From 15d7745e77900afab3961589526fb89e6d4667ee Mon Sep 17 00:00:00 2001
From: Surma <surma@surma.dev>
Date: Sun, 7 Mar 2021 19:06:17 +0000
Subject: [PATCH 1/6] Invert reference type null checks

---
 src/compiler.ts                               |  7 +-
 tests/compiler/features/reference-types.js    |  6 ++
 tests/compiler/features/reference-types.ts    | 40 ++++++++
 .../features/reference-types.untouched.wat    | 94 ++++++++++++-------
 4 files changed, 110 insertions(+), 37 deletions(-)

diff --git a/src/compiler.ts b/src/compiler.ts
index 7a6a435a72..3bb4d860b1 100644
--- a/src/compiler.ts
+++ b/src/compiler.ts
@@ -9941,7 +9941,12 @@ export class Compiler extends DiagnosticEmitter {
       case TypeKind.EQREF:
       case TypeKind.DATAREF:
       case TypeKind.I31REF: {
-        return module.ref_is(RefIsOp.RefIsNull, expr);
+        // Needs to be true when the ref is _not_ null.
+        // Therefore: 1 - <ref.is_null>
+        return type.size == 64
+          ? module.binary(BinaryOp.SubI64, module.i64(1), module.ref_is(RefIsOp.RefIsNull, expr))
+          : module.binary(BinaryOp.SubI32, module.i32(1), module.ref_is(RefIsOp.RefIsNull, expr));
+
       }
       default: {
         assert(false);
diff --git a/tests/compiler/features/reference-types.js b/tests/compiler/features/reference-types.js
index 50aeab08ba..078c91423f 100644
--- a/tests/compiler/features/reference-types.js
+++ b/tests/compiler/features/reference-types.js
@@ -9,6 +9,12 @@ exports.preInstantiate = function(imports, exports) {
     external: function(a) {
       return a;
     },
+    somethingReal() {
+      return {};
+    },
+    somethingNull() {
+      return null;
+    },
     someObject: {
       theKey: "Hello world!"
     },
diff --git a/tests/compiler/features/reference-types.ts b/tests/compiler/features/reference-types.ts
index d0b3e8d208..982c885c29 100644
--- a/tests/compiler/features/reference-types.ts
+++ b/tests/compiler/features/reference-types.ts
@@ -1,6 +1,8 @@
 // can use externref as a parameter or return type
 
 export declare function external(a: externref): externref;
+export declare function somethingReal(): externref;
+export declare function somethingNull(): externref;
 
 export function internal(a: externref): externref {
   const b = external(a);
@@ -26,6 +28,44 @@ console.log(someObject);
 console.log(someKey);
 console.log(Reflect.get(someObject, someKey));
 
+// Truthiness conversion
+if(!somethingReal()) {
+  assert(false);
+}
+if(!somethingNull()) {
+  // nop
+} else {
+  assert(false);
+}
+if(somethingReal()) {
+  // nop
+} else {
+  assert(false);
+}
+if(somethingNull()) {
+  assert(false);
+}
+
+// Explicit null checks (don’t work yet)
+/*
+if(somethingReal() !== null) {
+  // nop
+} else {
+  assert(false);
+}
+if(somethingReal() === null) {
+  assert(false);
+}
+if(somethingNull() === null) {
+  // nop
+} else {
+  assert(false);
+}
+if(somethingNull() !== null) {
+  assert(false);
+}
+*/
+
 // can represent and recognize 'null'
 
