Squashed 'third_party/gperftools/' content from commit 54505f1
Change-Id: Id02e833828732b0efe7dac722b8485279e67c5fa
git-subtree-dir: third_party/gperftools
git-subtree-split: 54505f1d50c2d1f4676f5e87090b64a117fd980e
diff --git a/src/base/atomicops-internals-x86.h b/src/base/atomicops-internals-x86.h
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+// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
+/* Copyright (c) 2006, 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
+ * 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.
+ *
+ * ---
+ * Author: Sanjay Ghemawat
+ */
+
+// Implementation of atomic operations for x86. This file should not
+// be included directly. Clients should instead include
+// "base/atomicops.h".
+
+#ifndef BASE_ATOMICOPS_INTERNALS_X86_H_
+#define BASE_ATOMICOPS_INTERNALS_X86_H_
+#include "base/basictypes.h"
+
+typedef int32_t Atomic32;
+#define BASE_HAS_ATOMIC64 1 // Use only in tests and base/atomic*
+
+
+// NOTE(vchen): x86 does not need to define AtomicWordCastType, because it
+// already matches Atomic32 or Atomic64, depending on the platform.
+
+
+// This struct is not part of the public API of this module; clients may not
+// use it.
+// Features of this x86. Values may not be correct before main() is run,
+// but are set conservatively.
+struct AtomicOps_x86CPUFeatureStruct {
+ bool has_sse2; // Processor has SSE2.
+ bool has_cmpxchg16b; // Processor supports cmpxchg16b instruction.
+};
+
+ATTRIBUTE_VISIBILITY_HIDDEN
+extern struct AtomicOps_x86CPUFeatureStruct AtomicOps_Internalx86CPUFeatures;
+
+
+#define ATOMICOPS_COMPILER_BARRIER() __asm__ __volatile__("" : : : "memory")
+
+
+namespace base {
+namespace subtle {
+
+typedef int64_t Atomic64;
+
+// 32-bit low-level operations on any platform.
+
+inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
+ Atomic32 old_value,
+ Atomic32 new_value) {
+ Atomic32 prev;
+ __asm__ __volatile__("lock; cmpxchgl %1,%2"
+ : "=a" (prev)
+ : "q" (new_value), "m" (*ptr), "0" (old_value)
+ : "memory");
+ return prev;
+}
+
+inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
+ Atomic32 new_value) {
+ __asm__ __volatile__("xchgl %1,%0" // The lock prefix is implicit for xchg.
+ : "=r" (new_value)
+ : "m" (*ptr), "0" (new_value)
+ : "memory");
+ return new_value; // Now it's the previous value.
+}
+
+inline Atomic32 Acquire_AtomicExchange(volatile Atomic32* ptr,
+ Atomic32 new_value) {
+ Atomic32 old_val = NoBarrier_AtomicExchange(ptr, new_value);
+ return old_val;
+}
+
+inline Atomic32 Release_AtomicExchange(volatile Atomic32* ptr,
+ Atomic32 new_value) {
+ // xchgl already has release memory barrier semantics.
+ return NoBarrier_AtomicExchange(ptr, new_value);
+}
+
+inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
+ Atomic32 old_value,
+ Atomic32 new_value) {
+ Atomic32 x = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+ return x;
+}
+
+inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
+ Atomic32 old_value,
+ Atomic32 new_value) {
+ return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+}
+
+inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
+ *ptr = value;
+}
+
+#if defined(__x86_64__)
+
+// 64-bit implementations of memory barrier can be simpler, because it
+// "mfence" is guaranteed to exist.
+inline void MemoryBarrier() {
+ __asm__ __volatile__("mfence" : : : "memory");
+}
+
+inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
+ *ptr = value;
+ MemoryBarrier();
+}
+
+#else
+
+inline void MemoryBarrier() {
+ if (AtomicOps_Internalx86CPUFeatures.has_sse2) {
+ __asm__ __volatile__("mfence" : : : "memory");
+ } else { // mfence is faster but not present on PIII
+ Atomic32 x = 0;
+ Acquire_AtomicExchange(&x, 0);
+ }
+}
+
+inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
+ if (AtomicOps_Internalx86CPUFeatures.has_sse2) {
+ *ptr = value;
+ __asm__ __volatile__("mfence" : : : "memory");
+ } else {
+ Acquire_AtomicExchange(ptr, value);
+ }
+}
+#endif
+
+inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
+ ATOMICOPS_COMPILER_BARRIER();
+ *ptr = value; // An x86 store acts as a release barrier.
