switch back to inline assembly in compression::instructions

[folly.git] / folly / experimental / Instructions.h

diff --git a/folly/experimental/Instructions.h b/folly/experimental/Instructions.h
index cdcd525777a34cef04883be9747d657ce5362935..ffc4fa1be73a2e5a1eefcf858750db8048a361a2 100644 (file)
--- a/folly/experimental/Instructions.h
+++ b/folly/experimental/Instructions.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 Facebook, Inc.
+ * Copyright 2016 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,10 +14,20 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EXPERIMENTAL_INSTRUCTIONS_H
-#define FOLLY_EXPERIMENTAL_INSTRUCTIONS_H
+#pragma once
+
+#include <glog/logging.h>
 
 #include <folly/CpuId.h>
+#include <folly/Portability.h>
+#include <folly/portability/Builtins.h>
+
+#if defined(__GNUC__) || defined(__clang__)
+// For compilers supporting AT&T assembly syntax.
+#define FOLLY_INSTRUCTIONS_SUPPORTED 1
+#else
+#define FOLLY_INSTRUCTIONS_SUPPORTED 0
+#endif
 
 namespace folly { namespace compression { namespace instructions {
 
@@ -30,30 +40,33 @@ namespace folly { namespace compression { namespace instructions {
 // use explicitly.
 
 struct Default {
-  static bool supported(const folly::CpuId& cpuId = {}) {
+  static bool supported(const folly::CpuId& /* cpuId */ = {}) {
     return true;
   }
-  static inline uint64_t popcount(uint64_t value) {
+  static FOLLY_ALWAYS_INLINE uint64_t popcount(uint64_t value) {
     return __builtin_popcountll(value);
   }
-  static inline int ctz(uint64_t value) {
+  static FOLLY_ALWAYS_INLINE int ctz(uint64_t value) {
     DCHECK_GT(value, 0);
     return __builtin_ctzll(value);
   }
-  static inline int clz(uint64_t value) {
+  static FOLLY_ALWAYS_INLINE int clz(uint64_t value) {
     DCHECK_GT(value, 0);
     return __builtin_clzll(value);
   }
-  static inline uint64_t blsr(uint64_t value) {
+  static FOLLY_ALWAYS_INLINE uint64_t blsr(uint64_t value) {
     return value & (value - 1);
   }
 };
 
+#if FOLLY_INSTRUCTIONS_SUPPORTED
+
 struct Nehalem : public Default {
   static bool supported(const folly::CpuId& cpuId = {}) {
     return cpuId.popcnt();
   }
-  static inline uint64_t popcount(uint64_t value) {
+
+  static FOLLY_ALWAYS_INLINE uint64_t popcount(uint64_t value) {
     // POPCNT is supported starting with Intel Nehalem, AMD K10.
     uint64_t result;
     asm ("popcntq %1, %0" : "=r" (result) : "r" (value));
@@ -65,7 +78,8 @@ struct Haswell : public Nehalem {
   static bool supported(const folly::CpuId& cpuId = {}) {
     return Nehalem::supported(cpuId) && cpuId.bmi1();
   }
-  static inline uint64_t blsr(uint64_t value) {
+
+  static FOLLY_ALWAYS_INLINE uint64_t blsr(uint64_t value) {
     // BMI1 is supported starting with Intel Haswell, AMD Piledriver.
     // BLSR combines two instuctions into one and reduces register pressure.
     uint64_t result;
@@ -74,6 +88,11 @@ struct Haswell : public Nehalem {
   }
 };
 
-}}}  // namespaces
+#else // FOLLY_INSTRUCTIONS_SUPPORTED
+
+struct Nehalem : public Default {};
+struct Haswell : public Nehalem {};
+
+#endif // FOLLY_INSTRUCTIONS_SUPPORTED
 
-#endif  // FOLLY_EXPERIMENTAL_INSTRUCTIONS_H
+}}} // namespaces