first codegen prototype

include/codegen/targets/fasm_x86_64_linux.hpp

@@ -0,0 +1,70 @@
+#pragma once
+#include "codegen/codegen.hpp"
+#include "ir/op.hpp"
+#include "ir/ops.hpp"
+#include "prelude/linkedlist.hpp"
+
+class FasmX86_64Generator : public CodeGenerator
+{
+public:
+    FasmX86_64Generator() = default;
+
+public:
+    bool Generate(const IR::OpView* ops) override
+    {
+        output().Extend("format ELF64\n");
+        output().Extend("section '.text' executable\n");
+
+        for (size_t i = 0; i < ops->size; ++i)
+        {
+            GenerateStatement(ops->data[i]);
+        }
+
+        return true;
+    }
+
+private:
+    void GenerateExtern(IR::ExternOp* extrn)
+    {
+        // TODO: instead of __<symbol, use some random UID or hash string
+        // for safety and collision considerations
+        output().AppendFormat("extrn '%s' as __%s\n", extrn->symbol().c_str(), extrn->symbol().c_str());
+        output().AppendFormat("%s = PLT __%s\n", extrn->symbol().c_str(), extrn->symbol().c_str());
+    }
+
+    void GenerateFunction(IR::FnOp* fn)
+    {
+        output().AppendFormat("public %s\n", fn->name().c_str());
+        output().AppendFormat("%s:\n", fn->name().c_str());
+        output().Extend("  push rbp\n");
+        output().Extend("  mov rbp, rsp\n");
+
+        for (auto cur = fn->body().ops().Begin(); cur != nullptr; cur = cur->next)
+        {
+            GenerateStatement(cur->value);
+        }
+
+        output().Extend("  leave\n");
+        output().Extend("  ret\n");
+    }
+
+    void GenerateCall(IR::CallOp* call)
+    {
+        output().AppendFormat("  call %s\n", call->callee().c_str());
+    }
+
+    void GenerateStatement(IR::Op* op)
+    {
+    switch(op->GetType())
+    {
+    case IR::OpType::EXTERN:
+        return GenerateExtern(reinterpret_cast<IR::ExternOp*>(op));
+    case IR::OpType::FN:
+        return GenerateFunction(reinterpret_cast<IR::FnOp*>(op));
+    case IR::OpType::CALL:
+        return GenerateCall(reinterpret_cast<IR::CallOp*>(op));
+    // TODO:
+    default: output().AppendFormat("  ; %d not implemented\n", op->GetType());
+    }
+    }
+};