 var funcGlobal: funcref;
diff --git a/tests/compiler/features/reference-types.untouched.wat b/tests/compiler/features/reference-types.untouched.wat
index b4212781f2..04f4a0f65b 100644
--- a/tests/compiler/features/reference-types.untouched.wat
+++ b/tests/compiler/features/reference-types.untouched.wat
@@ -1,5 +1,6 @@
 (module
  (type $none_=>_none (func))
+ (type $none_=>_externref (func (result externref)))
  (type $externref_=>_externref (func (param externref) (result externref)))
  (type $externref_=>_none (func (param externref)))
  (type $i32_i32_i32_i32_=>_none (func (param i32 i32 i32 i32)))
@@ -11,6 +12,8 @@
  (import "env" "abort" (func $~lib/builtins/abort (param i32 i32 i32 i32)))
  (import "console" "log" (func $~lib/bindings/console/log (param externref)))
  (import "Reflect" "get" (func $~lib/bindings/Reflect/get (param externref externref) (result externref)))
+ (import "reference-types" "somethingReal" (func $features/reference-types/somethingReal (result externref)))
+ (import "reference-types" "somethingNull" (func $features/reference-types/somethingNull (result externref)))
  (import "reference-types" "external" (func $features/reference-types/external (param externref) (result externref)))
  (memory $0 1)
  (data (i32.const 12) "L\00\00\00\00\00\00\00\00\00\00\00\01\00\00\006\00\00\00f\00e\00a\00t\00u\00r\00e\00s\00/\00r\00e\00f\00e\00r\00e\00n\00c\00e\00-\00t\00y\00p\00e\00s\00.\00t\00s\00\00\00\00\00\00\00")
@@ -26,6 +29,8 @@
  (global $~lib/memory/__stack_pointer (mut i32) (i32.const 16476))
  (global $~lib/memory/__heap_base i32 (i32.const 16476))
  (export "external" (func $features/reference-types/external))
+ (export "somethingReal" (func $features/reference-types/somethingReal))
+ (export "somethingNull" (func $features/reference-types/somethingNull))
  (export "internal" (func $features/reference-types/internal))
  (export "memory" (memory $0))
  (start $~start)
@@ -165,7 +170,6 @@
   nop
  )
  (func $start:features/reference-types
-  (local $0 funcref)
   global.get $features/reference-types/someObject
   global.get $features/reference-types/someKey
   call $~lib/bindings/Reflect/has
@@ -175,7 +179,7 @@
   if
    i32.const 0
    i32.const 32
-   i32.const 19
+   i32.const 21
    i32.const 1
    call $~lib/builtins/abort
    unreachable
@@ -188,57 +192,75 @@
   global.get $features/reference-types/someKey
   call $~lib/bindings/Reflect/get
   call $~lib/bindings/console/log
-  global.get $features/reference-types/funcGlobal
+  i32.const 1
+  call $features/reference-types/somethingReal
   ref.is_null
-  i32.eqz
+  i32.sub
   i32.eqz
   if
    i32.const 0
-   i32.const 32
-   i32.const 32
-   i32.const 1
-   call $~lib/builtins/abort
-   unreachable
+   i32.eqz
+   if
+    i32.const 0
+    i32.const 32
+    i32.const 33
+    i32.const 3
+    call $~lib/builtins/abort
+    unreachable
+   end
   end
-  ref.null func
-  global.set $features/reference-types/funcGlobal
-  global.get $features/reference-types/funcGlobal
+  i32.const 1
+  call $features/reference-types/somethingNull
   ref.is_null
-  i32.eqz
+  i32.sub
   i32.eqz
   if
+   nop
+  else
    i32.const 0
-   i32.const 32
-   i32.const 34
-   i32.const 1
-   call $~lib/builtins/abort
-   unreachable
+   i32.eqz
+   if
+    i32.const 0
+    i32.const 32
+    i32.const 38
+    i32.const 3
+    call $~lib/builtins/abort
+    unreachable
+   end
   end
-  ref.null func
-  global.set $features/reference-types/funcGlobalInit
-  global.get $features/reference-types/funcGlobalInit
+  i32.const 1
+  call $features/reference-types/somethingReal
   ref.is_null
-  i32.eqz
-  i32.eqz
+  i32.sub
   if
+   nop
+  else
    i32.const 0
-   i32.const 32
-   i32.const 36
-   i32.const 1
-   call $~lib/builtins/abort
-   unreachable
+   i32.eqz
+   if
+    i32.const 0
+    i32.const 32
+    i32.const 43
+    i32.const 3
+    call $~lib/builtins/abort
+    unreachable
+   end
   end
-  global.get $features/reference-types/externGlobal
+  i32.const 1
+  call $features/reference-types/somethingNull
   ref.is_null
-  i32.eqz
-  i32.eqz
+  i32.sub
   if
    i32.const 0
-   i32.const 32
-   i32.const 39
-   i32.const 1
-   call $~lib/builtins/abort
-   unreachable
+   i32.eqz
+   if
+    i32.const 0
+    i32.const 32
+    i32.const 46
+    i32.const 3
+    call $~lib/builtins/abort
+    unreachable
+   end
   end
   ref.null extern
   global.set $features/reference-types/externGlobal

