/*
* Copyright (C) 2024 olang maintainers
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*/
#include
#include
#include
#include "codegen_x86_64.h"
#include "list.h"
#include "map.h"
#include "scope.h"
#define SYS_exit (60)
#define PTR_HEX_CSTR_SIZE (16 + 1)
// The call instruction pushes EIP into stack so the first 8 bytes from stack
// must be preserved else the ret instruction will jump to nowere.
#define X86_CALL_ARG_SIZE 6
#define bytes_max(a, b) ((a) > (b) ? (a) : (b))
typedef enum x86_64_register_type
{
REG_ACCUMULATOR,
REG_BASE,
REG_COUNTER,
REG_DATA,
REG_SRC_IDX,
REG_DEST_IDX,
REG_STACK_PTR,
REG_BASE_PTR,
REG_R8,
REG_R9,
REG_R10,
REG_R11,
REG_R12,
REG_R13,
REG_R14,
REG_R15
} x86_64_register_type_t;
/**
* Arch/ABI arg1 arg2 arg3 arg4 arg5 arg6 arg7 Notes
* ──────────────────────────────────────────────────────────────
* x86-64 rdi rsi rdx r10 r8 r9 -
*/
static int x86_call_args[X86_CALL_ARG_SIZE] = { REG_DEST_IDX, REG_SRC_IDX,
REG_DATA, REG_R10,
REG_R8, REG_R9 };
static void
codegen_x86_64_emit_function(codegen_x86_64_t *codegen,
ast_fn_definition_t *fn);
static void
codegen_x86_64_emit_if(codegen_x86_64_t *codegen, ast_if_stmt_t is_stmt);
static void
codegen_x86_64_put_stack_offset(codegen_x86_64_t *codegen,
symbol_t *symbol,
size_t offset);
static size_t
codegen_x86_64_get_stack_offset(codegen_x86_64_t *codegen, symbol_t *symbol);
static size_t
type_to_bytes(type_t *type);
static char *
get_reg_for(x86_64_register_type_t type, size_t bytes);
void
codegen_x86_64_init(codegen_x86_64_t *codegen, arena_t *arena, FILE *out)
{
assert(codegen);
assert(arena);
assert(codegen);
codegen->base_offset = 0;
codegen->symbols_stack_offset = map_new(arena);
codegen->out = out;
codegen->arena = arena;
}
void
codegen_x86_64_emit_translation_unit(codegen_x86_64_t *codegen,
ast_node_t *node)
{
codegen->label_index = 0;
fprintf(codegen->out, ".text\n");
assert(node->kind == AST_NODE_TRANSLATION_UNIT);
ast_translation_unit_t translation_unit = node->as_translation_unit;
list_item_t *item = list_head(translation_unit.decls);
while (item != NULL) {
ast_node_t *decl = (ast_node_t *)item->value;
if (decl->kind == AST_NODE_FN_DEF) {
ast_fn_definition_t fn = decl->as_fn_def;
codegen_x86_64_emit_function(codegen, &fn);
} else {
assert(0 && "translation unit only supports function declarations");
}
item = list_next(item);
}
}
static size_t
codegen_x86_64_get_next_label(codegen_x86_64_t *codegen)
{
return ++codegen->label_index;
}
typedef size_t size_in_bytes_t;
static size_in_bytes_t
codegen_x86_64_emit_expression(codegen_x86_64_t *codegen, ast_node_t *expr_node)
{
switch (expr_node->kind) {
case AST_NODE_LITERAL: {
ast_literal_t literal_u32 = expr_node->as_literal;
assert(literal_u32.kind == AST_LITERAL_U32);
uint32_t n = literal_u32.as_u32;
fprintf(codegen->out, " mov $%d, %%eax\n", n);
return 4;
}
case AST_NODE_REF: {
ast_ref_t ref = expr_node->as_ref;
size_t offset =
codegen_x86_64_get_stack_offset(codegen, ref.ident.symbol);
size_t bytes = type_to_bytes(ref.ident.symbol->type);
fprintf(codegen->out,
" mov -%ld(%%rbp), %s\n",
offset,
get_reg_for(REG_ACCUMULATOR, bytes));
return bytes;
}
case AST_NODE_FN_CALL: {
ast_fn_call_t fn_call = expr_node->as_fn_call;
symbol_t *symbol = scope_lookup(fn_call.scope, fn_call.id);
assert(symbol);
size_t i = 0;
for (list_item_t *item = list_head(fn_call.args); item != NULL;
item = list_next(item)) {
// FIXME: add support for more args than X86_CALL_ARG_SIZE
assert(i < X86_CALL_ARG_SIZE);
ast_node_t *arg_node = (ast_node_t *)item->value;
codegen_x86_64_emit_expression(codegen, arg_node);
fprintf(codegen->out,
