Two actions failed on the test constant-loclist.ll. This PR doesn't touch this file so the problem seems to be on HEAD.

It would be good to hear @MrSidims 's opinion on this too, but I am not keen on making spirv-val a hard requirement for this many tests. Ideally, if spirv-val is not available, the test would skip validation but should still run the other steps.

I agree with Sven, we shouldn't skip that many tests.
Btw, I've just make a quick check on my machine with spirv-val non-installed and got the following result:
Total Discovered Tests: 877
Unsupported : 74 (8.44%)
Passed : 799 (91.11%)
Expectedly Failed: 4 (0.46%)

I interpret the result like this: there tests that require spirv-as/spirv-dis - and they are skipped. Meanwhile spirv-val tests are still being run as the number of Unsupported tests doesn't match the number of tests modified in this PR. So the question is: why do we need it?

Makes sense. So basically what we want is that if there's no spirv-val then we want to still run these test and skip just a spirv-val step, right? Now I see that in the lit.cfg.py:L80 there's no adding spirv-val to available_features and the else statement is most likely used to bypass this check (I guess). So to sum up I think we can drop this PR.

the else statement is most likely used to bypass this check (I guess).

Yes exactly, the else turns any spirv-val command into a no-op if spirv-val is not detected.

I think a comment to explain the optionality of spirv-val would be helpful, so I've opened #2765