Phase 8.1 Complete: WASM backend foundation implementation

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

src/backend/wasm/mod.rs

@@ -0,0 +1,131 @@
+/*!
+ * WASM Backend - Phase 8 Implementation
+ * 
+ * Converts MIR instructions to WebAssembly for sandboxed execution
+ * Targets browser execution and wasmtime runtime
+ */
+
+mod codegen;
+mod memory;
+mod runtime;
+
+pub use codegen::{WasmCodegen, WasmModule};
+pub use memory::{MemoryManager, BoxLayout};
+pub use runtime::RuntimeImports;
+
+use crate::mir::{MirModule, MirFunction};
+use std::collections::HashMap;
+
+/// WASM compilation error
+#[derive(Debug)]
+pub enum WasmError {
+    CodegenError(String),
+    MemoryError(String),
+    UnsupportedInstruction(String),
+    WasmValidationError(String),
+    IOError(String),
+}
+
+impl std::fmt::Display for WasmError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            WasmError::CodegenError(msg) => write!(f, "Codegen error: {}", msg),
+            WasmError::MemoryError(msg) => write!(f, "Memory error: {}", msg),
+            WasmError::UnsupportedInstruction(msg) => write!(f, "Unsupported instruction: {}", msg),
+            WasmError::WasmValidationError(msg) => write!(f, "WASM validation error: {}", msg),
+            WasmError::IOError(msg) => write!(f, "IO error: {}", msg),
+        }
+    }
+}
+
+impl std::error::Error for WasmError {}
+
+/// Main WASM backend compiler
+pub struct WasmBackend {
+    codegen: WasmCodegen,
+    memory_manager: MemoryManager,
+    runtime: RuntimeImports,
+}
+
+impl WasmBackend {
+    /// Create a new WASM backend
+    pub fn new() -> Self {
+        Self {
+            codegen: WasmCodegen::new(),
+            memory_manager: MemoryManager::new(),
+            runtime: RuntimeImports::new(),
+        }
+    }
+    
+    /// Compile MIR module to WASM bytes
+    pub fn compile_module(&mut self, mir_module: MirModule) -> Result<Vec<u8>, WasmError> {
+        // Generate WAT (WebAssembly Text) first for debugging
+        let wat_text = self.compile_to_wat(mir_module)?;
+        
+        // Convert WAT to WASM binary using wabt
+        wabt::wat2wasm(&wat_text)
+            .map_err(|e| WasmError::WasmValidationError(format!("WAT to WASM conversion failed: {}", e)))
+    }
+    
+    /// Compile MIR module to WAT text format (for debugging)
+    pub fn compile_to_wat(&mut self, mir_module: MirModule) -> Result<String, WasmError> {
+        let wasm_module = self.codegen.generate_module(mir_module, &self.memory_manager, &self.runtime)?;
+        Ok(wasm_module.to_wat())
+    }
+    
+    /// Execute WASM bytes using wasmtime (for testing)
+    pub fn execute_wasm(&self, wasm_bytes: &[u8]) -> Result<i32, WasmError> {
+        let engine = wasmtime::Engine::default();
+        let module = wasmtime::Module::new(&engine, wasm_bytes)
+            .map_err(|e| WasmError::WasmValidationError(format!("Module creation failed: {}", e)))?;
+        
+        let mut store = wasmtime::Store::new(&engine, ());
+        
+        // Create print function import
+        let print_func = wasmtime::Func::wrap(&mut store, |value: i32| {
+            println!("{}", value);
+        });
+        
+        let imports = [print_func.into()];
+        let instance = wasmtime::Instance::new(&mut store, &module, &imports)
+            .map_err(|e| WasmError::WasmValidationError(format!("Instance creation failed: {}", e)))?;
+        
+        // Call main function
+        let main_func = instance.get_typed_func::<(), i32>(&mut store, "main")
+            .map_err(|e| WasmError::WasmValidationError(format!("Main function not found: {}", e)))?;
+        
+        let result = main_func.call(&mut store, ())
+            .map_err(|e| WasmError::WasmValidationError(format!("Execution failed: {}", e)))?;
+        
+        Ok(result)
+    }
+}
+
+impl Default for WasmBackend {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::mir::MirModule;
+    
+    #[test]
+    fn test_backend_creation() {
+        let _backend = WasmBackend::new();
+        // Should not panic
+        assert!(true);
+    }
+    
+    #[test]
+    fn test_empty_module_compilation() {
+        let mut backend = WasmBackend::new();
+        let module = MirModule::new("test".to_string());
+        
+        // Should handle empty module gracefully
+        let result = backend.compile_to_wat(module);
+        assert!(result.is_ok());
+    }
+}