bpo-36957: Speed up math.isqrt (#13405)
* Add math.isqrt function computing the integer square root.
* Code cleanup: remove redundant comments, rename some variables.
* Tighten up code a bit more; use Py_XDECREF to simplify error handling.
* Update Modules/mathmodule.c
Co-Authored-By: Serhiy Storchaka <storchaka@gmail.com>
* Update Modules/mathmodule.c
Use real argument clinic type instead of an alias
Co-Authored-By: Serhiy Storchaka <storchaka@gmail.com>
* Add proof sketch
* Updates from review.
* Correct and expand documentation.
* Fix bad reference handling on error; make some variables block-local; other tidying.
* Style and consistency fixes.
* Add missing error check; don't try to DECREF a NULL a
* Simplify some error returns.
* Another two test cases:
- clarify that floats are rejected even if they happen to be
squares of small integers
- TypeError beats ValueError for a negative float
* Add fast path for small inputs. Needs tests.
* Speed up isqrt for n >= 2**64 as well; add extra tests.
* Reduce number of test-cases to avoid dominating the run-time of test_math.
* Don't perform unnecessary extra iterations when computing c_bit_length.
* Abstract common uint64_t code out into a separate function.
* Cleanup.
* Add a missing Py_DECREF in an error branch. More cleanup.
* Update Modules/mathmodule.c
Add missing `static` declaration to helper function.
Co-Authored-By: Serhiy Storchaka <storchaka@gmail.com>
* Add missing backtick.
2 files changed