Function aliases

cranelift/codegen/src/ir/dfg.rs:1752–1784

()

    #[test]
    fn aliases() {
        use crate::ir::InstBuilder;
        use crate::ir::condcodes::IntCC;

        let mut func = Function::new();
        let block0 = func.dfg.make_block();
        let mut pos = FuncCursor::new(&mut func);
        pos.insert_block(block0);

        // Build a little test program.
        let v1 = pos.ins().iconst(types::I32, 42);

        // Make sure we can resolve value aliases even when values is empty.
        assert_eq!(pos.func.dfg.resolve_aliases(v1), v1);

        let arg0 = pos.func.dfg.append_block_param(block0, types::I32);
        let (s, c) = pos.ins().uadd_overflow(v1, arg0);
        let iadd = match pos.func.dfg.value_def(s) {
            ValueDef::Result(i, 0) => i,
            _ => panic!(),
        };

        // Remove `c` from the result list.
        pos.func.stencil.dfg.results[iadd].remove(1, &mut pos.func.stencil.dfg.value_lists);

        // Replace `uadd_overflow` with a normal `iadd` and an `icmp`.
        pos.func.replace(iadd).iadd(v1, arg0);
        let c2 = pos.ins().icmp(IntCC::Equal, s, v1);
        pos.func.dfg.change_to_alias(c, c2);

        assert_eq!(pos.func.dfg.resolve_aliases(c2), c2);
        assert_eq!(pos.func.dfg.resolve_aliases(c), c2);
    }

    #[test]
    fn cloning() {