Remove code from libgcc and libc that is provided by the ROM.

This saves about 2.5k of iram.

common.mk

@@ -160,6 +160,26 @@ endif
 -include $$($(1)_OBJ_FILES:.o=.d)
 endef
 
+# Remove comment lines from libgcc.remove file
+$(BUILD_DIR)libgcc.remove: $(ROOT)lib/libgcc.remove | $(BUILD_DIR)
+	$(Q) grep -v "^#" $< | cat > $@
+
+# Remove unwanted object files listed in libgcc.remove
+$(BUILD_DIR)libgcc.a: $(ROOT)lib/libgcc.a $(BUILD_DIR)libgcc.remove | $(BUILD_DIR)
+	@echo "Removing unwanted objects from $<"
+	$(Q) cat $< > $@
+	$(Q) $(AR) d $@ @$(word 2,$^)
+
+# Remove comment lines from libc.remove file
+$(BUILD_DIR)libc.remove: $(ROOT)libc/libc.remove | $(BUILD_DIR)
+	$(Q) grep -v "^#" $< | cat > $@
+
+# Remove unwanted object files listed in libgcc.remove
+$(BUILD_DIR)libc.a: $(ROOT)libc/xtensa-lx106-elf/lib/libc.a $(BUILD_DIR)libc.remove | $(BUILD_DIR)
+	@echo "Removing unwanted objects from $<"
+	$(Q) cat $< > $@
+	$(Q) $(AR) d $@ @$(word 2,$^)
+
 ## Linking rules for SDK libraries
 ## SDK libraries are preprocessed to:
 # - remove object files named in <libname>.remove
@@ -208,9 +228,9 @@ $(foreach component,$(COMPONENTS), 					\
 )
 
 # final linking step to produce .elf
-$(PROGRAM_OUT): $(WHOLE_ARCHIVES) $(COMPONENT_ARS) $(SDK_PROCESSED_LIBS) $(LINKER_SCRIPTS)
+$(PROGRAM_OUT): $(WHOLE_ARCHIVES) $(COMPONENT_ARS) $(BUILD_DIR)libgcc.a $(BUILD_DIR)libc.a $(SDK_PROCESSED_LIBS) $(LINKER_SCRIPTS)
 	$(vecho) "LD $@"
-	$(Q) $(LD) $(LDFLAGS) -Wl,--whole-archive $(WHOLE_ARCHIVES) -Wl,--no-whole-archive -Wl,--start-group $(COMPONENT_ARS) $(LIB_ARGS) $(SDK_LIB_ARGS) -Wl,--end-group -o $@
+	$(Q) $(LD) $(LDFLAGS) -Wl,--whole-archive $(WHOLE_ARCHIVES) -Wl,--no-whole-archive -Wl,--start-group $(COMPONENT_ARS) $(BUILD_DIR)libgcc.a $(BUILD_DIR)libc.a $(LIB_ARGS) $(SDK_LIB_ARGS) -Wl,--end-group -o $@
 
 $(BUILD_DIR) $(FIRMWARE_DIR) $(BUILD_DIR)sdklib:
 	$(Q) mkdir -p $@

lib/libgcc.remove

@@ -0,0 +1,24 @@
+# Object files to be removed from libgcc
+# These are provided by the ROM.
+_addsubdf3.o
+_addsubsf3.o
+_divdf3.o
+_divdi3.o
+_divsi3.o
+_extendsfdf2.o
+_fixdfsi.o
+_fixunssfsi.o
+_floatsidf.o
+_floatsisf.o
+_floatunsidf.o
+_floatunsisf.o
+_muldf3.o
+_muldi3.o
+_mulsf3.o
+_subdf3.o
+_subsf3.o
+_truncdfsf2.o
+_udivdi3.o
+_umoddi3.o
+_umodsi3.o
+_umulsidi3.o

libc/libc.remove

@@ -0,0 +1,13 @@
+# Object files to remove from libc.a
+# These are provided by the ROM.
+lib_a-bzero.o
+lib_a-memcmp.o
+lib_a-memcpy.o
+lib_a-memmove.o
+lib_a-memset.o
+lib_a-strcmp.o
+lib_a-strcpy.o
+lib_a-strlen.o
+lib_a-strncmp.o
+lib_a-strncpy.o
+lib_a-strstr.o

parameters.mk

@@ -66,7 +66,7 @@ COMPONENTS     ?= $(EXTRA_COMPONENTS) FreeRTOS lwip core open_esplibs
 SDK_LIBS		?= main net80211 phy pp wpa
 
 # open source libraries linked in
-LIBS ?= hal gcc c
+LIBS ?= hal
 
 # set to 0 if you want to use the toolchain libc instead of esp-open-rtos newlib
 OWN_LIBC ?= 1