Fix removal of em_js strings (#3570)

2 files changed, 6 insertions, 8 deletions

diff --git a/src/wasm/wasm-emscripten.cpp b/src/wasm/wasm-emscripten.cpp
index 7a593f599..99c3216b6 100644
--- a/src/wasm/wasm-emscripten.cpp
+++ b/src/wasm/wasm-emscripten.cpp
@@ -447,7 +447,7 @@ EmJsWalker findEmJsFuncsAndReturnWalker(Module& wasm) {
   // We can detect this by checking for segments that contain only JS strings.
   // When we find such segements we remove them from the final binary.
   for (Index i = 0; i < wasm.memory.segments.size(); i++) {
-    Address start = walker.stringTracker.segmentOffsets[0];
+    Address start = walker.stringTracker.segmentOffsets[i];
     Address cur = start;
 
     while (cur < start + wasm.memory.segments[i].data.size()) {
diff --git a/test/lit/wasm-emscripten-finalize/em_js.wat b/test/lit/wasm-emscripten-finalize/em_js.wat
index 0cce1e3b5..85b3ece89 100644
--- a/test/lit/wasm-emscripten-finalize/em_js.wat
+++ b/test/lit/wasm-emscripten-finalize/em_js.wat
@@ -5,26 +5,24 @@
 
 ;; All functions should be stripped from the binary, regardless
 ;; of internal name
-;; CHECK-NOT:  (func
+;; CHECK-NOT: (func
 
 ;; The data section that contains only em_js strings should
-;; be stripped.
-;; CHECK-NOT: (i32.const 512) "Only em_js strings here\00")
-
-;; Data sections that also contain other stuff should not be stripped
+;; be stripped (shrunk to zero size):
 ;; CHECK: (data (i32.const 1024) "some JS string data\00xxx")
+;; CHECK: (data (i32.const 512) "")
 ;; CHECK: (data (i32.const 2048) "more JS string data\00yyy")
 
 ;;      CHECK:  "emJsFuncs": {
 ;; CHECK-NEXT:    "bar": "more JS string data",
-;; CHECK-NEXT:    "baz": "Only em_js strings here
+;; CHECK-NEXT:    "baz": "Only em_js strings here",
 ;; CHECK-NEXT:    "foo": "some JS string data"
 ;; CHECK-NEXT:  },
 
 (module
  (memory 1 1)
- (data (i32.const 512) "Only em_js strings here\00")
  (data (i32.const 1024) "some JS string data\00xxx")
+ (data (i32.const 512) "Only em_js strings here\00")
  (data (i32.const 2048) "more JS string data\00yyy")
  (export "__em_js__foo" (func $__em_js__foo))
  (export "__em_js__bar" (func $bar))