Refactored code structure

src/build/core/CompileCall.go

@@ -0,0 +1,39 @@
+package core
+
+import (
+	"git.akyoto.dev/cli/q/src/build/cpu"
+	"git.akyoto.dev/cli/q/src/build/expression"
+)
+
+// CompileCall executes a function call.
+// All call registers must hold the correct parameter values before the function invocation.
+// Registers that are in use must be saved if they are modified by the function.
+// After the function call, they must be restored in reverse order.
+func (f *Function) CompileCall(expr *expression.Expression) error {
+	_, err := f.EvaluateCall(expr)
+	return err
+}
+
+// CompileSyscall executes a syscall.
+func (f *Function) CompileSyscall(expr *expression.Expression) error {
+	parameters := expr.Children[1:]
+	registers := f.cpu.Syscall[:len(parameters)]
+	err := f.ExpressionsToRegisters(parameters, registers)
+	f.assembler.Syscall()
+	f.sideEffects++
+	return err
+}
+
+// ExpressionsToRegisters moves multiple expressions into the specified registers.
+func (f *Function) ExpressionsToRegisters(expressions []*expression.Expression, registers []cpu.Register) error {
+	for i := len(registers) - 1; i >= 0; i-- {
+		f.SaveRegister(registers[i])
+		err := f.EvaluateTo(expressions[i], registers[i])
+
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}