diff options
Diffstat (limited to 'compiler/rustc_mir_build/src/build/custom/parse.rs')
| -rw-r--r-- | compiler/rustc_mir_build/src/build/custom/parse.rs | 256 |
1 files changed, 256 insertions, 0 deletions
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) + } +} |