[ORC-RT] Add debug logging macros.

Inspired by LLVM_DEBUG, but using environment variables rather than command line
options.

Code can use ORC_RT_DEBUG(...) (if ORC_RT_DEBUG_TYPE is set), or
ORC_RT_DEBUG_WITH_TYPE(<type>, ...) (if ORC_RT_DEBUG_TYPE is not set. E.g. in
headers).

Debug logging is enabled in the executor by setting the ORC_RT_DEBUG environment
variable. Debug logging can be restricted by type by setting the
ORC_RT_DEBUG_TYPES environment variable to a comma separated list of types,
e.g. ORC_RT_DEBUG_TYPES=macho_platform,sps.

Differential Revision: https://reviews.llvm.org/D116139

compiler-rt/lib/orc/CMakeLists.txt

@@ -2,6 +2,7 @@
 
 # ORC runtime library implementation files.
 set(ORC_SOURCES
+  debug.cpp
   extensible_rtti.cpp
   log_error_to_stderr.cpp
   macho_ehframe_registration.cpp

compiler-rt/lib/orc/debug.cpp

@@ -0,0 +1,80 @@
+//===- debug.cpp ----------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of the ORC runtime support library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "debug.h"
+
+#include <cassert>
+#include <cstdio>
+#include <cstdlib>
+
+namespace __orc_rt {
+
+#ifndef NDEBUG
+
+std::atomic<const char *> DebugTypes;
+char DebugTypesAll;
+char DebugTypesNone;
+
+/// Sets the DebugState and DebugTypes values -- this function may be called
+/// concurrently on multiple threads, but will always assign the same values so
+/// this should be safe.
+const char *initializeDebug() {
+  if (const char *DT = getenv("ORC_RT_DEBUG")) {
+    // If ORC_RT_DEBUG=1 then log everything.
+    if (strcmp(DT, "1") == 0) {
+      DebugTypes.store(&DebugTypesAll, std::memory_order_relaxed);
+      return &DebugTypesAll;
+    }
+
+    // If ORC_RT_DEBUG is non-empty then record the string for use in
+    // debugTypeEnabled.
+    if (strcmp(DT, "") != 0) {
+      DebugTypes.store(DT, std::memory_order_relaxed);
+      return DT;
+    }
+  }
+
+  // If ORT_RT_DEBUG is undefined or defined as empty then log nothing.
+  DebugTypes.store(&DebugTypesNone, std::memory_order_relaxed);
+  return &DebugTypesNone;
+}
+
+bool debugTypeEnabled(const char *Type, const char *Types) {
+  assert(Types && Types != &DebugTypesAll && Types != &DebugTypesNone &&
+         "Invalid Types value");
+  size_t TypeLen = strlen(Type);
+  const char *Start = Types;
+  const char *End = Start;
+
+  do {
+    if (*End == '\0' || *End == ',') {
+      size_t ItemLen = End - Start;
+      if (ItemLen == TypeLen && memcmp(Type, Start, TypeLen) == 0)
+        return true;
+      if (*End == '\0')
+        return false;
+      Start = End + 1;
+    }
+    ++End;
+  } while (true);
+}
+
+void printdbg(const char *format, ...) {
+  va_list Args;
+  va_start(Args, format);
+  vfprintf(stderr, format, Args);
+  va_end(Args);
+}
+
+#endif // !NDEBUG
+
+} // end namespace __orc_rt

compiler-rt/lib/orc/debug.h

@@ -0,0 +1,56 @@
+//===- debug.h - Debugging output utilities ---------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of the ORC runtime support library.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef ORC_RT_DEBUG_H
+#define ORC_RT_DEBUG_H
+
+#include <atomic>
+
+#ifndef NDEBUG
+
+namespace __orc_rt {
+
+extern std::atomic<const char *> DebugTypes;
+extern char DebugTypesAll;
+extern char DebugTypesNone;
+
+const char *initializeDebug();
+bool debugTypeEnabled(const char *Type, const char *Types);
+void printdbg(const char *format, ...);
+
+} // namespace __orc_rt
+
+#define ORC_RT_DEBUG_WITH_TYPE(TYPE, X)                                        \
+  do {                                                                         \
+    const char *Types =                                                        \
+        ::__orc_rt::DebugTypes.load(std::memory_order_relaxed);                \
+    if (!Types)                                                                \
+      Types = initializeDebug();                                               \
+    if (Types == &DebugTypesNone)                                              \
+      break;                                                                   \
+    if (Types == &DebugTypesAll ||                                             \
+        ::__orc_rt::debugTypeEnabled(TYPE, Types)) {                           \
+      X;                                                                       \
+    }                                                                          \
+  } while (false)
+
+#else
+
+#define ORC_RT_DEBUG_WITH_TYPE(TYPE, X)                                        \
+  do {                                                                         \
+  } while (false)
+
+#endif // !NDEBUG
+
+#define ORC_RT_DEBUG(X) ORC_RT_DEBUG_WITH_TYPE(DEBUG_TYPE, X)
+
+#endif // ORC_RT_COMMON_H