* optimize: convert for-loop post-inc/dec to prefix to avoid zval copy
For-loop post-expressions (third clause of `for (init; cond; post)`) always
discard the return value, so $i++ is semantically identical to ++$i in this
context. Converting to prefix increment/decrement avoids the zval copy +
destructor overhead from operator++(int)'s return value, saving ~6ns per
increment per loop iteration.
Changes:
- LoopControlTrait: convert PostInc→PreInc, PostDec→PreDec in for-loop
post-expressions only (while/do-while body untouched)
- Add phpunit test verifying generated C++ contains ++i/--i for for-loops
and retains i++ in while/do-while bodies
- Add test data file with 7 test functions covering basic, multi-post,
nested, mixed, and while/do-while cases
* fix: restrict for-loop post-expr rewrite to simple variables only
韩天峰
yuan-dian