Tell Valgrind when we modify already-executed machine code so it knows

to re-instrument the code.  We depend on the system valgrind.h to
avoid adding a new license.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98529 91177308-0d34-0410-b5e6-96231b3b80d8

lib/System/Valgrind.cpp

@@ -0,0 +1,54 @@
+//===-- Valgrind.cpp - Implement Valgrind communication ---------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  Defines Valgrind communication methods, if HAVE_VALGRIND_VALGRIND_H is
+//  defined.  If we have valgrind.h but valgrind isn't running, its macros are
+//  no-ops.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/System/Valgrind.h"
+#include "llvm/Config/config.h"
+
+#if HAVE_VALGRIND_VALGRIND_H
+#include <valgrind/valgrind.h>
+
+static bool InitNotUnderValgrind() {
+  return !RUNNING_ON_VALGRIND;
+}
+
+// This bool is negated from what we'd expect because code may run before it
+// gets initialized.  If that happens, it will appear to be 0 (false), and we
+// want that to cause the rest of the code in this file to run the
+// Valgrind-provided macros.
+static const bool NotUnderValgrind = InitNotUnderValgrind();
+
+bool llvm::sys::RunningOnValgrind() {
+  if (NotUnderValgrind)
+    return false;
+  return RUNNING_ON_VALGRIND;
+}
+
+void llvm::sys::ValgrindDiscardTranslations(const void *Addr, size_t Len) {
+  if (NotUnderValgrind)
+    return;
+
+  VALGRIND_DISCARD_TRANSLATIONS(Addr, Len);
+}
+
+#else  // !HAVE_VALGRIND_VALGRIND_H
+
+bool llvm::sys::RunningOnValgrind() {
+  return false;
+}
+
+void llvm::sys::ValgrindDiscardTranslations(const void *Addr, size_t Len) {
+}
+
+#endif  // !HAVE_VALGRIND_VALGRIND_H