[GC] Fix name updating in GTO when only some fields are named (#7986)

When updating field names, that pass looped over the number of
field names. If all fields are named, that is fine, but if only some
are, we did not reach later ones.

Fixes #7982

Author: kripken

src/passes/GlobalTypeOptimization.cpp

@@ -444,11 +444,13 @@ struct GlobalTypeOptimization : public Pass {
 
             // Clear the old names and write the new ones.
             nameInfo.fieldNames.clear();
-            for (Index i = 0; i < oldFieldNames.size(); i++) {
+            for (Index i = 0; i < indexesAfterRemoval.size(); i++) {
               auto newIndex = indexesAfterRemoval[i];
-              if (newIndex != RemovedField && oldFieldNames.count(i)) {
-                assert(oldFieldNames[i].is());
-                nameInfo.fieldNames[newIndex] = oldFieldNames[i];
+              if (newIndex != RemovedField) {
+                auto iter = oldFieldNames.find(i);
+                if (iter != oldFieldNames.end()) {
+                  nameInfo.fieldNames[newIndex] = iter->second;
+                }
               }
             }
           }

test/lit/passes/gto-removals.wast

@@ -1675,3 +1675,45 @@
     )
   )
 )
+
+(module
+  ;; A struct with partial names: only some fields are named. We should still
+  ;; update names properly when removing and reordering.
+
+  ;; CHECK:      (rec
+  ;; CHECK-NEXT:  (type $struct (sub (struct (field (mut i32)) (field $named (mut i32)))))
+  (type $struct (sub (struct (field (mut i32)) (field (mut i32)) (field $named (mut i32)) (field (mut i32)) (field (mut i32)))))
+
+  ;; CHECK:       (type $1 (func (param (ref $struct))))
+
+  ;; CHECK:      (func $func (type $1) (param $x (ref $struct))
+  ;; CHECK-NEXT:  (struct.set $struct 0
+  ;; CHECK-NEXT:   (local.get $x)
+  ;; CHECK-NEXT:   (struct.get $struct 0
+  ;; CHECK-NEXT:    (local.get $x)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT:  (struct.set $struct $named
+  ;; CHECK-NEXT:   (local.get $x)
+  ;; CHECK-NEXT:   (struct.get $struct $named
+  ;; CHECK-NEXT:    (local.get $x)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $func (param $x (ref $struct))
+    ;; Use fields 1 and 2.
+    (struct.set $struct 1
+      (local.get $x)
+      (struct.get $struct 1
+        (local.get $x)
+      )
+    )
+    (struct.set $struct 2
+      (local.get $x)
+      (struct.get $struct 2
+        (local.get $x)
+      )
+    )
+  )
+)
+