From 170ffa276634045549bf6d329e3da1c3a57f0492 Mon Sep 17 00:00:00 2001
From: Yaron Wittenstein <yaron.wittenstein@gmail.com>
Date: Mon, 7 Oct 2019 13:01:54 +0300
Subject: [PATCH 01/11] adding tests for `state_creator` of `import_object`

---
 lib/runtime-core/src/import.rs | 50 ++++++++++++++++++++++++++++++++++
 lib/runtime-core/src/lib.rs    |  2 +-
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/lib/runtime-core/src/import.rs b/lib/runtime-core/src/import.rs
index 9d86205b156..aef51405549 100644
--- a/lib/runtime-core/src/import.rs
+++ b/lib/runtime-core/src/import.rs
@@ -254,6 +254,56 @@ mod test {
     use crate::export::Export;
     use crate::global::Global;
     use crate::types::Value;
+    use std::ffi::c_void;
+    use std::sync::Arc;
+
+    struct Data {
+        inner: *const c_void,
+    }
+
+    unsafe impl Send for Data {}
+    unsafe impl Sync for Data {}
+
+    fn dummy_state_creator(data: Arc<Data>) -> (*mut c_void, fn(*mut c_void)) {
+        let data: *mut Data = Arc::into_raw(data) as _;
+
+        (data as _, |_| {})
+    }
+
+    #[test]
+    fn state_creator_fn() {
+        let ptr = std::ptr::null();
+
+        let data = Arc::new(Data { inner: ptr });
+
+        let imports = imports! {
+            move || dummy_state_creator(Arc::clone(&data)),
+        };
+
+        let (state, _dtor) = imports.call_state_creator().unwrap();
+        let data: &mut Data = unsafe { &mut *(state as *mut Data) };
+
+        assert_eq!(ptr, data.inner);
+    }
+
+    #[test]
+    fn state_creator_closure() {
+        let ptr = std::ptr::null();
+
+        let data = Arc::new(Data { inner: ptr });
+
+        let imports = imports! {
+            move || {
+                let data: *mut Data = Arc::into_raw(Arc::clone(&data)) as _;
+                (data as _, |_| {})
+            },
+        };
+
+        let (state, _dtor) = imports.call_state_creator().unwrap();
+        let data: &mut Data = unsafe { &mut *(state as *mut Data) };
+
+        assert_eq!(ptr, data.inner);
+    }
 
     #[test]
     fn extending_works() {
diff --git a/lib/runtime-core/src/lib.rs b/lib/runtime-core/src/lib.rs
index 26a76f7dbf6..d9c0d06f0b3 100644
--- a/lib/runtime-core/src/lib.rs
+++ b/lib/runtime-core/src/lib.rs
@@ -1,4 +1,4 @@
-#![deny(
+#![allow(
     dead_code,
     nonstandard_style,
     unused_imports,

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 02/11] 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"]

From 4adfbc4f01f83c31d995f5f05480442c2ecdf4a6 Mon Sep 17 00:00:00 2001
From: Yaron Wittenstein <yaron.wittenstein@gmail.com>
Date: Mon, 7 Oct 2019 22:02:33 +0300
Subject: [PATCH 03/11] fixes to PR

---
 lib/runtime-core/src/import.rs | 8 +++-----
 lib/runtime-core/src/lib.rs    | 2 +-
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/lib/runtime-core/src/import.rs b/lib/runtime-core/src/import.rs
index aef51405549..51bfda71a33 100644
--- a/lib/runtime-core/src/import.rs
+++ b/lib/runtime-core/src/import.rs
@@ -258,7 +258,7 @@ mod test {
     use std::sync::Arc;
 
     struct Data {
-        inner: *const c_void,
+        inner: *const u32,
     }
 
     unsafe impl Send for Data {}
@@ -272,8 +272,7 @@ mod test {
 
     #[test]
     fn state_creator_fn() {
-        let ptr = std::ptr::null();
-
+        let ptr = &0xAABBCCDDu32 as *const u32;
         let data = Arc::new(Data { inner: ptr });
 
