Added build result struct

src/build/Result.go

@@ -0,0 +1,42 @@
+package build
+
+import (
+	"git.akyoto.dev/cli/q/src/build/arch/x64"
+	"git.akyoto.dev/cli/q/src/build/asm"
+	"git.akyoto.dev/cli/q/src/build/os/linux"
+)
+
+// Result contains all the compiled functions in a build.
+type Result struct {
+	Functions        map[string]*Function
+	instructionCount int
+}
+
+// Finalize generates the final machine code.
+func (r Result) Finalize() ([]byte, []byte) {
+	// This will be the entry point of the executable.
+	// The only job of the entry function is to call `main` and exit cleanly.
+	// The reason we call `main` instead of using `main` itself is to place
+	// a return address on the stack, which allows return statements in `main`.
+	final := asm.Assembler{
+		Instructions: make([]asm.Instruction, 0, r.instructionCount+4),
+	}
+
+	final.Call("main")
+	final.RegisterNumber(asm.MOVE, x64.SyscallRegisters[0], linux.Exit)
+	final.RegisterNumber(asm.MOVE, x64.SyscallRegisters[1], 0)
+	final.Syscall()
+
+	// Place the `main` function immediately after the entry point.
+	main := r.Functions["main"]
+	delete(r.Functions, "main")
+	final.Merge(&main.Assembler)
+
+	// Merge all the remaining functions.
+	for _, f := range r.Functions {
+		final.Merge(&f.Assembler)
+	}
+
+	code, data := final.Finalize()
+	return code, data
+}