Optimized (BMI2+PGO) builds for Linux+Windows.

See Makefile.bmi2 and use:
    make -f Makefile.bmi2 gull.syzygy.linux
    make -f Makefile.bmi2 gull.syzygy.windows

For Windows cross compilation is not supported.  Instead use MSYS2 configured
for 64-bit compilation.

Linux results (self-play versus old non-syzygy non-BMI2 Gull.linux):

LTC (60"+0.6", 1-thread, 6-man syzygy):

    Score: +1728-1351=6921
    Number of games: 10000
    Winning fraction: 0.51885
    Elo difference: +13.1045
    LOS: 1

STC (10"+0.1", 1-thread, 6-man syzygy):

    Score: +2040-1791=6169
    Number of games: 10000
    Winning fraction: 0.51245
    Elo difference: +8.65293
    LOS: 0.999971

Windows build has not yet been tested.

src/Gull.cpp

@@ -11,10 +11,10 @@
 #define _WIN32_WINNT 0x0501
 #endif
 
-#ifndef W32_BUILD
-#define HNI
-#undef HNI
-#endif
+// #ifndef W32_BUILD
+// #define HNI
+// #undef HNI
+// #endif
 
 #define CPU_TIMING
 #undef CPU_TIMING

src/Makefile.bmi2

@@ -0,0 +1,32 @@
+UNAME=$(shell uname -s)
+ifeq ($(UNAME),Linux)
+    TARGET_SYZYGY=gull.syzygy.linux
+endif
+ifeq ($(UNAME),Darwin)
+    TARGET_SYZYGY=gull.syzygy.macosx
+endif
+CC=g++
+STRIP=strip
+CFLAGS=-m64 -msse4.2 -mavx2 -mbmi -mbmi2 -mpopcnt -fno-exceptions -fno-rtti -Wno-parentheses -O3 -D HNI
+
+main: $(TARGET)
+
+gull.syzygy.linux:
+	rm -f *.gcda
+	$(CC) $(CFLAGS) -fprofile-generate -D LINUX -D TB Gull.cpp tbprobe.c -o Gull
+	./Gull bench 16 "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
+	$(CC) $(CFLAGS) -fprofile-use -fno-peel-loops -fno-tracer -D LINUX -D TB -D HNI Gull.cpp tbprobe.c -o Gull
+	$(STRIP) Gull
+	cp Gull Gull.syzygy.linux
+
+gull.syzygy.windows: CC=x86_64-w64-mingw32-g++
+gull.syzygy.windows:
+	rm -f *.gcda
+	$(CC) $(CFLAGS) -static -fprofile-generate -D WINDOWS -D TB Gull.cpp tbprobe.c -o Gull.exe
+	./Gull.exe bench 16 "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
+	$(CC) $(CFLAGS) -fprofile-use -fno-peel-loops -fno-tracer -D WINDOWS -D TB Gull.cpp tbprobe.c -o Gull.exe
+	$(STRIP) Gull.exe
+
+clean:
+	rm -f Gull
+