[wasm-split] Minimize names of newly created exports (#3905)

wasm-split would previously use internal function names to create the external
names of the functions that are newly exported from the primary module to be
imported into the secondary module. When the input module contains full function
names (as is commonly the case when emitting symbol maps), this caused the
function names to be preserved as the export names, even when names are
otherwise being stripped. To save on code size and properly anonymize functions,
generate minimal export names when debuginfo is disabled instead.

1 files changed, 10 insertions, 2 deletions

diff --git a/src/ir/module-splitting.cpp b/src/ir/module-splitting.cpp
index 5f9ba0aad..d6dca8994 100644
--- a/src/ir/module-splitting.cpp
+++ b/src/ir/module-splitting.cpp
@@ -266,6 +266,8 @@ struct ModuleSplitter {
 
   TableSlotManager tableManager;
 
+  Names::MinifiedNameGenerator minified;
+
   // Map from internal function names to (one of) their corresponding export
   // names.
   std::map<Name, Name> exportedPrimaryFuncs;
@@ -344,8 +346,14 @@ void ModuleSplitter::exportImportFunction(Name funcName) {
   if (exportIt != exportedPrimaryFuncs.end()) {
     exportName = exportIt->second;
   } else {
-    exportName = Names::getValidExportName(
-      primary, config.newExportPrefix + funcName.c_str());
+    if (config.minimizeNewExportNames) {
+      do {
+        exportName = config.newExportPrefix + minified.getName();
+      } while (primary.getExportOrNull(exportName) != nullptr);
+    } else {
+      exportName = Names::getValidExportName(
+        primary, config.newExportPrefix + funcName.c_str());
+    }
     primary.addExport(
       Builder::makeExport(exportName, funcName, ExternalKind::Function));
     exportedPrimaryFuncs[funcName] = exportName;