Notify valgrind when we modify code on x86.

src/ia32/cpu-ia32.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
 //       with the distribution.
 //     * Neither the name of Google Inc. nor the names of its
 //       contributors may be used to endorse or promote products derived
 //       from this software without specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // CPU specific code for ia32 independent of OS goes here.
 
+#ifdef __GNUC__
+#include "third_party/valgrind/valgrind.h"

[iposva, 2009/07/23 18:01:57]

The code in valgrind.h does not appear to distinguish between more than Linux
and AIX. I assume that the above test for __GNUC__ is intended to check for gcc
compilation to filter out Windows. But what happens if you compile with this
header on Windows using gcc or on Mac OS X?

+#endif
+
 #include "v8.h"
 
 #include "cpu.h"
 #include "macro-assembler.h"
 
 namespace v8 {
 namespace internal {
 
 void CPU::Setup() {
   CpuFeatures::Probe();
 }
 
 
 void CPU::FlushICache(void* start, size_t size) {
   // No need to flush the instruction cache on Intel. On Intel instruction
   // cache flushing is only necessary when multiple cores running the same
   // code simultaneously. V8 (and JavaScript) is single threaded and when code
   // is patched on an intel CPU the core performing the patching will have its
   // own instruction cache updated automatically.
 
   // If flushing of the instruction cache becomes necessary Windows has the
   // API function FlushInstructionCache.
+
+  // By default, valgrind only checks the stack for writes that might need to
+  // invalidate already cached translated code.  This leads to random
+  // instability when code patches or moves are sometimes unnoticed.  One
+  // solution is to run valgrind with --smc-check=all, but this comes at a big
+  // performance cost.  We can notify valgrind to invalidate its cache.
+#ifdef VALGRIND_DISCARD_TRANSLATIONS
+  VALGRIND_DISCARD_TRANSLATIONS(start, size);
+#endif
 }
 
 
 void CPU::DebugBreak() {
 #ifdef _MSC_VER
   // To avoid Visual Studio runtime support the following code can be used
   // instead
   // __asm { int 3 }
   __debugbreak();
 #else
   asm("int $3");
 #endif
 }
 
 } }  // namespace v8::internal