fix caching for other backends, improve default compiler code

CHANGELOG.md

@@ -5,6 +5,9 @@ All PRs to the Wasmer repository must add to this file.
 Blocks of changes will separated by version increments.
 
 ## **[Unreleased]**
+- [#579](https://github.com/wasmerio/wasmer/pull/579) Fix bug in caching with LLVM and Singlepass backends.
+  Add `default-backend-singlepass`, `default-backend-llvm`, and `default-backend-cranelift` features to `wasmer-runtime`
+  to control the `default_compiler()` function (this is a breaking change).  Add `compiler_for_backend` function in `wasmer-runtime`
 - [#561](https://github.com/wasmerio/wasmer/pull/561) Call the `data_finalizer` field on the `Ctx`
 - [#576](https://github.com/wasmerio/wasmer/pull/576) fix `Drop` of uninit `Ctx`
 - [#542](https://github.com/wasmerio/wasmer/pull/542) Add SIMD support to Wasmer (LLVM backend only)

Cargo.toml

@@ -66,15 +66,16 @@ glob = "0.2.11"
 rustc_version = "0.2.3"
 
 [features]
-default = ["fast-tests", "wasi"]
+default = ["fast-tests", "wasi", "backend-cranelift"]
 "loader-kernel" = ["wasmer-kernel-loader"]
 debug = ["wasmer-runtime-core/debug"]
 trace = ["wasmer-runtime-core/trace"]
 extra-debug = ["wasmer-clif-backend/debug", "wasmer-runtime-core/debug"]
 # This feature will allow cargo test to run much faster
 fast-tests = []
-"backend-llvm" = ["wasmer-llvm-backend", "wasmer-runtime-core/backend-llvm"]
-"backend-singlepass" = ["wasmer-singlepass-backend", "wasmer-runtime-core/backend-singlepass"]
+backend-cranelift = ["wasmer-runtime-core/backend-cranelift", "wasmer-runtime/cranelift"]
+backend-llvm = ["wasmer-llvm-backend", "wasmer-runtime-core/backend-llvm", "wasmer-runtime/llvm"]
+backend-singlepass = ["wasmer-singlepass-backend", "wasmer-runtime-core/backend-singlepass", "wasmer-runtime/singlepass"]
 wasi = ["wasmer-wasi"]
 # vfs = ["wasmer-runtime-abi"]
 

lib/runtime-core/Cargo.toml

@@ -55,5 +55,6 @@ cc = "1.0"
 debug = []
 trace = ["debug"]
 # backend flags used in conditional compilation of Backend::variants
+"backend-cranelift" = []
 "backend-singlepass" = []
 "backend-llvm" = []

lib/runtime-core/src/backend.rs

@@ -32,6 +32,7 @@ pub enum Backend {
 impl Backend {
     pub fn variants() -> &'static [&'static str] {
         &[
+            #[cfg(feature = "backend-cranelift")]
             "cranelift",
             #[cfg(feature = "backend-singlepass")]
             "singlepass",

lib/runtime-core/src/cache.rs

@@ -20,6 +20,7 @@ pub enum Error {
     Unknown(String),
     InvalidFile(InvalidFileType),
     InvalidatedCache,
+    UnsupportedBackend(Backend),
 }
 
 impl From<io::Error> for Error {

lib/runtime/Cargo.toml

@@ -32,12 +32,15 @@ path = "../llvm-backend"
 optional = true
 
 [features]
-default = ["default-compiler"]
-default-compiler = ["wasmer-clif-backend"]
-cache = ["default-compiler"]
+default = ["cranelift", "default-backend-cranelift"]
+cranelift = ["wasmer-clif-backend"]
+cache = ["cranelift"]
 debug = ["wasmer-clif-backend/debug", "wasmer-runtime-core/debug"]
 llvm = ["wasmer-llvm-backend"]
 singlepass = ["wasmer-singlepass-backend"]
+default-backend-singlepass = ["singlepass"]
+default-backend-llvm = ["llvm"]
+default-backend-cranelift = ["cranelift"]
 
 [[bench]]
 name = "nginx"

lib/runtime/src/cache.rs

@@ -103,7 +103,12 @@ impl Cache for FileSystemCache {
 
         let serialized_cache = Artifact::deserialize(&mmap[..])?;
         unsafe {
-            wasmer_runtime_core::load_cache_with(serialized_cache, &super::default_compiler())
+            wasmer_runtime_core::load_cache_with(
+                serialized_cache,
+                super::compiler_for_backend(backend)
+                    .ok_or_else(|| CacheError::UnsupportedBackend(backend))?
+                    .as_ref(),
+            )
         }
     }
 

lib/runtime/src/lib.rs

@@ -76,6 +76,7 @@
 //! [`wasmer-clif-backend`]: https://crates.io/crates/wasmer-clif-backend
 //! [`compile_with`]: fn.compile_with.html
 
+pub use wasmer_runtime_core::backend::Backend;
 pub use wasmer_runtime_core::codegen::{MiddlewareChain, StreamingCompiler};
 pub use wasmer_runtime_core::export::Export;
 pub use wasmer_runtime_core::global::Global;
@@ -179,17 +180,56 @@ pub fn instantiate(wasm: &[u8], import_object: &ImportObject) -> error::Result<I
 
 /// Get a single instance of the default compiler to use.
 pub fn default_compiler() -> impl Compiler {
-    #[cfg(feature = "llvm")]
+    #[cfg(any(
+        all(
+            feature = "default-backend-llvm",
+            any(
+                feature = "default-backend-cranelift",
+                feature = "default-backend-singlepass"
+            )
+        ),
+        all(
+            feature = "default-backend-cranelift",
+            feature = "default-backend-singlepass"
+        )
+    ))]
+    compile_error!(
+        "The `default-backend-X` features are mutually exclusive.  Please choose just one"
+    );
+
+    #[cfg(feature = "default-backend-llvm")]
     use wasmer_llvm_backend::LLVMCompiler as DefaultCompiler;
 
-    #[cfg(feature = "singlepass")]
+    #[cfg(feature = "default-backend-singlepass")]
     use wasmer_singlepass_backend::SinglePassCompiler as DefaultCompiler;
 
-    #[cfg(not(any(feature = "llvm", feature = "singlepass")))]
+    #[cfg(feature = "default-backend-cranelift")]
     use wasmer_clif_backend::CraneliftCompiler as DefaultCompiler;
 
     DefaultCompiler::new()
 }
 
+pub fn compiler_for_backend(backend: Backend) -> Option<Box<dyn Compiler>> {
+    match backend {
+        #[cfg(feature = "cranelift")]
+        Backend::Cranelift => Some(Box::new(wasmer_clif_backend::CraneliftCompiler::new())),
+
+        #[cfg(feature = "singlepass")]
+        Backend::Singlepass => Some(Box::new(
+            wasmer_singlepass_backend::SinglePassCompiler::new(),
+        )),
+
+        #[cfg(feature = "llvm")]
+        Backend::LLVM => Some(Box::new(wasmer_llvm_backend::LLVMCompiler::new())),
+
+        #[cfg(any(
+            not(feature = "llvm"),
+            not(feature = "singlepass"),
+            not(feature = "cranelift")
+        ))]
+        _ => None,
+    }
+}
+
 /// The current version of this crate
 pub const VERSION: &str = env!("CARGO_PKG_VERSION");