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GH-135904: Implement assembler optimization for AArch64.#139855

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markshannon merged 5 commits into
python:mainfrom
faster-cpython:optimize-jit-cfg-arm
Oct 17, 2025
Merged

GH-135904: Implement assembler optimization for AArch64.#139855
markshannon merged 5 commits into
python:mainfrom
faster-cpython:optimize-jit-cfg-arm

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@markshannon

@markshannon markshannon commented Oct 9, 2025 •
edited by bedevere-app Bot
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Implements #135904 for AArch64 to match the optimisation for x86.
Removes a number of unnecessary branches.

@markshannon
Implement assembler optimization for AArch64. …
4abdaa1 
Removes a number of unnecessary branches.

Change-Id: I4965fe8d8b79f7d859ff9076d9c53f3ac7f094b2
@markshannon markshannon force-pushed the optimize-jit-cfg-arm branch from 7dff6cc to 4abdaa1 Compare October 9, 2025 15:24
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@bedevere-app bedevere-app Bot mentioned this pull request Oct 9, 2025
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@markshannon

markshannon commented Oct 10, 2025

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It looks like there are three issues here:

  • The R_AARCH64_TSTBR14 relocation only allows a jump of 2**15 bytes, which is not enough for the JIT in debug mode. We could maybe workaround this, as it would be nice to have for the release build. But I think we can just drop support for optimising cbz and tbz instructions for now.
  • We don't have the symbol name for 19 bit relocations on Windows. This is an easy fix.
  • The llvm assembler is rejecting b.eq __JIT_ERROR_TARGET because "conditional branch requires assembler-local label", but the code is fine. This might be because the home-brew installed llvm is too old?

diegorusso
diegorusso approved these changes Oct 17, 2025
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Thanks for the PR and for finally implement this. It was in my todo list for long time :) @brandtbucher would be happy to see this implemented.

Of course this is OK (I've reviewed this internally at Arm)

Hide details View details @markshannon markshannon merged commit f188385 into python:main Oct 17, 2025
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bedevere-bot commented Oct 17, 2025

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⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot ARM64 macOS 3.x (tier-2) has failed when building commit f188385.

What do you need to do:

  1. Don't panic.
  2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
  3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/725/builds/12123) and take a look at the build logs.
  4. Check if the failure is related to this commit (f188385) or if it is a false positive.
  5. 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/725/builds/12123

Failed tests:

  • test_urllib2net

Failed subtests:

  • test_ftp - test.test_urllib2net.OtherNetworkTests.test_ftp

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

==

Click to see traceback logs 
Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_urllib2net.py", line 239, in _test_urls
    f = urlopen(url, req, support.INTERNET_TIMEOUT)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_urllib2net.py", line 28, in wrapped
    return _retry_thrice(func, exc, *args, **kwargs)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_urllib2net.py", line 24, in _retry_thrice
    raise last_exc
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_urllib2net.py", line 20, in _retry_thrice
    return func(*args, **kwargs)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 487, in open
    response = self._open(req, data)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 504, in _open
    result = self._call_chain(self.handle_open, protocol, protocol +
                              '_open', req)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 464, in _call_chain
    result = func(*args)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 1556, in ftp_open
    raise URLError(f"ftp error: {exp}") from exp
urllib.error.URLError: <urlopen error ftp error: timed out>


Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 1546, in ftp_open
    fp, retrlen = fw.retrfile(file, type)
                  ~~~~~~~~~~~^^^^^^^^^^^^
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 1806, in retrfile
    conn, retrlen = self.ftp.ntransfercmd(cmd)
                    ~~~~~~~~~~~~~~~~~~~~~^^^^^
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/ftplib.py", line 354, in ntransfercmd
    conn = socket.create_connection((host, port), self.timeout,
                                    source_address=self.source_address)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/socket.py", line 879, in create_connection
    raise exceptions[0]
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/socket.py", line 864, in create_connection
    sock.connect(sa)
    ~~~~~~~~~~~~^^^^
TimeoutError: timed out

StanFromIreland pushed a commit to StanFromIreland/cpython that referenced this pull request Dec 6, 2025
@markshannon @StanFromIreland
pythonGH-135904: Implement assembler optimization for AArch64. (pytho… …
0156947 
…nGH-139855)
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@diegorusso diegorusso diegorusso approved these changes

@brandtbucher brandtbucher Awaiting requested review from brandtbucher brandtbucher is a code owner

@savannahostrowski savannahostrowski Awaiting requested review from savannahostrowski

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@markshannon @bedevere-bot @diegorusso