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JIT: remove jumps at the end of every micro op on aarch64 #130887

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diegorusso opened this issue Mar 5, 2025 · 0 comments
Open

JIT: remove jumps at the end of every micro op on aarch64 #130887

diegorusso opened this issue Mar 5, 2025 · 0 comments
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@diegorusso
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3.14 new features, bugs and security fixes interpreter-core (Objects, Python, Grammar, and Parser dirs) performance Performance or resource usage topic-JIT triaged The issue has been accepted as valid by a triager.

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diegorusso commented Mar 5, 2025 •
edited by bedevere-app bot
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Feature or enhancement

Bug description:

AArch64 JIT stencils contain a jump at the end of every micro op:

...
    // d4: a8c17bfd      ldp     x29, x30, [sp], #0x10
    // d8: 14000000      b       0xd8 <_JIT_ENTRY+0xd8>
    // 00000000000000d8:  R_AARCH64_JUMP26     _JIT_CONTINUE

These jumps need to be removed and replaced with no-ops to keep the alignment of 8 bytes.
Also the current padding mechanism needs to be removed as well.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs
@diegorusso diegorusso added topic-JIT type-feature A feature request or enhancement labels Mar 5, 2025
@diegorusso diegorusso self-assigned this Mar 5, 2025
@brandtbucher brandtbucher added performance Performance or resource usage interpreter-core (Objects, Python, Grammar, and Parser dirs) 3.14 new features, bugs and security fixes and removed type-feature A feature request or enhancement labels Mar 5, 2025
@picnixz picnixz added the triaged The issue has been accepted as valid by a triager. label Mar 7, 2025
diegorusso added a commit to diegorusso/cpython that referenced this issue Mar 10, 2025
@diegorusso
pythongh-130887: remove trailing jump in AArch64 JIT stencils
46093f8 
In order to keep the alignment of the code body, the removed
jump and the 0 padding at the end of AArch64 JIT stencils
have been replaced with nop instructions.
@bedevere-app bedevere-app bot mentioned this issue Mar 10, 2025
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3.14 new features, bugs and security fixes interpreter-core (Objects, Python, Grammar, and Parser dirs) performance Performance or resource usage topic-JIT triaged The issue has been accepted as valid by a triager.
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