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Jeong, YunWon
d438b2ef16
* Align LOAD_FAST_BORROW analysis with CPython chain shape Three changes that bring optimize_load_fast_borrow closer to CPython's optimize_load_fast in flowgraph.c: * ir.rs: split mark_cold into the CPython-style two passes. Phase 1 propagates "warm" from the entry block, phase 2 propagates "cold" from except_handler blocks. Blocks reached by neither phase keep cold=false and stay in their original b_next position, matching CPython's handling of empty placeholders left by remove_unreachable (e.g. the inner_end of a nested try/except whose incoming jumps were re-routed by optimize_cfg). * ir.rs: in optimize_load_fast_borrow, push the fall-through successor only when the current block has a last instruction (is_some_and). Empty blocks now terminate fall-through propagation, matching the `term != NULL` check in optimize_load_fast. * compile.rs: add switch_to_new_or_reuse_empty() helper and use it in compile_while. The helper reuses the current block when it is empty and unlinked, mirroring USE_LABEL absorption in cfg_builder_maybe_start_new_block. This stops a stray empty block from appearing between e.g. a try/except end_block and the following while loop header. Four codegen tests that depended on the previous fall-through-through- empty behavior are marked #[ignore] with TODO comments. Also includes a handful of dictionary entries in .cspell.dict picked up during the work. * Interleave const fold passes per-block to match CPython Mirror CPython's optimize_basic_block() (flowgraph.c) by walking each block once in instruction order and trying tuple, list, set, unary, and binop folding at each position before advancing. This replaces the previous global-pass sequence where every fold_unary_constants pattern in the whole CFG was registered before any tuple constant, leaving negated literals like `-1` at co_consts positions earlier than CPython produces (e.g. snippets.py: -1 at idx 280 vs CPython idx 726). Changes: - Extract `fold_unary_constant_at` and `fold_binop_constant_at` per- position helpers from the existing global passes; the global passes now call the helpers in a loop. - Add `fold_constants_per_block` that walks each block to a fixed point, trying all five folds at each instruction position. - Call the new walker before the legacy global passes in optimize_finalize so co_consts insertion order matches CPython's. Measured on the full Lib tree: differing files 270 → 269; the only newly matching file is `test/test_ast/snippets.py`, the case raised in youknowone/RustPython#28. * Inline small fast-return blocks only through unconditional jumps `inline_small_fast_return_blocks` previously appended the target `LOAD_FAST(_BORROW)/RETURN_VALUE` block's instructions onto any predecessor whose fall-through eventually reached it, in addition to the unconditional-jump case CPython handles in `inline_small_or_no_lineno_blocks` (flowgraph.c:1210). CPython only inlines through unconditional jumps, leaving fall-through predecessors to reach the shared return block via the natural CFG layout. The extra fall-through branch duplicated the return tail (e.g. `if/elif/return` emitted two adjacent `LOAD_FAST_BORROW x; RETURN_VALUE` sequences). Remove the fall-through inlining branch and keep only the unconditional-jump path. Measured on the full Lib tree: differing files 270 → 239 (-31), no new regressions. Files newly matching include copy.py, argparse.py, dataclasses.py, logging/__init__.py, pathlib/__init__.py, etc. * Allow scope-exit/jump-back reorder within a shared except handler `reorder_conditional_scope_exit_and_jump_back_blocks` previously skipped any reorder where the conditional, scope-exit, or jump-back block had an `except_handler` attached, even when all three shared the same handler. CPython reorders these regardless of try/except context, as long as the blocks stay within the same protected region. The over- conservative guard left patterns like `try: for: if cond: return` with the loop body's scope-exit ahead of the backedge, while CPython places the backedge first and inverts the conditional. Replace the `block_is_protected` triple-check with a single `mismatched_protection` test: skip only when the three blocks do not share the same `except_handler`. Same-handler reorders preserve the protected range because every instruction's `except_handler` field stays attached as `.next` pointers shift. Measured on the full Lib tree: differing files 239 → 237; no new regressions. * Skip jump-over-cleanup reorder when target restarts an exception scope reorder_jump_over_exception_cleanup_blocks was swapping a small scope-exit target with a preceding cold cleanup chain even when the target block began a fresh try (SETUP_FINALLY/SETUP_CLEANUP/SETUP_WITH). The swap moved the next try's setup ahead of the prior handler's cleanup_end/next_handler/cleanup_block, making the cleanup_body's JUMP_FORWARD fall through directly to the cleanup_end and get elided as redundant. The bytecode then lacked the JUMP_FORWARD that skips the cleanup blocks and matched the prior handler's borrow tail incorrectly. Skip the reorder when the target block contains any block-push pseudo op so a new try's setup stays in source order. Re-enables the four named/typed except-cleanup borrow tests that were marked #[ignore] in commit 7481459ea. * fix if block_idx == BlockIdx::NULL