From 67062637f48e7d63e750dee63ba9e881ee6d9382 Mon Sep 17 00:00:00 2001
From: ppigazzini <pasquale.pigazzini@gmail.com>
Date: Mon, 17 Jan 2022 14:03:16 +0100
Subject: [PATCH] Improve Makefile for Windows native builds

A Windows Native Build (WNB) can be done:
 - on Windows, using a recent mingw-w64 g++/clang compiler
   distributed by msys2, cygwin and others
 - on Linux, using mingw-w64 g++ to cross compile

Improvements:
 - check for a WNB in a proper way and set a variable to simplify the code
 - set the proper EXE for a WNB
 - use the proper name for the mingw-w64 clang compiler
 - use the static linking for a WNB
 - use wine to make a PGO cross compile on Linux (also with Intel SDE)
 - enable the LTO build for mingw-w64 g++ compiler
 - set `lto=auto` to use the make's job server, if available, or otherwise
   to fall back to autodetection of the number of CPU threads
 - clean up all the temporary LTO files saved in the local directory

Tested on:
 - msys2 MINGW64 (g++), UCRT64 (g++), MINGW32 (g++), CLANG64 (clang)
   environments
 - cygwin mingw-w64 g++
 - Ubuntu 18.04 & 21.10 mingw-w64 PGO cross compile (also with Intel SDE)

closes #3891

No functional change
---
 src/Makefile | 80 +++++++++++++++++++++++++---------------------------
 1 file changed, 39 insertions(+), 41 deletions(-)

diff --git a/src/Makefile b/src/Makefile
index 90e596af..1b121299 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -19,11 +19,27 @@
 ### Section 1. General Configuration
 ### ==========================================================================
 
+### Establish the operating system name
+KERNEL = $(shell uname -s)
+ifeq ($(KERNEL),Linux)
+	OS = $(shell uname -o)
+endif
+
+### Target Windows OS
+ifeq ($(OS),Windows_NT)
+	target_windows = yes
+else ifeq ($(COMP),mingw)
+	target_windows = yes
+	ifeq ($(WINE_PATH),)
+		WINE_PATH = $(shell which wine)
+	endif
+endif
+
 ### Executable name
-ifeq ($(COMP),mingw)
-EXE = stockfish.exe
+ifeq ($(target_windows),yes)
+	EXE = stockfish.exe
 else
-EXE = stockfish
+	EXE = stockfish
 endif
 
 ### Installation dir definitions
@@ -32,9 +48,9 @@ BINDIR = $(PREFIX)/bin
 
 ### Built-in benchmark for pgo-builds
 ifeq ($(SDE_PATH),)
-	PGOBENCH = ./$(EXE) bench
+	PGOBENCH = $(WINE_PATH) ./$(EXE) bench
 else
-	PGOBENCH = $(SDE_PATH) -- ./$(EXE) bench
+	PGOBENCH = $(SDE_PATH) -- $(WINE_PATH) ./$(EXE) bench
 endif
 
 ### Source and object files
@@ -47,12 +63,6 @@ OBJS = $(notdir $(SRCS:.cpp=.o))
 
 VPATH = syzygy:nnue:nnue/features
 
-### Establish the operating system name
-KERNEL = $(shell uname -s)
-ifeq ($(KERNEL),Linux)
-	OS = $(shell uname -o)
-endif
-
 ### ==========================================================================
 ### Section 2. High-level Configuration
 ### ==========================================================================
@@ -365,6 +375,10 @@ ifeq ($(COMP),gcc)
 	endif
 endif
 
+ifeq ($(target_windows),yes)
+	LDFLAGS += -static
+endif
+
 ifeq ($(COMP),mingw)
 	comp=mingw
 
