389 lines
6.4 KiB
V
389 lines
6.4 KiB
V
// Copyright (c) 2019-2020 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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module x64
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import (
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v.ast
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// term
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)
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pub struct Gen {
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out_name string
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mut:
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buf []byte
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sect_header_name_pos int
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offset i64
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str_pos []i64
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strings []string // TODO use a map and don't duplicate strings
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file_size_pos i64
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main_fn_addr i64
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code_start_pos i64 // location of the start of the assembly instructions
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fn_addr map[string]i64
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// string_addr map[string]i64
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}
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enum Register {
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eax
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edi
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rax
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rdi
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rsi
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edx
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rdx
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r12
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}
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enum Size {
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_8
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_16
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_32
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_64
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}
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pub fn gen(files []ast.File, out_name string) {
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mut g := Gen{
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sect_header_name_pos: 0
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buf: []
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out_name: out_name
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}
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g.generate_elf_header()
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for file in files {
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for stmt in file.stmts {
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g.stmt(stmt)
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g.writeln('')
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}
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}
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g.generate_elf_footer()
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}
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/*
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pub fn new_gen(out_name string) &Gen {
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return &Gen{
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sect_header_name_pos: 0
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buf: []
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out_name: out_name
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}
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}
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*/
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pub fn (g &Gen) pos() i64 {
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return g.buf.len
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}
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fn (g mut Gen) write8(n int) {
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// write 1 byte
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g.buf << byte(n)
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}
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fn (g mut Gen) write16(n int) {
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// write 2 bytes
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g.buf << byte(n)
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g.buf << byte(n>>8)
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}
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fn (g mut Gen) write32(n int) {
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// write 4 bytes
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g.buf << byte(n)
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g.buf << byte(n>>8)
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g.buf << byte(n>>16)
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g.buf << byte(n>>24)
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}
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fn (g mut Gen) write64(n i64) {
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// write 8 bytes
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g.buf << byte(n)
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g.buf << byte(n>>8)
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g.buf << byte(n>>16)
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g.buf << byte(n>>24)
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g.buf << byte(n>>32)
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g.buf << byte(n>>40)
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g.buf << byte(n>>48)
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g.buf << byte(n>>56)
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}
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fn (g mut Gen) write64_at(n i64, at i64) {
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// write 8 bytes
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g.buf[at] = byte(n)
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g.buf[at + 1] = byte(n>>8)
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g.buf[at + 2] = byte(n>>16)
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g.buf[at + 3] = byte(n>>24)
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g.buf[at + 4] = byte(n>>32)
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g.buf[at + 5] = byte(n>>40)
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g.buf[at + 6] = byte(n>>48)
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g.buf[at + 7] = byte(n>>56)
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}
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fn (g mut Gen) write_string(s string) {
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for c in s {
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g.write8(int(c))
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}
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}
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fn (g mut Gen) inc(reg Register) {
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g.write16(0xff49)
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match reg {
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.r12 {
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g.write8(0xc4)
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}
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else {
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panic('unhandled inc $reg')
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}
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}
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}
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fn (g mut Gen) cmp(reg Register, size Size, val i64) {
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g.write8(0x49)
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// Second byte depends on the size of the value
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match size {
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._8 {
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g.write8(0x83)
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}
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._32 {
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g.write8(0x81)
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}
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else {
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panic('unhandled cmp')
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}
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}
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// Third byte depends on the register being compared to
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match reg {
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.r12 {
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g.write8(0xfc)
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}
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else {
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panic('unhandled cmp')
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}
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}
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g.write8(int(val))
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}
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fn abs(a i64) i64 {
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return if a < 0 { -a } else { a }
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}
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fn (g mut Gen) jle(addr i64) {
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// Calculate the relative offset to jump to
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// (`addr` is absolute address)
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offset := 0xff - int(abs(addr - g.buf.len)) - 1
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g.write8(0x7e)
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g.write8(offset)
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}
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fn (g mut Gen) jl(addr i64) {
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offset := 0xff - int(abs(addr - g.buf.len)) - 1
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g.write8(0x7c)
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g.write8(offset)
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}
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fn (g &Gen) abs_to_rel_addr(addr i64) int {
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return int(abs(addr - g.buf.len)) - 1
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}
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fn (g mut Gen) jmp(addr i64) {
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offset := 0xff - g.abs_to_rel_addr(addr)
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g.write8(0xe9)
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g.write8(offset)
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}
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fn (g mut Gen) mov64(reg Register, val i64) {
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match reg {
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.rsi {
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g.write8(0x48)
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g.write8(0xbe)
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}
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else {
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println('unhandled mov $reg')
