init of qbe backend

cmd/tools/builders/qbe_builder.v

@@ -0,0 +1,7 @@
+module main
+
+import v.builder.qbebuilder
+
+fn main() {
+	qbebuilder.start()
+}

cmd/v/v.v

@@ -202,5 +202,8 @@ fn rebuild(prefs &pref.Preferences) {
 		.wasm {
 			util.launch_tool(prefs.is_verbose, 'builders/wasm_builder', os.args[1..])
 		}
+		.qbe {
+			util.launch_tool(prefs.is_verbose, 'builders/qbe_builder', os.args[1..])
+		}
 	}
 }

vlib/v/builder/qbebuilder/qbe.md

@@ -0,0 +1,16 @@
+```bash
+# compile qbe_builder
+v cmd/tools/builders/qbe_builder.v -g -path "./vlib|@vmodules" -o ./qbe_builder
+
+# generate IL
+VTMP=./tmp ./qbe_builder qbe-test.v -skip-unused -no-builtin
+
+# oneliner for above
+v cmd/tools/builders/qbe_builder.v -g -path "./vlib|@vmodules" -o ./qbe_builder -v && VTMP=./tmp ./qbe_builder qbe-test.v -skip-unused -no-builtin -g -v
+
+# generate assembly
+../qbe/qbe tmp/qbe-test.ssa > tmp/qbe-test.s
+
+# final compilation
+cc -g -Lc tmp/qbe-test.s -o tmp/qbe-test
+```

vlib/v/builder/qbebuilder/qbebuilder.v

@@ -0,0 +1,66 @@
+module qbebuilder
+
+import v.pref
+import v.util
+import v.builder
+import v.gen.qbe
+import os
+
+pub fn start() {
+	mut args_and_flags := util.join_env_vflags_and_os_args()[1..]
+	prefs, _ := pref.parse_args([], args_and_flags)
+	builder.compile('build', prefs, compile_qbe)
+}
+
+pub fn compile_qbe(mut b builder.Builder) {
+	mut files := b.get_builtin_files()
+	files << b.get_user_files()
+	b.set_module_lookup_paths()
+	if b.pref.is_verbose {
+		println('all .v files:')
+		println(files)
+	}
+	out_name := b.pref.out_name
+
+	// TODO: replace latter with get_vtmp_filename below
+	vtmp := os.vtmp_dir()
+	fname := os.file_name(os.real_path(out_name)) + '.tmp.ssa'
+	out_name_ssa := os.real_path(os.join_path(vtmp, fname))
+	// out_name_ssa := b.get_vtmp_filename(b.pref.out_name, '.tmp.ssa')
+	out_name_s := out_name_ssa#[..-3] + 'S'
+	build_qbe(mut b, files, out_name_ssa)
+	if !os.exists_in_system_path('qbe') {
+		eprintln('qbe executable not found in PATH!')
+		eprintln('Please install it from https://c9x.me/compile/releases.html')
+		return
+	}
+	// QBE suports amd64_sysv (default), amd64_apple, arm64, arm64_apple, rv64
+	// arch := if b.pref.arch in [.amd64, .arm64, .rv64] {
+	// 	b.pref.arch.str()
+	// } else {
+	// 	eprintln('Unsuported architecture ${b.pref.arch}')
+	// 	exit(1)
+	// }
+	// os := match b.pref.os {
+	// 	.linux { 'sysv' }
+	// 	.macos { 'apple' }
+	// }
+	// target := '${arch}_'
+	res := os.execute('qbe ${out_name_ssa} > ${out_name_s}')
+	if res.exit_code != 0 {
+		eprintln(res.output)
+		exit(res.exit_code)
+	}
+	res_cc := os.execute('cc -g -Lc ${out_name_s} -o ${out_name}')
+	if res_cc.exit_code != 0 {
+		eprintln(res_cc.output)
+		exit(res_cc.exit_code)
+	}
+}
+
+pub fn build_qbe(mut b builder.Builder, v_files []string, out_file string) {
+	b.front_and_middle_stages(v_files) or { return }
+	util.timing_start('QBE GEN')
+	qbe.gen(b.parsed_files, mut b.table, out_file, b.pref)
+	util.timing_measure('QBE GEN')
+}