* 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
The tests for swapcase() were failing for two reasons. The first is
'𐐧' casing which should be fixed with modern Unicode tables. The second
failure is due to CPython's sigma override, which I implemented in
PR #7717.
* Add basic capi error support
* Add missing symbols to make tests compile again
* Add `pyerrors` to dictionary
* Return exception in `Py_GetConstantBorrowed`
* Remove `allow(dead_code)`
* Fix windows
* Load stdlib when calling `Py_InitializeEx`
* Debug tests
* Revert "Load stdlib when calling `Py_InitializeEx`"
This reverts commit bccd38e981.
* Disable tests on windows for now
* Truncate `PyType_GetFlags` to be always 32 bits
* Add test for exception type checking
* Remove subclass type flags
* Use latest pyo3 to make test work on windows
* Revert "Use latest pyo3 to make test work on windows"
This reverts commit b2c2f6913f.
* `set_main_interpreter` -> `init_main_interpreter`
Jeong, YunWon