Without this, pointer IVs in loops with small constant trip counts couldn't be proven no-self-wrap. This came up in a new LSR transform, but may also benefit other SCEV consumers as well.

Differential Revision: https://reviews.llvm.org/D146596

IR is now always parsed in opaque pointer mode, unless
-opaque-pointers=0 is explicitly given. There is no automatic
detection of typed pointers anymore.

The -opaque-pointers=0 option is added to any remaining IR tests
that haven't been migrated yet.

Differential Revision: https://reviews.llvm.org/D141912

Tests relying on this should explicitly use -passes='require<analysis>,foo'.

Depends on D117038.

Reviewed By: lebedev.ri

Differential Revision: https://reviews.llvm.org/D117039

Depends on D116935.

Reviewed By: nikic, lebedev.ri

Differential Revision: https://reviews.llvm.org/D116969

This makes improvements in follow-up patches more obvious.

This simplifies the return value of addRuntimeCheck from a pair of
instructions to a single `Value *`.

The existing users of addRuntimeChecks were ignoring the first element
of the pair, hence there is not reason to track FirstInst and return
it.

Additionally all users of addRuntimeChecks use the second returned
`Instruction *` just as `Value *`, so there is no need to return an
`Instruction *`. Therefore there is no need to create a redundant
dummy `and X, true` instruction any longer.

Effectively this change should not impact the generated code because the
redundant AND will be folded by later optimizations. But it is easy to
avoid creating it in the first place and it allows more accurately
estimating the cost of the runtime checks.

Follow-up to D82607
Revert an accidental change (empty.ll) of D82683