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
before building.

The changes introduce a new .mk file called "check.mk". The build system
includes this file so that it lists all necessary tools, verify the
existence of their executables, and aborts the build if any required
tool is missing.

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

@@ -42,6 +42,7 @@ 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/check.mk
 
 config:
 	$(Q)ln -s $(PWD)/$(SRCDIR)/$(ARCH)-codegen.c $(SRCDIR)/codegen.c

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/check.mk

@@ -0,0 +1,10 @@
+# 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
+$(warning "Necessary packages: $(PREREQ_LIST)")
+$(warning "Missing packages: $(PREREQ_MISSING)")
+$(error "Please check package installation")
+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