From 8ec6c9611c6a8d5448b29dd449a14100ae3b1278 Mon Sep 17 00:00:00 2001
From: Surma <surma@surma.dev>
Date: Sun, 7 Mar 2021 19:17:03 +0000
Subject: [PATCH 2/6] Fix fixture

---
 .../features/reference-types.untouched.wat    | 123 +++++++++++++++---
 1 file changed, 106 insertions(+), 17 deletions(-)

diff --git a/tests/compiler/features/reference-types.untouched.wat b/tests/compiler/features/reference-types.untouched.wat
index 04f4a0f65b..067ed2996e 100644
--- a/tests/compiler/features/reference-types.untouched.wat
+++ b/tests/compiler/features/reference-types.untouched.wat
@@ -37,42 +37,48 @@
  (func $features/reference-types/testLocal<funcref>
   (local $0 funcref)
   (local $1 funcref)
+  i32.const 1
   local.get $0
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 54
+   i32.const 94
    i32.const 3
    call $~lib/builtins/abort
    unreachable
   end
   ref.null func
   local.set $0
+  i32.const 1
   local.get $0
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 56
+   i32.const 96
    i32.const 3
    call $~lib/builtins/abort
    unreachable
   end
   ref.null func
   local.set $1
+  i32.const 1
   local.get $1
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 58
+   i32.const 98
    i32.const 3
    call $~lib/builtins/abort
    unreachable
@@ -81,42 +87,48 @@
  (func $features/reference-types/testLocal<externref>
   (local $0 externref)
   (local $1 externref)
+  i32.const 1
   local.get $0
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 54
+   i32.const 94
    i32.const 3
    call $~lib/builtins/abort
    unreachable
   end
   ref.null extern
   local.set $0
+  i32.const 1
   local.get $0
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 56
+   i32.const 96
    i32.const 3
    call $~lib/builtins/abort
    unreachable
   end
   ref.null extern
   local.set $1
+  i32.const 1
   local.get $1
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 58
+   i32.const 98
    i32.const 3
    call $~lib/builtins/abort
    unreachable
@@ -125,42 +137,48 @@
  (func $features/reference-types/testLocal<anyref>
   (local $0 anyref)
   (local $1 anyref)
+  i32.const 1
   local.get $0
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 54
+   i32.const 94
    i32.const 3
    call $~lib/builtins/abort
    unreachable
   end
   ref.null any
   local.set $0
+  i32.const 1
   local.get $0
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 56
+   i32.const 96
    i32.const 3
    call $~lib/builtins/abort
    unreachable
   end
   ref.null any
   local.set $1
+  i32.const 1
   local.get $1
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 58
+   i32.const 98
    i32.const 3
    call $~lib/builtins/abort
    unreachable
@@ -170,6 +188,7 @@
   nop
  )
  (func $start:features/reference-types
+  (local $0 funcref)
   global.get $features/reference-types/someObject
   global.get $features/reference-types/someKey
   call $~lib/bindings/Reflect/has
@@ -262,70 +281,140 @@
     unreachable
    end
   end
+  i32.const 1
+  global.get $features/reference-types/funcGlobal
+  ref.is_null
+  i32.sub
+  i32.eqz
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 32
+   i32.const 72
+   i32.const 1
+   call $~lib/builtins/abort
+   unreachable
+  end
+  ref.null func
+  global.set $features/reference-types/funcGlobal
+  i32.const 1
+  global.get $features/reference-types/funcGlobal
+  ref.is_null
+  i32.sub
+  i32.eqz
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 32
+   i32.const 74
+   i32.const 1
+   call $~lib/builtins/abort
+   unreachable
+  end
