`asm_experimental_arch`

The tracking issue for this feature is: #133416

This tracks support for additional registers in architectures where inline assembly is already stable.

Register classes

Architecture	Register class	Registers	LLVM constraint code
s390x	`vreg`	`v[0-31]`	`v`

Notes:

s390x vreg is clobber-only in stable.

Architecture	Register class	Target feature	Allowed types
s390x	`vreg`	`vector`	`i32`, `f32`, `i64`, `f64`, `i128`, `f128`, `i8x16`, `i16x8`, `i32x4`, `i64x2`, `f32x4`, `f64x2`
x86	`xmm_reg`	`sse`	`i128`
x86	`ymm_reg`	`avx`	`i128`
x86	`zmm_reg`	`avx512f`	`i128`

Architecture	Base register	Aliases

Architecture	Unsupported register	Reason

Architecture	Register class	Modifier	Example output	LLVM modifier
s390x	`vreg`	None	`%v0`	None