         let imports = imports! {
@@ -288,8 +287,7 @@ mod test {
 
     #[test]
     fn state_creator_closure() {
-        let ptr = std::ptr::null();
-
+        let ptr = &0xAABBCCDDu32 as *const u32;
         let data = Arc::new(Data { inner: ptr });
 
         let imports = imports! {
diff --git a/lib/runtime-core/src/lib.rs b/lib/runtime-core/src/lib.rs
index d9c0d06f0b3..26a76f7dbf6 100644
--- a/lib/runtime-core/src/lib.rs
+++ b/lib/runtime-core/src/lib.rs
@@ -1,4 +1,4 @@
-#![allow(
+#![deny(
     dead_code,
     nonstandard_style,
     unused_imports,

From 7ce5ec4df9ad6056b77389321003229253cddaa8 Mon Sep 17 00:00:00 2001
From: Yaron Wittenstein <yaron.wittenstein@gmail.com>
Date: Mon, 7 Oct 2019 22:34:32 +0300
Subject: [PATCH 04/11] fixes to PR comments

---
 Cargo.toml             | 3 +--
 lib/runtime/Cargo.toml | 2 +-
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 93479c41598..467e65419e5 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", default-features = false }
+wasmer-runtime = { path = "lib/runtime" }
 wasmer-runtime-core = { path = "lib/runtime-core" }
 wasmer-emscripten = { path = "lib/emscripten" }
 wasmer-llvm-backend = { path = "lib/llvm-backend", optional = true }
@@ -100,7 +100,6 @@ backend-singlepass = [
 ]
 wasi = ["wasmer-wasi"]
 managed = ["backend-singlepass", "wasmer-runtime-core/managed"]
-
 deterministic = ["wasmer-runtime/deterministic"]
 
 [[example]]
diff --git a/lib/runtime/Cargo.toml b/lib/runtime/Cargo.toml
index a3a59f7e50e..838eed3ce57 100644
--- a/lib/runtime/Cargo.toml
+++ b/lib/runtime/Cargo.toml
@@ -41,7 +41,7 @@ singlepass = ["wasmer-singlepass-backend"]
 default-backend-singlepass = ["singlepass"]
 default-backend-llvm = ["llvm"]
 default-backend-cranelift = ["cranelift"]
-deterministic = ["wasmer-singlepass-backend/deterministic"]
+deterministic = ["wasmer-singlepass-backend/deterministic", "wasmer-runtime-core/deterministic"]
 
 [[bench]]
 name = "nginx"

From 899099f3256a1c9ced175d9864da6a7ca5166cd7 Mon Sep 17 00:00:00 2001
From: Yaron Wittenstein <yaron.wittenstein@gmail.com>
Date: Mon, 7 Oct 2019 22:58:46 +0300
Subject: [PATCH 05/11] Cargo.toml - removing `deterministic` feature flag

---
 Cargo.toml | 1 -
 1 file changed, 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index 467e65419e5..4d619059e35 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -100,7 +100,6 @@ backend-singlepass = [
 ]
 wasi = ["wasmer-wasi"]
 managed = ["backend-singlepass", "wasmer-runtime-core/managed"]
-deterministic = ["wasmer-runtime/deterministic"]
 
 [[example]]
 name = "plugin"

From 3489bfb9b9814f84424b63cff7dec297a6a4f1d6 Mon Sep 17 00:00:00 2001
From: Yaron Wittenstein <yaron.wittenstein@gmail.com>
Date: Mon, 7 Oct 2019 23:07:20 +0300
Subject: [PATCH 06/11] renamed feature flag `deterministic` to
 `deterministic-execution`

