all: remove last traces of the C runtime

This increases code size on the nrf, but it is a fixed increase and can
hopefully be reduced in the future.
The Makefile gets a lot smaller with this which is a huge advantage
(less build time complexity).

Makefile

@@ -5,17 +5,9 @@ tgo: build/tgo
 
 .PHONY: all tgo run-test run-blinky run-blinky2 clean fmt gen-device gen-device-nrf
 
-# Custom LLVM toolchain.
-LLVM := $(shell go env GOPATH)/src/github.com/aykevl/llvm/bindings/go/llvm/workdir/llvm_build/bin/
-LINK = $(LLVM)llvm-link
-LLAS = $(LLVM)llvm-as
-OPT = $(LLVM)opt
-
-CFLAGS = -Wall -Werror -Os -fno-exceptions -flto -ffunction-sections -fdata-sections $(LLFLAGS)
+CFLAGS = -Wall -Werror -Os -fno-exceptions -ffunction-sections -fdata-sections $(LLFLAGS)
 CFLAGS += -fno-exceptions -fno-unwind-tables # Avoid .ARM.exidx etc.
 
-RUNTIME_PARTS = build/runtime.bc
-
 TARGET ?= unix
 
 ifeq ($(TARGET),unix)
@@ -30,13 +22,10 @@ SIZE = arm-none-eabi-size
 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_PARTS += build/nrfx_system_nrf52.bc
+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)
@@ -94,15 +83,11 @@ build/tgo: *.go
 	go build -o build/tgo -i .
 
 # Build IR with the Go compiler.
-build/%.o: src/examples/% src/examples/%/*.go build/tgo src/runtime/*.go build/runtime-$(TARGET)-combined.bc
-	./build/tgo build $(TGOFLAGS) -runtime build/runtime-$(TARGET)-combined.bc -o $@ $(subst src/,,$<)
-
-# Compile LLVM bitcode from LLVM source.
-build/%.bc: src/runtime/%.ll
-	$(LLAS) -o $@ $<
+build/%.o: src/examples/% src/examples/%/*.go build/tgo src/runtime/*.go
+	./build/tgo build $(TGOFLAGS) -o $@ $(subst src/,,$<)
 
 # Compile system_* file for the nRF.
-build/nrfx_%.bc: lib/nrfx/mdk/%.c
+build/nrfx_%.o: lib/nrfx/mdk/%.c
 	@mkdir -p build
 	clang $(CFLAGS) -c -o $@ $^
 
@@ -114,10 +99,6 @@ build/nrfx_%.o: lib/nrfx/mdk/gcc_%.S
 build/%.o: %.S
 	$(AS) -o $@ $^
 
-# Merge all runtime LLVM files together in a single bitcode file.
-build/runtime-$(TARGET)-combined.bc: $(RUNTIME_PARTS)
-	$(LINK) -o $@ $^
-
 # Generate output ELF executable.
 build/%: build/%.o $(OBJ)
 	$(LD) -o $@ $^

compiler.go

@@ -96,6 +96,8 @@ func NewCompiler(pkgName, triple string, dumpSSA bool) (*Compiler, error) {
 	c.targetData = c.machine.CreateTargetData()
 
 	c.mod = llvm.NewModule(pkgName)
+	c.mod.SetTarget(triple)
+	c.mod.SetDataLayout(c.targetData.String())
 	c.ctx = c.mod.Context()
 	c.builder = c.ctx.NewBuilder()
 	c.dibuilder = llvm.NewDIBuilder(c.mod)

src/runtime/runtime.h

@@ -1,13 +0,0 @@
-
-#pragma once
-
-#include <stdint.h>
-
-typedef struct {
-	uint32_t len;  // TODO: size_t (or, let max string size depend on target/flag)
-	uint8_t  *buf; // points to string buffer itself
-} string_t;
-
-typedef int32_t intgo_t; // may be 64-bit
-
-int main();

src/runtime/runtime.ll

@@ -1,3 +0,0 @@
-source_filename = "runtime/runtime.ll"
-
-; dummy file