[SwiftCompilerSources] add BridgedOStream and debugLog().

So we can trace optimizer passes using the same output stream as the
C++ passes and don't get garbled output.

Author: atrick

SwiftCompilerSources/Sources/Basic/Utils.swift

@@ -58,6 +58,14 @@ public func precondition(_ condition: Bool, _ message: @autoclosure () -> String
 //                            Debugging Utilities
 //===----------------------------------------------------------------------===//
 
+public func debugLog(prefix: Bool = true, _ message: @autoclosure () -> String) {
+  let formatted = (prefix ? "### " : "") + message()
+  formatted._withBridgedStringRef { ref in
+    Bridged_dbgs().write(ref)
+  }
+  Bridged_dbgs().newLine()
+}
+
 /// Let's lldb's `po` command not print any "internal" properties of the conforming type.
 ///
 /// This is useful if the `description` already contains all the information of a type instance.

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/LifetimeDependenceDiagnostics.swift

@@ -16,7 +16,7 @@ private let verbose = false
 
 private func log(prefix: Bool = true, _ message: @autoclosure () -> String) {
   if verbose {
-    print((prefix ? "### " : "") + message())
+    debugLog(prefix: prefix, message())
   }
 }
 

include/swift/Basic/BasicBridging.h

@@ -185,16 +185,12 @@ enum ENUM_EXTENSIBILITY_ATTR(open) BridgedFeature {
 #include "swift/Basic/Features.def"
 };
 
-//===----------------------------------------------------------------------===//
-// MARK: OStream
-//===----------------------------------------------------------------------===//
-
-BRIDGING_WRAPPER_NONNULL(llvm::raw_ostream, OStream)
-
 //===----------------------------------------------------------------------===//
 // MARK: StringRef
 //===----------------------------------------------------------------------===//
 
+class BridgedOStream;
+
 class BridgedStringRef {
   const char *_Nullable Data;
   size_t Length;
@@ -250,6 +246,39 @@ BRIDGED_INLINE SwiftInt BridgedOwnedString_count(BridgedOwnedString str);
 SWIFT_NAME("getter:BridgedOwnedString.isEmpty(self:)")
 BRIDGED_INLINE bool BridgedOwnedString_empty(BridgedOwnedString str);
 
+//===----------------------------------------------------------------------===//
+// MARK: OStream
+//===----------------------------------------------------------------------===//
+
+class BridgedOStream {
+  llvm::raw_ostream * _Nonnull os;
+
+public:
+  SWIFT_UNAVAILABLE("Use init(raw:) instead")
+  BridgedOStream(llvm::raw_ostream * _Nonnull os) : os(os) {}
+
+  SWIFT_UNAVAILABLE("Use '.raw' instead")
+  llvm::raw_ostream * _Nonnull unbridged() const { return os; }
+
+  void write(BridgedStringRef string) const;
+
+  void newLine() const;
+
+  void flush() const;
+};
+
+SWIFT_NAME("getter:BridgedOStream.raw(self:)")
+inline void * _Nonnull BridgedOStream_getRaw(BridgedOStream bridged) {
+  return bridged.unbridged();
+}
+
+SWIFT_NAME("BridgedOStream.init(raw:)")
+inline BridgedOStream BridgedOStream_fromRaw(void * _Nonnull os) {
+  return static_cast<llvm::raw_ostream *>(os);
+}
+
+BridgedOStream Bridged_dbgs();
+
 //===----------------------------------------------------------------------===//
 // MARK: SourceLoc
 //===----------------------------------------------------------------------===//

lib/Basic/BasicBridging.cpp

@@ -12,6 +12,7 @@
 
 #include "swift/Basic/Assertions.h"
 #include "swift/Basic/BasicBridging.h"
+#include "llvm/Support/Debug.h"
 #include "llvm/Support/JSON.h"
 #include "llvm/Support/raw_ostream.h"
 
@@ -28,6 +29,26 @@ void assertFail(const char * _Nonnull msg, const char * _Nonnull file,
   ASSERT_failure(msg, file, line, function);
 }
 
+//===----------------------------------------------------------------------===//
+// MARK: BridgedOStream
+//===----------------------------------------------------------------------===//
+
+void BridgedOStream::write(BridgedStringRef string) const {
+  *os << string.unbridged();
+}
+
+void BridgedOStream::newLine() const {
+  os->write('\n');
+}
+
+void BridgedOStream::flush() const {
+  os->flush();
+}
+
+BridgedOStream Bridged_dbgs() {
+  return BridgedOStream(&llvm::dbgs());
+}
+
 //===----------------------------------------------------------------------===//
 // MARK: BridgedStringRef
 //===----------------------------------------------------------------------===//