From: Philip Pronin <philipp@fb.com>
Date: Mon, 9 May 2016 07:06:57 +0000 (-0700)
Subject: Reverted commit D3265572
X-Git-Tag: 2016.07.26~266
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=0759dee48fca5973414d86505c8cd2ea82ec3a39;p=folly.git

Reverted commit D3265572

Summary:
I would switch these to just use the intrinsic functions, but GCC 4.8 doesn't support them.
MSVC supports the intrinsics, which is the primary reason for the switch.

Reviewed By: yfeldblum

Differential Revision: D3265572

fb-gh-sync-id: 3268f90d5234bdf77b3579504efd3dcd43f38aff
fbshipit-source-id: 3268f90d5234bdf77b3579504efd3dcd43f38aff
---

diff --git a/folly/Portability.h b/folly/Portability.h
index cbf1b71c..c9616ea7 100644
--- a/folly/Portability.h
+++ b/folly/Portability.h
@@ -92,13 +92,6 @@ constexpr bool kHasUnalignedAccess = false;
 # define FOLLY_ALWAYS_INLINE inline
 #endif
 
-// target
-#ifdef _MSC_VER
-# define FOLLY_TARGET_ATTRIBUTE(target)
-#else
-# define FOLLY_TARGET_ATTRIBUTE(target) __attribute__((__target__(target)))
-#endif
-
 // detection for 64 bit
 #if defined(__x86_64__) || defined(_M_X64)
 # define FOLLY_X64 1
diff --git a/folly/experimental/Instructions.h b/folly/experimental/Instructions.h
index 6a1d6ed6..97386ff1 100644
--- a/folly/experimental/Instructions.h
+++ b/folly/experimental/Instructions.h
@@ -17,10 +17,8 @@
 #pragma once
 
 #include <glog/logging.h>
-#include <immintrin.h>
 
 #include <folly/CpuId.h>
-#include <folly/portability/Builtins.h>
 
 namespace folly { namespace compression { namespace instructions {
 
@@ -54,17 +52,11 @@ struct Nehalem : public Default {
   static bool supported(const folly::CpuId& cpuId = {}) {
     return cpuId.popcnt();
   }
-  static inline uint64_t popcount(uint64_t value)
-      FOLLY_TARGET_ATTRIBUTE("popcnt") {
+  static inline uint64_t popcount(uint64_t value) {
     // POPCNT is supported starting with Intel Nehalem, AMD K10.
-#if defined(__GNUC__) && !__GNUC_PREREQ(4, 9)
-    // GCC 4.8 doesn't support the intrinsics.
     uint64_t result;
     asm ("popcntq %1, %0" : "=r" (result) : "r" (value));
     return result;
-#else
-    return _mm_popcnt_u64(value);
-#endif
   }
 };
 
@@ -72,17 +64,12 @@ 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) FOLLY_TARGET_ATTRIBUTE("bmi") {
+  static 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.
-#if defined(__GNUC__) && !__GNUC_PREREQ(4, 9)
-    // GCC 4.8 doesn't support the intrinsics.
     uint64_t result;
     asm ("blsrq %1, %0" : "=r" (result) : "r" (value));
     return result;
-#else
-    return _blsr_u64(value);
-#endif
   }
 };
 
diff --git a/folly/experimental/Select64.h b/folly/experimental/Select64.h
index 5d0fcaa5..9c2e03f9 100644
--- a/folly/experimental/Select64.h
+++ b/folly/experimental/Select64.h
@@ -62,15 +62,9 @@ inline uint64_t select64(uint64_t x, uint64_t k) {
   return place + detail::kSelectInByte[((x >> place) & 0xFF) | (byteRank << 8)];
 }
 
-template <>
-uint64_t select64<compression::instructions::Haswell>(uint64_t x, uint64_t k)
-  FOLLY_TARGET_ATTRIBUTE("bmi,bmi2");
-
 template <>
 inline uint64_t select64<compression::instructions::Haswell>(uint64_t x,
                                                              uint64_t k) {
-#if defined(__GNUC__) && !__GNUC_PREREQ(4, 9)
-  // GCC 4.8 doesn't support the intrinsics.
   uint64_t result = uint64_t(1) << k;
 
   asm("pdep %1, %0, %0\n\t"
@@ -79,9 +73,6 @@ inline uint64_t select64<compression::instructions::Haswell>(uint64_t x,
       : "r"(x));
 
   return result;
-#else
-  return _tzcnt_u64(_pdep_u64(x, 1ULL << k));
-#endif
 }
 
 } // namespace folly