---
 lib/runtime-core/Cargo.toml       |  2 +-
 lib/runtime-core/src/codegen.rs   |  2 +-
 lib/runtime-core/src/lib.rs       |  2 +-
 lib/runtime/Cargo.toml            |  2 +-
 lib/runtime/src/lib.rs            | 22 ++++++++++++++++------
 lib/singlepass-backend/Cargo.toml |  2 +-
 6 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/lib/runtime-core/Cargo.toml b/lib/runtime-core/Cargo.toml
index ee1fd19ebff..f4f80d985c5 100644
--- a/lib/runtime-core/Cargo.toml
+++ b/lib/runtime-core/Cargo.toml
@@ -58,4 +58,4 @@ trace = ["debug"]
 "backend-singlepass" = []
 "backend-llvm" = []
 managed = []
-deterministic = ["wasmparser/deterministic"]
+deterministic-execution = ["wasmparser/deterministic"]
diff --git a/lib/runtime-core/src/codegen.rs b/lib/runtime-core/src/codegen.rs
index 7027d6266a3..8d98bb0c0f9 100644
--- a/lib/runtime-core/src/codegen.rs
+++ b/lib/runtime-core/src/codegen.rs
@@ -146,7 +146,7 @@ pub fn validating_parser_config(features: &Features) -> wasmparser::ValidatingPa
             enable_bulk_memory: false,
             enable_multi_value: false,
 
-            #[cfg(feature = "deterministic")]
+            #[cfg(feature = "deterministic-execution")]
             deterministic_only: true,
         },
     }
diff --git a/lib/runtime-core/src/lib.rs b/lib/runtime-core/src/lib.rs
index d933b555f30..accea76414d 100644
--- a/lib/runtime-core/src/lib.rs
+++ b/lib/runtime-core/src/lib.rs
@@ -146,7 +146,7 @@ pub fn validate_and_report_errors_with_features(
             enable_reference_types: false,
             enable_threads: features.threads,
 
-            #[cfg(feature = "deterministic")]
+            #[cfg(feature = "deterministic-execution")]
             deterministic_only: true,
         },
     };
diff --git a/lib/runtime/Cargo.toml b/lib/runtime/Cargo.toml
index 838eed3ce57..8ed986c5041 100644
--- a/lib/runtime/Cargo.toml
+++ b/lib/runtime/Cargo.toml
@@ -41,7 +41,7 @@ singlepass = ["wasmer-singlepass-backend"]
 default-backend-singlepass = ["singlepass"]
 default-backend-llvm = ["llvm"]
 default-backend-cranelift = ["cranelift"]
-deterministic = ["wasmer-singlepass-backend/deterministic", "wasmer-runtime-core/deterministic"]
+deterministic-execution = ["wasmer-singlepass-backend/deterministic-execution", "wasmer-runtime-core/deterministic-execution"]
 
 [[bench]]
 name = "nginx"
diff --git a/lib/runtime/src/lib.rs b/lib/runtime/src/lib.rs
index 3505de6492d..903dc47836e 100644
--- a/lib/runtime/src/lib.rs
+++ b/lib/runtime/src/lib.rs
@@ -200,14 +200,20 @@ pub fn default_compiler() -> impl Compiler {
             any(
                 feature = "default-backend-cranelift",
                 feature = "default-backend-singlepass",
-                feature = "deterministic"
+                feature = "deterministic-execution"
             )
         ),
         all(
             feature = "default-backend-cranelift",
-            any(feature = "default-backend-singlepass", feature = "deterministic")
+            any(
+                feature = "default-backend-singlepass",
+                feature = "deterministic-execution"
+            )
         ),
-        all(feature = "default-backend-singlepass", feature = "deterministic")
+        all(
+            feature = "default-backend-singlepass",
+            feature = "deterministic-execution"
+        )
     ))]
     compile_error!(
         "The `default-backend-X` features are mutually exclusive.  Please choose just one"
@@ -216,7 +222,10 @@ pub fn default_compiler() -> impl Compiler {
     #[cfg(feature = "default-backend-llvm")]
     use wasmer_llvm_backend::LLVMCompiler as DefaultCompiler;
 
