1. [NFC] Test case refactor (details)
  2. [PowerPC] Avoid call to undef in test (NFC) (details)
  3. [InstSimplify] Fold call null/undef to poison (details)
  4. [InstSimplify] Canonicalize non-demanded shuffle op to poison (NFCI) (details)
Commit 0bfe100145634988e4a914da776b55509ba0bec0 by n.james93
[NFC] Test case refactor
The file was modifiedclang-tools-extra/clangd/unittests/TUSchedulerTests.cpp
Commit 7d48eff8ba172216fca3649a3c452de4c7c16c00 by nikita.ppv
[PowerPC] Avoid call to undef in test (NFC)

Replace call to undef with a dummy function, to avoid affecting
this change by changes to call undef folding.
The file was modifiedllvm/test/CodeGen/PowerPC/spe.ll
Commit d042f2db5bf0a852bdbef53ab0310d363031f56f by nikita.ppv
[InstSimplify] Fold call null/undef to poison

Calling null or undef results in immediate undefined behavior.
Return poison instead of undef in this case, similar to what
we do for immediate UB due to division by zero.
The file was modifiedllvm/test/Transforms/InstSimplify/call.ll
The file was modifiedllvm/test/Transforms/GVN/PRE/volatile.ll
The file was modifiedllvm/test/Transforms/InstSimplify/undef.ll
The file was modifiedllvm/lib/Analysis/InstructionSimplify.cpp
Commit 221c3b174b15855ec941ef60a551f22ac96a254e by nikita.ppv
[InstSimplify] Canonicalize non-demanded shuffle op to poison (NFCI)

I don't believe this has an observable effect, because the only
thing we care about here is replacing the operand with a constant
so following folds can apply. This change is just to make the
representation follow canonical unary shuffle form.
The file was modifiedllvm/lib/Analysis/InstructionSimplify.cpp