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}
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}
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g.write64(val)
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}
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fn (g mut Gen) call(addr int) {
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// rel := g.abs_to_rel_addr(addr)
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// rel := 0xffffffff - int(abs(addr - g.buf.len))-1
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println('call addr=$addr rel_addr=$addr pos=$g.buf.len')
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g.write8(0xe8)
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g.write32(addr)
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}
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fn (g mut Gen) syscall() {
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// g.write(0x050f)
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g.write8(0x0f)
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g.write8(0x05)
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}
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pub fn (g mut Gen) ret() {
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g.write8(0xc3)
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}
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// returns label's relative address
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pub fn (g mut Gen) gen_loop_start(from int) int {
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g.mov(.r12, from)
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label := g.buf.len
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g.inc(.r12)
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return label
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}
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pub fn (g mut Gen) gen_loop_end(to int, label int) {
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g.cmp(.r12, ._8, to)
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g.jl(label)
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}
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pub fn (g mut Gen) save_main_fn_addr() {
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g.main_fn_addr = g.buf.len
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}
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pub fn (g mut Gen) gen_print_from_expr(expr ast.Expr) {
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match expr {
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ast.StringLiteral {
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g.gen_print(it.val)
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}
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else {}
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}
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}
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pub fn (g mut Gen) gen_print(s string) {
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g.strings << s + '\n'
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// g.string_addr[s] = str_pos
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g.mov(.eax, 1)
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g.mov(.edi, 1)
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str_pos := g.buf.len + 2
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g.str_pos << str_pos
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g.mov64(.rsi, 0) // segment_start + 0x9f) // str pos // PLACEHOLDER
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g.mov(.edx, s.len + 1) // len
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g.syscall()
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}
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pub fn (g mut Gen) gen_exit() {
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// Return 0
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g.mov(.edi, 0) // ret value
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g.mov(.eax, 60)
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g.syscall()
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}
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fn (g mut Gen) mov(reg Register, val int) {
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match reg {
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.eax {
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g.write8(0xb8)
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}
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.edi {
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g.write8(0xbf)
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}
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.edx {
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g.write8(0xba)
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}
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.rsi {
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g.write8(0x48)
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g.write8(0xbe)
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}
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.r12 {
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g.write8(0x41)
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g.write8(0xbc) // r11 is 0xbb etc
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}
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else {
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panic('unhandled mov $reg')
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}
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}
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g.write32(val)
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}
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pub fn (g mut Gen) register_function_address(name string) {
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addr := g.pos()
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// println('reg fn addr $name $addr')
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g.fn_addr[name] = addr
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}
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pub fn (g &Gen) write(s string) {}
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pub fn (g &Gen) writeln(s string) {}
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pub fn (g mut Gen) call_fn(name string) {
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if !name.contains('__') {
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return
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}
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addr := g.fn_addr[name]
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g.call(int(addr))
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println('call $name $addr')
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}
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fn (g mut Gen) stmt(node ast.Stmt) {
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match node {
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ast.FnDecl {
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is_main := it.name == 'main'
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if is_main {
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g.save_main_fn_addr()
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}
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for arg in it.args {}
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for stmt in it.stmts {
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g.stmt(stmt)
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}
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if is_main {
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println('end of main: gen exit')
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g.gen_exit()
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}
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g.ret()
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}
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ast.Return {}
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ast.AssignStmt {}
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ast.VarDecl {}
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ast.ForStmt {}
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ast.StructDecl {}
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ast.ExprStmt {
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g.expr(it.expr)
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}
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else {
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verror('x64.stmt(): bad node')
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}
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}
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}
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fn (g mut Gen) expr(node ast.Expr) {
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// println('cgen expr()')
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match node {
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ast.AssignExpr {}
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ast.IntegerLiteral {}
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ast.FloatLiteral {}
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/*
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ast.UnaryExpr {
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g.expr(it.left)
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}
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*/
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ast.StringLiteral {}
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ast.InfixExpr {}
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// `user := User{name: 'Bob'}`
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ast.StructInit {}
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ast.CallExpr {
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if it.name == 'println' || it.name == 'print' {
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expr := it.args[0]
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g.gen_print_from_expr(expr)
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}
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/*
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g.write('${it.name}(')
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for i, expr in it.args {
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g.expr(expr)
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if i != it.args.len - 1 {
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g.write(', ')
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}
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}
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g.write(')')
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*/
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}
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ast.ArrayInit {}
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ast.Ident {}
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ast.BoolLiteral {}
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ast.IfExpr {}
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else {
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// println(term.red('x64.expr(): bad node'))
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}
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}
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}
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fn verror(s string) {
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println(s)
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exit(1)
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}
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