Bysyncify: async transform for wasm (#2172)

This adds a new pass, Bysyncify, which transforms code to allow unwind and rewinding the call stack and local state. This allows things like coroutines, turning synchronous code asynchronous, etc.

The new pass file itself has a large comment on top with docs.

So far the tests here seem to show this works, but this hasn't been tested heavily yet. My next step is to hook this up to emscripten as a replacement for asyncify/emterpreter, see emscripten-core/emscripten#8561

Note that this is completely usable by itself, so it could be useful for any language that needs coroutines etc., and not just ones using LLVM and/or emscripten. See docs on the ABI in the pass source.

1 files changed, 1541 insertions, 0 deletions

diff --git a/test/passes/bysyncify_optimize-level=1.txt b/test/passes/bysyncify_optimize-level=1.txt
new file mode 100644
index 000000000..6eb7217e4
--- /dev/null
+++ b/test/passes/bysyncify_optimize-level=1.txt
@@ -0,0 +1,1541 @@
+(module
+ (type $FUNCSIG$v (func))
+ (type $FUNCSIG$i (func (result i32)))
+ (type $FUNCSIG$vi (func (param i32)))
+ (type $FUNCSIG$ii (func (param i32) (result i32)))
+ (import "env" "import" (func $import))
+ (import "env" "import2" (func $import2 (result i32)))
+ (import "env" "import3" (func $import3 (param i32)))
+ (memory $0 1 2)
+ (global $__bysyncify_state (mut i32) (i32.const 0))
+ (global $__bysyncify_data (mut i32) (i32.const 0))
+ (export "bysyncify_start_unwind" (func $bysyncify_start_unwind))
+ (export "bysyncify_start_rewind" (func $bysyncify_start_rewind))
+ (export "bysyncify_stop_rewind" (func $bysyncify_stop_rewind))
+ (func $calls-import (; 3 ;) (type $FUNCSIG$v)
+  (local $0 i32)
+  (local.set $0
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (select
+      (i32.eqz
+       (if (result i32)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 2)
+        )
+        (block (result i32)
+         (i32.store
+          (global.get $__bysyncify_data)
+          (i32.add
+           (i32.load
+            (global.get $__bysyncify_data)
+           )
+           (i32.const -4)
+          )
+         )
+         (i32.load
+          (i32.load
+           (global.get $__bysyncify_data)
+          )
+         )
+        )
+        (local.get $0)
+       )
+      )
+      (i32.const 1)
+      (global.get $__bysyncify_state)
+     )
+     (block
+      (call $import)
+      (drop
+       (br_if $__bysyncify_unwind
+        (i32.const 0)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 1)
+        )
+       )
+      )
+     )
+    )
+    (return)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $0)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+ )
+ (func $calls-import2 (; 4 ;) (type $FUNCSIG$i) (result i32)
+  (local $0 i32)
+  (local $1 i32)
+  (if
+   (i32.eq
+    (global.get $__bysyncify_state)
+    (i32.const 2)
+   )
+   (block
+    (i32.store
+     (global.get $__bysyncify_data)
+     (i32.add
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+      (i32.const -4)
+     )
+    )
+    (local.set $0
+     (i32.load
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+     )
+    )
+   )
+  )
+  (local.set $1
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (select
+      (i32.eqz
+       (if (result i32)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 2)
+        )
+        (block (result i32)
+         (i32.store
+          (global.get $__bysyncify_data)
+          (i32.add
+           (i32.load
+            (global.get $__bysyncify_data)
+           )
+           (i32.const -4)
+          )
+         )
+         (i32.load
+          (i32.load
+           (global.get $__bysyncify_data)
+          )
+         )
+        )
+        (local.get $1)
+       )
+      )
+      (i32.const 1)
+      (global.get $__bysyncify_state)
+     )
+     (block
+      (local.set $0
+       (call $import2)
+      )
+      (drop
+       (br_if $__bysyncify_unwind
+        (i32.const 0)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 1)
