Be able to actually run the blinky example on an nRF

runtime.Sleep() doesn't work yet so it prints a lot of data. Also, this
depends on a small patch to nrfx.

Makefile

@@ -2,27 +2,96 @@
 # aliases
 all: tgo
 tgo: build/tgo
-test: build/hello.o
 
-.PHONY: all tgo test run-test clean
+.PHONY: all tgo run-hello run-blinky flash-blinky clean
 
-CFLAGS = -Wall -Werror -O2 -g -flto
+# Custom LLVM toolchain.
+LLVM =
+LINK = $(LLVM)llvm-link
+LLC = $(LLVM)llc
 
-build/tgo: *.go
-	@mkdir -p build
-	@go build -o build/tgo -i .
+CFLAGS = -Wall -Werror -Os -g -fno-exceptions -flto -ffunction-sections -fdata-sections $(LLFLAGS)
 
-build/hello.o: build/tgo src/examples/hello/*.go src/runtime/*.go
-	@./build/tgo -printir -o build/hello.o examples/hello
+RUNTIME = build/runtime.bc
 
-build/runtime.o: src/runtime/*.c src/runtime/*.h
-	clang $(CFLAGS) -c -o $@ src/runtime/*.c
+ifeq ($(TARGET),pca10040)
+GCC = arm-none-eabi-gcc
+LD = arm-none-eabi-ld -T arm.ld
+OBJCOPY = arm-none-eabi-objcopy
+LLFLAGS += -target armv7m-none-eabi
+TGOFLAGS += -target $(TARGET)
+CFLAGS += -I$(CURDIR)/src/runtime
+CFLAGS += -I$(CURDIR)/lib/nrfx
+CFLAGS += -I$(CURDIR)/lib/nrfx/mdk
+CFLAGS += -I$(CURDIR)/lib/CMSIS/CMSIS/Include
+CFLAGS += -DNRF52832_XXAA
+CFLAGS += -Wno-uninitialized
+RUNTIME += build/runtime_nrf.bc
+RUNTIME += build/system_nrf52.bc
+OBJ += build/startup_nrf51.o # TODO nrf52, see https://bugs.llvm.org/show_bug.cgi?id=31601
 
-build/hello: build/hello.o build/runtime.o
-	@clang $(CFLAGS) -o $@ $^
+else
+# Regular *nix system.
+GCC = gcc
+LD = clang
+endif
 
-run-test: build/hello
-	@./build/hello
+
+
+run-hello: build/hello
+	./build/hello
+
+run-blinky: build/blinky
+	./build/blinky
+
+flash-blinky: build/blinky.hex
+	nrfjprog -f nrf52 --sectorerase --program $< --reset
 
 clean:
 	@rm -rf build
+
+
+
+# Build the Go compiler.
+build/tgo: *.go
+	@mkdir -p build
+	go build -o build/tgo -i .
+
+# Build textual IR with the Go compiler.
+build/%.ll: src/examples/% src/examples/%/*.go build/tgo src/runtime/*.go
+	./build/tgo $(TGOFLAGS) -printir -o $@ $(subst src/,,$<)
+
+# Compile C sources for the runtime.
+build/%.bc: src/runtime/%.c src/runtime/*.h
+	@mkdir -p build
+	clang $(CFLAGS) -c -o $@ $<
+
+# Compile system_* file for the nRF.
+build/%.bc: lib/nrfx/mdk/%.c
+	@mkdir -p build
+	clang $(CFLAGS) -c -o $@ $^
+
+# Compile startup_* file for the nRF.
+build/%.o: lib/nrfx/mdk/gcc_%.S
+	@mkdir -p build
+	clang $(CFLAGS) -c -o $@ $^
+
+# Merge all LLVM files together in a single bitcode file.
+build/%.bc: $(RUNTIME) build/%.ll
+	$(LINK) -o $@ $^
+
+# Generate an ELF object file from a LLVM bitcode file.
+build/%.o: build/%.bc
+	$(LLC) -filetype=obj -O2 -o $@ $^
+
+# Generate output ELF executable.
+build/%: build/%.o $(OBJ)
+	$(LD) -o $@ $^
+
+# Generate output ELF for use in objcopy (on a microcontroller).
+build/%.elf: build/%.o $(OBJ)
+	$(LD) -o $@ $^
+
+# Convert executable to Intel hex file (for flashing).
+build/%.hex: build/%.elf
+	$(OBJCOPY) -O ihex $^ $@