Improve the handling of optimization flags, add --enable-lto.

* Added --enable-lto for enabling link-time optimization.
* The default debug optimization level is now -Og.
* Sanitizer flags are now applied independently of release/debug.
* Removed redundant optimization flags from console ports.

Makefile

@@ -225,49 +225,56 @@ PTHREAD_LDFLAGS ?= -lpthread
 #
 # Set up general CFLAGS/LDFLAGS
 #
-OPTIMIZE_CFLAGS ?= -O3
-DEBUG_CFLAGS    ?= -O0
 
-ifeq (${DEBUG},1)
 #
 # Usually, just disable the optimizer for "true" debug builds and
 # define "DEBUG" to enable optional code at compile time.
+# Optimized builds have assert() compiled out.
 #
-# Sanitizer builds turn on some optimizations for the sake of being usable.
+ifneq (${DEBUG},1)
+OPTIMIZE_FLAGS := -O3 ${OPTIMIZE_CFLAGS} ${OPTIMIZE_FLAGS}
+OPTIMIZE_DEF   ?= -DNDEBUG
+else
+OPTIMIZE_FLAGS := -Og ${DEBUG_CFLAGS} ${OPTIMIZE_FLAGS}
+OPTIMIZE_DEF   ?= -DDEBUG
+endif
+
+#
+# Enable a sanitizer and its corresponding extra options, if selected.
 #
 ifeq (${SANITIZER},address)
-DEBUG_CFLAGS := -fsanitize=address -O1 -fno-omit-frame-pointer
+OPTIMIZE_FLAGS += -fsanitize=address -fno-omit-frame-pointer
 endif
 ifeq (${SANITIZER},undefined)
 # Signed integer overflows (shift-base, signed-integer-overflow)
 # are pretty much inevitable in Robotic, so ignore them.
-DEBUG_CFLAGS := -fsanitize=undefined -O0 -fno-omit-frame-pointer \
+OPTIMIZE_FLAGS += -fsanitize=undefined -fno-omit-frame-pointer \
  -fno-sanitize-recover=all -fno-sanitize=shift-base,signed-integer-overflow
 endif
 ifeq (${SANITIZER},thread)
-DEBUG_CFLAGS := -fsanitize=thread -O2 -fno-omit-frame-pointer -fPIE
+OPTIMIZE_FLAGS += -fsanitize=thread -fno-omit-frame-pointer -fPIE
 ARCH_EXE_LDFLAGS += -pie
 endif
 ifeq (${SANITIZER},memory)
 # Note: to be useful, this requires a fairly special build with most
 # external libraries turned off or re-built with instrumentation.
 # This sanitizer is only implemented by clang.
-DEBUG_CFLAGS := -fsanitize=memory -O1 -fno-omit-frame-pointer -fPIC \
+OPTIMIZE_FLAGS += -fsanitize=memory -fno-omit-frame-pointer -fPIC \
  -fsanitize-recover=memory -fsanitize-memory-track-origins=2
 ARCH_EXE_LDFLAGS += -pie
 endif
 
-CFLAGS   = ${DEBUG_CFLAGS} -DDEBUG
-CXXFLAGS = ${DEBUG_CFLAGS} -DDEBUG
-LDFLAGS += ${DEBUG_CFLAGS}
-else
 #
-# Optimized builds have assert() compiled out
+# Enable link-time optimization.
 #
-CFLAGS   += ${OPTIMIZE_CFLAGS} -DNDEBUG
-CXXFLAGS += ${OPTIMIZE_CFLAGS} -DNDEBUG
+ifeq (${LTO},1)
+OPTIMIZE_FLAGS += -flto
 endif
 