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.eqz
+      (global.get $__bysyncify_state)
+     )
+     (return
+      (local.get $0)
+     )
+    )
+    (unreachable)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $1)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $0)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+  (i32.const 0)
+ )
+ (func $calls-import2-drop (; 5 ;) (type $FUNCSIG$v)
+  (local $0 i32)
+  (local.set $0
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (select
+      (i32.eqz
+       (if (result i32)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 2)
+        )
+        (block (result i32)
+         (i32.store
+          (global.get $__bysyncify_data)
+          (i32.add
+           (i32.load
+            (global.get $__bysyncify_data)
+           )
+           (i32.const -4)
+          )
+         )
+         (i32.load
+          (i32.load
+           (global.get $__bysyncify_data)
+          )
+         )
+        )
+        (local.get $0)
+       )
+      )
+      (i32.const 1)
+      (global.get $__bysyncify_state)
+     )
+     (block
+      (drop
+       (call $import2)
+      )
+      (drop
+       (br_if $__bysyncify_unwind
+        (i32.const 0)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 1)
+        )
+       )
+      )
+     )
+    )
+    (return)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $0)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+ )
+ (func $calls-nothing (; 6 ;) (type $FUNCSIG$v)
+  (nop)
+ )
+ (func $many-locals (; 7 ;) (type $FUNCSIG$ii) (param $0 i32) (result i32)
+  (local $1 i32)
+  (local $2 i32)
+  (if
+   (i32.eq
+    (global.get $__bysyncify_state)
+    (i32.const 2)
+   )
+   (block
+    (i32.store
+     (global.get $__bysyncify_data)
+     (i32.add
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+      (i32.const -8)
+     )
+    )
+    (local.set $0
+     (i32.load
+      (local.tee $1
+       (i32.load
+        (global.get $__bysyncify_data)
+       )
+      )
+     )
+    )
+    (local.set $1
+     (i32.load offset=4
+      (local.get $1)
+     )
+    )
+   )
+  )
+  (local.set $2
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (i32.eq
+      (global.get $__bysyncify_state)
+      (i32.const 2)
+     )
+     (block
+      (i32.store
+       (global.get $__bysyncify_data)
+       (i32.add
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+        (i32.const -4)
+       )
+      )
+      (local.set $2
+       (i32.load
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.eqz
+      (global.get $__bysyncify_state)
+     )
+     (loop $l
+      (br_if $l
+       (local.tee $1
+        (i32.div_s
+         (i32.add
+          (local.get $1)
+          (i32.const 1)
+         )
+         (i32.const 3)
+        )
+       )
+      )
+     )
+    )
+    (if
+     (select
+      (i32.eqz
+       (local.get $2)
+      )
+      (i32.const 1)
+      (global.get $__bysyncify_state)
+     )
+     (block
+      (call $import)
+      (drop
+       (br_if $__bysyncify_unwind
+        (i32.const 0)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 1)
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.eqz
+      (global.get $__bysyncify_state)
+     )
+     (return
+      (local.get $1)
+     )
+    )
+    (unreachable)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $2)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+  (i32.store
+   (local.tee $2
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+   )
+   (local.get $0)
+  )
+  (i32.store offset=4
+   (local.get $2)
+   (local.get $1)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 8)
+   )
+  )
+  (i32.const 0)
+ )
+ (func $calls-import2-if (; 8 ;) (type $FUNCSIG$vi) (param $0 i32)
+  (local $1 i32)
+  (if
+   (i32.eq
+    (global.get $__bysyncify_state)
+    (i32.const 2)
+   )
+   (block
+    (i32.store
+     (global.get $__bysyncify_data)
+     (i32.add
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+      (i32.const -4)
+     )
+    )
+    (local.set $0
+     (i32.load