" push %s\n",
get_reg_for(REG_ACCUMULATOR, 8));
++i;
}
for (; i > 0; --i) {
fprintf(codegen->out,
" pop %s\n",
get_reg_for(x86_call_args[i - 1], 8));
}
fprintf(codegen->out, " call " SV_FMT "\n", SV_ARG(fn_call.id));
return type_to_bytes(symbol->type);
}
case AST_NODE_BINARY_OP: {
ast_binary_op_t bin_op = expr_node->as_bin_op;
switch (bin_op.kind) {
case AST_BINOP_ADDITION: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" add %s, %s\n",
get_reg_for(REG_COUNTER, expr_bytes),
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_BINOP_MULTIPLICATION: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" mul %s\n",
get_reg_for(REG_COUNTER, expr_bytes));
return expr_bytes;
}
case AST_BINOP_DIVISION: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out, " xor %%rdx, %%rdx\n");
fprintf(codegen->out,
" div %s\n",
get_reg_for(REG_COUNTER, expr_bytes));
return expr_bytes;
}
case AST_BINOP_REMINDER: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out, " xor %%rdx, %%rdx\n");
fprintf(codegen->out,
" div %s\n",
get_reg_for(REG_COUNTER, expr_bytes));
fprintf(codegen->out,
" mov %s, %s\n",
get_reg_for(REG_DATA, expr_bytes),
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_BINOP_SUBTRACTION: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" sub %s, %s\n",
get_reg_for(REG_COUNTER, expr_bytes),
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_BINOP_CMP_EQ: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" cmp %s, %s\n",
get_reg_for(REG_COUNTER, expr_bytes),
get_reg_for(REG_ACCUMULATOR, expr_bytes));
fprintf(codegen->out, " sete %%al\n");
fprintf(codegen->out,
" movzb %%al, %s\n",
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_BINOP_CMP_LT: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" cmp %s, %s\n",
get_reg_for(REG_COUNTER, expr_bytes),
get_reg_for(REG_ACCUMULATOR, expr_bytes));
fprintf(codegen->out, " setl %%al\n");
fprintf(codegen->out,
" movzb %%al, %s\n",
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_BINOP_CMP_GT: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" cmp %s, %s\n",
get_reg_for(REG_COUNTER, expr_bytes),
get_reg_for(REG_ACCUMULATOR, expr_bytes));
fprintf(codegen->out, " setg %%al\n");
fprintf(codegen->out,
" movzb %%al, %s\n",
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_BINOP_CMP_NEQ: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" cmp %s, %s\n",
get_reg_for(REG_COUNTER, expr_bytes),
get_reg_for(REG_ACCUMULATOR, expr_bytes));
fprintf(codegen->out, " setne %%al\n");
fprintf(codegen->out,
" movzb %%al, %s\n",
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_BINOP_CMP_LEQ: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" cmp %s, %s\n",
get_reg_for(REG_COUNTER, expr_bytes),
get_reg_for(REG_ACCUMULATOR, expr_bytes));
fprintf(codegen->out, " setle %%al\n");
fprintf(codegen->out,
" movzb %%al, %s\n",
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_BINOP_CMP_GEQ: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" cmp %s, %s\n",
get_reg_for(REG_COUNTER, expr_bytes),
get_reg_for(REG_ACCUMULATOR, expr_bytes));
fprintf(codegen->out, " setge %%al\n");
fprintf(codegen->out,
" movzb %%al, %s\n",
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_BINOP_BITWISE_LSHIFT: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" shl %%cl, %s\n",
get_reg_for(REG_ACCUMULATOR, lhs_bytes));
return lhs_bytes;
}
case AST_BINOP_BITWISE_RSHIFT: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" shr %%cl, %s\n",
get_reg_for(REG_ACCUMULATOR, lhs_bytes));
return lhs_bytes;
}
case AST_BINOP_BITWISE_XOR: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" xor %s, %s\n",
