LR not correctly saved for inline assembly clobbering LR

[programmerjake]

Bugzilla Link	47811
Version	11.0
OS	Linux
CC	@nemanjai,@programmerjake

Extended Description

The following IR is miscompiled:
https://gcc.godbolt.org/z/s6c6vT

target triple = "powerpc64le-unknown-linux-gnu"

define void @​f() {
call void asm sideeffect "mtlr 31", "~{lr}"()
ret void
}

Generated Assembly (trimmed to just f()):
f: # @​f
.Lfunc_begin0:
.cfi_startproc

%bb.0:

    #APP
    mtlr    31
    #NO_APP
    blr

This causes f to return to whatever address was in r31 instead of to the caller. I expect LLVM to instead store the return address that was in LR to another register or to the stack and restore it before returning.

[chenzheng1030]

Although trunk llc does not show the error instructions: https://godbolt.org/z/9ad8K4fG8

        mtlr    31
        addi 1, 1, 32
        ld 0, 16(1)
        mtlr 0
        blr

the assembly and the mtlr does not recognize as dependent. So the bug should still be there. And should be same with #47156, clobber ~{lr} is not same with lr8 in mtlr instruction's definitions.