VM: Print more details with grain-dump.

[schungx]

grain-dump is a very useful tool.

This PR extends it with more information, such as constant values, variable/function names, etc. plus flushing out the display for the Switch and Chain opcodes.

Previous:

    184  56:9      Call { name: 16, argc: 2, op: Some(0), capture_parent_scope: false }
    190  56:9      JumpIfFalse { target: 223 }
    195            LoadLocal(9)
    198  57:22     Chain(8)
    201  57:13     AssignLocal { slot: 8, var_name: 14, op: Some(0) }
    208            Const(9)
    211  58:7      AssignLocal { slot: 9, var_name: 15, op: Some(0) }
    218            Jump(177)
    223            Unit
    224            Pop
    225            Checkpoint
    226            Unit
    227            DeclareLocal { name: 19, is_const: false }
    230            Checkpoint
    231  67:10     PushHandler { target: 296, catch_var: Some(20) }
    238            LoadLocal(8)
    241            Const(7)
    244  63:16     Call { name: 21, argc: 2, op: Some(1), capture_parent_scope: false }
    250  63:16     JumpIfTrue { target: 269 }
    255  63:28     Chain(9, 0 total operands): Local { slot: 4, name: 4 }
    258  63:28     JumpIfTrue { target: 269 }
    263            Bool(false)
    264            Jump(270)
    269            Bool(true)
    270  63:20     JumpIfFalse { target: 279 }
    275            Const(10) = thrown
    278  64:9      Throw
    279            Const(11)
    282  66:20     Chain(10)
    285  66:12     AssignLocal { slot: 10, var_name: 19, op: None }
    290            PopHandler
    291            Jump(308)
    296            LoadLocal(11)
    299  68:12     AssignLocal { slot: 10, var_name: 19, op: None }

Now:

    184  56:9      Call { name: 16, argc: 2, op: Some(0), capture_parent_scope: false } : < (LessThan)
    190  56:9      JumpIfFalse { target: 223 }
    195            LoadLocal(9)
    198  57:22     Chain(8, 1 total operands): Local { slot: 1, name: 1 } counts [0]
    201  57:13     AssignLocal { slot: 8, var_name: 14, op: Some(0) } : doubled += (PlusAssign) / + (Plus)
    208            Const(9) = 1
    211  58:7      AssignLocal { slot: 9, var_name: 15, op: Some(0) } : i += (PlusAssign) / + (Plus)
    218            Jump(177)
    223            Unit
    224            Pop
    225            Checkpoint
    226            Unit
    227            DeclareLocal { name: 19, is_const: false } : let caught
    230            Checkpoint
    231  67:10     PushHandler { target: 296, catch_var: Some(20) }
    238            LoadLocal(8)
    241            Const(7) = 0
    244  63:16     Call { name: 21, argc: 2, op: Some(1), capture_parent_scope: false } : > (GreaterThan)
    250  63:16     JumpIfTrue { target: 269 }
    255  63:28     Chain(9, 0 total operands): Local { slot: 4, name: 4 } flags .off
    258  63:28     JumpIfTrue { target: 269 }
    263            Bool(false)
    264            Jump(270)
    269            Bool(true)
    270  63:20     JumpIfFalse { target: 279 }
    275            Const(10) = thrown
    278  64:9      Throw
    279            Const(11) = 99
    282  66:20     Chain(10, 1 total operands): Local { slot: 1, name: 1 } counts [0]
    285  66:12     AssignLocal { slot: 10, var_name: 19, op: None } : caught
    290            PopHandler
    291            Jump(308)
    296            LoadLocal(11)
    299  68:12     AssignLocal { slot: 10, var_name: 19, op: None } : caught