get_reg_for(REG_COUNTER, expr_bytes),
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_BINOP_BITWISE_AND: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" and %s, %s\n",
get_reg_for(REG_COUNTER, expr_bytes),
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_BINOP_BITWISE_OR: {
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out, " push %%rax\n");
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
size_in_bytes_t expr_bytes =
bytes_max(rhs_bytes, lhs_bytes);
fprintf(codegen->out, " pop %%rcx\n");
fprintf(codegen->out,
" or %s, %s\n",
get_reg_for(REG_COUNTER, expr_bytes),
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_BINOP_LOGICAL_AND: {
size_t label_exit = codegen_x86_64_get_next_label(codegen);
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
fprintf(codegen->out,
" cmp $0, %s\n",
get_reg_for(REG_ACCUMULATOR, lhs_bytes));
fprintf(codegen->out, " je .L%ld\n", label_exit);
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out,
" cmp $0, %s\n",
get_reg_for(REG_ACCUMULATOR, rhs_bytes));
fprintf(codegen->out, " je .L%ld\n", label_exit);
fprintf(codegen->out, " mov $1, %%rax\n");
fprintf(codegen->out, ".L%ld:\n", label_exit);
return 1;
}
case AST_BINOP_LOGICAL_OR: {
size_t label_t = codegen_x86_64_get_next_label(codegen);
size_t label_f = codegen_x86_64_get_next_label(codegen);
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t lhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
fprintf(codegen->out,
" cmp $0, %s\n",
get_reg_for(REG_ACCUMULATOR, lhs_bytes));
fprintf(codegen->out, " jne .L%ld\n", label_t);
fprintf(codegen->out, " xor %%rax, %%rax\n");
size_in_bytes_t rhs_bytes =
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
fprintf(codegen->out,
" cmp $0, %s\n",
get_reg_for(REG_ACCUMULATOR, rhs_bytes));
fprintf(codegen->out, " je .L%ld\n", label_f);
fprintf(codegen->out, ".L%ld:\n", label_t);
fprintf(codegen->out, " mov $1, %%rax\n");
fprintf(codegen->out, ".L%ld:\n", label_f);
return 1;
}
case AST_BINOP_ASSIGN: {
switch (bin_op.lhs->kind) {
case AST_NODE_REF: {
ast_ref_t ref = bin_op.lhs->as_ref;
size_t offset = codegen_x86_64_get_stack_offset(
codegen, ref.ident.symbol);
codegen_x86_64_emit_expression(codegen, bin_op.rhs);
size_t type_size =
type_to_bytes(ref.ident.symbol->type);
fprintf(codegen->out,
" mov %s, -%ld(%%rbp)\n",
get_reg_for(REG_ACCUMULATOR, type_size),
offset);
break;
}
case AST_NODE_UNARY_OP: {
assert(bin_op.lhs->as_unary_op.kind ==
AST_UNARY_DEREFERENCE &&
"unsupported assignment lhs");
codegen_x86_64_emit_expression(codegen, bin_op.lhs);
fprintf(codegen->out, " push %%rax\n");
size_t type_size = codegen_x86_64_emit_expression(
codegen, bin_op.rhs);
fprintf(codegen->out, " pop %%rdx\n");
fprintf(codegen->out,
" mov %s, (%%rdx) \n",
get_reg_for(REG_ACCUMULATOR, type_size));
break;
}
default: {
assert(false && "unsupported assignment lhs");
}
}
// FIXME: we don't support a = b = c
return 0;
}
default: {
assert(0 && "unsupported binary operation");
return 0;
}
}
}
case AST_NODE_UNARY_OP: {
ast_unary_op_t unary_op = expr_node->as_unary_op;
switch (unary_op.kind) {
case AST_UNARY_BITWISE_NOT: {
size_in_bytes_t expr_bytes = codegen_x86_64_emit_expression(
codegen, unary_op.operand);
fprintf(codegen->out,
" not %s\n",
get_reg_for(REG_ACCUMULATOR, expr_bytes));
return expr_bytes;
}
case AST_UNARY_ADDRESSOF: {
assert(unary_op.operand->kind == AST_NODE_REF &&
"unsupported unary expression for addressof (&)");
ast_ref_t ref = unary_op.operand->as_ref;
size_t offset = codegen_x86_64_get_stack_offset(
codegen, ref.ident.symbol);
fprintf(
codegen->out, " lea -%ld(%%rbp), %%rax\n", offset);
