Fix EM_ASM+pthreads (#1891)

To calculate the metadata, we must look at the segments. If we split them out earlier (which we do for threads), they aren't there.

1 files changed, 9 insertions, 6 deletions

diff --git a/src/tools/wasm-emscripten-finalize.cpp b/src/tools/wasm-emscripten-finalize.cpp
index d0b664c0c..f2c74221d 100644
--- a/src/tools/wasm-emscripten-finalize.cpp
+++ b/src/tools/wasm-emscripten-finalize.cpp
@@ -204,12 +204,8 @@ int main(int argc, const char *argv[]) {
 
   generator.generateDynCallThunks();
   generator.generateJSCallThunks(numReservedFunctionPointers);
-  if (!dataSegmentFile.empty()) {
-    Output memInitFile(dataSegmentFile, Flags::Binary, Flags::Release);
-    generator.separateDataSegments(&memInitFile);
-  }
 
-  // Finally, legalize the wasm.
+  // Legalize the wasm.
   {
     PassRunner passRunner(&wasm);
     passRunner.setDebug(options.debug);
@@ -221,9 +217,16 @@ int main(int argc, const char *argv[]) {
     passRunner.run();
   }
 
-  // All changes to the wasm are done, create the metadata.
+  // Substantial changes to the wasm are done, enough to create the metadata.
   std::string metadata = generator.generateEmscriptenMetadata(dataSize, initializerFunctions, numReservedFunctionPointers);
 
+  // Finally, separate out data segments if relevant (they may have been needed
+  // for metadata).
+  if (!dataSegmentFile.empty()) {
+    Output memInitFile(dataSegmentFile, Flags::Binary, Flags::Release);
+    generator.separateDataSegments(&memInitFile);
+  }
+
   if (options.debug) {
     std::cerr << "Module after:\n";
     WasmPrinter::printModule(&wasm, std::cerr);