From 6ca581279811aee9d26d77ed2b7372a6153fe3bf Mon Sep 17 00:00:00 2001
From: Yaron Wittenstein <yaron.wittenstein@gmail.com>
Date: Mon, 7 Oct 2019 16:58:58 +0300
Subject: [PATCH] When `deterministic` feature will be enabled (turned-off by
 default) it'll guarantee deterministic execution of wasm programs across
 different hardware/circumstances. This is very useful for Blockchain projects
 having wasm smart-contracts

This is critical for Blockchain projects that require execution to be deterministic
in order to reach a consensus of the state transition of each smart-contract transaction.
---
 Cargo.toml                        |  4 +++-
 lib/runtime-core/Cargo.toml       |  1 +
 lib/runtime-core/src/codegen.rs   |  3 +++
 lib/runtime-core/src/lib.rs       |  3 +++
 lib/runtime/Cargo.toml            |  1 +
 lib/runtime/src/lib.rs            | 12 +++++++-----
 lib/singlepass-backend/Cargo.toml |  4 ++++
 7 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 4d619059e35..93479c41598 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -26,7 +26,7 @@ wabt = "0.9.1"
 wasmer-clif-backend = { path = "lib/clif-backend" }
 wasmer-singlepass-backend = { path = "lib/singlepass-backend", optional = true }
 wasmer-middleware-common = { path = "lib/middleware-common" }
-wasmer-runtime = { path = "lib/runtime" }
+wasmer-runtime = { path = "lib/runtime", default-features = false }
 wasmer-runtime-core = { path = "lib/runtime-core" }
 wasmer-emscripten = { path = "lib/emscripten" }
 wasmer-llvm-backend = { path = "lib/llvm-backend", optional = true }
@@ -101,6 +101,8 @@ backend-singlepass = [
 wasi = ["wasmer-wasi"]
 managed = ["backend-singlepass", "wasmer-runtime-core/managed"]
 
+deterministic = ["wasmer-runtime/deterministic"]
+
 [[example]]
 name = "plugin"
 crate-type = ["bin"]
diff --git a/lib/runtime-core/Cargo.toml b/lib/runtime-core/Cargo.toml
index 7fd9e32e835..ee1fd19ebff 100644
--- a/lib/runtime-core/Cargo.toml
+++ b/lib/runtime-core/Cargo.toml
@@ -58,3 +58,4 @@ trace = ["debug"]
 "backend-singlepass" = []
 "backend-llvm" = []
 managed = []
+deterministic = ["wasmparser/deterministic"]
diff --git a/lib/runtime-core/src/codegen.rs b/lib/runtime-core/src/codegen.rs
index 3db1b374368..7027d6266a3 100644
--- a/lib/runtime-core/src/codegen.rs
+++ b/lib/runtime-core/src/codegen.rs
@@ -145,6 +145,9 @@ pub fn validating_parser_config(features: &Features) -> wasmparser::ValidatingPa
             enable_simd: features.simd,
             enable_bulk_memory: false,
             enable_multi_value: false,
+
+            #[cfg(feature = "deterministic")]
+            deterministic_only: true,
         },
     }
 }
diff --git a/lib/runtime-core/src/lib.rs b/lib/runtime-core/src/lib.rs
index 26a76f7dbf6..d933b555f30 100644
--- a/lib/runtime-core/src/lib.rs
+++ b/lib/runtime-core/src/lib.rs
@@ -145,6 +145,9 @@ pub fn validate_and_report_errors_with_features(
             enable_multi_value: false,
             enable_reference_types: false,
             enable_threads: features.threads,
+
+            #[cfg(feature = "deterministic")]
+            deterministic_only: true,
         },
     };
     let mut parser = wasmparser::ValidatingParser::new(wasm, Some(config));
diff --git a/lib/runtime/Cargo.toml b/lib/runtime/Cargo.toml
index 2e42055c2e4..a3a59f7e50e 100644
--- a/lib/runtime/Cargo.toml
+++ b/lib/runtime/Cargo.toml
@@ -41,6 +41,7 @@ singlepass = ["wasmer-singlepass-backend"]
 default-backend-singlepass = ["singlepass"]
 default-backend-llvm = ["llvm"]
 default-backend-cranelift = ["cranelift"]
+deterministic = ["wasmer-singlepass-backend/deterministic"]
 
 [[bench]]
 name = "nginx"
diff --git a/lib/runtime/src/lib.rs b/lib/runtime/src/lib.rs
index 2945ff3d534..3505de6492d 100644
--- a/lib/runtime/src/lib.rs
+++ b/lib/runtime/src/lib.rs
@@ -70,7 +70,7 @@
 //!     let value = add_one.call(42)?;
 //!
 //!     assert_eq!(value, 43);
-//!     
+//!
 //!     Ok(())
 //! }
 //! ```
@@ -199,13 +199,15 @@ pub fn default_compiler() -> impl Compiler {
             feature = "default-backend-llvm",
             any(
                 feature = "default-backend-cranelift",
-                feature = "default-backend-singlepass"
+                feature = "default-backend-singlepass",
+                feature = "deterministic"
             )
         ),
         all(
             feature = "default-backend-cranelift",
-            feature = "default-backend-singlepass"
-        )
+            any(feature = "default-backend-singlepass", feature = "deterministic")
+        ),
+        all(feature = "default-backend-singlepass", feature = "deterministic")
     ))]
     compile_error!(
         "The `default-backend-X` features are mutually exclusive.  Please choose just one"
@@ -214,7 +216,7 @@ pub fn default_compiler() -> impl Compiler {
     #[cfg(feature = "default-backend-llvm")]
     use wasmer_llvm_backend::LLVMCompiler as DefaultCompiler;
 
-    #[cfg(feature = "default-backend-singlepass")]
+    #[cfg(any(feature = "default-backend-singlepass", feature = "deterministic"))]
     use wasmer_singlepass_backend::SinglePassCompiler as DefaultCompiler;
 
     #[cfg(feature = "default-backend-cranelift")]
diff --git a/lib/singlepass-backend/Cargo.toml b/lib/singlepass-backend/Cargo.toml
index 5243cc60150..d6dc63c7a2d 100644
--- a/lib/singlepass-backend/Cargo.toml
+++ b/lib/singlepass-backend/Cargo.toml
@@ -18,3 +18,7 @@ byteorder = "1.3"
 nix = "0.15"
 libc = "0.2.60"
 smallvec = "0.6"
+
+[features]
+default = []
+deterministic = ["wasmparser/deterministic", "wasmer-runtime-core/deterministic"]