } + + fn parse_operand(&self, expr_id: ExprId) -> PResult<Operand<'tcx>> { + parse_by_kind!(self, expr_id, expr, "operand", + @call("mir_move", args) => self.parse_place(args[0]).map(Operand::Move), + @call("mir_static", args) => self.parse_static(args[0]), + @call("mir_static_mut", args) => self.parse_static(args[0]), + ExprKind::Literal { .. } + | ExprKind::NamedConst { .. } + | ExprKind::NonHirLiteral { .. } + | ExprKind::ZstLiteral { .. } + | ExprKind::ConstParam { .. } + | ExprKind::ConstBlock { .. } => { + Ok(Operand::Constant(Box::new( + crate::build::expr::as_constant::as_constant_inner(expr, |_| None, self.tcx) + ))) + }, + _ => self.parse_place(expr_id).map(Operand::Copy), + ) + } + + fn parse_place(&self, expr_id: ExprId) -> PResult<Place<'tcx>> { + parse_by_kind!(self, expr_id, _, "place", + ExprKind::Deref { arg } => Ok( + self.parse_place(*arg)?.project_deeper(&[PlaceElem::Deref], self.tcx) + ), + _ => self.parse_local(expr_id).map(Place::from), + ) + } + + fn parse_local(&self, expr_id: ExprId) -> PResult<Local> { + parse_by_kind!(self, expr_id, _, "local", + ExprKind::VarRef { id } => Ok(self.local_map[id]), + ) + } + + fn parse_block(&self, expr_id: ExprId) -> PResult<BasicBlock> { + parse_by_kind!(self, expr_id, _, "basic block", + ExprKind::VarRef { id } => Ok(self.block_map[id]), + ) + } + + fn parse_static(&self, expr_id: ExprId) -> PResult<Operand<'tcx>> { + let expr_id = parse_by_kind!(self, expr_id, _, "static", + ExprKind::Deref { arg } => *arg, + ); + + parse_by_kind!(self, expr_id, expr, "static", + ExprKind::StaticRef { alloc_id, ty, .. } => { + let const_val = + ConstValue::Scalar(Scalar::from_pointer((*alloc_id).into(), &self.tcx)); + let literal = ConstantKind::Val(const_val, *ty); + + Ok(Operand::Constant(Box::new(Constant { + span: expr.span, + user_ty: None, + literal + }))) + }, + ) + } +} |