4 files changed, 40 insertions, 25 deletions

diff --git a/src/wasm-validator.h b/src/wasm-validator.h
index 29787a510..b657b67a6 100644
--- a/src/wasm-validator.h
+++ b/src/wasm-validator.h
@@ -390,15 +390,7 @@ public:
   }
   void visitUnary(Unary *curr) {
     shouldBeUnequal(curr->value->type, none, curr, "unaries must not receive a none as their input");
-    switch (curr->op) {
-      case EqZInt32:
-      case EqZInt64: {
-        shouldBeEqual(curr->type, i32, curr, "eqz must return i32");
-        break;
-      }
-      default: {}
-    }
-    if (curr->value->type == unreachable) return;
+    if (curr->value->type == unreachable) return; // nothing to check
     switch (curr->op) {
       case ClzInt32:
       case CtzInt32:
@@ -420,9 +412,7 @@ public:
       case TruncFloat64:
       case NearestFloat64:
       case SqrtFloat64: {
-        if (curr->value->type != unreachable) {
-          shouldBeEqual(curr->value->type, curr->type, curr, "non-conversion unaries must return the same type");
-        }
+        shouldBeEqual(curr->value->type, curr->type, curr, "non-conversion unaries must return the same type");
         break;
       }
       case EqZInt32: {
diff --git a/src/wasm.h b/src/wasm.h
index 4804322b6..b23dab918 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -299,6 +299,8 @@ public:
   Name default_;
   Expression* condition;
   Expression* value;
+
+  void finalize();
 };
 
 class Call : public SpecificExpression<Expression::CallId> {
diff --git a/src/wasm/wasm.cpp b/src/wasm/wasm.cpp
index 36eff681f..96ca8fbc8 100644
--- a/src/wasm/wasm.cpp
+++ b/src/wasm/wasm.cpp
@@ -248,7 +248,9 @@ void Loop::finalize() {
 
 void Break::finalize() {
   if (condition) {
-    if (value) {
+    if (condition->type == unreachable) {
+      type = unreachable;
+    } else if (value) {
       type = value->type;
     } else {
       type = none;
@@ -258,6 +260,10 @@ void Break::finalize() {
   }
 }
 
+void Switch::finalize() {
+  type = unreachable;
+}
+
 bool FunctionType::structuralComparison(FunctionType& b) {
   if (result != b.result) return false;
   if (params.size() != b.params.size()) return false;
@@ -286,6 +292,11 @@ void SetLocal::setTee(bool is) {
 
 void Store::finalize() {
   assert(valueType != none); // must be set
+  if (ptr->type == unreachable || value->type == unreachable) {
+    type = unreachable;
+  } else {
+    type = none;
+  }
 }
 
 Const* Const::set(Literal value_) {
@@ -299,6 +310,10 @@ bool Unary::isRelational() {
 }
 
 void Unary::finalize() {
+  if (value->type == unreachable) {
+    type = unreachable;
+    return;
+  }
   switch (op) {
     case ClzInt32:
     case CtzInt32:
@@ -390,16 +405,22 @@ bool Binary::isRelational() {
 
 void Binary::finalize() {
   assert(left && right);
-  if (isRelational()) {
+  if (left->type == unreachable || right->type == unreachable) {
+    type = unreachable;
+  } else if (isRelational()) {
     type = i32;
   } else {
-    type = getReachableWasmType(left->type, right->type);
+    type = left->type;
   }
 }
 
 void Select::finalize() {
   assert(ifTrue && ifFalse);
-  type = getReachableWasmType(ifTrue->type, ifFalse->type);
+  if (ifTrue->type == unreachable || ifFalse->type == unreachable || condition->type == unreachable) {
+    type = unreachable;
+  } else {
+    type = ifTrue->type;
+  }
 }
 
 void Host::finalize() {
diff --git a/test/passes/dce.txt b/test/passes/dce.txt
index 6aaad92b5..98f0ea177 100644
--- a/test/passes/dce.txt
+++ b/test/passes/dce.txt
@@ -235,7 +235,7 @@
   (if
    (i32.const 88)
    (drop
-    (block i32
+    (block
      (drop
       (i32.const 0)
      )
@@ -250,7 +250,7 @@
   (if
    (i32.const 100)
    (drop
-    (block i32
+    (block
      (drop
       (i32.const 123)
      )
@@ -264,7 +264,7 @@
   (if
    (i32.const 101)
    (drop
-    (block i32
+    (block
      (drop
       (i32.const 123)
      )
@@ -367,7 +367,7 @@
     (br $label$0
      (block $label$1 i32
       (drop
-       (block i32
+       (block
         (drop
          (i32.const 4104)
         )
@@ -390,12 +390,14 @@
     (get_local $var$1)
    )
    (block $label$1 i64
-    (call $call-unreach
-     (i64.sub
-      (get_local $var$0)
-      (i64.const 1)
+    (block i64
+     (drop
+      (i64.sub
+       (get_local $var$0)
+       (i64.const 1)
+      )
      )
-     (block i64
+     (block
       (drop
        (block $block i64
         (set_local $2