x64: function calls; http: download_file()

examples/x64/hello_world.v

@@ -1,6 +1,11 @@
 fn main() {
+	println('x64 test')
 	for _ in 0..5 {
 		println('Hello world from V x64 machine code generator!')
 	}
 	println('Hello again!')
 }
+
+fn test_fn() {
+	println('test fn')
+}	

vlib/compiler/fn.v

@@ -44,6 +44,7 @@ mut:
 	fn_name_token_idx int // used by error reporting
 	comptime_define string
 	is_used bool // so that we can skip unused fns in resulting C code
+	//x64_addr i64 // address in the generated x64 binary
 }
 
 struct TypeInst {
@@ -397,6 +398,9 @@ fn (p mut Parser) fn_decl() {
 	str_args := f.str_args(p.table)
 	// Special case for main() args
 	if f.name == 'main__main' && !has_receiver {
+		if p.pref.x64 && !p.first_pass() {
+			p.x64.save_main_fn_addr()
+		}	
 		if str_args != '' || typ != 'void' {
 			p.error_with_token_index('fn main must have no arguments and no return values', f.fn_name_token_idx)
 		}
@@ -525,6 +529,12 @@ fn (p mut Parser) fn_decl() {
 		//p.genln('// live_function body end')
 		p.genln('pthread_mutex_unlock(&live_fn_mutex);')
 	}
+	if p.pref.x64 && f.name == 'main__main' && !p.first_pass() {
+		p.x64.gen_exit()
+	}	
+	if p.pref.x64 && !p.first_pass() {
+		p.x64.ret()
+	}
 	// {} closed correctly? scope_level should be 0
 	if p.mod == 'main' {
 		// println(p.cur_fn.scope_level)
@@ -541,6 +551,7 @@ fn (p mut Parser) fn_decl() {
 	p.check_unused_variables()
 	p.set_current_fn( EmptyFn )
 	p.returns = false
+	
 }
 
 [inline]

vlib/compiler/main.v

@@ -367,7 +367,6 @@ pub fn (v mut V) compile_x64() {
 		v.parse(f, .main)
 	}
 	v.x64.generate_elf_footer()
-	
 }	
 
 fn (v mut V) generate_init() {

vlib/compiler/match.v

@@ -167,7 +167,7 @@ fn (p mut Parser) match_statement(is_expr bool) string {
 		p.gen(')')
 
 		if p.tok == .arrow {
-			p.warn(warn_match_arrow)
+			p.error(warn_match_arrow)
 			p.check(.arrow)
 		}	
 

vlib/compiler/x64/elf.v

@@ -69,6 +69,8 @@ pub fn (g mut Gen) generate_elf_header() {
 	g.write64(0x1000) // p_align
 	// user code starts here at
 	// address: 00070 and a half
+	g.code_start_pos = g.buf.len
+	g.call(0)// call main function, it's not guaranteed to be the first
 }
 
 pub fn (g mut Gen) generate_elf_footer() {
@@ -87,6 +89,12 @@ pub fn (g mut Gen) generate_elf_footer() {
 	file_size := g.buf.len
 	g.write64_at(file_size, g.file_size_pos) // set file size 64 bit value
 	g.write64_at(file_size, g.file_size_pos+8)
+	// call main function, it's not guaranteed to be the first
+	// we generated call(0) ("e8 0")
+	// no need to replace "0" with a relative address of the main function
+	// +1 is for "e8"
+	// -5 is for "e8 00 00 00 00"
+	g.write64_at(int(g.main_fn_addr - g.code_start_pos) - 5, g.code_start_pos+1)
 	// Create the binary
 	f := os.create(g.out_name) or { panic(err) }
 	os.chmod(g.out_name, 0775)

vlib/compiler/x64/gen.v

@@ -12,8 +12,9 @@ mut:
 	offset i64
 	str_pos []i64
 	strings []string // TODO use a map and don't duplicate strings
-	//str string
 	file_size_pos i64
+	main_fn_addr i64
+	code_start_pos i64 // location of the start of the assembly instructions
 	//string_addr map[string]i64
 }	
 
@@ -120,11 +121,29 @@ fn (g mut Gen) cmp(reg Register, size Size, val i64) {
 fn abs(a i64) i64 { return if a < 0 { -a } else { a } }
 
 fn (g mut Gen) jle(addr i64) {
+	// Calculate the relative offset to jump to
+	// (`addr` is absolute address)
 	offset := 0xff - int(abs(addr - g.buf.len))-1
 	g.write8(0x7e)
 	g.write8(offset)
 }
 
+fn (g mut Gen) jl(addr i64) {
+	offset := 0xff - int(abs(addr - g.buf.len))-1
+	g.write8(0x7c)
+	g.write8(offset)
+}
+
+fn (g &Gen) abs_to_rel_addr(addr i64) int {
+	return int(abs(addr - g.buf.len))-1
+}	
+
+fn (g mut Gen) jmp (addr i64) {
+	offset := 0xff - g.abs_to_rel_addr(addr)
+	g.write8(0xe9)
+	g.write8(offset)
+}
+
 fn (g mut Gen) mov64(reg Register, val i64) {
 	match reg {
 		.rsi {
@@ -137,7 +156,9 @@ fn (g mut Gen) mov64(reg Register, val i64) {
 }
 
 fn (g mut Gen) call(val int) {
+	//println('call val=$val')
 	g.write8(0xe8)
+	g.write32(val)
 }
 
 fn (g mut Gen) syscall() {
@@ -146,7 +167,7 @@ fn (g mut Gen) syscall() {
 	g.write8(0x05)
 }
 
-fn (g mut Gen) ret() {
+pub fn (g mut Gen) ret() {
 	g.write8(0xc3)
 }
 
@@ -163,6 +184,10 @@ pub fn (g mut Gen) gen_loop_end(to int, label int) {
 	g.jle(label)
 }
 
+pub fn (g mut Gen) save_main_fn_addr() {
+	g.main_fn_addr = g.buf.len
+}
+
 pub fn (g mut Gen) gen_print(s string) {
 	g.strings << s + '\n'
 	//g.string_addr[s] = str_pos
@@ -175,6 +200,13 @@ pub fn (g mut Gen) gen_print(s string) {
 	g.syscall()
 }	
 
+pub fn (g mut Gen) gen_exit() {
+	// Return 0
+	g.mov(.edi, 0) // ret value
+	g.mov(.eax, 60)
+	g.syscall()
+}
+
 fn (g mut Gen) mov(reg Register, val int) {
 	match reg {
 		.eax { g.write8(0xb8) }

vlib/http/download.v

@@ -0,0 +1,14 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+module http
+
+import os
+
+fn download_file(url, out string) bool {
+	s := http.get(url) or { return false }
+	os.write_file(out, s.text)
+	return true
+	//download_file_with_progress(url, out, empty, empty)
+}

vlib/http/download_nix.v

@@ -51,10 +51,6 @@ fn download_file_with_progress(url, out string, cb downloadfn, cb_finished fn())
 */
 }
 
-fn download_file(url, out string) {
-	//download_file_with_progress(url, out, empty, empty) 
-}
-
 fn empty() {
 
 }

vlib/http/download_windows.v

@@ -11,6 +11,7 @@ module http
 fn download_file_with_progress(url, out string, cb, cb_finished voidptr) {
 }
 
+/*
 pub fn download_file(url, out string) {
 	C.URLDownloadToFile(0, url.to_wide(), out.to_wide(), 0, 0)
 	/*
@@ -25,3 +26,4 @@ pub fn download_file(url, out string) {
 	# }
 	*/
 }
+*/