+CFLAGS   += ${OPTIMIZE_FLAGS} ${OPTIMIZE_DEF}
+CXXFLAGS += ${OPTIMIZE_FLAGS} ${OPTIMIZE_DEF}
+LDFLAGS  += ${OPTIMIZE_FLAGS}
+
 #
 # Enable C++11 for compilers that support it.
 # Anything actually using C++11 should be optional or platform-specific,

arch/3ds/Makefile.in

@@ -51,12 +51,10 @@ PORTLIBS_LIBS     := $(foreach dir, $(PORTLIBS), -L$(dir)/lib)
 EXTRA_INCLUDES := -isystem $(CTRULIB)/include ${PORTLIBS_INCLUDES}
 EXTRA_LIBS := -L$(CTRULIB)/lib ${PORTLIBS_LIBS}
 ifeq (${DEBUG},1)
-  ARCH_CFLAGS += -Og
-  EXTRA_LIBS += -lcitro3dd -lctrud -lpng16 -lz
+EXTRA_LIBS += -lcitro3dd -lctrud -lpng16 -lz
 else
-  OPTIMIZE_CFLAGS = -O3 -fomit-frame-pointer -ffunction-sections
-# OPTIMIZE_CFLAGS += -flto
-  EXTRA_LIBS += -lcitro3d -lctru -lpng16 -lz
+OPTIMIZE_FLAGS += -fomit-frame-pointer -ffunction-sections
+EXTRA_LIBS += -lcitro3d -lctru -lpng16 -lz
 endif
 
 MACHDEP = -march=armv6k -mtune=mpcore -mfloat-abi=hard -mtp=soft -mword-relocations

arch/emscripten/Makefile.in

@@ -49,13 +49,10 @@ ARCH_LDFLAGS += -g4 --source-map-base ${SOURCE_MAP_BASE}
 endif
 
 ifeq (${DEBUG},1)
-	ARCH_CFLAGS += -s ASSERTIONS=1 --profiling-funcs
-	ARCH_LDFLAGS += -s ASSERTIONS=1 --profiling-funcs
-	EMSCRIPTEN_FRONTEND_BUILD_PROFILE = build
+OPTIMIZE_FLAGS += -s ASSERTIONS=1 --profiling-funcs
+EMSCRIPTEN_FRONTEND_BUILD_PROFILE = build
 else
-	ARCH_LDFLAGS += -O3
-	OPTIMIZE_CFLAGS = -O3
-	EMSCRIPTEN_FRONTEND_BUILD_PROFILE = build-release
+EMSCRIPTEN_FRONTEND_BUILD_PROFILE = build-release
 endif
 
 clean:

arch/switch/Makefile.in

@@ -38,12 +38,12 @@ SUPPRESS_HOST_TARGETS ?= 1
 MACHDEP    := -D__SWITCH__ -march=armv8-a -mtune=cortex-a57 -mtp=soft -fPIE
 
 ifeq (${DEBUG},1)
-  #DRM_NOUVEAU := drm_nouveaud
-  NX := nxd
+#DRM_NOUVEAU := drm_nouveaud
+NX := nxd
 else
-  OPTIMIZE_CFLAGS := -O3 -ffunction-sections
-  #DRM_NOUVEAU := drm_nouveau
-  NX := nx
+OPTIMIZE_FLAGS += -ffunction-sections
+#DRM_NOUVEAU := drm_nouveau
+NX := nx
 endif
 
 MESA_LIBS :=

arch/wiiu/Makefile.in

@@ -36,10 +36,10 @@ SUPPRESS_HOST_TARGETS ?= 1
 MACHDEP    := -DESPRESSO -mcpu=750 -meabi -mhard-float
 
 ifeq (${DEBUG},1)
-  WUT := wutd
+WUT := wutd
 else
-  OPTIMIZE_CFLAGS := -O3 -ffunction-sections
-  WUT := wut
+OPTIMIZE_FLAGS += -ffunction-sections
+WUT := wut
 endif
 
 SDL_PREFIX := ${PORTLIBS_PATH}/wiiu

config.sh

@@ -53,7 +53,9 @@ usage() {
 	echo "  --as-needed-hack          Pass --as-needed through to GNU ld."
 	echo "  --enable-release          Optimize and remove debugging code."
 	echo "  --enable-verbose          Build system is always verbose (V=1)."
+	echo "  --optimize-speed          Perform speed optimizations (-O3, default)."
 	echo "  --optimize-size           Perform size optimizations (-Os)."
+	echo "  --enable-lto              Perform link-time optimizations (-flto)."
 	echo "  --enable-asan             Enable AddressSanitizer for debug builds."
 	echo "  --enable-msan             Enable MemorySanitizer for debug builds."
 	echo "  --enable-tsan             Enable ThreadSanitizer for debug builds."
@@ -155,6 +157,7 @@ DATE_STAMP="true"
 AS_NEEDED="false"
 RELEASE="false"
 OPT_SIZE="false"
+LTO="false"
 SANITIZER="false"
 ANALYZER="false"
 STACK_PROTECTOR="true"
@@ -299,6 +302,9 @@ while [ "$1" != "" ]; do
 	[ "$1" = "--optimize-size" ]  && OPT_SIZE="true"
 	[ "$1" = "--optimize-speed" ] && OPT_SIZE="false"
 
