X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitcount.h;h=b32314d8201ee88db1a6ee5a050d92d398803b86;hp=4747afc6aa73861e7a34785833352fc905c030e4;hb=8a504d36f9b740c6d4c5bba6855148c5be40556e;hpb=5d79af9e0d466572217dc47f5c307f6fd382a646

diff --git a/src/bitcount.h b/src/bitcount.h
index 4747afc6..b32314d8 100644
--- a/src/bitcount.h
+++ b/src/bitcount.h
@@ -22,19 +22,14 @@
 #if !defined(BITCOUNT_H_INCLUDED)
 #define BITCOUNT_H_INCLUDED
 
-// To disable POPCNT support uncomment following line. You should do it only
-// in PGO compiling to exercise the default fallback path. Don't forget to
-// re-comment the line for the final optimized compile though ;-)
-//#define DISABLE_POPCNT_SUPPORT
-
-
 #include "types.h"
 
-// Select type of intrinsic bit count instruction to use
+// Select type of intrinsic bit count instruction to use, see
+// README.txt on how to pgo compile with POPCNT support.
 
-#if defined(_MSC_VER) && defined(_WIN64) // Microsoft compiler
+#if defined(__INTEL_COMPILER) && defined(USE_POPCNT) // Intel compiler
 
-#include <intrin.h>
+#include <nmmintrin.h>
 
 inline bool cpu_has_popcnt() {
 
@@ -43,11 +38,11 @@ inline bool cpu_has_popcnt() {
   return (CPUInfo[2] >> 23) & 1;
 }
 
-#define POPCNT_INTRINSIC(x) __popcnt64(x)
+#define POPCNT_INTRINSIC(x) _mm_popcnt_u64(x)
 
-#elif defined(__INTEL_COMPILER) && (defined(__x86_64) || defined(_M_X64)) // Intel compiler
+#elif defined(_MSC_VER) && defined(USE_POPCNT) // Microsoft compiler
 
-#include <nmmintrin.h>
+#include <intrin.h>
 
 inline bool cpu_has_popcnt() {
 
@@ -56,15 +51,39 @@ inline bool cpu_has_popcnt() {
   return (CPUInfo[2] >> 23) & 1;
 }
 
-#define POPCNT_INTRINSIC(x) _mm_popcnt_u64(x)
+#define POPCNT_INTRINSIC(x) __popcnt64(x)
 
-#else // Safe fallback for unsupported compilers
+#elif defined(__GNUC__) && defined(USE_POPCNT) // Gcc compiler
+
+inline void __cpuid(unsigned int op,
+                    unsigned int *eax, unsigned int *ebx,
+                    unsigned int *ecx, unsigned int *edx)
+{
+  *eax = op;
+  *ecx = 0;
+  __asm__("cpuid" : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
+                  : "0" (*eax), "2" (*ecx));
+}
+
+inline bool cpu_has_popcnt() {
+
+  unsigned int eax, ebx, ecx, edx;
+  __cpuid(1, &eax, &ebx, &ecx, &edx);
+  return (ecx >> 23) & 1;
+}
+
+#define POPCNT_INTRINSIC(x) ({ \
+   unsigned long __ret; \
+   __asm__("popcnt %1, %0" : "=r" (__ret) : "r" (x)); \
+   __ret; })
+
+#else // Safe fallback for unsupported compilers or when USE_POPCNT is disabled
 
 inline bool cpu_has_popcnt() { return false; }
 
-#define POPCNT_INTRINSIC(x) count_1s(x)
+#define POPCNT_INTRINSIC(x) 0
 
-#endif // cpu_has_popcnt() selection
+#endif // cpu_has_popcnt() and POPCNT_INTRINSIC() definitions
 
 
 /// Software implementation of bit count functions
@@ -131,18 +150,14 @@ inline int count_1s_max_15(Bitboard b) {
 }
 
 
-// Global variable initialized at startup that is set to true if
+// Global constant initialized at startup that is set to true if
 // CPU on which application runs supports POPCNT intrinsic. Unless
-// DISABLE_POPCNT_SUPPORT is defined.
-#if defined(DISABLE_POPCNT_SUPPORT)
-const bool CpuHasPOPCNT = false;
-#else
+// USE_POPCNT is not defined.
 const bool CpuHasPOPCNT = cpu_has_popcnt();
-#endif
 
 
-// Global variable used to print info about the use of 64 optimized
-// functions to verify that a 64bit compile has been correctly built.
+// Global constant used to print info about the use of 64 optimized
+// functions to verify that a 64 bit compile has been correctly built.
 #if defined(IS_64BIT)
 const bool CpuHas64BitPath = true;
 #else