This converts all ptr element shuffle vectors to s64, so that the
existing vector legalization handling can lower them as needed. This
prevents a lot of fallbacks that currently try to generate things like
`<2 x ptr> G_EXT`.

I'm not sure if bitcast/inttoptr/ptrtoint is intended to be necessary
for vectors of pointers, but it uses buildCast for the casts, which now
generates a ptrtoint/inttoptr.

There are patterns for:
* {nxv2s32, s32, s64},
* {nxv4s16, s16, s64},
* {nxv2s16, s16, s64}

Reverts llvm/llvm-project#114310

There are patterns for:
* {nxv2s32, s32, s64},
* {nxv4s16, s16, s64},
* {nxv2s16, s16, s64}

This patch supports legalizing load and store instruction for scalable
vectors in RISCV

This patch replaces isPowerOf2_32 with llvm::has_single_bit<uint32_t>
where the argument is wider than uint32_t.

This is really a replacement for memSizeInBytesNotPow2 that actually
does what most every target wants. In particular, since s1 rounds to 1
byte, it wasn't lowered by this predicate. This results in targets
needing to think harder and add more matchers to catch all the
degenerate cases.

Also small bug fix that prevented the correct insertion of
G_ASSERT_ZEXT in the AArch64 use case.

Legalizing G_MUL for non-standard types (like i33) generated an error. Putting
minScalar and maxScalar instead of clampScalar. Also using new rule, instead
of widening to the next power of 2, widen to the next multiple of the passed
argument (32 in this case), so instead of widening i65 to i128, we widen it to
i96.

Patch by: Mateja Marjanovic

Differential Revision: https://reviews.llvm.org/D109228

This enables proper lowering of non-byte sized loads. We still aren't
faithfully preserving memory types everywhere, so the legality checks
still only consider the size.