+  ref.null func
+  global.set $features/reference-types/funcGlobalInit
+  i32.const 1
+  global.get $features/reference-types/funcGlobalInit
+  ref.is_null
+  i32.sub
+  i32.eqz
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 32
+   i32.const 76
+   i32.const 1
+   call $~lib/builtins/abort
+   unreachable
+  end
+  i32.const 1
+  global.get $features/reference-types/externGlobal
+  ref.is_null
+  i32.sub
+  i32.eqz
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 32
+   i32.const 79
+   i32.const 1
+   call $~lib/builtins/abort
+   unreachable
+  end
   ref.null extern
   global.set $features/reference-types/externGlobal
+  i32.const 1
   global.get $features/reference-types/externGlobal
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 41
+   i32.const 81
    i32.const 1
    call $~lib/builtins/abort
    unreachable
   end
   ref.null extern
   global.set $features/reference-types/externGlobalInit
+  i32.const 1
   global.get $features/reference-types/externGlobalInit
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 43
+   i32.const 83
    i32.const 1
    call $~lib/builtins/abort
    unreachable
   end
+  i32.const 1
   global.get $features/reference-types/anyGlobal
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 46
+   i32.const 86
    i32.const 1
    call $~lib/builtins/abort
    unreachable
   end
   ref.null any
   global.set $features/reference-types/anyGlobal
+  i32.const 1
   global.get $features/reference-types/anyGlobal
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 48
+   i32.const 88
    i32.const 1
    call $~lib/builtins/abort
    unreachable
   end
   ref.null any
   global.set $features/reference-types/anyGlobalInit
+  i32.const 1
   global.get $features/reference-types/anyGlobalInit
   ref.is_null
+  i32.sub
   i32.eqz
   i32.eqz
   if
    i32.const 0
    i32.const 32
-   i32.const 50
+   i32.const 90
    i32.const 1
    call $~lib/builtins/abort
    unreachable
@@ -340,7 +429,7 @@
   if
    i32.const 0
    i32.const 32
-   i32.const 68
+   i32.const 108
    i32.const 1
    call $~lib/builtins/abort
    unreachable
@@ -352,7 +441,7 @@
   if
    i32.const 0
    i32.const 32
-   i32.const 70
+   i32.const 110
    i32.const 1
    call $~lib/builtins/abort
    unreachable
@@ -364,7 +453,7 @@
   if
    i32.const 0
    i32.const 32
-   i32.const 73
+   i32.const 113
    i32.const 3
    call $~lib/builtins/abort
    unreachable

From 528fc7dbda4c13b842c39ce9f6e0fe052672609b Mon Sep 17 00:00:00 2001
From: Surma <surma@surmair.de>
Date: Sun, 7 Mar 2021 19:17:53 +0000
Subject: [PATCH 3/6] Use Eqz instead

Co-authored-by: Max Graey <maxgraey@gmail.com>
---
 src/compiler.ts                               |  4 +-
 .../features/reference-types.untouched.wat    | 66 +++++++------------
 2 files changed, 24 insertions(+), 46 deletions(-)

diff --git a/src/compiler.ts b/src/compiler.ts
index 3bb4d860b1..80621132ac 100644
--- a/src/compiler.ts
+++ b/src/compiler.ts
@@ -9944,8 +9944,8 @@ export class Compiler extends DiagnosticEmitter {
         // Needs to be true when the ref is _not_ null.
         // Therefore: 1 - <ref.is_null>
         return type.size == 64
-          ? module.binary(BinaryOp.SubI64, module.i64(1), module.ref_is(RefIsOp.RefIsNull, expr))
-          : module.binary(BinaryOp.SubI32, module.i32(1), module.ref_is(RefIsOp.RefIsNull, expr));
+          ? module.unary(UnaryOp.EqzI64, module.ref_is(RefIsOp.RefIsNull, expr))
+          : module.unary(UnaryOp.EqzI32, module.ref_is(RefIsOp.RefIsNull, expr));
 
