software: revert LTO changes (Disable it).

It seems LTO is not yet fully working with all configurations, so it's better
reverting the changes for now.
- cause issues with LM32 available compilers.
- seems to cause issues with min/lite variant of VexRiscv.
- seems to cause issues with some litex-buildenv configurations. (see #417).

litex/soc/software/bios/Makefile

@@ -29,7 +29,7 @@ bios.elf: $(BIOS_DIRECTORY)/linker.ld $(OBJECTS)
 
 
 %.elf: ../libbase/crt0-$(CPU)-ctr.o ../libnet/libnet.a ../libbase/libbase-nofloat.a ../libcompiler_rt/libcompiler_rt.a
-	$(CC) $(LDFLAGS) -T $(BIOS_DIRECTORY)/linker.ld -N -o $@ \
+	$(LD) $(LDFLAGS) -T $(BIOS_DIRECTORY)/linker.ld -N -o $@ \
 		../libbase/crt0-$(CPU)-ctr.o \
 		$(OBJECTS) \
 		-L../libnet \

litex/soc/software/common.mak

@@ -7,24 +7,14 @@ endif
 RM ?= rm -f
 PYTHON ?= python3
 
-ifeq ($(CPU), lm32)
-LTO = 0
-else
-LTO = 1
-endif
-
-ifeq ($(CLANG), 1)
+ifeq ($(CLANG),1)
 CC_normal      := clang -target $(TRIPLE) -integrated-as
 CX_normal      := clang++ -target $(TRIPLE) -integrated-as
 else
 CC_normal      := $(TARGET_PREFIX)gcc -std=gnu99
 CX_normal      := $(TARGET_PREFIX)g++
 endif
-ifeq ($(LTO), 1)
-AR_normal      := $(TARGET_PREFIX)gcc-ar
-else
 AR_normal      := $(TARGET_PREFIX)ar
-endif
 LD_normal      := $(TARGET_PREFIX)ld
 OBJCOPY_normal := $(TARGET_PREFIX)objcopy
 
@@ -34,7 +24,7 @@ AR_quiet      = @echo " AR      " $@ && $(AR_normal)
 LD_quiet      = @echo " LD      " $@ && $(LD_normal)
 OBJCOPY_quiet = @echo " OBJCOPY " $@ && $(OBJCOPY_normal)
 
-ifeq ($(V), 1)
+ifeq ($(V),1)
 	CC = $(CC_normal)
 	CX = $(CX_normal)
 	AR = $(AR_normal)
@@ -55,15 +45,11 @@ DEPFLAGS += -MD -MP
 
 # Toolchain options
 #
-INCLUDES    = -I$(SOC_DIRECTORY)/software/include/base -I$(SOC_DIRECTORY)/software/include -I$(SOC_DIRECTORY)/common -I$(BUILDINC_DIRECTORY)
+INCLUDES = -I$(SOC_DIRECTORY)/software/include/base -I$(SOC_DIRECTORY)/software/include -I$(SOC_DIRECTORY)/common -I$(BUILDINC_DIRECTORY)
 COMMONFLAGS = $(DEPFLAGS) -Os $(CPUFLAGS) -g3 -fomit-frame-pointer -Wall -fno-builtin -nostdinc $(INCLUDES)
-COMMONFLAGS += -ffunction-sections -fdata-sections -nostartfiles -nostdlib -nodefaultlibs
-ifeq ($(LTO), 1)
-COMMONFLAGS += -flto -fuse-linker-plugin
-endif
-CFLAGS   = $(COMMONFLAGS) -fexceptions -Wstrict-prototypes -Wold-style-definition -Wmissing-prototypes
+CFLAGS = $(COMMONFLAGS) -fexceptions -Wstrict-prototypes -Wold-style-definition -Wmissing-prototypes
 CXXFLAGS = $(COMMONFLAGS) -std=c++11 -I$(SOC_DIRECTORY)/software/include/basec++ -fexceptions -fno-rtti -ffreestanding
-LDFLAGS  = -nostdlib -nodefaultlibs -Os $(CPUFLAGS) -L$(BUILDINC_DIRECTORY)
+LDFLAGS = -nostdlib -nodefaultlibs -L$(BUILDINC_DIRECTORY)
 
 define compilexx
 $(CX) -c $(CXXFLAGS) $(1) $< -o $@