Add clif-backend crate and runtime example

lib/clif-backend/src/lib.rs

@@ -0,0 +1,70 @@
+mod codegen;
+mod libcalls;
+mod relocation;
+mod resolver;
+
+use wasmer_runtime::{Compiler, Module};
+use cranelift_codegen::{settings::{self, Configurable}, isa};
+use target_lexicon::Triple;
+use wasmparser::{self, WasmDecoder};
+
+use self::codegen::CraneliftModule;
+use self::codegen::converter;
+
+pub struct CraneliftCompiler {}
+
+impl CraneliftCompiler {
+    pub fn new() -> Self {
+        Self {}
+    }
+}
+
+impl Compiler for CraneliftCompiler {
+    // Compiles wasm binary to a wasmer module
+    fn compile(&self, wasm: &[u8]) -> Result<Module, String> {
+        validate(wasm)?;
+
+        let isa = get_isa();
+        // Generate a Cranlift module from wasm binary
+        let cranelift_module = CraneliftModule::from_bytes(&wasm.to_vec(), isa.frontend_config())?;
+
+        // Convert Cranelift module to wasmer module
+        let wasmer_module = converter::convert_module(cranelift_module);
+
+        // Return new wasmer module
+        Ok(Module::new(wasmer_module))
+    }
+}
+
+fn get_isa() -> Box<isa::TargetIsa> {
+    let flags = {
+        let mut builder = settings::builder();
+        builder.set("opt_level", "best").unwrap();
+
+        if cfg!(not(test)) {
+            builder.set("enable_verifier", "false").unwrap();
+        }
+
+        let flags = settings::Flags::new(builder);
+        debug_assert_eq!(flags.opt_level(), settings::OptLevel::Best);
+        flags
+    };
+    isa::lookup(Triple::host()).unwrap().finish(flags)
+}
+
+fn validate(bytes: &[u8]) -> Result<(), String> {
+    let mut parser = wasmparser::ValidatingParser::new(bytes, None);
+    loop {
+        let state = parser.read();
+        match *state {
+            wasmparser::ParserState::EndWasm => return Ok(()),
+            wasmparser::ParserState::Error(err) => {
+                return Err(format!(
+                    "Validation error: {}",
+                    err.message
+                ));
+            }
+            _ => (),
+        }
+    }
+}