diff options
Diffstat (limited to 'vm')
| -rw-r--r-- | vm/vm.go | 12 |
1 files changed, 12 insertions, 0 deletions
@@ -22,6 +22,7 @@ const ( Dup // addr -- value ; value = mem[addr] Fdup // addr -- value ; value = mem[addr] Equal // n1 n2 -- cond ; cond = n1 == n2 + EqualSet // n1 n2 -- n1 cond ; cond = n1 == n2 Exit // -- ; Greater // n1 n2 -- cond; cond = n1 > n2 Jump // -- ; ip += $1 @@ -48,6 +49,7 @@ var strop = [...]string{ // for VM tracing. CallX: "CallX", Dup: "Dup", Equal: "Equal", + EqualSet: "EqualSet", Exit: "Exit", Fassign: "Fassign", Fdup: "Fdup", @@ -141,6 +143,16 @@ func (m *Machine) Run() (err error) { case Equal: mem[sp-2] = mem[sp-2].(int) == mem[sp-1].(int) mem = mem[:sp-1] + case EqualSet: + if mem[sp-2].(int) == mem[sp-1].(int) { + // If equal then lhs and rhs are popped, replaced by test result, as in Equal. + mem[sp-2] = true + mem = mem[:sp-1] + } else { + // If not equal then the lhs is let on stack for further processing. + // This is used to simplify bytecode in case clauses of switch statments. + mem[sp-1] = false + } case Exit: return err case Fdup: |