Fix bitcount.h compile warnings under Intel compiler

[stockfish] / src / bitcount.h

diff --git a/src/bitcount.h b/src/bitcount.h
index d57b3f407339d9d2c311f9cf1a1ac12f7fbb8a94..6b5f5b5789bb5f8b0b895fafa650566ceba107c2 100644 (file)
--- a/src/bitcount.h
+++ b/src/bitcount.h
@@ -22,41 +22,21 @@
 #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
+// To enable POPCNT support uncomment USE_POPCNT define. For PGO compile on a Core i7
+// you may want to collect profile data first with USE_POPCNT disabled and then, in a
+// second profiling session, with USE_POPCNT enabled so to exercise both paths. Don't
+// forget to leave USE_POPCNT enabled for the final optimized compile though ;-)
 
+//#define USE_POPCNT
 
-#include "bitboard.h"
-
-
-// Select type of software bit count function to use
-
-#if !defined(AUTO_CONFIGURATION) || defined(IS_64BIT)
-
-//#define USE_COMPACT_ROOK_ATTACKS
-//#define USE_32BIT_ATTACKS
-#define USE_FOLDED_BITSCAN
-
-#define BITCOUNT_SWAR_64
-//#define BITCOUNT_SWAR_32
-//#define BITCOUNT_LOOP
-
-#else
-
-#define USE_32BIT_ATTACKS
-#define USE_FOLDED_BITSCAN
-#define BITCOUNT_SWAR_32
-
-#endif
 
+#include "types.h"
 
 // Select type of intrinsic bit count instruction to use
 
-#if defined(_MSC_VER) && defined(_WIN64) // Microsoft compiler
+#if defined(__INTEL_COMPILER) && defined(IS_64BIT) && defined(USE_POPCNT) // Intel compiler
 
-#include <intrin.h>
+#include <nmmintrin.h>
 
 inline bool cpu_has_popcnt() {
 
@@ -65,11 +45,19 @@ inline bool cpu_has_popcnt() {
   return (CPUInfo[2] >> 23) & 1;
 }
 
-#define POPCNT_INTRINSIC(x) __popcnt64(x)
+// Define a dummy template to workaround a compile error if _mm_popcnt_u64() is not defined.
+//
+// If _mm_popcnt_u64() is defined in <nmmintrin.h> it will be choosen first due to
+// C++ overload rules that always prefer a function to a template with the same name.
+// If not, we avoid a compile error and because cpu_has_popcnt() should return false,
+// our templetized _mm_popcnt_u64() is never called anyway.
+template<typename T> inline unsigned _mm_popcnt_u64(T) { return 0; } // Is never called
 
-#elif defined(__INTEL_COMPILER) && (defined(__x86_64) || defined(_M_X64)) // Intel compiler
+#define POPCNT_INTRINSIC(x) _mm_popcnt_u64(x)
 
-#include <nmmintrin.h>
+#elif defined(_MSC_VER) && defined(IS_64BIT) && defined(USE_POPCNT) // Microsoft compiler
+
+#include <intrin.h>
 
 inline bool cpu_has_popcnt() {
 
@@ -78,32 +66,40 @@ inline bool cpu_has_popcnt() {
   return (CPUInfo[2] >> 23) & 1;
 }
 
-#define POPCNT_INTRINSIC(x) _mm_popcnt_u64(x)
+// See comment of _mm_popcnt_u64<>() few lines above for an explanation.
+template<typename T> inline unsigned __popcnt64(T) { return 0; } // Is never called
 
-#else // Safe fallback for unsupported compilers
+#define POPCNT_INTRINSIC(x) __popcnt64(x)
+
+#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
+#endif // cpu_has_popcnt() and POPCNT_INTRINSIC() definitions
 
 
 /// Software implementation of bit count functions
 
-#if defined(BITCOUNT_LOOP)
+#if defined(IS_64BIT)
 
 inline int count_1s(Bitboard b) {
-  int r;
-  for(r = 0; b; r++, b &= b - 1);
-  return r;
+  b -= ((b>>1) & 0x5555555555555555ULL);
+  b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
+  b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
+  b *= 0x0101010101010101ULL;
+  return int(b >> 56);
 }
 
 inline int count_1s_max_15(Bitboard b) {
-  return count_1s(b);
+  b -= (b>>1) & 0x5555555555555555ULL;
+  b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
+  b *= 0x1111111111111111ULL;
+  return int(b >> 60);
 }
 
-#elif defined(BITCOUNT_SWAR_32)
+#else // if !defined(IS_64BIT)
 
 inline int count_1s(Bitboard b) {
   unsigned w = unsigned(b >> 32), v = unsigned(b);
@@ -128,23 +124,6 @@ inline int count_1s_max_15(Bitboard b) {
   return int(v >> 28);
 }
 
-#elif defined(BITCOUNT_SWAR_64)
-
-inline int count_1s(Bitboard b) {
-  b -= ((b>>1) & 0x5555555555555555ULL);
-  b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
-  b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
-  b *= 0x0101010101010101ULL;
-  return int(b >> 56);
-}
-
-inline int count_1s_max_15(Bitboard b) {
-  b -= (b>>1) & 0x5555555555555555ULL;
-  b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
-  b *= 0x1111111111111111ULL;
-  return int(b >> 60);
-}
-
 #endif // BITCOUNT
 
 
@@ -165,19 +144,15 @@ 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.
-#if defined(BITCOUNT_SWAR_64)
+// 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
 const bool CpuHas64BitPath = false;