polfg 9c5ea2f2bc Reconstruct 3.11 while-loops (bottom-test optimization) ...

Python 3.11 compiles 'while cond:' with a bottom test: an entry guard
(eval cond; POP_JUMP_FORWARD_IF_FALSE end) before the body, and a
back-edge (eval cond; POP_JUMP_BACKWARD_IF_TRUE loop_start) at the end.
pycdc rendered both halves as separate 'if' blocks, so EVERY while loop
came out as 'if cond: ... if not cond: pass' and never looped.

- New ScanWhileLoops pre-pass pairs each conditional backward jump with
  the forward guard immediately preceding its target (guard skipping to
  the instruction after the back-edge) to identify genuine while loops.
- At the guard, open a BLK_WHILE with the condition instead of an if.
- At the back-edge, discard the duplicated condition and close the loop,
  but only when a BLK_WHILE is actually open (guard against a
  misidentified back-edge collapsing the block stack and crashing).

Fixes while loops across all files (including nested loops and
continue). decompilation target: 237/239 files, corpus 41/95 (+1: signature; 0 regressions).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

2026-06-08 12:27:24 +02:00

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