+ // See comments in Atomic64 version of Release_Store(), below.
+}
+
+inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
+ return *ptr;
+}
+
+inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
+ Atomic32 value = *ptr; // An x86 load acts as a acquire barrier.
+ // See comments in Atomic64 version of Release_Store(), below.
+ ATOMICOPS_COMPILER_BARRIER();
+ return value;
+}
+
+inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
+ MemoryBarrier();
+ return *ptr;
+}
+
+#if defined(__x86_64__)
+
+// 64-bit low-level operations on 64-bit platform.
+
+inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
+ Atomic64 old_value,
+ Atomic64 new_value) {
+ Atomic64 prev;
+ __asm__ __volatile__("lock; cmpxchgq %1,%2"
+ : "=a" (prev)
+ : "q" (new_value), "m" (*ptr), "0" (old_value)
+ : "memory");
+ return prev;
+}
+
+inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
+ Atomic64 new_value) {
+ __asm__ __volatile__("xchgq %1,%0" // The lock prefix is implicit for xchg.
+ : "=r" (new_value)
+ : "m" (*ptr), "0" (new_value)
+ : "memory");
+ return new_value; // Now it's the previous value.
+}
+
+inline Atomic64 Acquire_AtomicExchange(volatile Atomic64* ptr,
+ Atomic64 new_value) {
+ Atomic64 old_val = NoBarrier_AtomicExchange(ptr, new_value);
+ return old_val;
+}
+
+inline Atomic64 Release_AtomicExchange(volatile Atomic64* ptr,
+ Atomic64 new_value) {
+ // xchgq already has release memory barrier semantics.
+ return NoBarrier_AtomicExchange(ptr, new_value);
+}
+
+inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
+ *ptr = value;
+}
+
+inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) {
+ *ptr = value;
+ MemoryBarrier();
+}
+
+inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
+ ATOMICOPS_COMPILER_BARRIER();
+
+ *ptr = value; // An x86 store acts as a release barrier
+ // for current AMD/Intel chips as of Jan 2008.
+ // See also Acquire_Load(), below.
+
+ // When new chips come out, check:
+ // IA-32 Intel Architecture Software Developer's Manual, Volume 3:
+ // System Programming Guide, Chatper 7: Multiple-processor management,
+ // Section 7.2, Memory Ordering.
+ // Last seen at:
+ // http://developer.intel.com/design/pentium4/manuals/index_new.htm
+ //
+ // x86 stores/loads fail to act as barriers for a few instructions (clflush
+ // maskmovdqu maskmovq movntdq movnti movntpd movntps movntq) but these are
+ // not generated by the compiler, and are rare. Users of these instructions
+ // need to know about cache behaviour in any case since all of these involve
+ // either flushing cache lines or non-temporal cache hints.
+}
+
+inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
+ return *ptr;
+}
+
+inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
+ Atomic64 value = *ptr; // An x86 load acts as a acquire barrier,
+ // for current AMD/Intel chips as of Jan 2008.
+ // See also Release_Store(), above.
+ ATOMICOPS_COMPILER_BARRIER();
+ return value;
+}
+
+inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
+ MemoryBarrier();
+ return *ptr;
+}
+
+#else // defined(__x86_64__)
+
+// 64-bit low-level operations on 32-bit platform.
+
+#if !((__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1))
+// For compilers older than gcc 4.1, we use inline asm.
+//
+// Potential pitfalls:
+//
+// 1. %ebx points to Global offset table (GOT) with -fPIC.
+// We need to preserve this register.
+// 2. When explicit registers are used in inline asm, the
+// compiler may not be aware of it and might try to reuse
+// the same register for another argument which has constraints
+// that allow it ("r" for example).