-    #[cfg(any(feature = "default-backend-singlepass", feature = "deterministic"))]
+    #[cfg(any(
+        feature = "default-backend-singlepass",
+        feature = "deterministic-execution"
+    ))]
     use wasmer_singlepass_backend::SinglePassCompiler as DefaultCompiler;
 
     #[cfg(feature = "default-backend-cranelift")]
@@ -235,7 +244,7 @@ pub fn compiler_for_backend(backend: Backend) -> Option<Box<dyn Compiler>> {
         #[cfg(feature = "cranelift")]
         Backend::Cranelift => Some(Box::new(wasmer_clif_backend::CraneliftCompiler::new())),
 
-        #[cfg(feature = "singlepass")]
+        #[cfg(any(feature = "singlepass", feature = "deterministic-execution"))]
         Backend::Singlepass => Some(Box::new(
             wasmer_singlepass_backend::SinglePassCompiler::new(),
         )),
@@ -246,7 +255,8 @@ pub fn compiler_for_backend(backend: Backend) -> Option<Box<dyn Compiler>> {
         #[cfg(any(
             not(feature = "llvm"),
             not(feature = "singlepass"),
-            not(feature = "cranelift")
+            not(feature = "cranelift"),
+            not(feature = "deterministic-execution"),
         ))]
         _ => None,
     }
diff --git a/lib/singlepass-backend/Cargo.toml b/lib/singlepass-backend/Cargo.toml
index d6dc63c7a2d..e3a40548ecd 100644
--- a/lib/singlepass-backend/Cargo.toml
+++ b/lib/singlepass-backend/Cargo.toml
@@ -21,4 +21,4 @@ smallvec = "0.6"
 
 [features]
 default = []
-deterministic = ["wasmparser/deterministic", "wasmer-runtime-core/deterministic"]
+deterministic-execution = ["wasmparser/deterministic", "wasmer-runtime-core/deterministic-execution"]

From 176b938cb617493faa4fff33727eeecda5baa82a Mon Sep 17 00:00:00 2001
From: Mark McCaskey <5770194+MarkMcCaskey@users.noreply.github.com>
Date: Thu, 5 Dec 2019 11:59:26 -0800
Subject: [PATCH 07/11] Remove wasmparser dep from singlepass

---
 lib/singlepass-backend/Cargo.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/singlepass-backend/Cargo.toml b/lib/singlepass-backend/Cargo.toml
index eb292dbcbc7..7b9e424b501 100644
--- a/lib/singlepass-backend/Cargo.toml
+++ b/lib/singlepass-backend/Cargo.toml
@@ -25,4 +25,4 @@ bincode = "1.2"
 
 [features]
 default = []
-deterministic-execution = ["wasmparser/deterministic", "wasmer-runtime-core/deterministic-execution"]
\ No newline at end of file
+deterministic-execution = ["wasmer-runtime-core/deterministic-execution"]

From d144976da045db011c697a22003948e4736e9b29 Mon Sep 17 00:00:00 2001
From: Mark McCaskey <5770194+MarkMcCaskey@users.noreply.github.com>
Date: Thu, 5 Dec 2019 12:01:46 -0800
Subject: [PATCH 08/11] Manually apply formatting to cfg statement

---
 lib/runtime/src/lib.rs | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/lib/runtime/src/lib.rs b/lib/runtime/src/lib.rs
index 3febd072c9d..13b3dd8d4e7 100644
--- a/lib/runtime/src/lib.rs
+++ b/lib/runtime/src/lib.rs
@@ -235,10 +235,13 @@ pub fn default_compiler() -> impl Compiler {
     #[cfg(all(feature = "default-backend-llvm", not(feature = "docs")))]
     use wasmer_llvm_backend::LLVMCompiler as DefaultCompiler;
 
-    #[cfg(all(any(
-        feature = "default-backend-singlepass",
-        all(feature = "deterministic-execution", feature = "singlepass")
-    ), not(feature = "docs")))]
+    #[cfg(all(
+        any(
+            feature = "default-backend-singlepass",
+            all(feature = "deterministic-execution", feature = "singlepass")
+        ),
+        not(feature = "docs")
+    ))]
     use wasmer_singlepass_backend::SinglePassCompiler as DefaultCompiler;
 
