[GC] Do not crash on unreachable inputs to struct.get/set (#3542)

If the reference is unreachable then we cannot find the heap type to print
in the text format. Instead of crashing or emitting something invalid, print
a block instead - the block contains the children so they are emitted, and
as the instruction was unreachable anyhow, this has no noticeable effect.
It also parallels what we do in the binary format - skip unreachable code.

4 files changed, 27 insertions, 0 deletions

diff --git a/test/heap-types.wast b/test/heap-types.wast
index 7558e1676..87d751691 100644
--- a/test/heap-types.wast
+++ b/test/heap-types.wast
@@ -226,4 +226,12 @@
       )
     )
   )
+  (func $unreachables
+    (drop
+      (struct.get $struct.A 0 (unreachable))
+    )
+    (drop
+      (struct.set $struct.A 0 (unreachable) (unreachable))
+    )
+  )
 )
diff --git a/test/heap-types.wast.from-wast b/test/heap-types.wast.from-wast
index a93bd0d90..458842a7b 100644
--- a/test/heap-types.wast.from-wast
+++ b/test/heap-types.wast.from-wast
@@ -282,4 +282,17 @@
    )
   )
  )
+ (func $unreachables
+  (drop
+   (block 
+    (unreachable)
+   )
+  )
+  (drop
+   (block 
+    (unreachable)
+    (unreachable)
+   )
+  )
+ )
 )
diff --git a/test/heap-types.wast.fromBinary b/test/heap-types.wast.fromBinary
index d8ddb48ed..5e48da116 100644
--- a/test/heap-types.wast.fromBinary
+++ b/test/heap-types.wast.fromBinary
@@ -281,5 +281,8 @@
    )
   )
  )
+ (func $unreachables
+  (unreachable)
+ )
 )
 
diff --git a/test/heap-types.wast.fromBinary.noDebugInfo b/test/heap-types.wast.fromBinary.noDebugInfo
index 63f7e132e..d49d5fa1e 100644
--- a/test/heap-types.wast.fromBinary.noDebugInfo
+++ b/test/heap-types.wast.fromBinary.noDebugInfo
@@ -281,5 +281,8 @@
    )
   )
  )
+ (func $8
+  (unreachable)
+ )
 )