pc-bios/s390-ccw: detect CC options just once

In preparation for adding Docker container support, detect compiler options
just once rather than once per Make run; container startup overhead is
substantial and doing the detection just once makes things faster.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20220929114231.583801-15-alex.bennee@linaro.org>

pc-bios/s390-ccw/Makefile

@@ -6,9 +6,12 @@ include config-host.mak
 CFLAGS = -O2 -g
 MAKEFLAGS += -rR
 
+NULL :=
+SPACE := $(NULL) #
+TARGET_PREFIX := $(patsubst %/,%:$(SPACE),$(TARGET_DIR))
+
+quiet-@ = $(if $(V),,@)
 quiet-command = $(if $(V),$1,$(if $(2),@printf "  %-7s %s\n" $2 $3 && $1, @$1))
-cc-option = $(if $(shell $(CC) $1 $2 -S -o /dev/null -xc /dev/null \
-			 >/dev/null 2>&1 && echo OK),$2,$3)
 
 VPATH_SUFFIXES = %.c %.h %.S %.m %.mak %.sh %.rc Kconfig% %.json.in
 set-vpath = $(if $1,$(foreach PATTERN,$(VPATH_SUFFIXES),$(eval vpath $(PATTERN) $1)))
@@ -25,22 +28,33 @@ QEMU_DGFLAGS = -MMD -MP -MT $@ -MF $(@D)/$(*F).d
 	$(call quiet-command,$(CCAS) $(EXTRA_CFLAGS) $(QEMU_DGFLAGS) $(CFLAGS) \
 	       -c -o $@ $<,"CCAS","$(TARGET_DIR)$@")
 
-.PHONY : all clean build-all
+.PHONY : all clean build-all distclean
 
 OBJECTS = start.o main.o bootmap.o jump2ipl.o sclp.o menu.o \
 	  virtio.o virtio-scsi.o virtio-blkdev.o libc.o cio.o dasd-ipl.o
 
-EXTRA_CFLAGS := $(EXTRA_CFLAGS) -Wall
-EXTRA_CFLAGS += $(call cc-option,-Werror $(EXTRA_CFLAGS),-Wno-stringop-overflow)
+EXTRA_CFLAGS += -Wall
 EXTRA_CFLAGS += -ffreestanding -fno-delete-null-pointer-checks -fno-common -fPIE
 EXTRA_CFLAGS += -fwrapv -fno-strict-aliasing -fno-asynchronous-unwind-tables
-EXTRA_CFLAGS += $(call cc-option, $(EXTRA_CFLAGS), -fno-stack-protector)
-EXTRA_CFLAGS += $(call cc-option, $(EXTRA_CFLAGS), -Wno-array-bounds)
 EXTRA_CFLAGS += -msoft-float
-EXTRA_CFLAGS += $(call cc-option, $(EXTRA_CFLAGS),-march=z900,-march=z10)
 EXTRA_CFLAGS += -std=gnu99
 LDFLAGS += -Wl,-pie -nostdlib
 
+cc-test = $(CC) -Werror $1 -c -o /dev/null -xc /dev/null >/dev/null 2>/dev/null
+cc-option = if $(call cc-test, $1); then \
+    echo "$(TARGET_PREFIX)$1 detected" && echo "EXTRA_CFLAGS += $1" >&3; else \
+    echo "$(TARGET_PREFIX)$1 not detected" $(if $2,&& echo "EXTRA_CFLAGS += $2" >&3); fi
+
+config-cc.mak: Makefile
+	$(quiet-@)($(call cc-option,-Wno-stringop-overflow); \
+	    $(call cc-option,-fno-stack-protector); \
+	    $(call cc-option,-Wno-array-bounds); \
+	    $(call cc-option,-Wno-gnu); \
+	    $(call cc-option,-march=z900,-march=z10)) 3> config-cc.mak
+-include config-cc.mak
+
+LDFLAGS += -Wl,-pie -nostdlib
+
 build-all: s390-ccw.img s390-netboot.img
 
 s390-ccw.elf: $(OBJECTS)
@@ -63,3 +77,6 @@ ALL_OBJS = $(sort $(OBJECTS) $(NETOBJS) $(LIBCOBJS) $(LIBNETOBJS))
 
 clean:
 	rm -f *.o *.d *.img *.elf *~ *.a
+
+distclean:
+	rm -f config-cc.mak

pc-bios/s390-ccw/netboot.mak

@@ -16,12 +16,9 @@ s390-netboot.elf: $(NETOBJS) libnet.a libc.a
 s390-netboot.img: s390-netboot.elf
 	$(call quiet-command,$(STRIP) --strip-unneeded $< -o $@,"STRIP","$(TARGET_DIR)$@")
 
-# SLOF is GCC-only, so ignore warnings about GNU extensions with Clang here
-NO_GNU_WARN := $(call cc-option,-Werror $(QEMU_CFLAGS),-Wno-gnu)
-
 # libc files:
 
-LIBC_CFLAGS = $(EXTRA_CFLAGS) $(CFLAGS) $(NO_GNU_WARN) $(LIBC_INC) $(LIBNET_INC) \
+LIBC_CFLAGS = $(EXTRA_CFLAGS) $(CFLAGS) $(LIBC_INC) $(LIBNET_INC) \
 	      -MMD -MP -MT $@ -MF $(@:%.o=%.d)
 
 CTYPE_OBJS = isdigit.o isxdigit.o toupper.o
@@ -55,7 +52,7 @@ libc.a: $(LIBCOBJS)
 
 LIBNETOBJS := args.o dhcp.o dns.o icmpv6.o ipv6.o tcp.o udp.o bootp.o \
 	      dhcpv6.o ethernet.o ipv4.o ndp.o tftp.o pxelinux.o
-LIBNETCFLAGS = $(EXTRA_CFLAGS) $(CFLAGS) $(NO_GNU_WARN) $(LIBC_INC) $(LIBNET_INC) \
+LIBNETCFLAGS = $(EXTRA_CFLAGS) $(CFLAGS) $(LIBC_INC) $(LIBNET_INC) \
 	       -DDHCPARCH=0x1F -MMD -MP -MT $@ -MF $(@:%.o=%.d)
 
 %.o : $(SLOF_DIR)/lib/libnet/%.c