爱特每羊队
93 lines
3.8 KiB
Rust
93 lines
3.8 KiB
Rust
//! try/catch/finally 语句 emit：`emit_try_statement` 生成 TRY_BEGIN 与处理入口。
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use crate::{CompileCtx, Emitter};
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use oxide_bytecode::opcode::OpCode;
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use oxide_ir::inst::Inst;
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use oxide_ir::operand::Operand;
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use oxide_parser::{Statement, VariableDeclarationKind};
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impl Emitter {
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pub(crate) fn emit_try_statement(&self, stmt: &Statement, ctx: &mut CompileCtx) -> Result<Option<u32>, String> {
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let Statement::TryStatement(ts) = stmt else {
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return Ok(None);
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};
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let catch_label = ctx.next_label_id();
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let finally_label = ctx.next_label_id();
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let try_end_label = ctx.next_label_id();
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let has_catch = ts.handler.is_some();
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let has_finally = ts.finalizer.is_some();
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let result_reg = ctx.alloc_reg();
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if has_finally {
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// finally 域跨整个语句（try 体 + catch 体 + finally 体）：期间 break/continue
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// 逃出语句时须穿越本 finally，词法上记录域深度供跨越计数。
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ctx.push_finally_domain();
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ctx.inst(Inst::try_finally_begin(finally_label));
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}
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if has_catch {
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ctx.inst(Inst::try_begin(catch_label));
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}
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let mut last_try_result: Option<u32> = None;
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for s in &ts.block.body {
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if let Some(r) = self.emit_statement(s, ctx)? {
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last_try_result = Some(r);
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}
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}
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ctx.inst(Inst::new(
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OpCode::LOAD_VAR,
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Operand::Reg(result_reg),
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Operand::Reg(last_try_result.unwrap_or(result_reg)),
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Operand::None,
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));
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if has_catch {
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ctx.inst(Inst::new(OpCode::TRY_END, Operand::None, Operand::None, Operand::None));
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}
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let jmp_needed = has_catch || has_finally;
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if jmp_needed {
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let target = if has_finally { finally_label } else { try_end_label };
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ctx.inst(Inst::jmp(target));
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}
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ctx.labels.set_label_pos(catch_label, ctx.insts.len());
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if let Some(catch) = &ts.handler {
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ctx.push_scope();
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if let Some(param) = &catch.param {
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let src_reg = ctx.alloc_reg();
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// 异常值在 VM 物理 regs[0]（unwind 展开处写入），STORE_VAR a=None 读回。
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ctx.inst(Inst::new(OpCode::STORE_VAR, Operand::Reg(src_reg), Operand::None, Operand::None));
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self.emit_binding_pattern(¶m.pattern, src_reg, VariableDeclarationKind::Let, false, ctx)?;
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}
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let mut last_catch_result: Option<u32> = None;
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for s in &catch.body.body {
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if let Some(r) = self.emit_statement(s, ctx)? {
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last_catch_result = Some(r);
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}
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}
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ctx.inst(Inst::new(
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OpCode::LOAD_VAR,
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Operand::Reg(result_reg),
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Operand::Reg(last_catch_result.unwrap_or(result_reg)),
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Operand::None,
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));
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ctx.pop_scope();
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}
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if has_finally {
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ctx.labels.set_label_pos(finally_label, ctx.insts.len());
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let mut last_finally_result: Option<u32> = None;
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for s in &ts.finalizer.as_ref().unwrap().body {
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if let Some(r) = self.emit_statement(s, ctx)? {
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last_finally_result = Some(r);
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}
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}
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ctx.inst(Inst::new(
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OpCode::LOAD_VAR,
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Operand::Reg(result_reg),
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Operand::Reg(last_finally_result.unwrap_or(result_reg)),
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Operand::None,
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));
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ctx.inst(Inst::new(OpCode::TRY_FINALLY_END, Operand::None, Operand::None, Operand::None));
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ctx.pop_finally_domain();
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}
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ctx.labels.set_label_pos(try_end_label, ctx.insts.len());
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Ok(Some(result_reg))
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}
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}
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