[llvm] [IR] Allow poison argument to lifetime markers (PR #151148)

[Nikita Popov via llvm-commits]

================
@@ -26656,14 +26656,17 @@ Arguments:
 The first argument is a constant integer, which is ignored and will be removed
 in the future.
 
-The second argument is a pointer to an ``alloca`` instruction.
+The second argument is either a pointer to an ``alloca`` instruction or
+a ``poison`` value.
----------------
nikic wrote:

I'd rather not broaden this if we can be avoided at all.

Adding some special cases to llvm-reduce should be fine to avoid invalid reductions, e.g. https://github.com/llvm/llvm-project/issues/93713 is now more relevant. We can also skip the zero replacement for lifetimes, which just is not a useful thing to do (it should be either dropped entirely or left alone -- also the fact that llvm-reduce replaces the size argument with zero is really annoying, though that will go away soon anyway).

https://github.com/llvm/llvm-project/pull/151148