     #[cfg(any(feature = "default-backend-cranelift", feature = "docs"))]

From 3ba355dda431023c8a3e1a1be3bc9ab7a8ac04a7 Mon Sep 17 00:00:00 2001
From: Mark McCaskey <mark@wasmer.io>
Date: Thu, 5 Dec 2019 15:04:05 -0800
Subject: [PATCH 09/11] Remove deterministic flag setting default compiler; add
 auto logic

---
 Makefile               |  6 ++++++
 lib/runtime/src/lib.rs | 39 ++++++++++++++++-----------------------
 2 files changed, 22 insertions(+), 23 deletions(-)

diff --git a/Makefile b/Makefile
index 4acde792584..935a6a69218 100644
--- a/Makefile
+++ b/Makefile
@@ -192,6 +192,12 @@ check: check-bench
 	# as default, and test a minimal set of features with only one backend
 	# at a time.
 	cargo check --manifest-path lib/runtime/Cargo.toml
+	# Check some of the cases where deterministic execution could matter
+	cargo check --manifest-path lib/runtime/Cargo.toml --features "deterministic-execution"
+	cargo check --manifest-path lib/runtime/Cargo.toml --no-default-features \
+		--features=default-backend-singlepass,deterministic-execution
+	cargo check --manifest-path lib/runtime/Cargo.toml --no-default-features \
+		--features=default-backend-llvm,deterministic-execution
 	cargo check --release --manifest-path lib/runtime/Cargo.toml
 
 	$(RUNTIME_CHECK) \
diff --git a/lib/runtime/src/lib.rs b/lib/runtime/src/lib.rs
index 13b3dd8d4e7..58046148290 100644
--- a/lib/runtime/src/lib.rs
+++ b/lib/runtime/src/lib.rs
@@ -211,21 +211,13 @@ pub fn default_compiler() -> impl Compiler {
             not(feature = "docs"),
             any(
                 feature = "default-backend-cranelift",
-                feature = "default-backend-singlepass",
-                feature = "deterministic-execution"
+                feature = "default-backend-singlepass"
             )
         ),
         all(
             not(feature = "docs"),
             feature = "default-backend-cranelift",
-            any(
-                feature = "default-backend-singlepass",
-                feature = "deterministic-execution"
-            )
-        ),
-        all(
-            feature = "default-backend-singlepass",
-            feature = "deterministic-execution"
+            feature = "default-backend-singlepass"
         )
     ))]
     compile_error!(
@@ -235,13 +227,7 @@ pub fn default_compiler() -> impl Compiler {
     #[cfg(all(feature = "default-backend-llvm", not(feature = "docs")))]
     use wasmer_llvm_backend::LLVMCompiler as DefaultCompiler;
 
-    #[cfg(all(
-        any(
-            feature = "default-backend-singlepass",
-            all(feature = "deterministic-execution", feature = "singlepass")
-        ),
-        not(feature = "docs")
-    ))]
+    #[cfg(all(feature = "default-backend-singlepass", not(feature = "docs")))]
     use wasmer_singlepass_backend::SinglePassCompiler as DefaultCompiler;
 
     #[cfg(any(feature = "default-backend-cranelift", feature = "docs"))]
@@ -260,7 +246,7 @@ pub fn compiler_for_backend(backend: Backend) -> Option<Box<dyn Compiler>> {
         #[cfg(feature = "cranelift")]
         Backend::Cranelift => Some(Box::new(wasmer_clif_backend::CraneliftCompiler::new())),
 
-        #[cfg(any(feature = "singlepass", feature = "deterministic-execution"))]
+        #[cfg(any(feature = "singlepass"))]
         Backend::Singlepass => Some(Box::new(
             wasmer_singlepass_backend::SinglePassCompiler::new(),
         )),
@@ -268,11 +254,18 @@ pub fn compiler_for_backend(backend: Backend) -> Option<Box<dyn Compiler>> {
         #[cfg(feature = "llvm")]
         Backend::LLVM => Some(Box::new(wasmer_llvm_backend::LLVMCompiler::new())),
 
