merge blocks in remove-unused-names only when their type is identical, so branches to them are interchangeable

Author: kripken

src/passes/RemoveUnusedNames.cpp

@@ -57,7 +57,7 @@ struct RemoveUnusedNames : public WalkerPass<PostWalker<RemoveUnusedNames>> {
   void visitBlock(Block *curr) {
     if (curr->name.is() && curr->list.size() == 1) {
       auto* child = curr->list[0]->dynCast<Block>();
-      if (child && child->name.is()) {
+      if (child && child->name.is() && child->type == curr->type) {
         // we have just one child, this block, so breaking out of it goes to the same place as breaking out of us, we just need one name (and block)
         auto& branches = branchesSeen[curr->name];
         for (auto* branch : branches) {

test/passes/remove-unused-names.txt

@@ -1,6 +1,7 @@
 (module
  (type $0 (func (param i32) (result i32)))
  (type $1 (func))
+ (type $2 (func (result i32)))
  (memory $0 256 256)
  (func $b0 (type $0) (param $i1 i32) (result i32)
   (i32.const 0)
@@ -63,4 +64,20 @@
    )
   )
  )
+ (func $merge-typed-with-unreachable-child (type $2) (result i32)
+  (local $0 f32)
+  (block $label$0 (result i32)
+   (block $label$1
+    (br_if $label$1
+     (i32.const 0)
+     (br_if $label$0
+      (i32.const 0)
+      (br $label$0
+       (i32.const 0)
+      )
+     )
+    )
+   )
+  )
+ )
 )

test/passes/remove-unused-names.wast

@@ -77,4 +77,20 @@
       )
     )
   )
+  (func $merge-typed-with-unreachable-child (result i32)
+   (local $0 f32)
+   (block $label$0 (result i32)
+    (block $label$1
+     (br_if $label$1
+      (i32.const 0)
+      (br_if $label$0
+       (i32.const 0)
+       (br $label$0
+        (i32.const 0)
+       )
+      )
+     )
+    )
+   )
+  )
 )