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+     )
+    )
+   )
+  )
+  (local.set $1
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (i32.eq
+      (global.get $__bysyncify_state)
+      (i32.const 2)
+     )
+     (block
+      (i32.store
+       (global.get $__bysyncify_data)
+       (i32.add
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+        (i32.const -4)
+       )
+      )
+      (local.set $1
+       (i32.load
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.or
+      (local.get $0)
+      (i32.eq
+       (global.get $__bysyncify_state)
+       (i32.const 2)
+      )
+     )
+     (if
+      (select
+       (i32.eqz
+        (local.get $1)
+       )
+       (i32.const 1)
+       (global.get $__bysyncify_state)
+      )
+      (block
+       (call $import)
+       (drop
+        (br_if $__bysyncify_unwind
+         (i32.const 0)
+         (i32.eq
+          (global.get $__bysyncify_state)
+          (i32.const 1)
+         )
+        )
+       )
+      )
+     )
+    )
+    (return)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $1)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $0)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+ )
+ (func $calls-import2-if-else (; 9 ;) (type $FUNCSIG$vi) (param $0 i32)
+  (local $1 i32)
+  (if
+   (i32.eq
+    (global.get $__bysyncify_state)
+    (i32.const 2)
+   )
+   (block
+    (i32.store
+     (global.get $__bysyncify_data)
+     (i32.add
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+      (i32.const -4)
+     )
+    )
+    (local.set $0
+     (i32.load
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+     )
+    )
+   )
+  )
+  (local.set $1
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (i32.eq
+      (global.get $__bysyncify_state)
+      (i32.const 2)
+     )
+     (block
+      (i32.store
+       (global.get $__bysyncify_data)
+       (i32.add
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+        (i32.const -4)
+       )
+      )
+      (local.set $1
+       (i32.load
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.or
+      (local.get $0)
+      (i32.eq
+       (global.get $__bysyncify_state)
+       (i32.const 2)
+      )
+     )
+     (if
+      (select
+       (i32.eqz
+        (local.get $1)
+       )
+       (i32.const 1)
+       (global.get $__bysyncify_state)
+      )
+      (block
+       (call $import3
+        (i32.const 1)
+       )
+       (drop
+        (br_if $__bysyncify_unwind
+         (i32.const 0)
+         (i32.eq
+          (global.get $__bysyncify_state)
+          (i32.const 1)
+         )
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.or
+      (i32.eqz
+       (local.get $0)
+      )
+      (i32.eq
+       (global.get $__bysyncify_state)
+       (i32.const 2)
+      )
+     )
+     (if
+      (select
+       (i32.eq
+        (local.get $1)
+        (i32.const 1)
+       )
+       (i32.const 1)
+       (global.get $__bysyncify_state)
+      )
+      (block
+       (call $import3
+        (i32.const 2)
+       )
+       (drop
+        (br_if $__bysyncify_unwind
+         (i32.const 1)
+         (i32.eq
+          (global.get $__bysyncify_state)
+          (i32.const 1)
+         )
+        )
+       )
+      )
+     )
+    )
+    (return)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $1)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $0)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+ )
+ (func $calls-import2-if-else-oneside (; 10 ;) (type $FUNCSIG$ii) (param $0 i32) (result i32)
+  (local $1 i32)
+  (if
+   (i32.eq
+    (global.get $__bysyncify_state)
+    (i32.const 2)
+   )
+   (block
+    (i32.store
+     (global.get $__bysyncify_data)
+     (i32.add
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+      (i32.const -4)
+     )
+    )
+    (local.set $0
+     (i32.load
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+     )
+    )
+   )
+  )
+  (local.set $1
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (i32.eq
+      (global.get $__bysyncify_state)
+      (i32.const 2)
+     )
+     (block
