Implemented a basic optimization

src/build/asm/Instructions.go

@@ -15,6 +15,10 @@ func (a *Assembler) RegisterNumber(mnemonic Mnemonic, reg cpu.Register, number i
 
 // RegisterRegister adds an instruction using two registers.
 func (a *Assembler) RegisterRegister(mnemonic Mnemonic, left cpu.Register, right cpu.Register) {
+	if a.unnecessary(mnemonic, left, right) {
+		return
+	}
+
 	a.Instructions = append(a.Instructions, Instruction{
 		Mnemonic: mnemonic,
 		Data: &RegisterRegister{

src/build/asm/Optimizer.go

@@ -0,0 +1,34 @@
+package asm
+
+import "git.akyoto.dev/cli/q/src/build/cpu"
+
+// unnecessary returns true if the register/register operation can be skipped.
+func (a *Assembler) unnecessary(mnemonic Mnemonic, left cpu.Register, right cpu.Register) bool {
+	if mnemonic == MOVE && left == right {
+		return true
+	}
+
+	if len(a.Instructions) == 0 {
+		return false
+	}
+
+	last := a.Instructions[len(a.Instructions)-1]
+
+	if mnemonic == MOVE && last.Mnemonic == MOVE {
+		data, isRegReg := last.Data.(*RegisterRegister)
+
+		if !isRegReg {
+			return false
+		}
+
+		if data.Destination == left && data.Source == right {
+			return true
+		}
+
+		if data.Destination == right && data.Source == left {
+			return true
+		}
+	}
+
+	return false
+}