NewGVN is likely screwing up in the presence of lifetime.start and end

[llvmbot]

Bugzilla Link	31511
Version	trunk
OS	All
Blocks	#30343
Reporter	LLVM Bugzilla Contributor

Extended Description

MemorySSA is smart enough to understand that lifetime.start and lifetime.end don't actually alias anything.

However, this means when we make replacements of loads with stores, etc, we probably have situations where we are extending the life part the lifetime.start or end on either side.

I'll work up some testcases and test them

[ManuelJBrito]

This is a bit outdated. Now lifetime.* are clobbers by default, and uses are disambiguated by the walker.
Therefore, I don't think uses past the lifetime are a concern.
https://godbolt.org/z/Y1MWsqjrv
@alinas @nikic