@@ -381,9 +395,7 @@ ifeq ($(COMP),mingw)
 			CXX=i686-w64-mingw32-c++-posix
 		endif
 	endif
-
 	CXXFLAGS += -pedantic -Wextra -Wshadow
-	LDFLAGS += -static
 endif
 
 ifeq ($(COMP),icc)
@@ -395,19 +407,19 @@ endif
 ifeq ($(COMP),clang)
 	comp=clang
 	CXX=clang++
+	ifeq ($(target_windows),yes)
+		CXX=x86_64-w64-mingw32-clang++
+	endif
+
 	CXXFLAGS += -pedantic -Wextra -Wshadow
 
-	ifneq ($(KERNEL),Darwin)
-	ifneq ($(KERNEL),OpenBSD)
-	ifneq ($(KERNEL),FreeBSD)
-	ifneq ($(findstring MINGW,$(KERNEL)),MINGW)
+	ifeq ($(filter $(KERNEL),Darwin OpenBSD FreeBSD),)
+	ifeq ($(target_windows),)
 	ifneq ($(RTLIB),compiler-rt)
 		LDFLAGS += -latomic
 	endif
 	endif
 	endif
-	endif
-	endif
 
 	ifeq ($(arch),$(filter $(arch),armv7 armv8))
 		ifeq ($(OS),Android)
@@ -418,11 +430,6 @@ ifeq ($(COMP),clang)
 		CXXFLAGS += -m$(bits)
 		LDFLAGS += -m$(bits)
 	endif
-
-	ifeq ($(findstring MINGW,$(KERNEL)),MINGW)
-		LDFLAGS += -static
-	endif
-
 endif
 
 ifeq ($(KERNEL),Darwin)
@@ -656,9 +663,7 @@ ifeq ($(optimize),yes)
 ifeq ($(debug), no)
 	ifeq ($(comp),clang)
 		CXXFLAGS += -flto
-		ifneq ($(findstring MINGW,$(KERNEL)),)
-			CXXFLAGS += -fuse-ld=lld
-		else ifneq ($(findstring MSYS,$(KERNEL)),)
+		ifeq ($(target_windows),yes)
 			CXXFLAGS += -fuse-ld=lld
 		endif
 		LDFLAGS += $(CXXFLAGS)
@@ -669,25 +674,17 @@ ifeq ($(debug), no)
 	ifeq ($(gccisclang),)
 		CXXFLAGS += -flto
 		LDFLAGS += $(CXXFLAGS) -flto=jobserver
-		ifneq ($(findstring MINGW,$(KERNEL)),)
-			LDFLAGS += -save-temps
-		else ifneq ($(findstring MSYS,$(KERNEL)),)
-			LDFLAGS += -save-temps
-		endif
 	else
 		CXXFLAGS += -flto
 		LDFLAGS += $(CXXFLAGS)
 	endif
 
-# To use LTO and static linking on windows, the tool chain requires a recent gcc:
-# gcc version 10.1 in msys2 or TDM-GCC version 9.2 are known to work, older might not.
-# So, only enable it for a cross from Linux by default.
+# To use LTO and static linking on Windows,
+# the tool chain requires gcc version 10.1 or later.
 	else ifeq ($(comp),mingw)
-	ifeq ($(KERNEL),Linux)
 	ifneq ($(arch),i386)
-		CXXFLAGS += -flto
-		LDFLAGS += $(CXXFLAGS) -flto=jobserver
-	endif
+		CXXFLAGS += -flto=auto
+		LDFLAGS += $(CXXFLAGS) -save-temps
 	endif
 	endif
 endif
@@ -843,8 +840,9 @@ profileclean:
 	@rm -rf profdir
 	@rm -f bench.txt *.gcda *.gcno ./syzygy/*.gcda ./nnue/*.gcda ./nnue/features/*.gcda *.s
 	@rm -f stockfish.profdata *.profraw
-	@rm -f stockfish.exe.lto_wrapper_args
-	@rm -f stockfish.exe.ltrans.out
+	@rm -f stockfish.*args*
+	@rm -f stockfish.*lt*
+	@rm -f stockfish.res
 	@rm -f ./-lstdc++.res
 
 default: