[llvm] [LV][EVL] Disable fixed-order recurrence idiom with EVL tail folding. (PR #122458)

[Luke Lau via llvm-commits]

lukel97 wrote:

> I'm curious if testing could be improved to catch things like this earlier. As this is part of llvm-test-suite, does this mean that there isn't any automatic runtime testing running llvm-test-suite with EVL mode enabled?

I'm currently running nightly performance tests with an EVL tail folding configuration on SPEC CPU 2017, it's publicly available here in case others find it useful: https://lnt.lukelau.me/db_default/v4/nts/98

To save time it only runs the train dataset and it skips the speed tests. It's picked up two failing benchmarks so far, 525.x264_r and 502.gcc_r.

Hopefully I'll get some extra time and hardware soon to also run the llvm-test-suite benchmarks.

As for the unit tests in llvm-test-suite, I'll see if we (Igalia) can set up a buildbot for it. 

https://github.com/llvm/llvm-project/pull/122458