return 8;
}
case AST_UNARY_DEREFERENCE: {
// FIXME: support dereference of dereference (**)
assert(unary_op.operand->kind == AST_NODE_REF &&
"unsupported unary expression for dereference (*)");
return codegen_x86_64_emit_expression(codegen,
unary_op.operand);
}
default: {
assert(0 && "unsupported unary operation");
return 0;
}
}
}
default:
assert(0 && "unsupported expression");
}
}
static void
codegen_x86_64_emit_block(codegen_x86_64_t *codegen, ast_block_t *block)
{
size_t block_offset = codegen->base_offset;
size_t nodes_len = list_size(block->nodes);
for (size_t i = 0; i < nodes_len; ++i) {
ast_node_t *node = list_get(block->nodes, i)->value;
switch (node->kind) {
case AST_NODE_RETURN_STMT: {
ast_return_stmt_t return_stmt = node->as_return_stmt;
ast_node_t *value = return_stmt.value;
codegen_x86_64_emit_expression(codegen, value);
fprintf(codegen->out, " mov %%rbp, %%rsp\n");
fprintf(codegen->out, " pop %%rbp\n");
fprintf(codegen->out, " ret\n");
break;
}
case AST_NODE_VAR_DEF: {
ast_var_definition_t var_def = node->as_var_def;
size_t type_size = type_to_bytes(var_def.ident.symbol->type);
codegen->base_offset += type_size;
codegen_x86_64_put_stack_offset(
codegen, var_def.ident.symbol, codegen->base_offset);
if (var_def.value) {
codegen_x86_64_emit_expression(codegen, var_def.value);
}
fprintf(codegen->out,
" mov %s, -%ld(%%rbp)\n",
get_reg_for(REG_ACCUMULATOR, type_size),
codegen->base_offset);
break;
}
case AST_NODE_BINARY_OP:
case AST_NODE_FN_CALL: {
codegen_x86_64_emit_expression(codegen, node);
break;
}
case AST_NODE_IF_STMT: {
codegen_x86_64_emit_if(codegen, node->as_if_stmt);
break;
}
case AST_NODE_WHILE_STMT: {
ast_while_stmt_t while_stmt = node->as_while_stmt;
ast_node_t *cond = while_stmt.cond;
ast_node_t *then = while_stmt.then;
size_t begin_label = codegen_x86_64_get_next_label(codegen);
size_t end_label = codegen_x86_64_get_next_label(codegen);
fprintf(codegen->out, ".L%ld:\n", begin_label);
codegen_x86_64_emit_expression(codegen, cond);
fprintf(codegen->out, " cmp $1, %%rax\n");
fprintf(codegen->out, " jnz .L%ld\n", end_label);
assert(then->kind == AST_NODE_BLOCK &&
"invalid while-then block");
ast_block_t then_block = then->as_block;
codegen_x86_64_emit_block(codegen, &then_block);
fprintf(codegen->out, " jmp .L%ld\n", begin_label);
fprintf(codegen->out, ".L%ld:\n", end_label);
break;
}
default: {
// FIXME: improve error: replace the node->kind to a string
// representation
fprintf(stderr, "node kind %d not supported\n", node->kind);
assert(0 && "unsupported block statement");
break;
}
}
}
codegen->base_offset = block_offset;
}
static void
codegen_x86_64_emit_if(codegen_x86_64_t *codegen, ast_if_stmt_t if_stmt)
{
ast_node_t *cond = if_stmt.cond;
ast_node_t *then = if_stmt.then;
ast_node_t *_else = if_stmt._else;
size_t end_if_label = codegen_x86_64_get_next_label(codegen);
size_t end_else_label = codegen_x86_64_get_next_label(codegen);
codegen_x86_64_emit_expression(codegen, cond);
fprintf(codegen->out, " cmp $1, %%rax\n");
fprintf(codegen->out, " jnz .L%ld\n", end_if_label);
assert(then->kind == AST_NODE_BLOCK && "invalid if-then block");
ast_block_t then_block = then->as_block;
codegen_x86_64_emit_block(codegen, &then_block);
fprintf(codegen->out, " jmp .L%ld\n", end_else_label);
fprintf(codegen->out, ".L%ld:\n", end_if_label);
if (_else != NULL) {
if (_else->kind == AST_NODE_IF_STMT) {
ast_if_stmt_t else_if = _else->as_if_stmt;
codegen_x86_64_emit_if(codegen, else_if);
} else {
ast_block_t else_block = _else->as_block;
codegen_x86_64_emit_block(codegen, &else_block);
}
}
fprintf(codegen->out, ".L%ld:\n", end_else_label);