+      (i32.store
+       (global.get $__bysyncify_data)
+       (i32.add
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+        (i32.const -4)
+       )
+      )
+      (local.set $1
+       (i32.load
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.or
+      (local.get $0)
+      (i32.eq
+       (global.get $__bysyncify_state)
+       (i32.const 2)
+      )
+     )
+     (if
+      (i32.eqz
+       (global.get $__bysyncify_state)
+      )
+      (return
+       (i32.const 1)
+      )
+     )
+    )
+    (if
+     (i32.or
+      (i32.eqz
+       (local.get $0)
+      )
+      (i32.eq
+       (global.get $__bysyncify_state)
+       (i32.const 2)
+      )
+     )
+     (if
+      (select
+       (i32.eqz
+        (local.get $1)
+       )
+       (i32.const 1)
+       (global.get $__bysyncify_state)
+      )
+      (block
+       (call $import3
+        (i32.const 2)
+       )
+       (drop
+        (br_if $__bysyncify_unwind
+         (i32.const 0)
+         (i32.eq
+          (global.get $__bysyncify_state)
+          (i32.const 1)
+         )
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.eqz
+      (global.get $__bysyncify_state)
+     )
+     (return
+      (i32.const 3)
+     )
+    )
+    (unreachable)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $1)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $0)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+  (i32.const 0)
+ )
+ (func $calls-import2-if-else-oneside2 (; 11 ;) (type $FUNCSIG$ii) (param $0 i32) (result i32)
+  (local $1 i32)
+  (if
+   (i32.eq
+    (global.get $__bysyncify_state)
+    (i32.const 2)
+   )
+   (block
+    (i32.store
+     (global.get $__bysyncify_data)
+     (i32.add
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+      (i32.const -4)
+     )
+    )
+    (local.set $0
+     (i32.load
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+     )
+    )
+   )
+  )
+  (local.set $1
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (i32.eq
+      (global.get $__bysyncify_state)
+      (i32.const 2)
+     )
+     (block
+      (i32.store
+       (global.get $__bysyncify_data)
+       (i32.add
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+        (i32.const -4)
+       )
+      )
+      (local.set $1
+       (i32.load
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.or
+      (local.get $0)
+      (i32.eq
+       (global.get $__bysyncify_state)
+       (i32.const 2)
+      )
+     )
+     (if
+      (select
+       (i32.eqz
+        (local.get $1)
+       )
+       (i32.const 1)
+       (global.get $__bysyncify_state)
+      )
+      (block
+       (call $import3
+        (i32.const 1)
+       )
+       (drop
+        (br_if $__bysyncify_unwind
+         (i32.const 0)
+         (i32.eq
+          (global.get $__bysyncify_state)
+          (i32.const 1)
+         )
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.or
+      (i32.eqz
+       (local.get $0)
+      )
+      (i32.eq
+       (global.get $__bysyncify_state)
+       (i32.const 2)
+      )
+     )
+     (if
+      (i32.eqz
+       (global.get $__bysyncify_state)
+      )
+      (return
+       (i32.const 2)
+      )
+     )
+    )
+    (if
+     (i32.eqz
+      (global.get $__bysyncify_state)
+     )
+     (return
+      (i32.const 3)
+     )
+    )
+    (unreachable)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $1)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $0)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+  (i32.const 0)
+ )
+ (func $calls-loop (; 12 ;) (type $FUNCSIG$vi) (param $0 i32)
+  (local $1 i32)
+  (if
+   (i32.eq
+    (global.get $__bysyncify_state)
+    (i32.const 2)
+   )
+   (block
+    (i32.store
+     (global.get $__bysyncify_data)
+     (i32.add
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+      (i32.const -4)
+     )
+    )
+    (local.set $0
+     (i32.load
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+     )
+    )
+   )
+  )
+  (local.set $1
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (i32.eq
