4 files changed, 37 insertions, 16 deletions

diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index 68a2e4cb6..a90ef4669 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -2838,8 +2838,9 @@ void PrintSExpression::handleSignature(HeapType curr, Name name) {
 void PrintSExpression::visitExport(Export* curr) {
   o << '(';
   printMedium(o, "export ");
-  // TODO: Escape the string properly.
-  printText(o, curr->name.str.data()) << " (";
+  std::stringstream escaped;
+  String::printEscaped(escaped, curr->name.str);
+  printText(o, escaped.str(), false) << " (";
   switch (curr->kind) {
     case ExternalKind::Function:
       o << "func";
@@ -2865,9 +2866,11 @@ void PrintSExpression::visitExport(Export* curr) {
 
 void PrintSExpression::emitImportHeader(Importable* curr) {
   printMedium(o, "import ");
-  // TODO: Escape the strings properly and use std::string_view.
-  printText(o, curr->module.str.data()) << ' ';
-  printText(o, curr->base.str.data()) << ' ';
+  std::stringstream escapedModule, escapedBase;
+  String::printEscaped(escapedModule, curr->module.str);
+  String::printEscaped(escapedBase, curr->base.str);
+  printText(o, escapedModule.str(), false) << ' ';
+  printText(o, escapedBase.str(), false) << ' ';
 }
 
 void PrintSExpression::visitGlobal(Global* curr) {
diff --git a/src/passes/StringLowering.cpp b/src/passes/StringLowering.cpp
index df2d66860..dd7428546 100644
--- a/src/passes/StringLowering.cpp
+++ b/src/passes/StringLowering.cpp
@@ -189,6 +189,13 @@ struct StringGathering : public Pass {
 };
 
 struct StringLowering : public StringGathering {
+  // If true, then encode well-formed strings as (import "'" "string...")
+  // instead of emitting them into the JSON custom section.
+  bool useMagicImports;
+
+  StringLowering(bool useMagicImports = false)
+    : useMagicImports(useMagicImports) {}
+
   void run(Module* module) override {
     if (!module->features.has(FeatureSet::Strings)) {
       return;
@@ -217,25 +224,30 @@ struct StringLowering : public StringGathering {
   }
 
   void makeImports(Module* module) {
-    Index importIndex = 0;
+    Index jsonImportIndex = 0;
     std::stringstream json;
     json << '[';
     bool first = true;
-    std::vector<Name> importedStrings;
     for (auto& global : module->globals) {
       if (global->init) {
         if (auto* c = global->init->dynCast<StringConst>()) {
-          global->module = "string.const";
-          global->base = std::to_string(importIndex);
-          importIndex++;
-          global->init = nullptr;
-
-          if (first) {
-            first = false;
+          std::stringstream utf8;
+          if (useMagicImports &&
+              String::convertUTF16ToUTF8(utf8, c->string.str)) {
+            global->module = "'";
+            global->base = Name(utf8.str());
           } else {
-            json << ',';
+            global->module = "string.const";
+            global->base = std::to_string(jsonImportIndex);
+            if (first) {
+              first = false;
+            } else {
+              json << ',';
+            }
+            String::printEscapedJSON(json, c->string.str);
+            jsonImportIndex++;
           }
-          String::printEscapedJSON(json, c->string.str);
+          global->init = nullptr;
         }
       }
     }
@@ -516,5 +528,6 @@ struct StringLowering : public StringGathering {
 
 Pass* createStringGatheringPass() { return new StringGathering(); }
 Pass* createStringLoweringPass() { return new StringLowering(); }
+Pass* createStringLoweringMagicImportPass() { return new StringLowering(true); }
 
 } // namespace wasm
diff --git a/src/passes/pass.cpp b/src/passes/pass.cpp
index 0955082ac..19ddaf2d4 100644
--- a/src/passes/pass.cpp
+++ b/src/passes/pass.cpp
@@ -484,6 +484,10 @@ void PassRegistry::registerPasses() {
                "lowers wasm strings and operations to imports",
                createStringLoweringPass);
   registerPass(
+    "string-lowering-magic-imports",
+    "same as string-lowering, but encodes well-formed strings as magic imports",
+    createStringLoweringMagicImportPass);
+  registerPass(
     "strip", "deprecated; same as strip-debug", createStripDebugPass);
   registerPass("stack-check",
                "enforce limits on llvm's __stack_pointer global",
diff --git a/src/passes/passes.h b/src/passes/passes.h
index 1b1ca99c6..23a9ea70b 100644
--- a/src/passes/passes.h
+++ b/src/passes/passes.h
@@ -156,6 +156,7 @@ Pass* createSimplifyLocalsNoTeeNoStructurePass();
 Pass* createStackCheckPass();
 Pass* createStringGatheringPass();
 Pass* createStringLoweringPass();
+Pass* createStringLoweringMagicImportPass();
 Pass* createStripDebugPass();
 Pass* createStripDWARFPass();
 Pass* createStripProducersPass();