Add DWARF5 debug info for wx compile --debug - #14
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Introduces a `--debug` compile mode alongside today's Release path: - `mir::scheduler` lowers the MIR expression tree directly to wasm (no inlining, no CSE, no scheduling) so every source local keeps a fixed wasm slot and instructions stay in source order — legible for a debugger even though it forgoes Release's opt::builder/scheduler optimizations. - Local/parameter names are threaded from TIR through MIR (`mir::Local.name`) and into a new `wasm::Function.locals_debug`, alongside per-function `(low_pc, high_pc)` captured during codegen. - `dwarf::mod.rs` hand-rolls a DWARF5 encoder (compile unit, subprogram/parameter/variable DIEs, a line-number program, and a type-DIE table) emitted as `.debug_info`/`.debug_line`/`.debug_str`/ `.debug_line_str`/`.debug_abbrev`/`.debug_aranges` wasm custom sections — no sidecar file, self-contained in the `.wasm` output. `gimli` is a dev-dependency only, used to round-trip our own encoder's output in tests. - Struct locals (split across consecutive wasm locals) use chained `DW_OP_WASM_location`+`DW_OP_stack_value`+`DW_OP_piece` per flattened field. The `DW_OP_stack_value` marker is required per general DWARF semantics (marks the local as a value, not an address to dereference) — its absence crashes wasmtime's own DWARF→native transform on any module with no declared linear memory; a regression test pins this. Also adds a working wasmtime + CodeLLDB VS Code debugging setup (`.vscode/launch.json`) for JIT'd wasm modules, and a `dwarf-playground/` scratch area with a writeup of three wasmtime DWARF-transform issues found during this work (`wasmtime-dwarf-transform-bug.md`). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Introduces a
--debugcompile mode alongside today's Release path:mir::schedulerlowers the MIR expression tree directly to wasm (no inlining, no CSE, no scheduling) so every source local keeps a fixed wasm slot and instructions stay in source order — legible for a debugger even though it forgoes Release's opt::builder/scheduler optimizations.mir::Local.name) and into a newwasm::Function.locals_debug, alongside per-function(low_pc, high_pc)captured during codegen.dwarf::mod.rshand-rolls a DWARF5 encoder (compile unit, subprogram/parameter/variable DIEs, a line-number program, and a type-DIE table) emitted as.debug_info/.debug_line/.debug_str/.debug_line_str/.debug_abbrev/.debug_arangeswasm custom sections — no sidecar file, self-contained in the.wasmoutput.gimliis a dev-dependency only, used to round-trip our own encoder's output in tests.DW_OP_WASM_location+DW_OP_stack_value+DW_OP_pieceper flattened field. TheDW_OP_stack_valuemarker is required per general DWARF semantics (marks the local as a value, not an address to dereference) — its absence crashes wasmtime's own DWARF→native transform on any module with no declared linear memory; a regression test pins this.Also adds a working wasmtime + CodeLLDB VS Code debugging setup (
.vscode/launch.json) for JIT'd wasm modules, and adwarf-playground/scratch area with a writeup of three wasmtime DWARF-transform issues found during this work(
wasmtime-dwarf-transform-bug.md).