[NFC] Use quick_exit to skip global cleanup

src/support/file.cpp

@@ -135,3 +135,9 @@ size_t wasm::file_size(std::string filename) {
                        std::ifstream::ate | std::ifstream::binary);
   return infile.tellg();
 }
+
+void wasm::flush_and_quick_exit() {
+  std::cout << std::flush;
+  std::cerr << std::flush;
+  std::quick_exit(0);
+}

src/support/file.h

@@ -72,9 +72,15 @@ class Output {
 // Copies a file to another file
 void copy_file(std::string input, std::string output);
 
-// Retusn the size of a file
+// Return the size of a file
 size_t file_size(std::string filename);
 
+// Flush stdout and stderr, and quickly exit. This assumes that all files that
+// need flushing have been flushed, that is, no global ctors or RAII in main's
+// top level are depended on (using quick_exit then avoids running global dtors,
+// which saves otherwise wasted time).
+void flush_and_quick_exit();
+
 } // namespace wasm
 
 #endif // wasm_support_file_h

src/tools/wasm-as.cpp

@@ -131,19 +131,25 @@ int main(int argc, const char* argv[]) {
   if (options.debug) {
     std::cerr << "writing..." << std::endl;
   }
-  ModuleWriter writer(options.passOptions);
-  writer.setBinary(true);
-  writer.setDebugInfo(debugInfo);
-  if (sourceMapFilename.size()) {
-    writer.setSourceMapFilename(sourceMapFilename);
-    writer.setSourceMapUrl(sourceMapUrl);
-  }
-  if (symbolMap.size() > 0) {
-    writer.setSymbolMap(symbolMap);
+
+  // Ensure the destructor of ModuleWriter runs before quick_exit.
+  {
+    ModuleWriter writer(options.passOptions);
+    writer.setBinary(true);
+    writer.setDebugInfo(debugInfo);
+    if (sourceMapFilename.size()) {
+      writer.setSourceMapFilename(sourceMapFilename);
+      writer.setSourceMapUrl(sourceMapUrl);
+    }
+    if (symbolMap.size() > 0) {
+      writer.setSymbolMap(symbolMap);
+    }
+    writer.write(wasm, options.extra["output"]);
   }
-  writer.write(wasm, options.extra["output"]);
 
   if (options.debug) {
     std::cerr << "Done." << std::endl;
   }
+
+  flush_and_quick_exit();
 }

src/tools/wasm-ctor-eval.cpp

@@ -1618,4 +1618,6 @@ int main(int argc, const char* argv[]) {
     writer.setDebugInfo(debugInfo);
     writer.write(wasm, options.extra["output"]);
   }
+
+  flush_and_quick_exit();
 }

src/tools/wasm-dis.cpp

@@ -98,10 +98,16 @@ int main(int argc, const char* argv[]) {
   if (options.debug) {
     std::cerr << "Printing..." << std::endl;
   }
-  Output output(options.extra["output"], Flags::Text);
-  output.getStream() << wasm << '\n';
+
+  // Ensure the destructor of Output runs before quick_exit.
+  {
+    Output output(options.extra["output"], Flags::Text);
+    output.getStream() << wasm << '\n';
+  }
 
   if (options.debug) {
     std::cerr << "Done." << std::endl;
   }
+
+  flush_and_quick_exit();
 }

src/tools/wasm-emscripten-finalize.cpp

@@ -289,5 +289,6 @@ int main(int argc, const char* argv[]) {
     }
     writer.write(wasm, output);
   }
-  return 0;
+
+  flush_and_quick_exit();
 }

src/tools/wasm-merge.cpp

@@ -832,4 +832,6 @@ Input source maps can be specified by adding an -ism option right after the modu
     }
     writer.write(merged, options.extra["output"]);
   }
+
+  flush_and_quick_exit();
 }

src/tools/wasm-metadce.cpp

@@ -674,4 +674,6 @@ int main(int argc, const char* argv[]) {
 
   // Clean up
   free(copy);
+
+  flush_and_quick_exit();
 }

src/tools/wasm-opt.cpp

@@ -496,5 +496,6 @@ For more on how to optimize effectively, see
       Fatal() << "extra fuzz command output differs\n";
     }
   }
-  return 0;
+
+  flush_and_quick_exit();
 }

src/tools/wasm-shell.cpp

@@ -603,4 +603,6 @@ int main(int argc, const char* argv[]) {
   Colors::bold(std::cerr);
   std::cerr << "all checks passed.\n";
   Colors::normal(std::cerr);
+
+  flush_and_quick_exit();
 }

src/tools/wasm2js.cpp

@@ -993,14 +993,20 @@ int main(int argc, const char* argv[]) {
   if (options.debug) {
     std::cerr << "j-printing..." << std::endl;
   }
-  Output output(options.extra["output"], Flags::Text);
-  if (script && options.extra["asserts"] == "1") {
-    AssertionEmitter(*script, output, flags, options).emit();
-  } else {
-    emitWasm(*wasm, output, flags, options.passOptions, "asmFunc");
+
+  // Ensure the destructor of Output runs before quick_exit.
+  {
+    Output output(options.extra["output"], Flags::Text);
+    if (script && options.extra["asserts"] == "1") {
+      AssertionEmitter(*script, output, flags, options).emit();
+    } else {
+      emitWasm(*wasm, output, flags, options.passOptions, "asmFunc");
+    }
   }
 
   if (options.debug) {
     std::cerr << "done." << std::endl;
   }
+
+  flush_and_quick_exit();
 }