Validate the prerequisites before building

To prevent users from building shecc without certain required packages,
these changes modify the build system to check for prerequisites
when building.

The build system now lists all necessary tools, verify the existence
of their executables, and prints warning messages if any required tool
is missing.

If qemu is required but missing, the build process will proceed only
up to stage 0, print warning messages and stop at the beginning of
stage 1.

Additionally, these changes modify main.yml to install all necessary
tools for the host-arm build, so the build won't fail due to missing
packages.

Close #44

Author: DrXiao

.github/workflows/main.yml

@@ -39,7 +39,7 @@ jobs:
         githubToken: ${{ github.token }}
         install: |
           apt-get update -qq -y
-          apt-get install -yqq build-essential
+          apt-get install -yqq build-essential graphviz jq
         run: |
           make config ARCH=arm
           make check || exit 1

Makefile

@@ -16,7 +16,6 @@ CFLAGS := -O -g \
 
 BUILD_SESSION := .session.mk
 
-include mk/common.mk
 -include $(BUILD_SESSION)
 
 STAGE0 := shecc
@@ -26,6 +25,7 @@ STAGE2 := shecc-stage2.elf
 OUT ?= out
 ARCHS = arm riscv
 ARCH ?= $(firstword $(ARCHS))
+HOST_ARCH = $(shell arch 2>/dev/null)
 SRCDIR := $(shell find src -type d)
 LIBDIR := $(shell find lib -type d)
 
@@ -42,12 +42,14 @@ ifeq (,$(filter $(ARCH),$(ARCHS)))
 $(error Support ARM and RISC-V only. Select the target with "ARCH=arm" or "ARCH=riscv")
 endif
 include mk/$(ARCH).mk
+include mk/common.mk
 
 config:
 	$(Q)ln -s $(PWD)/$(SRCDIR)/$(ARCH)-codegen.c $(SRCDIR)/codegen.c
 	$(call $(ARCH)-specific-defs) > $@
 	$(VECHO) "Target machine code switch to %s\n" $(ARCH)
 	$(Q)$(MAKE) $(BUILD_SESSION) --silent
+	$(CONFIG_CHECK_CMD)
 
 $(OUT)/tests/%.elf: tests/%.c $(OUT)/$(STAGE0)
 	$(VECHO) "  SHECC\t$@\n"
@@ -103,6 +105,7 @@ $(OUT)/$(STAGE0): $(OUT)/libc.inc $(OBJS)
 	$(Q)$(CC) $(OBJS) -o $@
 
 $(OUT)/$(STAGE1): $(OUT)/$(STAGE0)
+	$(STAGE1_CHECK_CMD)
 	$(VECHO) "  SHECC\t$@\n"
 	$(Q)$(OUT)/$(STAGE0) --dump-ir -o $@ $(SRCDIR)/main.c > $(OUT)/shecc-stage1.log
 	$(Q)chmod a+x $@

mk/arm.mk

@@ -1,12 +1,8 @@
 ifeq ($(HOST_ARCH),armv7l) # detect ARMv7-A only and assume Linux-compatible
     TARGET_EXEC :=
 else
-    TARGET_EXEC = qemu-arm
-    TARGET_EXEC := $(shell which $(TARGET_EXEC))
-    ifndef TARGET_EXEC
-    $(warning "no qemu-arm found. Please check package installation")
-    ARM_EXEC = echo WARN: unable to run
-    endif
+    ARCH_EXEC = qemu-arm
+    TARGET_EXEC := $(shell which $(ARCH_EXEC))
 endif
 
 export TARGET_EXEC

mk/common.mk

@@ -5,8 +5,6 @@ else
     PRINTF = env printf
 endif
 
-HOST_ARCH = $(shell arch 2>/dev/null)
-
 # Control the build verbosity
 ifeq ("$(VERBOSE)","1")
     Q :=
@@ -23,3 +21,20 @@ PASS_COLOR = \e[32;01m
 NO_COLOR = \e[0m
 
 pass = $(PRINTF) "$(PASS_COLOR)$1 Passed$(NO_COLOR)\n"
+
+# Check the prerequisites
+PREREQ_LIST := dot jq $(ARCH_EXEC)
+PREREQ_EXEC := $(shell which $(PREREQ_LIST))
+PREREQ_MISSING := $(filter-out $(notdir $(PREREQ_EXEC)),$(PREREQ_LIST))
+
+ifdef PREREQ_MISSING
+CONFIG_WARN_MSG := "Warning: missing packages: $(PREREQ_MISSING)\nWarning: Please check package installation\n"
+CONFIG_CHECK_CMD := $(Q)$(VECHO) $(CONFIG_WARN_MSG)
+endif
+
+ifdef ARCH_EXEC
+ifeq ($(filter $(ARCH_EXEC),$(notdir $(PREREQ_EXEC))),)
+STAGE1_WARN_MSG := "Warning: failed to build the stage 1 and stage 2 compilers due to missing $(ARCH_EXEC)\n"
+STAGE1_CHECK_CMD := $(Q)$(VECHO) $(STAGE1_WARN_MSG) && exit 1
+endif
+endif

mk/riscv.mk

@@ -1,9 +1,5 @@
-TARGET_EXEC = qemu-riscv32
-TARGET_EXEC := $(shell which $(TARGET_EXEC))
-ifndef TARGET_EXEC
-$(warning "no qemu-riscv32 found. Please check package installation")
-TARGET_EXEC = echo WARN: unable to run
-endif
+ARCH_EXEC = qemu-riscv32
+TARGET_EXEC := $(shell which $(ARCH_EXEC))
 
 export TARGET_EXEC