This reverts commit 8dd160f4767f971572eac065c8650d9202ff5bf9.

The recommit contains an adjustment to planContainsAdditionalSimplifications,
which considers changes to the original predicate for compares.

Original commit message:

Add simplification to fold negation into a compare, if the negation is
the only user of the compare. This removes a number of redundant
negations.

Alive2 Proofs for FPCMP test changes:  https://alive2.llvm.org/ce/z/WGDz9U

PR: https://github.com/llvm/llvm-project/pull/129430

Extend sinking logic to duplicate scalar steps recipe if it enables
sinking, that is if all users in a destination block require all lanes.

This should be the last step before removing legacy sinkScalarOperands.

PR: https://github.com/llvm/llvm-project/pull/136021

Add an initial CFG simplification transform, which removes the dead
edges for blocks terminated with BranchOnCond true.

At the moment, this removes the edge between middle block and scalar
preheader when folding the tail.

PR: https://github.com/llvm/llvm-project/pull/106748

After unrolling, there may be additional simplifications that can be
applied. One example is removing SCALAR-STEPS for the first part where
only the first lane is demanded.

This removes redundant adds of 0 from a large number of tests (~200),
many which I am still working on updating.

In preparation for removing redundant WideIV steps added in
https://github.com/llvm/llvm-project/pull/119284.

PR: https://github.com/llvm/llvm-project/pull/123655

Reverts llvm/llvm-project#129430

this seems to have introduced a divergence between legacy and
VPlan-based cost model

https://lab.llvm.org/buildbot/#/builders/30/builds/17159

Add simplification to fold negation into a compare, if the negation is
the only user of the compare. This removes a number of redundant
negations.

Alive2 Proofs for FPCMP test changes:  https://alive2.llvm.org/ce/z/WGDz9U

PR: https://github.com/llvm/llvm-project/pull/129430

The mapping of IR ExitBB to a VPBB isn't used. It also sets an incorrect
VPBB for the ExitBB; the regions successor is the middle block, no the
exit block.

It also unnecessarily triggers an assertion after 38376dee922.

If IVUpdateMayOverflow is false, we proved that the induction increment
cannot overflow in the vector loop. This allows setting NUW in some
cases when folding the tail.

PR: https://github.com/llvm/llvm-project/pull/111758

This patch moves branch condition creation to enter the scalar epilogue
loop to VPlan. Modeling the branch in the middle block also requires
modeling the successor blocks. This is done using the recently
introduced VPIRBasicBlock.

Note that the middle.block is still created as part of the skeleton and
then patched in during VPlan execution. Unfortunately the skeleton needs
to create the middle.block early on, as it is also used for induction
resume value creation and is also needed to properly update the
dominator tree during skeleton creation.

After this patch lands, I plan to move induction resume value and phi
node creation in the scalar preheader to VPlan. Once that is done, we
should be able to create the middle.block in VPlan directly.

This is a re-worked version based on the earlier
https://reviews.llvm.org/D150398 and the main change is the use of
VPIRBasicBlock.

Depends on https://github.com/llvm/llvm-project/pull/92525

PR: https://github.com/llvm/llvm-project/pull/92651