+      (global.get $__bysyncify_state)
+      (i32.const 2)
+     )
+     (block
+      (i32.store
+       (global.get $__bysyncify_data)
+       (i32.add
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+        (i32.const -4)
+       )
+      )
+      (local.set $1
+       (i32.load
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+       )
+      )
+     )
+    )
+    (loop $l
+     (if
+      (select
+       (i32.eqz
+        (local.get $1)
+       )
+       (i32.const 1)
+       (global.get $__bysyncify_state)
+      )
+      (block
+       (call $import3
+        (i32.const 1)
+       )
+       (drop
+        (br_if $__bysyncify_unwind
+         (i32.const 0)
+         (i32.eq
+          (global.get $__bysyncify_state)
+          (i32.const 1)
+         )
+        )
+       )
+      )
+     )
+     (if
+      (i32.eqz
+       (global.get $__bysyncify_state)
+      )
+      (br_if $l
+       (local.tee $0
+        (i32.add
+         (local.get $0)
+         (i32.const 1)
+        )
+       )
+      )
+     )
+    )
+    (return)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $1)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $0)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+ )
+ (func $calls-loop2 (; 13 ;) (type $FUNCSIG$v)
+  (local $0 i32)
+  (local $1 i32)
+  (if
+   (i32.eq
+    (global.get $__bysyncify_state)
+    (i32.const 2)
+   )
+   (block
+    (i32.store
+     (global.get $__bysyncify_data)
+     (i32.add
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+      (i32.const -4)
+     )
+    )
+    (local.set $0
+     (i32.load
+      (i32.load
+       (global.get $__bysyncify_data)
+      )
+     )
+    )
+   )
+  )
+  (local.set $1
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (i32.eq
+      (global.get $__bysyncify_state)
+      (i32.const 2)
+     )
+     (block
+      (i32.store
+       (global.get $__bysyncify_data)
+       (i32.add
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+        (i32.const -4)
+       )
+      )
+      (local.set $1
+       (i32.load
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+       )
+      )
+     )
+    )
+    (loop $l
+     (if
+      (select
+       (i32.eqz
+        (local.get $1)
+       )
+       (i32.const 1)
+       (global.get $__bysyncify_state)
+      )
+      (block
+       (local.set $0
+        (call $import2)
+       )
+       (drop
+        (br_if $__bysyncify_unwind
+         (i32.const 0)
+         (i32.eq
+          (global.get $__bysyncify_state)
+          (i32.const 1)
+         )
+        )
+       )
+      )
+     )
+     (if
+      (i32.eqz
+       (global.get $__bysyncify_state)
+      )
+      (br_if $l
+       (local.get $0)
+      )
+     )
+    )
+    (return)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $1)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $0)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+ )
+ (func $calls-mix (; 14 ;) (type $FUNCSIG$v)
+  (local $0 i32)
+  (local.set $0
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (i32.eq
+      (global.get $__bysyncify_state)
+      (i32.const 2)
+     )
+     (block
+      (i32.store
+       (global.get $__bysyncify_data)
+       (i32.add
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+        (i32.const -4)
+       )
+      )
+      (local.set $0
+       (i32.load
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.eqz
+      (global.get $__bysyncify_state)
+     )
+     (call $boring)
+    )
+    (if
+     (select
+      (i32.eqz
+       (local.get $0)
+      )
+      (i32.const 1)
+      (global.get $__bysyncify_state)
+     )
+     (block
+      (call $import)
+      (drop
+       (br_if $__bysyncify_unwind
+        (i32.const 0)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 1)
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.eqz
+      (global.get $__bysyncify_state)
+     )
+     (call $boring)
+    )
+    (if
+     (select
+      (i32.eq
+       (local.get $0)
+       (i32.const 1)
+      )
+      (i32.const 1)
+      (global.get $__bysyncify_state)
