[RISCV] Clear vill for whole vector register moves in vsetvli insertion (#118283)

This is an alternative to #117866 that works by demanding a valid vtype
instead of using a separate pass.

The ma

[RISCV] Clear vill for whole vector register moves in vsetvli insertion (#118283)

This is an alternative to #117866 that works by demanding a valid vtype
instead of using a separate pass.

The main advantage of this is that it allows coalesceVSETVLIs to just
reuse an existing vsetvli later in the block.

To do this we need to first transfer the vsetvli info to some arbitrary
valid state in transferBefore when we encounter a vector copy. Then we
add a new vill demanded field that will happily accept any other known
vtype, which allows us to coalesce these where possible.

Note we also need to check for vector copies in computeVLVTYPEChanges,
otherwise the pass will completely skip over functions that only have
vector copies and nothing else.

This is one part of a fix for #114518. We still need to check if there's
other cases where vector copies/whole register moves that are inserted
after vsetvli insertion.

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[RISCV] Add support for inline asm constraint vd (#111653)

It constrains vector registers excluding v0. Refer to
https://gcc.gnu.org/onlinedocs/gcc/Machine-Constraints.html RISC-V part.

This pat

[RISCV] Add support for inline asm constraint vd (#111653)

It constrains vector registers excluding v0. Refer to
https://gcc.gnu.org/onlinedocs/gcc/Machine-Constraints.html RISC-V part.

This patch also adds a testcase for constraints vr, vd and vm.

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