Add ARCH x86-64-bmi2 support

Intel Haswell and newer CPUs can calculate sliders
attacks using special PEXT asm instructions instead
of magic bitboards. This gives a +3% speed up.

To enable it just compile with ARCH=x86-64-bmi2

No functional change.

src/Makefile

@@ -60,21 +60,22 @@ OBJS = benchmark.o bitbase.o bitboard.o book.o endgame.o evaluate.o main.o \
 #                                              with GCC and ICC 64-bit)
 # popcnt = yes/no     --- -DUSE_POPCNT     --- Use popcnt x86_64 asm-instruction
 # sse = yes/no        --- -msse            --- Use Intel Streaming SIMD Extensions
+# pext = yes/no       --- -DUSE_PEXT       --- Use pext x86_64 asm-instruction
 #
 # Note that Makefile is space sensitive, so when adding new architectures
 # or modifying existing flags, you have to make sure there are no extra spaces
 # at the end of the line for flag values.
 
 ### 2.1. General and architecture defaults
-debug = no
 optimize = yes
-
+debug = no
 os = any
 bits = 32
 prefetch = no
 bsfq = no
 popcnt = no
 sse = no
+pext = no
 
 ### 2.2 Architecture specific
 
@@ -114,6 +115,16 @@ ifeq ($(ARCH),x86-64-modern)
 	sse = yes
 endif
 
+ifeq ($(ARCH),x86-64-bmi2)
+	arch = x86_64
+	bits = 64
+	prefetch = yes
+	bsfq = yes
+	popcnt = yes
+	sse = yes
+	pext = yes
+endif
+
 ifeq ($(ARCH),armv7)
 	arch = armv7
 	prefetch = yes
@@ -310,7 +321,15 @@ ifeq ($(popcnt),yes)
 	CXXFLAGS += -msse3 -DUSE_POPCNT
 endif
 
-### 3.10 Link Time Optimization, it works since gcc 4.5 but not on mingw.
+### 3.10 pext
+ifeq ($(pext),yes)
+	CXXFLAGS += -DUSE_PEXT
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw))
+		CXXFLAGS += -mbmi2
+	endif
+endif
+
+### 3.11 Link Time Optimization, it works since gcc 4.5 but not on mingw.
 ### This is a mix of compile and link time options because the lto link phase
 ### needs access to the optimization flags.
 ifeq ($(comp),gcc)
@@ -350,6 +369,7 @@ help:
 	@echo ""
 	@echo "x86-64                  > x86 64-bit"
 	@echo "x86-64-modern           > x86 64-bit with popcnt support"
+	@echo "x86-64-bmi2             > x86 64-bit with pext support"
 	@echo "x86-32                  > x86 32-bit with SSE support"
 	@echo "x86-32-old              > x86 32-bit fall back for old hardware"
 	@echo "linux-ppc-64            > PPC-Linux 64 bit"
@@ -448,6 +468,7 @@ config-sanity:
 	@echo "bsfq: '$(bsfq)'"
 	@echo "popcnt: '$(popcnt)'"
 	@echo "sse: '$(sse)'"
+	@echo "pext: '$(pext)'"
 	@echo ""
 	@echo "Flags:"
 	@echo "CXX: $(CXX)"
@@ -466,6 +487,7 @@ config-sanity:
 	@test "$(bsfq)" = "yes" || test "$(bsfq)" = "no"
 	@test "$(popcnt)" = "yes" || test "$(popcnt)" = "no"
 	@test "$(sse)" = "yes" || test "$(sse)" = "no"
+	@test "$(pext)" = "yes" || test "$(pext)" = "no"
 	@test "$(comp)" = "gcc" || test "$(comp)" = "icc" || test "$(comp)" = "mingw" || test "$(comp)" = "clang"
 
 $(EXE): $(OBJS)

src/misc.cpp

@@ -51,7 +51,7 @@ const string engine_info(bool to_uci) {
   }
 
   ss << (Is64Bit ? " 64" : "")
-     << (HasPopCnt ? " SSE4.2" : "")
+     << (HasPext ? " BMI2" : (HasPopCnt ? " SSE4.2" : ""))
      << (to_uci  ? "\nid author ": " by ")
      << "Tord Romstad, Marco Costalba and Joona Kiiski";
 

src/types.h

@@ -55,7 +55,7 @@
 #endif
 
 #if defined(USE_PEXT)
-#  include <x86intrin.h> // Gcc header for _pext_u64() intrinsic
+#  include <immintrin.h> // Header for _pext_u64() intrinsic
 #else
 #  define _pext_u64(b, m) (0)
 #endif