3 files changed, 104 insertions, 12 deletions

diff --git a/src/tools/wasm-ctor-eval.cpp b/src/tools/wasm-ctor-eval.cpp
index d41094c67..13e2d5767 100644
--- a/src/tools/wasm-ctor-eval.cpp
+++ b/src/tools/wasm-ctor-eval.cpp
@@ -154,6 +154,13 @@ struct CtorEvalExternalInterface : EvallingModuleRunner::ExternalInterface {
   // A representation of the contents of wasm memory as we execute.
   std::unordered_map<Name, std::vector<char>> memories;
 
+  // All the names of globals we've seen in the module. We cannot reuse these.
+  // We must track these manually as we will be adding more, and as we do so we
+  // also reorder them, so we remove and re-add globals, which means the module
+  // itself is not aware of all the globals that belong to it (those that have
+  // not yet been re-added are a blind spot for it).
+  std::unordered_set<Name> usedGlobalNames;
+
   CtorEvalExternalInterface(
     std::map<Name, std::shared_ptr<EvallingModuleRunner>> linkedInstances_ =
       {}) {
@@ -182,6 +189,10 @@ struct CtorEvalExternalInterface : EvallingModuleRunner::ExternalInterface {
         memories[memory->name] = data;
       }
     }
+
+    for (auto& global : wasm->globals) {
+      usedGlobalNames.insert(global->name);
+    }
   }
 
   void importGlobals(GlobalValueSet& globals, Module& wasm_) override {
@@ -526,20 +537,21 @@ private:
       Name name;
       if (!oldGlobal->mutable_ && oldGlobal->type == oldGlobal->init->type) {
         // This has the properties we need of a defining global - immutable and
-        // of the precise type - so use it.
+        // of the precise type - so use it as such.
         name = oldGlobal->name;
       }
 
-      // If there is a value here to serialize, do so. (If there is no value,
-      // then this global was added after the interpreter initialized the
-      // module, which means it is a new global we've added since; we don't need
-      // to do anything for such a global - if it is needed it will show up as a
-      // dependency of something, and be emitted at the right time and place.)
+      // If the instance has an evalled value here, compute the serialization
+      // for it. (If there is no value, then this is a new global we've added
+      // during execution, for whom we've already set up a proper serialized
+      // value when we created it.)
       auto iter = instance->globals.find(oldGlobal->name);
       if (iter != instance->globals.end()) {
         oldGlobal->init = getSerialization(iter->second, name);
-        wasm->addGlobal(std::move(oldGlobal));
       }
+
+      // Add the global back to the module.
+      wasm->addGlobal(std::move(oldGlobal));
     }
   }
 
@@ -616,7 +628,9 @@ public:
       }
 
       // Allocate a new defining global.
-      auto name = Names::getValidGlobalName(*wasm, "ctor-eval$global");
+      auto name =
+        Names::getValidNameGivenExisting("ctor-eval$global", usedGlobalNames);
+      usedGlobalNames.insert(name);
       wasm->addGlobal(builder.makeGlobal(name, type, init, Builder::Immutable));
       definingGlobal = name;
     }
diff --git a/test/ctor-eval/gc.wast.out b/test/ctor-eval/gc.wast.out
index 6ca1f50d9..4a30752e0 100644
--- a/test/ctor-eval/gc.wast.out
+++ b/test/ctor-eval/gc.wast.out
@@ -7,11 +7,11 @@
  (global $global1 (ref $struct) (struct.new $struct
   (i32.const 1337)
  ))
- (global $ctor-eval$global (ref $struct) (struct.new $struct
+ (global $ctor-eval$global_1 (ref $struct) (struct.new $struct
   (i32.const 42)
  ))
- (global $global2 (mut (ref null $struct)) (global.get $ctor-eval$global))
- (global $ctor-eval$global_0 (ref $struct) (struct.new $struct
+ (global $global2 (mut (ref null $struct)) (global.get $ctor-eval$global_1))
+ (global $ctor-eval$global_2 (ref $struct) (struct.new $struct
   (i32.const 99)
  ))
  (export "test1" (func $0_0))
@@ -29,7 +29,7 @@
  (func $0_0 (type $none_=>_none)
   (local $0 (ref $struct))
   (local.set $0
-   (global.get $ctor-eval$global_0)
+   (global.get $ctor-eval$global_2)
   )
   (call $import
    (ref.null none)
diff --git a/test/lit/ctor-eval/ctor_after_serialization.wat b/test/lit/ctor-eval/ctor_after_serialization.wat
new file mode 100644
index 000000000..7a4871398
--- /dev/null
+++ b/test/lit/ctor-eval/ctor_after_serialization.wat
@@ -0,0 +1,78 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py --all-items and should not be edited.
+;; RUN: foreach %s %t wasm-ctor-eval --ctors=new,nop --kept-exports=new,nop --quiet -all -S -o - | filecheck %s
+
+;; We can eval $new, and afterwards also eval $nop as well. When doing the
+;; latter we should not undo or break the previous work in any way. In
+;; particular, we should have a valid global for $new to refer to (which
+;; contains the serialization of the struct.new instruction).
+
+(module
+ ;; CHECK:      (type $A (struct ))
+ (type $A (struct))
+
+ ;; CHECK:      (type $none_=>_ref|any| (func (result (ref any))))
+
+ ;; CHECK:      (type $none_=>_none (func))
+
+ ;; CHECK:      (global $ctor-eval$global (ref $A) (struct.new_default $A))
+
+ ;; CHECK:      (export "new" (func $new_0))
+ (export "new" (func $new))
+ ;; CHECK:      (export "nop" (func $nop_0))
+ (export "nop" (func $nop))
+
+ (func $new (result (ref any))
+  (struct.new $A)
+ )
+
+ (func $nop
+  (nop)
+ )
+)
+
+;; CHECK:      (func $new_0 (type $none_=>_ref|any|) (result (ref any))
+;; CHECK-NEXT:  (global.get $ctor-eval$global)
+;; CHECK-NEXT: )
+
+;; CHECK:      (func $nop_0 (type $none_=>_none)
+;; CHECK-NEXT:  (nop)
+;; CHECK-NEXT: )
+(module
+ ;; As above, but now there is an existing global with the name that we want to
+ ;; use. We should not collide.
+
+ ;; CHECK:      (type $A (struct ))
+ (type $A (struct))
+
+ ;; CHECK:      (type $none_=>_ref|any| (func (result (ref any))))
+
+ ;; CHECK:      (type $none_=>_anyref (func (result anyref)))
+
+ ;; CHECK:      (global $ctor-eval$global (ref $A) (struct.new_default $A))
+ (global $ctor-eval$global (ref $A)
+  (struct.new_default $A)
+ )
+
+ ;; CHECK:      (global $ctor-eval$global_0 (ref $A) (struct.new_default $A))
+
+ ;; CHECK:      (export "new" (func $new_0))
+ (export "new" (func $new))
+ ;; CHECK:      (export "nop" (func $nop_0))
+ (export "nop" (func $nop))
+
+ (func $new (result (ref any))
+  (struct.new $A)
+ )
+
+ (func $nop (result anyref)
+  ;; Use the existing global to keep it alive.
+  (global.get $ctor-eval$global)
+ )
+)
+;; CHECK:      (func $new_0 (type $none_=>_ref|any|) (result (ref any))
+;; CHECK-NEXT:  (global.get $ctor-eval$global_0)
+;; CHECK-NEXT: )
+
+;; CHECK:      (func $nop_0 (type $none_=>_anyref) (result anyref)
+;; CHECK-NEXT:  (global.get $ctor-eval$global)
+;; CHECK-NEXT: )