Makefile: use the compiler driver directly

Makefile

@@ -5,37 +5,22 @@ tgo: build/tgo
 
 .PHONY: all tgo run-test run-blinky run-blinky2 clean fmt gen-device gen-device-nrf
 
-CFLAGS = -Wall -Werror -Os -fno-exceptions -ffunction-sections -fdata-sections $(LLFLAGS)
-CFLAGS += -fno-exceptions -fno-unwind-tables # Avoid .ARM.exidx etc.
-
 TARGET ?= unix
 
 ifeq ($(TARGET),unix)
 # Regular *nix system.
-LD = clang
 SIZE = size
 
 else ifeq ($(TARGET),pca10040)
 # PCA10040: nRF52832 development board
-LD = arm-none-eabi-ld -T arm.ld --gc-sections
 SIZE = arm-none-eabi-size
 OBJCOPY = arm-none-eabi-objcopy
-LLFLAGS += -target armv7m-none-eabi
 TGOFLAGS += -target $(TARGET)
-CFLAGS += -I$(CURDIR)/lib/CMSIS/CMSIS/Include
-CFLAGS += -DNRF52832_XXAA
-CFLAGS += -Wno-uninitialized
-OBJ += build/nrfx_system_nrf52.o
-OBJ += build/nrfx_startup_nrf51.o # TODO nrf52, see https://bugs.llvm.org/show_bug.cgi?id=31601
 
 else ifeq ($(TARGET),arduino)
-AS = avr-as -mmcu=atmega328p
-LD = avr-ld -T avr.ld --gc-sections
 SIZE = avr-size
 OBJCOPY = avr-objcopy
-LLFLAGS += -target avr8--
 TGOFLAGS += -target $(TARGET)
-OBJ += build/avr.o
 
 else
 $(error Unknown target)
@@ -82,32 +67,15 @@ build/tgo: *.go
 	@mkdir -p build
 	go build -o build/tgo -i .
 
-# Build IR with the Go compiler.
-build/%.o: src/examples/% src/examples/%/*.go build/tgo src/runtime/*.go
+# Binary that can run on the host.
+build/%: src/examples/% src/examples/%/*.go build/tgo src/runtime/*.go
 	./build/tgo build $(TGOFLAGS) -o $@ $(subst src/,,$<)
+	@$(SIZE) $@
 
-# Compile system_* file for the nRF.
-build/nrfx_%.o: lib/nrfx/mdk/%.c
-	@mkdir -p build
-	clang $(CFLAGS) -c -o $@ $^
-
-# Compile startup_* file for the nRF.
-build/nrfx_%.o: lib/nrfx/mdk/gcc_%.S
-	@mkdir -p build
-	clang $(CFLAGS) -D__STARTUP_CLEAR_BSS -c -o $@ $^
-
-build/%.o: %.S
-	$(AS) -o $@ $^
-
-# Generate output ELF executable.
-build/%: build/%.o $(OBJ)
-	$(LD) -o $@ $^
-	$(SIZE) $@
-
-# Generate output ELF for use in objcopy (on a microcontroller).
-build/%.elf: build/%.o $(OBJ)
-	$(LD) -o $@ $^
-	$(SIZE) $@
+# ELF file that can run on a microcontroller.
+build/%.elf: src/examples/% src/examples/%/*.go build/tgo src/runtime/*.go
+	./build/tgo build $(TGOFLAGS) -o $@ $(subst src/,,$<)
+	@$(SIZE) $@
 
 # Convert executable to Intel hex file (for flashing).
 build/%.hex: build/%.elf