Implement LLVM backend basic structure - Phase 9.78 Week 1 foundation

Co-authored-by: moe-charm <217100418+moe-charm@users.noreply.github.com>

src/backend/llvm/context.rs

@@ -0,0 +1,70 @@
+/*!
+ * LLVM Context Management - Handle LLVM context, module, and target setup
+ */
+
+#[cfg(feature = "llvm")]
+use inkwell::context::Context;
+#[cfg(feature = "llvm")]
+use inkwell::module::Module;
+#[cfg(feature = "llvm")]
+use inkwell::builder::Builder;
+#[cfg(feature = "llvm")]
+use inkwell::targets::{Target, TargetMachine, TargetTriple, InitializationConfig};
+
+#[cfg(feature = "llvm")]
+pub struct CodegenContext<'ctx> {
+    pub context: &'ctx Context,
+    pub module: Module<'ctx>,
+    pub builder: Builder<'ctx>,
+    pub target_machine: TargetMachine,
+}
+
+#[cfg(feature = "llvm")]
+impl<'ctx> CodegenContext<'ctx> {
+    pub fn new(context: &'ctx Context, module_name: &str) -> Result<Self, String> {
+        // 1. ターゲット初期化
+        Target::initialize_native(&InitializationConfig::default())
+            .map_err(|e| format!("Failed to initialize native target: {}", e))?;
+        
+        // 2. モジュール作成
+        let module = context.create_module(module_name);
+        
+        // 3. ターゲットマシン作成
+        let triple = TargetMachine::get_default_triple();
+        let target = Target::from_triple(&triple)
+            .map_err(|e| format!("Failed to get target: {}", e))?;
+        let target_machine = target
+            .create_target_machine(
+                &triple,
+                "generic",
+                "",
+                inkwell::OptimizationLevel::None,
+                inkwell::targets::RelocMode::Default,
+                inkwell::targets::CodeModel::Default,
+            )
+            .ok_or_else(|| "Failed to create target machine".to_string())?;
+        
+        // 4. データレイアウト設定
+        module.set_triple(&triple);
+        module.set_data_layout(&target_machine.get_target_data().get_data_layout());
+        
+        Ok(Self {
+            context,
+            module,
+            builder: context.create_builder(),
+            target_machine,
+        })
+    }
+}
+
+#[cfg(not(feature = "llvm"))]
+pub struct CodegenContext<'ctx> {
+    _phantom: std::marker::PhantomData<&'ctx ()>,
+}
+
+#[cfg(not(feature = "llvm"))]
+impl<'ctx> CodegenContext<'ctx> {
+    pub fn new(_context: &'ctx (), _module_name: &str) -> Result<Self, String> {
+        Err("LLVM feature not enabled".to_string())
+    }
+}