3 files changed, 64 insertions, 8 deletions

diff --git a/src/tools/fuzzing.h b/src/tools/fuzzing.h
index 56c633f14..63e7dca43 100644
--- a/src/tools/fuzzing.h
+++ b/src/tools/fuzzing.h
@@ -727,6 +727,9 @@ private:
                         &Self::makeSelect,
                         &Self::makeGetGlobal)
                    .add(FeatureSet::SIMD, &Self::makeSIMD);
+    if (type == none) {
+      options.add(FeatureSet::BulkMemory, &Self::makeBulkMemory);
+    }
     if (type == i32 || type == i64) {
       options.add(FeatureSet::Atomics, &Self::makeAtomic);
     }
@@ -1713,6 +1716,44 @@ private:
     return builder.makeSIMDShift(op, vec, shift);
   }
 
+  Expression* makeBulkMemory(Type type) {
+    assert(features.hasBulkMemory());
+    assert(type == none);
+    switch (upTo(4)) {
+      case 0: return makeMemoryInit();
+      case 1: return makeDataDrop();
+      case 2: return makeMemoryCopy();
+      case 3: return makeMemoryFill();
+    }
+    WASM_UNREACHABLE();
+  }
+
+  Expression* makeMemoryInit() {
+    auto segment = uint32_t(get32());
+    Expression* dest = make(i32);
+    Expression* offset = make(i32);
+    Expression* size = make(i32);
+    return builder.makeMemoryInit(segment, dest, offset, size);
+  }
+
+  Expression* makeDataDrop() {
+    return builder.makeDataDrop(get32());
+  }
+
+  Expression* makeMemoryCopy() {
+    Expression* dest = make(i32);
+    Expression* source = make(i32);
+    Expression* size = make(i32);
+    return builder.makeMemoryCopy(dest, source, size);
+  }
+
+  Expression* makeMemoryFill() {
+    Expression* dest = make(i32);
+    Expression* value = make(i32);
+    Expression* size = make(i32);
+    return builder.makeMemoryFill(dest, value, size);
+  }
+
   // special makers
 
   Expression* makeLogging() {
diff --git a/src/tools/tool-options.h b/src/tools/tool-options.h
index 9aff8e619..5620883ec 100644
--- a/src/tools/tool-options.h
+++ b/src/tools/tool-options.h
@@ -72,17 +72,29 @@ struct ToolOptions : public Options {
                passOptions.features.setTruncSat(false);
              })
         .add("--enable-simd", "",
-             "Enable nontrapping float-to-int operations",
+             "Enable SIMD operations and types",
              Options::Arguments::Zero,
              [this](Options *o, const std::string& arguments) {
                passOptions.features.setSIMD();
              })
         .add("--disable-simd", "",
-             "Disable nontrapping float-to-int operations",
+             "Disable SIMD operations and types",
              Options::Arguments::Zero,
              [this](Options *o, const std::string& arguments) {
                passOptions.features.setSIMD(false);
              })
+        .add("--enable-bulk-memory", "",
+             "Enable bulk memory operations",
+             Options::Arguments::Zero,
+             [this](Options *o, const std::string& arguments) {
+               passOptions.features.setBulkMemory();
+             })
+        .add("--disable-bulk-memory", "",
+             "Disable bulk memory operations",
+             Options::Arguments::Zero,
+             [this](Options *o, const std::string& arguments) {
+               passOptions.features.setBulkMemory(false);
+             })
         .add("--no-validation", "-n", "Disables validation, assumes inputs are correct",
              Options::Arguments::Zero,
              [this](Options* o, const std::string& argument) {
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);