Function program_with_loop

cranelift/frontend/src/ssa.rs:851–973

()

    #[test]
    fn program_with_loop() {
        let mut func = Function::new();
        let mut ssa = SSABuilder::default();
        let block0 = func.dfg.make_block();
        let block1 = func.dfg.make_block();
        let block2 = func.dfg.make_block();
        let block3 = func.dfg.make_block();
        {
            let mut cur = FuncCursor::new(&mut func);
            cur.insert_block(block0);
            cur.insert_block(block1);
            cur.insert_block(block2);
            cur.insert_block(block3);
        }
        // Here is the pseudo-program we want to translate:
        // block0:
        //    x = 1;
        //    y = 2;
        //    z = x + y;
        //    jump block1
        // block1:
        //    z = z + y;
        //    brif y, block3, block2;
        // block2:
        //    z = z - x;
        //    return y
        // block3:
        //    y = y - x
        //    jump block1

        // block0
        ssa.declare_block(block0);
        ssa.seal_block(block0, &mut func);
        let x_var = Variable::new(0);
        let x1 = {
            let mut cur = FuncCursor::new(&mut func).at_bottom(block0);
            cur.ins().iconst(I32, 1)
        };
        ssa.def_var(x_var, x1, block0);
        let y_var = Variable::new(1);
        let y1 = {
            let mut cur = FuncCursor::new(&mut func).at_bottom(block0);
            cur.ins().iconst(I32, 2)
        };
        ssa.def_var(y_var, y1, block0);
        let z_var = Variable::new(2);
        let x2 = ssa.use_var(&mut func, x_var, I32, block0).0;
        let y2 = ssa.use_var(&mut func, y_var, I32, block0).0;
        let z1 = {
            let mut cur = FuncCursor::new(&mut func).at_bottom(block0);
            cur.ins().iadd(x2, y2)
        };
        ssa.def_var(z_var, z1, block0);
        let jump_block0_block1 = {
            let mut cur = FuncCursor::new(&mut func).at_bottom(block0);
            cur.ins().jump(block1, &[])
        };
        assert_eq!(ssa.use_var(&mut func, x_var, I32, block0).0, x1);