       }
       default: {
diff --git a/tests/compiler/features/reference-types.untouched.wat b/tests/compiler/features/reference-types.untouched.wat
index 067ed2996e..d11e0d6bcb 100644
--- a/tests/compiler/features/reference-types.untouched.wat
+++ b/tests/compiler/features/reference-types.untouched.wat
@@ -37,10 +37,9 @@
  (func $features/reference-types/testLocal<funcref>
   (local $0 funcref)
   (local $1 funcref)
-  i32.const 1
   local.get $0
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -53,10 +52,9 @@
   end
   ref.null func
   local.set $0
-  i32.const 1
   local.get $0
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -69,10 +67,9 @@
   end
   ref.null func
   local.set $1
-  i32.const 1
   local.get $1
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -87,10 +84,9 @@
  (func $features/reference-types/testLocal<externref>
   (local $0 externref)
   (local $1 externref)
-  i32.const 1
   local.get $0
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -103,10 +99,9 @@
   end
   ref.null extern
   local.set $0
-  i32.const 1
   local.get $0
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -119,10 +114,9 @@
   end
   ref.null extern
   local.set $1
-  i32.const 1
   local.get $1
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -137,10 +131,9 @@
  (func $features/reference-types/testLocal<anyref>
   (local $0 anyref)
   (local $1 anyref)
-  i32.const 1
   local.get $0
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -153,10 +146,9 @@
   end
   ref.null any
   local.set $0
-  i32.const 1
   local.get $0
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -169,10 +161,9 @@
   end
   ref.null any
   local.set $1
-  i32.const 1
   local.get $1
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -211,10 +202,9 @@
   global.get $features/reference-types/someKey
   call $~lib/bindings/Reflect/get
   call $~lib/bindings/console/log
-  i32.const 1
   call $features/reference-types/somethingReal
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   if
    i32.const 0
@@ -228,10 +218,9 @@
     unreachable
    end
   end
-  i32.const 1
   call $features/reference-types/somethingNull
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   if
    nop
@@ -247,10 +236,9 @@
     unreachable
    end
   end
-  i32.const 1
   call $features/reference-types/somethingReal
   ref.is_null
-  i32.sub
+  i32.eqz
   if
    nop
   else
@@ -265,10 +253,9 @@
     unreachable
    end
   end
-  i32.const 1
   call $features/reference-types/somethingNull
   ref.is_null
-  i32.sub
+  i32.eqz
   if
    i32.const 0
    i32.eqz
@@ -281,10 +268,9 @@
     unreachable
    end
   end
-  i32.const 1
   global.get $features/reference-types/funcGlobal
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -297,10 +283,9 @@
   end
   ref.null func
   global.set $features/reference-types/funcGlobal
-  i32.const 1
   global.get $features/reference-types/funcGlobal
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -313,10 +298,9 @@
   end
   ref.null func
   global.set $features/reference-types/funcGlobalInit
-  i32.const 1
   global.get $features/reference-types/funcGlobalInit
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -327,10 +311,9 @@
    call $~lib/builtins/abort
    unreachable
   end
-  i32.const 1
   global.get $features/reference-types/externGlobal
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -343,10 +326,9 @@
   end
   ref.null extern
   global.set $features/reference-types/externGlobal
-  i32.const 1
   global.get $features/reference-types/externGlobal
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -359,10 +341,9 @@
   end
   ref.null extern
   global.set $features/reference-types/externGlobalInit
-  i32.const 1
   global.get $features/reference-types/externGlobalInit
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -373,10 +354,9 @@
    call $~lib/builtins/abort
    unreachable
   end
-  i32.const 1
   global.get $features/reference-types/anyGlobal
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -389,10 +369,9 @@
   end
   ref.null any
   global.set $features/reference-types/anyGlobal
-  i32.const 1
   global.get $features/reference-types/anyGlobal
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if
@@ -405,10 +384,9 @@
   end
   ref.null any
   global.set $features/reference-types/anyGlobalInit
-  i32.const 1
   global.get $features/reference-types/anyGlobalInit
   ref.is_null
-  i32.sub
+  i32.eqz
   i32.eqz
   i32.eqz
   if