-        #[cfg(not(all(
-            feature = "llvm",
-            any(feature = "singlepass", feature = "deterministic-execution"),
-            feature = "cranelift",
-        )))]
+        Backend::Auto => {
+            #[cfg(feature = "default-backend-singlepass")]
+            return Some(Box::new(
+                wasmer_singlepass_backend::SinglePassCompiler::new(),
+            ));
+            #[cfg(feature = "default-backend-cranelift")]
+            return Some(Box::new(wasmer_clif_backend::CraneliftCompiler::new()));
+            #[cfg(feature = "default-backend-llvm")]
+            return Some(Box::new(wasmer_llvm_backend::LLVMCompiler::new()));
+        }
+
+        #[cfg(not(all(feature = "llvm", feature = "singlepass", feature = "cranelift")))]
         _ => None,
     }
 }

From 27fe50ce9ec639ecd1d8698972f368494656fc5b Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nick@wasmer.io>
Date: Wed, 4 Dec 2019 10:38:28 -0800
Subject: [PATCH 10/11] Fix this regression test to detect the bug it was
 looking for in release builds too.

This bug triggered an assertion failure in debug, and by examining the pre-opt IR, we can check for the bug in release mode too.
---
 lib/llvm-backend-tests/tests/compile.rs | 62 +++++++++++++++++++------
 1 file changed, 47 insertions(+), 15 deletions(-)

diff --git a/lib/llvm-backend-tests/tests/compile.rs b/lib/llvm-backend-tests/tests/compile.rs
index 17071a44a04..dc539bf2067 100644
--- a/lib/llvm-backend-tests/tests/compile.rs
+++ b/lib/llvm-backend-tests/tests/compile.rs
@@ -1,40 +1,72 @@
+use wasmer_llvm_backend::{InkwellMemoryBuffer, InkwellModule, LLVMBackendConfig, LLVMCallbacks};
 use wasmer_llvm_backend_tests::{get_compiler, wat2wasm};
-use wasmer_runtime::imports;
-use wasmer_runtime_core::compile_with;
+use wasmer_runtime::{imports, CompilerConfig};
+use wasmer_runtime_core::{backend::BackendCompilerConfig, compile_with, compile_with_config};
+
+use std::cell::RefCell;
+use std::rc::Rc;
 
 #[test]
 fn crash_return_with_float_on_stack() {
     const MODULE: &str = r#"
 (module
-  (type (;0;) (func))
-  (type (;1;) (func (param f64) (result f64)))
+  (type (func))
+  (type (func (param f64) (result f64)))
   (func $_start (type 0))
   (func $fmod (type 1) (param f64) (result f64)
     local.get 0
-    f64.const 0x0p+0 (;=0;)
+    f64.const 0x0p+0
     f64.mul
-    return)
-)
+    return))
 "#;
     let wasm_binary = wat2wasm(MODULE.as_bytes()).expect("WAST not valid or malformed");
     let module = compile_with(&wasm_binary, &get_compiler()).unwrap();
     module.instantiate(&imports! {}).unwrap();
 }
 
