Instead of looking up the narrower reduction type via getRecurrenceType
we can generate the needed extend directly at constructiond re-use the
truncated value from the loop.

PR: https://github.com/llvm/llvm-project/pull/141860

This put the onus on the caller to ensure the result type is big enough.
In the unlikely event a cropped result is required then explicitly
truncate a safe value.

This brings the printing of scalable vector constant splats inline with
their fixed length counterparts.

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

Use VPIRBasicBlock to wrap the middle block and implement patching up
branches in predecessors in VPIRBasicBlock::execute. The IR middle block
is only created after skeleton creation. Initially a regular
VPBasicBlock is created, which will later be replaced by a
VPIRBasicBlock once the middle IR basic block has been created.

Note that this slightly changes the order of instructions created in the
middle block; code generated by recipe execution in the middle block
will now be inserted before the terminator (and in between the compare
to used by the terminator). The original order will be restored in
https://github.com/llvm/llvm-project/pull/92651.


PR: https://github.com/llvm/llvm-project/pull/95816

UF * VF is loop invariant and can be computed directly in the preheader.
This prepares the code for #74761 and reduces the test changes.

This reverts commit e4ea0997486000b460c4875a00301b73b3c0d6a7.

The recommit fixes a reported crash by adding a missing check to make
sure the cast recipes are only introduced when vectorizing.

Test coverage added in 3cac608fbd0811b2f5c59c6e13148162ccd8543e.
Original commit message:
   Update the code to create Trunc/Ext recipes directly in
    adjustRecipesForReductions instead of fixing it up later in
    fixReductions.

    This explicitly models the required conversions and also makes sure they
    are generated at the right place (instead of after the exit condition),
    hence the changes in a few tests.

This reverts commit fd311126349b8fe1684d62154a9fa5a7bbb0b713.

There are two different crash reports on https://github.com/llvm/llvm-project/commit/fd311126349b8fe1684d62154a9fa5a7bbb0b713

Update the code to create Trunc/Ext recipes directly in
adjustRecipesForReductions instead of fixing it up later in
fixReductions.

This explicitly models the required conversions and also makes sure they
are generated at the right place (instead of after the exit condition),
hence the changes in a few tests.