Added fibonacci example

src/build/core/SaveRegister.go

@@ -0,0 +1,37 @@
+package core
+
+import (
+	"fmt"
+
+	"git.akyoto.dev/cli/q/src/build/asm"
+	"git.akyoto.dev/cli/q/src/build/config"
+	"git.akyoto.dev/cli/q/src/build/cpu"
+)
+
+// SaveRegister attempts to move a variable occupying this register to another register.
+func (f *Function) SaveRegister(register cpu.Register) {
+	var variable *Variable
+
+	for _, v := range f.variables {
+		if v.Register == register {
+			variable = v
+			break
+		}
+	}
+
+	if variable == nil || variable.Alive == 0 {
+		return
+	}
+
+	newRegister := f.cpu.MustFindFree(f.cpu.General)
+	f.cpu.Reserve(newRegister)
+	f.cpu.Use(newRegister)
+
+	if config.Comments {
+		f.assembler.Comment(fmt.Sprintf("save %s to %s", register, newRegister))
+	}
+
+	f.assembler.RegisterRegister(asm.MOVE, newRegister, register)
+	f.cpu.Free(register)
+	variable.Register = newRegister
+}