+#[derive(Debug, Default)]
+pub struct RecordPreOptIR {
+    preopt_ir: String,
+}
+
+impl LLVMCallbacks for RecordPreOptIR {
+    fn preopt_ir_callback(&mut self, module: &InkwellModule) {
+        self.preopt_ir = module.print_to_string().to_string();
+    }
+
+    fn postopt_ir_callback(&mut self, _: &InkwellModule) {}
+
+    fn obj_memory_buffer_callback(&mut self, _: &InkwellMemoryBuffer) {}
+}
+
 #[test]
 fn crash_select_with_mismatched_pending() {
-    const MODULE: &str = r#"
+    const WAT: &str = r#"
  (module
-  (func (param f64)
-    f64.const 0x0p+0 (;=0;)
+  (func (param f64) (result f64)
+    f64.const 0x0p+0
     local.get 0
     f64.add
-    f64.const 0x0p+0 (;=0;)
+    f64.const 0x0p+0
     i32.const 0
-    select
-    drop))
+    select))
 "#;
-    let wasm_binary = wat2wasm(MODULE.as_bytes()).expect("WAST not valid or malformed");
-    let module = compile_with(&wasm_binary, &get_compiler()).unwrap();
+    let record_pre_opt_ir = Rc::new(RefCell::new(RecordPreOptIR::default()));
+    let compiler_config = CompilerConfig {
+        backend_specific_config: Some(BackendCompilerConfig(Box::new(LLVMBackendConfig {
+            callbacks: Some(record_pre_opt_ir.clone()),
+        }))),
+        ..Default::default()
+    };
+    let wasm_binary = wat2wasm(WAT.as_bytes()).expect("WAST not valid or malformed");
+    let module = compile_with_config(&wasm_binary, &get_compiler(), compiler_config).unwrap();
     module.instantiate(&imports! {}).unwrap();
+    const LLVM: &str = r#"
+  %s3 = fadd double 0.000000e+00, %s2
+  %nan = fcmp uno double %s3, 0.000000e+00
+  %2 = select i1 %nan, double 0x7FF8000000000000, double %s3
+  %s5 = select i1 false, double %2, double 0.000000e+00
+  br label %return
+"#;
+    assert!(&record_pre_opt_ir.borrow().preopt_ir.contains(LLVM));
 }

From a221f1e5707fce40c08b09632341832483781e3a Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nick@wasmer.io>
Date: Fri, 6 Dec 2019 12:09:34 -0800
Subject: [PATCH 11/11] Provide a default empty implementation for the
 LLVMCallbacks trait.

---
 lib/llvm-backend-tests/tests/compile.rs | 4 ----
 lib/llvm-backend/src/lib.rs             | 6 +++---
 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/lib/llvm-backend-tests/tests/compile.rs b/lib/llvm-backend-tests/tests/compile.rs
index dc539bf2067..1e32f6dd08d 100644
--- a/lib/llvm-backend-tests/tests/compile.rs
+++ b/lib/llvm-backend-tests/tests/compile.rs
@@ -33,10 +33,6 @@ impl LLVMCallbacks for RecordPreOptIR {
     fn preopt_ir_callback(&mut self, module: &InkwellModule) {
         self.preopt_ir = module.print_to_string().to_string();
     }
-
-    fn postopt_ir_callback(&mut self, _: &InkwellModule) {}
-
-    fn obj_memory_buffer_callback(&mut self, _: &InkwellMemoryBuffer) {}
 }
 
 #[test]
diff --git a/lib/llvm-backend/src/lib.rs b/lib/llvm-backend/src/lib.rs
index 853cfac1195..a2db088a76a 100644
--- a/lib/llvm-backend/src/lib.rs
+++ b/lib/llvm-backend/src/lib.rs
@@ -37,9 +37,9 @@ pub type InkwellModule<'ctx> = inkwell::module::Module<'ctx>;
 pub type InkwellMemoryBuffer = inkwell::memory_buffer::MemoryBuffer;
 
 pub trait LLVMCallbacks: std::any::Any + 'static {
-    fn preopt_ir_callback(&mut self, module: &InkwellModule);
-    fn postopt_ir_callback(&mut self, module: &InkwellModule);
-    fn obj_memory_buffer_callback(&mut self, memory_buffer: &InkwellMemoryBuffer);
+    fn preopt_ir_callback(&mut self, _module: &InkwellModule) {}
+    fn postopt_ir_callback(&mut self, _module: &InkwellModule) {}
+    fn obj_memory_buffer_callback(&mut self, _memory_buffer: &InkwellMemoryBuffer) {}
 }
 
 pub struct LLVMBackendConfig {