+     )
+     (block
+      (call $import)
+      (drop
+       (br_if $__bysyncify_unwind
+        (i32.const 1)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 1)
+        )
+       )
+      )
+     )
+    )
+    (return)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $0)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+ )
+ (func $boring (; 15 ;) (type $FUNCSIG$v)
+  (nop)
+ )
+ (func $calls-mix-deep (; 16 ;) (type $FUNCSIG$v)
+  (local $0 i32)
+  (local.set $0
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (i32.eq
+      (global.get $__bysyncify_state)
+      (i32.const 2)
+     )
+     (block
+      (i32.store
+       (global.get $__bysyncify_data)
+       (i32.add
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+        (i32.const -4)
+       )
+      )
+      (local.set $0
+       (i32.load
+        (i32.load
+         (global.get $__bysyncify_data)
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.eqz
+      (global.get $__bysyncify_state)
+     )
+     (call $boring-deep)
+    )
+    (if
+     (select
+      (i32.eqz
+       (local.get $0)
+      )
+      (i32.const 1)
+      (global.get $__bysyncify_state)
+     )
+     (block
+      (call $import-deep)
+      (drop
+       (br_if $__bysyncify_unwind
+        (i32.const 0)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 1)
+        )
+       )
+      )
+     )
+    )
+    (if
+     (i32.eqz
+      (global.get $__bysyncify_state)
+     )
+     (call $boring)
+    )
+    (if
+     (select
+      (i32.eq
+       (local.get $0)
+       (i32.const 1)
+      )
+      (i32.const 1)
+      (global.get $__bysyncify_state)
+     )
+     (block
+      (call $import)
+      (drop
+       (br_if $__bysyncify_unwind
+        (i32.const 1)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 1)
+        )
+       )
+      )
+     )
+    )
+    (return)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $0)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+ )
+ (func $boring-deep (; 17 ;) (type $FUNCSIG$v)
+  (call $boring)
+ )
+ (func $import-deep (; 18 ;) (type $FUNCSIG$v)
+  (local $0 i32)
+  (local.set $0
+   (block $__bysyncify_unwind (result i32)
+    (if
+     (select
+      (i32.eqz
+       (if (result i32)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 2)
+        )
+        (block (result i32)
+         (i32.store
+          (global.get $__bysyncify_data)
+          (i32.add
+           (i32.load
+            (global.get $__bysyncify_data)
+           )
+           (i32.const -4)
+          )
+         )
+         (i32.load
+          (i32.load
+           (global.get $__bysyncify_data)
+          )
+         )
+        )
+        (local.get $0)
+       )
+      )
+      (i32.const 1)
+      (global.get $__bysyncify_state)
+     )
+     (block
+      (call $import)
+      (drop
+       (br_if $__bysyncify_unwind
+        (i32.const 0)
+        (i32.eq
+         (global.get $__bysyncify_state)
+         (i32.const 1)
+        )
+       )
+      )
+     )
+    )
+    (return)
+   )
+  )
+  (i32.store
+   (i32.load
+    (global.get $__bysyncify_data)
+   )
+   (local.get $0)
+  )
+  (i32.store
+   (global.get $__bysyncify_data)
+   (i32.add
+    (i32.load
+     (global.get $__bysyncify_data)
+    )
+    (i32.const 4)
+   )
+  )
+ )
+ (func $bysyncify_start_unwind (; 19 ;) (param $0 i32)
+  (if
+   (i32.gt_u
+    (i32.load
+     (local.get $0)
+    )
+    (i32.load offset=4
+     (local.get $0)
+    )
+   )
+   (unreachable)
+  )
+  (global.set $__bysyncify_state
+   (i32.const 1)
+  )
+  (global.set $__bysyncify_data
+   (local.get $0)
+  )
+ )
+ (func $bysyncify_start_rewind (; 20 ;) (param $0 i32)
+  (if
+   (i32.gt_u
+    (i32.load
+     (local.get $0)
+    )
+    (i32.load offset=4
+     (local.get $0)
+    )
+   )
+   (unreachable)
+  )
+  (global.set $__bysyncify_state
+   (i32.const 2)
+  )
+  (global.set $__bysyncify_data
+   (local.get $0)
+  )
+ )
+ (func $bysyncify_stop_rewind (; 21 ;)
+  (global.set $__bysyncify_state
+   (i32.const 0)
+  )
+ )
+)