RVV assert in inline asm for tied constraints

[Rexicon226]

target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128"
target triple = "riscv64-unknown-linux5.10.0-musl"

define i16 @foo() {
Entry:
  %0 = call <2 x i8> asm "vadd.vv ${0}, ${1}, ${2}", "=&m,{x11},{x12}"(<2 x i8> zeroinitializer, <2 x i8> zeroinitializer)
  ret i16 0
}

Assertion failed: ((OpInfo.isMultipleAlternative || (OpInfo.Type == InlineAsm::isInput)) && "Can only indirectify direct input operands!"), function visitInlineAsm, file SelectionDAGBuilder.cpp, line 9901.

https://llc.godbolt.org/z/Y8qj3nTdx

Should probably result in an error when selecting the constraint instead of an Assert.

[topperc]

Did this come from clang or another frontend?

[llvmbot]

@llvm/issue-subscribers-backend-risc-v

Author: David Rubin (Rexicon226)

```llvm target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128" target triple = "riscv64-unknown-linux5.10.0-musl"

define i16 @foo() {
Entry:
%0 = call <2 x i8> asm "vadd.vv ${0}, ${1}, ${2}", "=&m,{x11},{x12}"(<2 x i8> zeroinitializer, <2 x i8> zeroinitializer)
ret i16 0
}

Assertion failed: ((OpInfo.isMultipleAlternative || (OpInfo.Type == InlineAsm::isInput)) && "Can only indirectify direct input operands!"), function visitInlineAsm, file SelectionDAGBuilder.cpp, line 9901.

https://llc.godbolt.org/z/Y8qj3nTdx

Should probably result in an error when selecting the constraint instead of an Assert.
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