Non-determinism: remove threads, simd, add stack check

src/execution_impl.rs

@@ -10,7 +10,8 @@ use as_ffi_bindings::{Read as ASRead, StringPtr, Write as ASWrite};
 use std::sync::Arc;
 use wasmer::WasmerEnv;
 use wasmer::{
-    imports, CompilerConfig, Function, ImportObject, Instance, Module, Store, Universal, Val,
+    imports, CompilerConfig, Features, Function, ImportObject, Instance, Module, Store, Universal,
+    Val,
 };
 use wasmer::{wasmparser::Operator, BaseTunables, Pages, Target};
 use wasmer_compiler_singlepass::Singlepass;
@@ -24,17 +25,34 @@ fn create_instance(limit: u64, module: &[u8], env: &Env) -> Result<Instance> {
     // See https://docs.rs/wasmer-compiler-singlepass/latest/wasmer_compiler_singlepass/
     let mut compiler_config = Singlepass::new();
 
-    // NaNs are non-deterministic in WASM: https://github.com/WebAssembly/design/blob/main/Nondeterminism.md
-    // Ensure determinism by canonicalizing their representation
+    // Turning-off sources of potential non-determinism,
+    // see https://github.com/WebAssembly/design/blob/037c6fe94151eb13e30d174f5f7ce851be0a573e/Nondeterminism.md
+
+    // Turning-off in the compiler:
+
+    // Canonicalize NaN.
     compiler_config.canonicalize_nans(true);
 
+    // Enable stack check.
+    compiler_config.enable_stack_check(true);
+
+    // Turning-off in wasmer feature flags:
+    let mut features = Features::new();
+
+    // Disable threads.
+    features.threads(false);
+
+    // Turn-off experimental SIMD feature.
+    features.simd(false);
+
     // Add metering middleware
     let metering = Arc::new(Metering::new(limit, |_: &Operator| -> u64 { 1 }));
     compiler_config.push_middleware(metering);
 
     let base = BaseTunables::for_target(&Target::default());
     let tunables = LimitingTunables::new(base, Pages(max_number_of_pages()));
-    let store = Store::new_with_tunables(&Universal::new(compiler_config).engine(), tunables);
+    let engine = Universal::new(compiler_config).features(features).engine();
+    let store = Store::new_with_tunables(&engine, tunables);
     let resolver: ImportObject = imports! {
         "env" => {
             // Needed by wasm generated by AssemblyScript.