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The existing volatile `left`/`right` pointers guarantee that the reads will all occur, but does not guarantee that they will be _used_. So a compiler can still short-circuit the loop, saving e.g. the overhead of doing the xors and especially the overhead of the data dependency between `result` and the reads. That would change performance depending on where the first unequal byte occurs. This change removes that optimization. (This is change GH-1 from https://bugs.python.org/issue40791 .) (cherry picked from commit 3172936) Co-authored-by: Devin Jeanpierre <jeanpierreda@google.com>
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…ythonGH-23767) The existing volatile `left`/`right` pointers guarantee that the reads will all occur, but does not guarantee that they will be _used_. So a compiler can still short-circuit the loop, saving e.g. the overhead of doing the xors and especially the overhead of the data dependency between `result` and the reads. That would change performance depending on where the first unequal byte occurs. This change removes that optimization. (This is change GH-1 from https://bugs.python.org/issue40791 .) (cherry picked from commit 3172936) Co-authored-by: Devin Jeanpierre <jeanpierreda@google.com>
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```
Direct leak of 8 byte(s) in 1 object(s) allocated from:
GH-0 0x7f008bf19667 in __interceptor_malloc (/lib64/libasan.so.6+0xb0667)
GH-1 0x7f007a0bee4a in subprocess_fork_exec /home/heimes/dev/python/cpython/Modules/_posixsubprocess.c:774
GH-2 0xe0305b in cfunction_call Objects/methodobject.c:546
```
Signed-off-by: Christian Heimes <christian@python.org>
(cherry picked from commit 0d3350d)
Co-authored-by: Christian Heimes <christian@python.org>
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* bpo-40791: Make compare_digest more constant-time. The existing volatile `left`/`right` pointers guarantee that the reads will all occur, but does not guarantee that they will be _used_. So a compiler can still short-circuit the loop, saving e.g. the overhead of doing the xors and especially the overhead of the data dependency between `result` and the reads. That would change performance depending on where the first unequal byte occurs. This change removes that optimization. (This is change GH-1 from https://bugs.python.org/issue40791 .) (cherry picked from commit 3172936) Co-authored-by: Devin Jeanpierre <jeanpierreda@google.com>
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…ython#119498) (#1… (python#119905) Revert "[3.12] pythongh-69214: Fix fcntl.ioctl() request type (python#119498) (python#119505)" This reverts commit 078da88. The change modified how negative values, like termios.TIOCSWINSZ, was treated and is actually backward incompatible.
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