1 files changed, 78 insertions, 0 deletions
diff --git a/src/passes/SeparateDataSegments.cpp b/src/passes/SeparateDataSegments.cpp
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+++ b/src/passes/SeparateDataSegments.cpp
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+/*
+ * Copyright 2023 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//
+// Emits the data segments to a file. The file contains data from address base
+// onwards (we must pass in base, as we can't tell it from the wasm - the
+// first segment may start after a run of zeros, but we need those zeros in
+// the file.
+//
+
+#include "pass.h"
+#include "support/file.h"
+#include "wasm-features.h"
+#include "wasm.h"
+
+namespace wasm {
+
+struct SeparateDataSegments : public Pass {
+  bool modifiesBinaryenIR() override { return false; }
+
+  void run(Module* module) override {
+    std::string outfileName =
+      getPassOptions().getArgument("separate-data-segments",
+                                   "SeparateDataSegments usage: wasm-opt "
+                                   "--separate-data-segments@FILENAME");
+    Output outfile(outfileName, Flags::Binary);
+    std::string baseStr = getPassOptions().getArgument(
+      "separate-data-segments-global-base",
+      "SeparateDataSegments usage: wasm-opt "
+      "--pass-arg=separate-data-segments-global-base@NUMBER");
+    Address base = std::stoi(baseStr);
+    size_t lastEnd = 0;
+    for (auto& seg : module->dataSegments) {
+      if (seg->isPassive) {
+        Fatal() << "separating passive segments not implemented";
+      }
+      if (!seg->offset->is<Const>()) {
+        Fatal() << "separating relocatable segments not implemented";
+      }
+      size_t offset = seg->offset->cast<Const>()->value.getInteger();
+      offset -= base;
+      size_t fill = offset - lastEnd;
+      if (fill > 0) {
+        std::vector<char> buf(fill);
+        outfile.write(buf.data(), fill);
+      }
+      outfile.write(seg->data.data(), seg->data.size());
+      lastEnd = offset + seg->data.size();
+    }
+    module->dataSegments.clear();
+    // Remove the start/stop symbols that the PostEmscripten uses to remove
+    // em_asm/em_js data.  Since we just removed all the data segments from the
+    // file there is nothing more for that pass to do.
+    // TODO(sbc): Fix the ordering so that the removal the EM_ASM/EM_JS data
+    // comes before this pass.
+    module->removeExport("__start_em_asm");
+    module->removeExport("__stop_em_asm");
+    module->removeExport("__start_em_js");
+    module->removeExport("__stop_em_js");
+  }
+};
+
+Pass* createSeparateDataSegmentsPass() { return new SeparateDataSegments(); }
+
+} // namespace wasm