This patch adds a new preheader block the VPlan to place SCEV expansions
expansions like the trip count. This preheader block is disconnected
at the moment, as the bypass blocks of the skeleton are not yet modeled
in VPlan.
The preheader block is executed before skeleton creation, so the SCEV
expansion results can be used during skeleton creation. At the moment,
the trip count expression and induction steps are expanded in the new
preheader. The remainder of SCEV expansions will be moved gradually in
the future.
D147965 will update skeleton creation to use the steps expanded in the
pre-header to fix#58811.
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D147964
The entry to the plan is the preheader of the vector loop and
guaranteed to be a VPBasicBlock. Make sure this is the case by
adjusting the type.
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D149005
This updates the GraphTraits specialization for VPBlockBase to recurse
through VPRegionBlocks.
This in turn enables using VPDominatorTree to query dominance between
any block in a plan. This should enable additional use cases, including
improvements to def-use verification and porting IR-based transforms
that rely on the dominator tree.
Specifically, this change means that for regions, the entry and exit
blocks dominate the successors of the region.
Depends on D140512 and D142162.
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D140513
