when finalizing a block in MergeBlocks, use its type, so that we don't need to consider type changes for its parent (changing it from a forced i32 to an unreachable might mean the parent needs to become unreachable too)

Author: kripken

src/passes/MergeBlocks.cpp

@@ -213,7 +213,7 @@ static void optimizeBlock(Block* curr, Module* module) {
       break;
     }
   }
-  if (changed) curr->finalize();
+  if (changed) curr->finalize(curr->type);
 }
 
 void BreakValueDropper::visitBlock(Block* curr) {

test/passes/merge-blocks.txt

@@ -87,4 +87,17 @@
    )
   )
  )
+ (func $drop-block-squared-iloop (type $0)
+  (drop
+   (block $label$0 (result i32)
+    (block $label$1
+     (drop
+      (loop $label$2
+       (br $label$2)
+      )
+     )
+    )
+   )
+  )
+ )
 )

test/passes/merge-blocks.wast

@@ -69,5 +69,18 @@
      )
     )
   )
+  (func $drop-block-squared-iloop
+   (drop
+    (block $label$0 (result i32) ;; this block's type should not change, so the drop remains none and valid
+     (drop
+      (block $label$1
+       (loop $label$2
+        (br $label$2)
+       )
+      )
+     )
+    )
+   )
+  )
 )