[wasm-split] Do not add exports of imported memories (#4133)

We can assume that imported memories (and the profiling data they contain) are
already accessible from the module's environment, so there's no need to export
them. This also avoids needing to add knowledge of "profile-memory" to
Emscripten's library_dylink.js.

1 files changed, 14 insertions, 12 deletions

diff --git a/src/tools/wasm-split/instrumenter.cpp b/src/tools/wasm-split/instrumenter.cpp
index 36875bfc0..c23a70f06 100644
--- a/src/tools/wasm-split/instrumenter.cpp
+++ b/src/tools/wasm-split/instrumenter.cpp
@@ -266,19 +266,21 @@ void Instrumenter::addProfileExport() {
     }
   }
 
-  // Export the memory if it is not already exported.
-  bool memoryExported = false;
-  for (auto& ex : wasm->exports) {
-    if (ex->kind == ExternalKind::Memory) {
-      memoryExported = true;
-      break;
+  // Export the memory if it is not already exported or imported.
+  if (!wasm->memory.imported()) {
+    bool memoryExported = false;
+    for (auto& ex : wasm->exports) {
+      if (ex->kind == ExternalKind::Memory) {
+        memoryExported = true;
+        break;
+      }
+    }
+    if (!memoryExported) {
+      wasm->addExport(
+        Builder::makeExport("profile-memory",
+                            Names::getValidExportName(*wasm, wasm->memory.name),
+                            ExternalKind::Memory));
     }
-  }
-  if (!memoryExported) {
-    wasm->addExport(
-      Builder::makeExport("profile-memory",
-                          Names::getValidExportName(*wasm, wasm->memory.name),
-                          ExternalKind::Memory));
   }
 }