[Memory64Lowering/Table64Lowering] Avoid dependency in visitation order. NFC

Followup to #6599.

This reverts the changes to visitation order that were made in #6599.

Author: sbc100

src/passes/Memory64Lowering.cpp

@@ -116,20 +116,7 @@ struct Memory64Lowering : public WalkerPass<PostWalker<Memory64Lowering>> {
     wrapAddress64(curr->ptr, curr->memory);
   }
 
-  void visitMemory(Memory* memory) {
-    // This is visited last.
-    seenMemory = true;
-    if (memory->is64()) {
-      memory->indexType = Type::i32;
-      if (memory->hasMax() && memory->max > Memory::kMaxSize32) {
-        memory->max = Memory::kMaxSize32;
-      }
-    }
-  }
-
   void visitDataSegment(DataSegment* segment) {
-    // We assume that memories are visited after segments, so assert that here.
-    assert(!seenMemory);
     auto& module = *getModule();
 
     // passive segments don't have any offset to adjust
@@ -172,10 +159,19 @@ struct Memory64Lowering : public WalkerPass<PostWalker<Memory64Lowering>> {
       return;
     }
     super::run(module);
+    // Don't modify the memories themselves until after the traversal since we
+    // that would require memories to be the last thing that get visited, and
+    // we don't want to depend on that specific ordering.
+    for (auto& memory : module->memories) {
+      if (memory->is64()) {
+        memory->indexType = Type::i32;
+        if (memory->hasMax() && memory->max > Memory::kMaxSize32) {
+          memory->max = Memory::kMaxSize32;
+        }
+      }
+    }
     module->features.disable(FeatureSet::Memory64);
   }
-
-  bool seenMemory = false;
 };
 
 Pass* createMemory64LoweringPass() { return new Memory64Lowering(); }

src/passes/Table64Lowering.cpp

@@ -95,17 +95,7 @@ struct Table64Lowering : public WalkerPass<PostWalker<Table64Lowering>> {
     wrapAddress64(curr->target, curr->table);
   }
 
-  void visitTable(Table* table) {
-    // This is visited last.
-    seenTable = true;
-    if (table->is64()) {
-      table->indexType = Type::i32;
-    }
-  }
-
   void visitElementSegment(ElementSegment* segment) {
-    // We assume that tables are visited after segments, so assert that here.
-    assert(!seenTable);
     auto& module = *getModule();
 
     // Passive segments don't have any offset to update.
@@ -143,7 +133,17 @@ struct Table64Lowering : public WalkerPass<PostWalker<Table64Lowering>> {
     }
   }
 
-  bool seenTable = false;
+  void run(Module* module) override {
+    super::run(module);
+    // Don't modify the tables themselves until after the traversal since we
+    // that would require tables to be the last thing that get visited, and
+    // we don't want to depend on that specific ordering.
+    for (auto& table : module->tables) {
+      if (table->is64()) {
+        table->indexType = Type::i32;
+      }
+    }
+  }
 };
 
 Pass* createTable64LoweringPass() { return new Table64Lowering(); }

src/wasm-traversal.h

@@ -256,18 +256,18 @@ struct Walker : public VisitorType {
         self->walkTag(curr.get());
       }
     }
-    for (auto& curr : module->elementSegments) {
-      self->walkElementSegment(curr.get());
-    }
     for (auto& curr : module->tables) {
       self->walkTable(curr.get());
     }
-    for (auto& curr : module->dataSegments) {
-      self->walkDataSegment(curr.get());
+    for (auto& curr : module->elementSegments) {
+      self->walkElementSegment(curr.get());
     }
     for (auto& curr : module->memories) {
       self->walkMemory(curr.get());
     }
+    for (auto& curr : module->dataSegments) {
+      self->walkDataSegment(curr.get());
+    }
   }
 
   // Walks module-level code, that is, code that is not in functions.