After https://github.com/llvm/llvm-project/pull/153643, there may be a
BranchOnCond with constant condition in the entry block.
Simplify those in removeBranchOnConst. This removes a number of
redundant conditional branch from entry blocks.
In some cases, it may also make the original scalar loop unreachable,
because we know it will never execute. In that case, we need to remove
the loop from LoopInfo, because all unreachable blocks may dominate each
other, making LoopInfo invalid. In those cases, we can also completely
remove the loop, for which I'll share a follow-up patch.
Depends on https://github.com/llvm/llvm-project/pull/153643.
PR: https://github.com/llvm/llvm-project/pull/154510
Epilogue vectorization currently relies on the resume phi for the
canonical induction being always available, which is why VPPhi are
considered to have side-effects, to prevent their removal.
This patch adds a new ResumeForEpilogue opcode to mark the resume phi as
used for epilogue vectorization. This allows treating VPPhis in general
as not having side-effects, enabling removal of unused VPPhis.
Materialize constant vector trip counts before ::execute, if the trip
count can be computed as Original (TC / (VF * UF)) * (VF * UF). For now
this excludes when the tail is folded or scalar epilogues are required.
This enables removing a number of redundant branches from the middle
block.
For now this is also only done when not vectorizing the epilogue, as the
simplification complicates stitching the 2 plans together.
PR: https://github.com/llvm/llvm-project/pull/142309
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
Optimize the IR generated for a VPWidenIntOrFpInductionRecipe to use the
narrowest type necessary, when the trip-count of a loop is known to be
constant and the only use of the recipe is the condition used by the
vector loop's backedge branch.
