Merge tcmalloc r111 (perftools v. 1.8) with the chromium/ branch.

third_party/tcmalloc/chromium/src/base/cycleclock.h

 // Copyright (c) 2004, Google Inc.
 // 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
@@ skipping 32 matching lines @@
 // ----------------------------------------------------------------------
 
 #ifndef GOOGLE_BASE_CYCLECLOCK_H_
 #define GOOGLE_BASE_CYCLECLOCK_H_
 
 #include "base/basictypes.h"   // make sure we get the def for int64
 #include "base/arm_instruction_set_select.h"
 #if defined(__MACH__) && defined(__APPLE__)
 # include <mach/mach_time.h>
 #endif
-// For MSVC, we want the __rdtsc intrinsic, declared in <intrin.h>.
-// Unfortunately, in some environments, <windows.h> and <intrin.h> have
-// conflicting declarations of some other intrinsics, breaking compilation.
+// For MSVC, we want to use '_asm rdtsc' when possible (since it works
+// with even ancient MSVC compilers), and when not possible the
+// __rdtsc intrinsic, declared in <intrin.h>.  Unfortunately, in some
+// environments, <windows.h> and <intrin.h> have conflicting
+// declarations of some other intrinsics, breaking compilation.
 // Therefore, we simply declare __rdtsc ourselves. See also
 // http://connect.microsoft.com/VisualStudio/feedback/details/262047
-#if defined(_MSC_VER)
+#if defined(_MSC_VER) && !defined(_M_IX86)
 extern "C" uint64 __rdtsc();
 #pragma intrinsic(__rdtsc)
 #endif
-#ifdef HAVE_SYS_TIME_H
+#ifdef ARMV3
 #include <sys/time.h>
 #endif
 
 // NOTE: only i386 and x86_64 have been well tested.
 // PPC, sparc, alpha, and ia64 are based on
 //    http://peter.kuscsik.com/wordpress/?p=14
 // with modifications by m3b.  See also
 //    https://setisvn.ssl.berkeley.edu/svn/lib/fftw-3.0.1/kernel/cycle.h
 struct CycleClock {
   // This should return the number of cycles since power-on.  Thread-safe.
@@ skipping 28 matching lines @@
     return (tbu1 << 32) | tbl;
 #elif defined(__sparc__)
     int64 tick;
     asm(".byte 0x83, 0x41, 0x00, 0x00");
     asm("mov   %%g1, %0" : "=r" (tick));
     return tick;
 #elif defined(__ia64__)
     int64 itc;
     asm("mov %0 = ar.itc" : "=r" (itc));
     return itc;
+#elif defined(_MSC_VER) && defined(_M_IX86)
+    // Older MSVC compilers (like 7.x) don't seem to support the
+    // __rdtsc intrinsic properly, so I prefer to use _asm instead
+    // when I know it will work.  Otherwise, I'll use __rdtsc and hope
+    // the code is being compiled with a non-ancient compiler.
+    _asm rdtsc
 #elif defined(_MSC_VER)
     return __rdtsc();
 #elif defined(ARMV3)
 #if defined(ARMV6)  // V6 is the earliest arch that has a standard cyclecount
     uint32 pmccntr;
     uint32 pmuseren;
     uint32 pmcntenset;
     // Read the user mode perf monitor counter access permissions.
     asm("mrc p15, 0, %0, c9, c14, 0" : "=r" (pmuseren));
     if (pmuseren & 1) {  // Allows reading perfmon counters for user mode code.
@@ skipping 12 matching lines @@
 // The soft failover to a generic implementation is automatic only for ARM.
 // For other platforms the developer is expected to make an attempt to create
 // a fast implementation and use generic version if nothing better is available.
 #error You need to define CycleTimer for your O/S and CPU
 #endif
   }
 };
 
 
 #endif  // GOOGLE_BASE_CYCLECLOCK_H_