+
+inline Atomic64 __sync_val_compare_and_swap(volatile Atomic64* ptr,
+ Atomic64 old_value,
+ Atomic64 new_value) {
+ Atomic64 prev;
+ __asm__ __volatile__("push %%ebx\n\t"
+ "movl (%3), %%ebx\n\t" // Move 64-bit new_value into
+ "movl 4(%3), %%ecx\n\t" // ecx:ebx
+ "lock; cmpxchg8b (%1)\n\t"// If edx:eax (old_value) same
+ "pop %%ebx\n\t"
+ : "=A" (prev) // as contents of ptr:
+ : "D" (ptr), // ecx:ebx => ptr
+ "0" (old_value), // else:
+ "S" (&new_value) // old *ptr => edx:eax
+ : "memory", "%ecx");
+ return prev;
+}
+#endif // Compiler < gcc-4.1
+
+inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
+ Atomic64 old_val,
+ Atomic64 new_val) {
+ return __sync_val_compare_and_swap(ptr, old_val, new_val);
+}
+
+inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
+ Atomic64 new_val) {
+ Atomic64 old_val;
+
+ do {
+ old_val = *ptr;
+ } while (__sync_val_compare_and_swap(ptr, old_val, new_val) != old_val);
+
+ return old_val;
+}
+
+inline Atomic64 Acquire_AtomicExchange(volatile Atomic64* ptr,
+ Atomic64 new_val) {
+ Atomic64 old_val = NoBarrier_AtomicExchange(ptr, new_val);
+ return old_val;
+}
+
+inline Atomic64 Release_AtomicExchange(volatile Atomic64* ptr,
+ Atomic64 new_val) {
+ return NoBarrier_AtomicExchange(ptr, new_val);
+}
+
+inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
+ __asm__ __volatile__("movq %1, %%mm0\n\t" // Use mmx reg for 64-bit atomic
+ "movq %%mm0, %0\n\t" // moves (ptr could be read-only)
+ "emms\n\t" // Empty mmx state/Reset FP regs
+ : "=m" (*ptr)
+ : "m" (value)
+ : // mark the FP stack and mmx registers as clobbered
+ "st", "st(1)", "st(2)", "st(3)", "st(4)",
+ "st(5)", "st(6)", "st(7)", "mm0", "mm1",
+ "mm2", "mm3", "mm4", "mm5", "mm6", "mm7");
+}
+
+inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) {
+ NoBarrier_Store(ptr, value);
+ MemoryBarrier();
+}
+
+inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
+ ATOMICOPS_COMPILER_BARRIER();
+ NoBarrier_Store(ptr, value);
+}
+
+inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
+ Atomic64 value;
+ __asm__ __volatile__("movq %1, %%mm0\n\t" // Use mmx reg for 64-bit atomic
+ "movq %%mm0, %0\n\t" // moves (ptr could be read-only)
+ "emms\n\t" // Empty mmx state/Reset FP regs
+ : "=m" (value)
+ : "m" (*ptr)
+ : // mark the FP stack and mmx registers as clobbered
+ "st", "st(1)", "st(2)", "st(3)", "st(4)",
+ "st(5)", "st(6)", "st(7)", "mm0", "mm1",
+ "mm2", "mm3", "mm4", "mm5", "mm6", "mm7");
+ return value;
+}
+
+inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
+ Atomic64 value = NoBarrier_Load(ptr);
+ ATOMICOPS_COMPILER_BARRIER();
+ return value;
+}
+
+inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
+ MemoryBarrier();
+ return NoBarrier_Load(ptr);
+}
+
+#endif // defined(__x86_64__)
+
+inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
+ Atomic64 old_value,
+ Atomic64 new_value) {
+ Atomic64 x = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+ return x;
+}
+
+inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
+ Atomic64 old_value,
+ Atomic64 new_value) {
+ return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+}
+
+} // namespace base::subtle
+} // namespace base
+
+#undef ATOMICOPS_COMPILER_BARRIER
+
+#endif // BASE_ATOMICOPS_INTERNALS_X86_H_