Method set_vreg_alias

cranelift/codegen/src/machinst/vcode.rs:1786–1794

Rewrite any mention of `from` into `to`.

(&mut self, from: Reg, to: Reg)

    /// Rewrite any mention of `from` into `to`.
    pub fn set_vreg_alias(&mut self, from: Reg, to: Reg) {
        let from = from.into();
        let resolved_to = self.resolve_vreg_alias(to.into());
        // Disallow cycles (see below).
        assert_ne!(resolved_to, from);

        let old_alias = self.vreg_aliases.insert(from, resolved_to);
        debug_assert_eq!(old_alias, None);
    }

    fn resolve_vreg_alias(&self, mut vreg: regalloc2::VReg) -> regalloc2::VReg {
        // We prevent cycles from existing by resolving targets of