Update VPlan to populate VPIRFlags during VPInstruction construction and
use it when creating widened recipes, instead of constructing VPIRFlags
from the underlying IR instruction each time. The VPRecipeWithIRFlags
constructor taking an underlying instruction and setting the flags based
on it has been removed.

This centralizes initial VPIRFlags creation and ensures flags are
consistently available throughout VPlan transformations and makes sure
we don't accidentally re-add flags from the underlying instruction that
already got dropped during transformations.

Follow-up to https://github.com/llvm/llvm-project/pull/167253, which did
the same for VPIRMetadata.

Should be NFC w.r.t. to the generated IR.

PR: https://github.com/llvm/llvm-project/pull/168450

Update VPlan to populate VPIRMetadata during VPInstruction construction
and use it when creating widened recipes, instead of constructing
VPIRMetadata from the underlying IR instruction each time.

This centralizes VPIRMetadata in VPInstructions and ensures metadata is
consistently available throughout VPlan transformations.

PR: https://github.com/llvm/llvm-project/pull/167253

Changes: The previous patch had to be reverted to a mismatching-OpType
assert in cse. The reduced-test has now been added corresponding to a
RVV pointer-induction, and the pointer-induction case has been updated
to use createOverflowingBinaryOp.

While at it, record VPIRFlags in VPWidenInductionRecipe.

Update VPInstruction constructor to accept VPIRMetadata between the
Flags and DebugLoc parameters. This allows metadata to be passed during
construction rather than assigned afterward.

Add getConstantInt helper methods to VPlan to simplify the common
pattern of creating constant integer live-ins.

Suggested as follow-up in
https://github.com/llvm/llvm-project/pull/164127.

createWidenCast doesn't set the flag type, so when we simplify trunc
(zext nneg x) -> zext x we would hit an assertion in CSE that the flag
types don't match with other VPWidenCastRecipes that weren't simplified.

This fixes it the same way trunc flags are handled too.

As an aside I think it should be correct to preserve the nneg flag in
this case since the input operand is still non-negative after the
transform. But that's left to another PR.

Fixes https://github.com/llvm/llvm-project/issues/164171

VPWidenCastRecipes with Trunc opcodes where missing the correct OpType
for IR flags. Update createWidenCast to set the correct flags for
truncs, and use it consistenly.

Fixes https://github.com/llvm/llvm-project/issues/162374.

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

This patch consolidates updating loop metadata and profile info for both
the remainder and vector loops in a single place. This is NFC, modulo
consistently applying vectorization specific metadata also in the
experimental VPlan-native path.

Split off from https://github.com/llvm/llvm-project/pull/154510.

In case of equal costs Prefer epilogue with fixed-width over scalable VF.
That is helpful in cases like post-LTO vectorization where epilogue with
fixed-width VF can be removed when we eventually know that the trip count
is less than the epilogue iterations.