GH-135379: Specialize int operations for compact ints only #135668

markshannon · 2025-06-18T11:20:33Z

This changes the way we handle ints during specialization.
Instead of handling all ints we only specialize for compact ints.
Since compact ints represent the large majority of ints we get a faster common path, at the cost of a few more de-optimizations.
Using compact ints only, and de-optimizing in the extremely rare no-memory case, we can simplify the performance critical paths for integer operations.

This is helpful for top-of-stack caching as the newer simpler instructions to not escape or need to handle errors, so avoids the need to spill to memory.

This also gives us the potential to use BINARY_OP_EXTEND for multi-digit ints in the future.

Issue: Top-of-stack caching in the JIT #135379

…tion in case of overflow

Fidget-Spinner · 2025-06-18T11:44:30Z

Can you please add tests for the new synbol to optimizer_symbols.c?

Fidget-Spinner

Need tests and one comment. Otherwise LGTM.

Fidget-Spinner · 2025-06-18T12:28:55Z

Python/optimizer_symbols.c

+            return;
+        case JIT_SYM_KNOWN_VALUE_TAG:
+            if (!PyLong_CheckCompact(sym->value.value)) {
+                Py_CLEAR(sym->value.value);


I don't think you need to clear things here? It's automatically cleared on finalization of the whole optimizer I think.

We need to do it here (we do the same in _Py_uop_sym_set_type) as we are changing the tag, so the finalization won't know there was an object there.

AH ok that's very tricky! Good observation.

markshannon · 2025-06-19T10:10:10Z

Performance is about neutral, all within noise:

Linux ARM 0.2% slower
Linux x86 1.4% faster
Windows x86 1.0% slower
Mac ARM 0.0% slower

Which is good, as the main point of this PR is to ultimately improve tier 2 performance as this will enable better TOS caching and easier implementation of tagged ints.

bedevere-bot · 2025-06-19T10:17:35Z

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 CentOS9 NoGIL 3.x (tier-1) has failed when building commit 9731dd2.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1609/builds/2948) and take a look at the build logs.
Check if the failure is related to this commit (9731dd2) or if it is a false positive.
If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1609/builds/2948

Failed tests:

test_cext

Failed subtests:

test_build - test.test_cext.TestExt.test_build
test_build_c11 - test.test_cext.TestExt.test_build_c11
test_build_c99 - test.test_cext.TestExt.test_build_c99

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 34, in test_build
    self.check_build('_test_cext')
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 57, in check_build
    self._check_build(extension_name, python_exe,
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                      std=std, limited=limited)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 94, in _check_build
    run_cmd('Install', cmd)
    ~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 75, in run_cmd
    subprocess.run(cmd, check=True, env=env)
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/subprocess.py", line 577, in run
    raise CalledProcessError(retcode, process.args,
                             output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/build/test_python_2169572æ/tempcwd/env/bin/python', '-X', 'dev', '-m', 'pip', 'install', '--no-build-isolation', '/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/build/test_python_2169572æ/tempcwd/pkg', '-v']' returned non-zero exit status 1.


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 34, in test_build
    self.check_build('_test_cext')
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 57, in check_build
    self._check_build(extension_name, python_exe,
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                      std=std, limited=limited)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 94, in _check_build
    run_cmd('Install', cmd)
    ~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 75, in run_cmd
    subprocess.run(cmd, check=True, env=env)
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/subprocess.py", line 577, in run
    raise CalledProcessError(retcode, process.args,
                             output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/build/test_python_2213783æ/tempcwd/env/bin/python', '-X', 'dev', '-m', 'pip', 'install', '--no-build-isolation', '/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/build/test_python_2213783æ/tempcwd/pkg', '-v']' returned non-zero exit status 1.