From be87ecd3699eb4949ace57a08e15ca0a80572043 Mon Sep 17 00:00:00 2001
From: Surma <surma@surmair.de>
Date: Sun, 7 Mar 2021 19:20:28 +0000
Subject: [PATCH 4/6] Update src/compiler.ts

Co-authored-by: Max Graey <maxgraey@gmail.com>
---
 src/compiler.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/compiler.ts b/src/compiler.ts
index 80621132ac..d74f43b79c 100644
--- a/src/compiler.ts
+++ b/src/compiler.ts
@@ -9943,6 +9943,7 @@ export class Compiler extends DiagnosticEmitter {
       case TypeKind.I31REF: {
         // Needs to be true when the ref is _not_ null.
         // Therefore: 1 - <ref.is_null>
+        // Therefore: !(<ref.is_null>)
         return type.size == 64
           ? module.unary(UnaryOp.EqzI64, module.ref_is(RefIsOp.RefIsNull, expr))
           : module.unary(UnaryOp.EqzI32, module.ref_is(RefIsOp.RefIsNull, expr));

From 186a78f51ccafedc342a9a2b3cd3ea83ead0a2f2 Mon Sep 17 00:00:00 2001
From: Surma <surma@surmair.de>
Date: Sun, 7 Mar 2021 22:04:32 +0000
Subject: [PATCH 5/6] Update src/compiler.ts

Co-authored-by: Daniel Wirtz <dcode@dcode.io>
---
 src/compiler.ts | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/compiler.ts b/src/compiler.ts
index d74f43b79c..c653c237e5 100644
--- a/src/compiler.ts
+++ b/src/compiler.ts
@@ -9944,9 +9944,7 @@ export class Compiler extends DiagnosticEmitter {
         // Needs to be true when the ref is _not_ null.
         // Therefore: 1 - <ref.is_null>
         // Therefore: !(<ref.is_null>)
-        return type.size == 64
-          ? module.unary(UnaryOp.EqzI64, module.ref_is(RefIsOp.RefIsNull, expr))
-          : module.unary(UnaryOp.EqzI32, module.ref_is(RefIsOp.RefIsNull, expr));
+        return module.unary(UnaryOp.EqzI32, module.ref_is(RefIsOp.RefIsNull, expr));
 
       }
       default: {

From 8384aa3e184bc67a1bf4e50e9f82e19da946b576 Mon Sep 17 00:00:00 2001
From: Surma <surma@surma.dev>
Date: Sun, 7 Mar 2021 22:16:54 +0000
Subject: [PATCH 6/6] Update comment

---
 src/compiler.ts | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/compiler.ts b/src/compiler.ts
index c653c237e5..9a60c12214 100644
--- a/src/compiler.ts
+++ b/src/compiler.ts
@@ -9941,9 +9941,8 @@ export class Compiler extends DiagnosticEmitter {
       case TypeKind.EQREF:
       case TypeKind.DATAREF:
       case TypeKind.I31REF: {
-        // Needs to be true when the ref is _not_ null.
-        // Therefore: 1 - <ref.is_null>
-        // Therefore: !(<ref.is_null>)
+        // Needs to be true (i.e. not zero) when the ref is _not_ null,
+        // which means `ref.is_null` returns false (i.e. zero).
         return module.unary(UnaryOp.EqzI32, module.ref_is(RefIsOp.RefIsNull, expr));
 
       }