Revert "Revert "Strip the full path from __FILE__ in the LDBG macro and keep only the filename (#150677)""

This reverts commit a15b629.

The revert made things worse. Oops.

Author: jroelofs

llvm/cmake/modules/LLVMProcessSources.cmake

@@ -58,6 +58,21 @@ function(llvm_process_sources OUT_VAR)
   set(sources ${ARG_UNPARSED_ARGUMENTS})
   llvm_check_source_file_list(${sources})
 
+  # Don't generate __SHORT_FILE__ on VS builds as it can prevent build parallelisation.
+  if(NOT CMAKE_GENERATOR MATCHES "Visual Studio")
+    foreach(fn ${sources})
+      get_filename_component(suf ${fn} EXT)
+      if("${suf}" STREQUAL ".cpp" OR "${suf}" STREQUAL ".c")
+        get_filename_component(short_name ${fn} NAME)
+        set_property(
+            SOURCE ${fn}
+            APPEND
+            PROPERTY COMPILE_DEFINITIONS __SHORT_FILE__="${short_name}")
+      endif()
+    endforeach()
+  endif()
+
+
   # This adds .td and .h files to the Visual Studio solution:
   add_td_sources(sources)
   find_all_header_files(hdrs "${ARG_ADDITIONAL_HEADER_DIRS}")

llvm/include/llvm/Support/DebugLog.h

@@ -41,32 +41,81 @@ namespace llvm {
 //
 #define LDBG(...) _GET_LDBG_MACRO(__VA_ARGS__)(__VA_ARGS__)
 
-#define DEBUGLOG_WITH_STREAM_AND_TYPE(STREAM, TYPE)                            \
-  for (bool _c = (::llvm::DebugFlag && ::llvm::isCurrentDebugType(TYPE)); _c;  \
-       _c = false)                                                             \
-  ::llvm::impl::LogWithNewline(TYPE, __FILE__, __LINE__, (STREAM))
+// Helper macros to choose the correct macro based on the number of arguments.
+#define LDBG_FUNC_CHOOSER(_f1, _f2, ...) _f2
+#define LDBG_FUNC_RECOMPOSER(argsWithParentheses)                              \
+  LDBG_FUNC_CHOOSER argsWithParentheses
+#define LDBG_CHOOSE_FROM_ARG_COUNT(...)                                        \
+  LDBG_FUNC_RECOMPOSER((__VA_ARGS__, LDBG_LOG_LEVEL, ))
+#define LDBG_NO_ARG_EXPANDER() , LDBG_LOG_LEVEL_1
+#define _GET_LDBG_MACRO(...)                                                   \
+  LDBG_CHOOSE_FROM_ARG_COUNT(LDBG_NO_ARG_EXPANDER __VA_ARGS__())
+
+// Dispatch macros to support the `level` argument or none (default to 1)
+#define LDBG_LOG_LEVEL(LEVEL)                                                  \
+  DEBUGLOG_WITH_STREAM_AND_TYPE(llvm::dbgs(), LEVEL, DEBUG_TYPE)
+#define LDBG_LOG_LEVEL_1() LDBG_LOG_LEVEL(1)
+
+#define DEBUGLOG_WITH_STREAM_TYPE_FILE_AND_LINE(STREAM, LEVEL, TYPE, FILE,     \
+                                                LINE)                          \
+  for (bool _c =                                                               \
+           (::llvm::DebugFlag && ::llvm::isCurrentDebugType(TYPE, LEVEL));     \
+       _c; _c = false)                                                         \
+    for (::llvm::impl::RAIINewLineStream NewLineStream{(STREAM)}; _c;          \
+         _c = false)                                                           \
+  ::llvm::impl::raw_ldbg_ostream{                                              \
+      ::llvm::impl::computePrefix(TYPE, FILE, LINE, LEVEL), NewLineStream}     \
+      .asLvalue()
+
+#define DEBUGLOG_WITH_STREAM_TYPE_AND_FILE(STREAM, LEVEL, TYPE, FILE)          \
+  DEBUGLOG_WITH_STREAM_TYPE_FILE_AND_LINE(STREAM, LEVEL, TYPE, FILE, __LINE__)
+// When __SHORT_FILE__ is not defined, the File is the full path,
+// otherwise __SHORT_FILE__ is defined in CMake to provide the file name
+// without the path prefix.
+#if defined(__SHORT_FILE__)
+#define DEBUGLOG_WITH_STREAM_AND_TYPE(STREAM, LEVEL, TYPE)                     \
+  DEBUGLOG_WITH_STREAM_TYPE_AND_FILE(STREAM, LEVEL, TYPE, __SHORT_FILE__)
+#else
+#define DEBUGLOG_WITH_STREAM_AND_TYPE(STREAM, LEVEL, TYPE)                     \
+  DEBUGLOG_WITH_STREAM_TYPE_AND_FILE(STREAM, LEVEL, TYPE,                      \
+                                     ::llvm::impl::getShortFileName(__FILE__))
+#endif
 
 namespace impl {
-class LogWithNewline {
-public:
-  LogWithNewline(const char *debug_type, const char *file, int line,
-                 raw_ostream &os)
-      : os(os) {
-    if (debug_type)
-      os << "[" << debug_type << "] ";
-    os << file << ":" << line << " ";
+
+/// A raw_ostream that tracks `\n` and print the prefix after each
+/// newline.
+class LLVM_ABI raw_ldbg_ostream final : public raw_ostream {
+  std::string Prefix;
+  raw_ostream &Os;
+  bool HasPendingNewline;
+
+  /// Split the line on newlines and insert the prefix before each
+  /// newline. Forward everything to the underlying stream.
+  void write_impl(const char *Ptr, size_t Size) final {
+    auto Str = StringRef(Ptr, Size);
+    // Handle the initial prefix.
+    if (!Str.empty())
+      writeWithPrefix(StringRef());
+
+    auto Eol = Str.find('\n');
+    while (Eol != StringRef::npos) {
+      StringRef Line = Str.take_front(Eol + 1);
+      if (!Line.empty())
+        writeWithPrefix(Line);
+      HasPendingNewline = true;
+      Str = Str.drop_front(Eol + 1);
+      Eol = Str.find('\n');
+    }
+    if (!Str.empty())
+      writeWithPrefix(Str);
   }
-  ~LogWithNewline() { os << '\n'; }
-  template <typename T> raw_ostream &operator<<(const T &t) && {
-    return os << t;
+  void emitPrefix() { Os.write(Prefix.c_str(), Prefix.size()); }
+  void writeWithPrefix(StringRef Str) {
+    flushEol();
+    Os.write(Str.data(), Str.size());
   }
 
-  // Prevent copying, as this class manages newline responsibility and is
-  // intended for use as a temporary.
-  LogWithNewline(const LogWithNewline &) = delete;
-  LogWithNewline &operator=(const LogWithNewline &) = delete;
-  LogWithNewline &operator=(LogWithNewline &&) = delete;
-
 public:
   explicit raw_ldbg_ostream(std::string Prefix, raw_ostream &Os,
                             bool HasPendingNewline = true)