libswift: add back legacy pass to fix Windows test

Author: MaxDesiatov

include/swift/SILOptimizer/PassManager/Passes.def

@@ -131,7 +131,7 @@ PASS(ArrayCountPropagation, "array-count-propagation",
      "Array Count Propagation")
 PASS(ArrayElementPropagation, "array-element-propagation",
      "Array Element Propagation")
-SWIFT_FUNCTION_PASS(AssumeSingleThreaded, "sil-assume-single-threaded",
+SWIFT_FUNCTION_PASS_WITH_LEGACY(AssumeSingleThreaded, "sil-assume-single-threaded",
      "Assume Single-Threaded Environment")
 PASS(BasicInstructionPropertyDumper, "basic-instruction-property-dump",
      "Print SIL Instruction MemBehavior and ReleaseBehavior Information")

lib/SILOptimizer/Transforms/AssumeSingleThreaded.cpp

@@ -0,0 +1,57 @@
+//===--- AssumeSingleThreaded.cpp - Assume single-threaded execution  -----===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// Assume that user code is single-thread.
+//
+// Convert all reference counting operations into non-atomic ones.
+//
+// To get read of most atomic reference counting operations, the standard
+// library should be compiled in this mode as well
+//
+// This pass affects only reference counting operations resulting from SIL
+// instructions. It wouldn't affect places in the runtime C++ code which
+// hard-code calls to retain/release. We could take advantage of the Instruments
+// instrumentation stubs to redirect calls from the runtime if it was
+// significant, or else just build a single-threaded variant of the runtime.
+//
+//===----------------------------------------------------------------------===//
+
+#include "swift/SIL/SILFunction.h"
+#include "swift/SIL/SILInstruction.h"
+#include "swift/SIL/SILModule.h"
+#include "swift/SILOptimizer/PassManager/Passes.h"
+#include "swift/SILOptimizer/PassManager/Transforms.h"
+#include "swift/SILOptimizer/Utils/InstOptUtils.h"
+#include "llvm/Support/CommandLine.h"
+
+using namespace swift;
+
+namespace {
+class AssumeSingleThreaded : public swift::SILFunctionTransform {
+  /// The entry point to the transformation.
+  void run() override {
+    if (!getOptions().AssumeSingleThreaded)
+      return;
+    for (auto &BB : *getFunction()) {
+      for (auto &I : BB) {
+        if (auto RCInst = dyn_cast<RefCountingInst>(&I))
+          RCInst->setNonAtomic();
+      }
+    }
+    invalidateAnalysis(SILAnalysis::InvalidationKind::Instructions);
+  }
+};
+} // end anonymous namespace
+
+SILTransform *swift::createLegacyAssumeSingleThreaded() {
+  return new AssumeSingleThreaded();
+}

lib/SILOptimizer/Transforms/CMakeLists.txt

@@ -7,6 +7,7 @@ target_sources(swiftSILOptimizer PRIVATE
   AllocBoxToStack.cpp
   ArrayCountPropagation.cpp
   ArrayElementValuePropagation.cpp
+  AssumeSingleThreaded.cpp
   COWOpts.cpp
   CSE.cpp
   ConditionForwarding.cpp