+	[ "$1" = "--enable-lto" ]  && LTO="true"
+	[ "$1" = "--disable-lto" ] && LTO="false"
+
 	[ "$1" = "--enable-asan" ]  && SANITIZER="address"
 	[ "$1" = "--disable-asan" ] && SANITIZER="false"
 
@@ -1300,19 +1306,22 @@ if [ "$RELEASE" = "true" ]; then
 	#
 	if [ "$OPT_SIZE" = "true" ]; then
 		echo "Optimizing for size."
-		echo "OPTIMIZE_CFLAGS=-Os" >> platform.inc
+		echo "OPTIMIZE_FLAGS=-Os" >> platform.inc
 	else
 		echo "Optimizing for speed."
 	fi
+	#
+	# Enable link-time optimizations.
+	#
+	if [ "$LTO" = "true" ]; then
+		echo "Link-time optimizations enabled."
+		echo "LTO=1" >> platform.inc
+	else
+		echo "Link-time optimizations disabled."
+	fi
 else
 	echo "Disabling optimization, debug enabled."
 	echo "DEBUG=1" >> platform.inc
-
-	if [ "$SANITIZER" != "false" ]; then
-		echo "Enabling $SANITIZER sanitizer (may enable some optimizations)."
-		echo "SANITIZER=$SANITIZER" >> platform.inc
-	fi
-
 	#
 	# Trace logging for debug builds, if enabled.
 	#
@@ -1322,6 +1331,14 @@ else
 	fi
 fi
 
+#
+# Enable sanitizers.
+#
+if [ "$SANITIZER" != "false" ]; then
+	echo "Enabling $SANITIZER sanitizer (may enable some optimizations)."
+	echo "SANITIZER=$SANITIZER" >> platform.inc
+fi
+
 #
 # Enable stack protector.
 #

docs/changelog.txt

@@ -7,6 +7,10 @@ USERS
 
 DEVELOPERS
 
++ -Og is now the default debug optimization level (was -O0).
++ Added --enable-lto to enable link-time optimizations.
++ The sanitizer config.sh options can now be used with release
+  builds e.g. --enable-release --enable-asan.
 + Simplified the configuration of system directories for ports
   in config.sh, which now prints more information about them.
 + Fixed config.sh output of "/usr/bin/git" and the Git HEAD.

unit/Makefile.in

@@ -104,19 +104,20 @@ unit_common_objs += \
 endif
 
 #
-# This may already be set with sanitizer flags.
+# Build unit tests with debug optimizations and without link-time optimzations.
+# (Overrides these optimization flags from the global flags.)
 #
-DEBUG_CFLAGS ?= -O0
+UNIT_OPTIMIZE_FLAGS += -Og -fno-lto
 
 #
-# Use DEBUG_CFLAGS to override any optimization flags in the global flags.
 # Build without -DDEBUG to suppress debug messages,
 # build without -DNDEBUG to allow assert().
 # Turn on exceptions explicitly, since the global CXXFLAGS turn them off.
 #
-unit_cflags ?= ${CXXFLAGS} ${DEBUG_CFLAGS} -UDEBUG -UNDEBUG
+unit_cflags ?= ${CXXFLAGS}
+unit_cflags += ${UNIT_OPTIMIZE_FLAGS} -UDEBUG -UNDEBUG
 unit_cflags += -fexceptions -funsigned-char -std=gnu++11
-unit_ldflags += ${DEBUG_CFLAGS}
+unit_ldflags += ${UNIT_OPTIMIZE_FLAGS}
 
 unit_cflags += ${SDL_CFLAGS} -Umain
 unit_ldflags += ${SDL_LDFLAGS} ${ZLIB_LDFLAGS}