momchil-velikov wrote:

> Do we already understand the root causes for some of the larger regressions, 
> e.g. `736.ocio_r | 1.91%` or `714.cpython_r | 1.80%`.

* Half of `cpython` regression  is due to higher L1I cache refills (compared to 
main) which disappear after manual alignment of a couple of key functions.
* The other half of the regression due to higher L1D refills, but essentially 
the same amount of memory operations across identical hot spots. Experiment 
with inserting extra data block to force the same `brk(NULL)` in both versions 
of the benchmark (main + disabnle-pre-lto-vec) show regression going down to 
0.5-0.7%

Sometimes `cpython` even shows improvement.

https://github.com/llvm/llvm-project/pull/195886
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