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 37, in test_build_c11
    self.check_build('_test_c11_cext', std='c11')
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 57, in check_build
    self._check_build(extension_name, python_exe,
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                      std=std, limited=limited)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 94, in _check_build
    run_cmd('Install', cmd)
    ~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 75, in run_cmd
    subprocess.run(cmd, check=True, env=env)
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/subprocess.py", line 577, in run
    raise CalledProcessError(retcode, process.args,
                             output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/build/test_python_2213783æ/tempcwd/env/bin/python', '-X', 'dev', '-m', 'pip', 'install', '--no-build-isolation', '/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/build/test_python_2213783æ/tempcwd/pkg', '-v']' returned non-zero exit status 1.


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 44, in test_build_c99
    self.check_build('_test_c99_cext', std='c99')
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 57, in check_build
    self._check_build(extension_name, python_exe,
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                      std=std, limited=limited)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 94, in _check_build
    run_cmd('Install', cmd)
    ~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 75, in run_cmd
    subprocess.run(cmd, check=True, env=env)
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/subprocess.py", line 577, in run
    raise CalledProcessError(retcode, process.args,
                             output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/build/test_python_2213783æ/tempcwd/env/bin/python', '-X', 'dev', '-m', 'pip', 'install', '--no-build-isolation', '/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/build/test_python_2213783æ/tempcwd/pkg', '-v']' returned non-zero exit status 1.


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 37, in test_build_c11
    self.check_build('_test_c11_cext', std='c11')
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 57, in check_build
    self._check_build(extension_name, python_exe,
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                      std=std, limited=limited)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 94, in _check_build
    run_cmd('Install', cmd)
    ~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 75, in run_cmd
    subprocess.run(cmd, check=True, env=env)
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/subprocess.py", line 577, in run
    raise CalledProcessError(retcode, process.args,
                             output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/build/test_python_2169572æ/tempcwd/env/bin/python', '-X', 'dev', '-m', 'pip', 'install', '--no-build-isolation', '/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/build/test_python_2169572æ/tempcwd/pkg', '-v']' returned non-zero exit status 1.


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 44, in test_build_c99
    self.check_build('_test_c99_cext', std='c99')
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 57, in check_build
    self._check_build(extension_name, python_exe,
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                      std=std, limited=limited)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 94, in _check_build
    run_cmd('Install', cmd)
    ~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_cext/__init__.py", line 75, in run_cmd
    subprocess.run(cmd, check=True, env=env)
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/subprocess.py", line 577, in run
    raise CalledProcessError(retcode, process.args,
                             output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/build/test_python_2169572æ/tempcwd/env/bin/python', '-X', 'dev', '-m', 'pip', 'install', '--no-build-isolation', '/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/build/test_python_2169572æ/tempcwd/pkg', '-v']' returned non-zero exit status 1.

markshannon added 2 commits June 18, 2025 12:06

Specialize int operations for compact ints only. Deopts before alloca…

a7c92fc

…tion in case of overflow

Add news

e27d994

markshannon requested a review from Fidget-Spinner as a code owner June 18, 2025 11:20

bedevere-app bot added the awaiting core review label Jun 18, 2025

bedevere-app bot mentioned this pull request Jun 18, 2025

Top-of-stack caching in the JIT #135379

Open

Fidget-Spinner reviewed Jun 18, 2025

View reviewed changes

markshannon added 2 commits June 18, 2025 14:09

Merge branch 'main' into specialize-for-compact-ints

6a3cd5c

Add tests

996899b

Fidget-Spinner approved these changes Jun 18, 2025

View reviewed changes

bedevere-app bot added awaiting merge and removed awaiting core review labels Jun 18, 2025

markshannon merged commit 9731dd2 into python:main Jun 19, 2025
72 checks passed

bedevere-app bot removed the awaiting merge label Jun 19, 2025

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GH-135379: Specialize int operations for compact ints only #135668

GH-135379: Specialize int operations for compact ints only #135668

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GH-135379: Specialize int operations for compact ints only #135668

GH-135379: Specialize int operations for compact ints only #135668

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⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

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markshannon commented Jun 18, 2025 •

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