Linearization gives `bad save-stack` when regalloc uses RAX to save the stack pointer

[sarranz]

This program

fn f1() -> reg u32 {
    reg u32 r z y;
    r = 0;
    y = 0;
    z = 0;
    r = r ^ y;
    r = r ^ z;
    return r;
}

fn f2(reg u32 _a _b _c) -> reg u32 {
    reg u32 r;
    r = 0;
    return r;
}

fn g(reg ptr u32[12] state, reg u64 column) -> reg ptr u32[12] {
    reg u32 x y z a;
    x = 0;
    y = 0;
    z = 0;
    a = f1();
    state[column] = a;
    a = f2(x,y,z);
    state[column] = a;

    return state;
}

export
fn jazz_g(reg ptr u32[12] state, reg u64 c) -> reg ptr u32[12] {
    #inline state = g(state, c);
    return state;
}

export
fn jazz_g2(reg ptr u32[12] state) -> reg ptr u32[12] {
    reg u64 c;
    c = 0;
    state = g(state, c);
    return state;
}

gives

compilation error in function jazz_g:
linearization: bad save-stack

because registar allocation chooses RAX to save the stack pointer, but linearization does not allow this.