}
static size_t
type_to_bytes(type_t *type)
{
switch (type->kind) {
case TYPE_PRIMITIVE: {
return type->as_primitive.size;
}
case TYPE_PTR: {
return 8;
}
case TYPE_UNKNOWN: {
assert(0 && "cannot calculate size of an unknown type: probably a "
"parser issue.");
}
}
assert(0 && "unreachable");
}
static size_t
calculate_fn_local_size(scope_t *scope)
{
assert(scope);
// The local_size starts with 8 bytes since the first 8 bytes from the
// stack are reserved to store RBP during the prelude
size_t local_size = 8;
map_kv_t *kvs[scope->symbols->size];
map_get_kvs(scope->symbols, kvs);
for (size_t i = 0; i < scope->symbols->size; ++i) {
symbol_t *symbol = (symbol_t *)kvs[i]->value;
local_size += type_to_bytes(symbol->type);
}
size_t max_child_local_size = 0;
list_item_t *item = list_head(scope->children);
while (item != NULL) {
size_t child_local_size =
calculate_fn_local_size((scope_t *)item->value);
if (child_local_size > max_child_local_size) {
max_child_local_size = child_local_size;
}
item = list_next(item);
}
return local_size + max_child_local_size;
}
static void
codegen_x86_64_emit_function(codegen_x86_64_t *codegen,
ast_fn_definition_t *fn_def)
{
if (fn_def->_extern) {
return;
}
fprintf(codegen->out, ".globl " SV_FMT "\n", SV_ARG(fn_def->id));
codegen->base_offset = 0;
ast_node_t *block_node = fn_def->block;
fprintf(codegen->out, "" SV_FMT ":\n", SV_ARG(fn_def->id));
fprintf(codegen->out, " push %%rbp\n");
fprintf(codegen->out, " mov %%rsp, %%rbp\n");
size_t i = 0;
for (list_item_t *item = list_head(fn_def->params); item != NULL;
item = list_next(item)) {
assert(i < X86_CALL_ARG_SIZE);
ast_fn_param_t *param = item->value;
symbol_t *symbol = scope_lookup(fn_def->scope, param->id);
assert(symbol);
// FIXME: add offset according to the param size
codegen->base_offset += 8;
size_t offset = codegen->base_offset;
codegen_x86_64_put_stack_offset(codegen, symbol, codegen->base_offset);
fprintf(codegen->out,
" mov %s, -%ld(%%rbp)\n",
// FIXME: Type may not be an as_primitive
get_reg_for(x86_call_args[i], symbol->type->as_primitive.size),
offset);
++i;
}
size_t local_size = calculate_fn_local_size(fn_def->scope);
if (local_size != 0) {
fprintf(codegen->out, " sub $%ld, %%rsp\n", local_size);
}
assert(block_node->kind == AST_NODE_BLOCK);
ast_block_t block = block_node->as_block;
codegen_x86_64_emit_block(codegen, &block);
}
static void
codegen_x86_64_put_stack_offset(codegen_x86_64_t *codegen,
symbol_t *symbol,
size_t offset)
{
size_t *stack_offset = arena_alloc(codegen->arena, sizeof(size_t));
*stack_offset = offset;
char symbol_ptr[PTR_HEX_CSTR_SIZE];
sprintf(symbol_ptr, "%lx", (uintptr_t)symbol);
map_put(codegen->symbols_stack_offset, symbol_ptr, stack_offset);
}
static size_t
codegen_x86_64_get_stack_offset(codegen_x86_64_t *codegen, symbol_t *symbol)
{
char symbol_ptr[PTR_HEX_CSTR_SIZE];
sprintf(symbol_ptr, "%lx", (uintptr_t)symbol);
return *(size_t *)map_get(codegen->symbols_stack_offset, symbol_ptr);
}
static char *
get_reg_for(x86_64_register_type_t type, size_t bytes)
{
switch (type) {
case REG_ACCUMULATOR: {
if (bytes <= 1) {
return "%al";
} else if (bytes <= 2) {
return "%ax";
} else if (bytes <= 4) {
return "%eax";
}
return "%rax";
}
case REG_BASE: {
if (bytes <= 1) {
return "%bl";
} else if (bytes <= 2) {
return "%bx";
} else if (bytes <= 4) {
return "%ebx";
}
return "%rbx";
}
case REG_COUNTER: {
if (bytes <= 1) {
return "%cl";
} else if (bytes <= 2) {
return "%cx";
} else if (bytes <= 4) {
return "%ecx";
}
return "%rcx";
}
case REG_DATA: {
if (bytes <= 1) {
return "%dl";
} else if (bytes <= 2) {
return "%dx";
} else if (bytes <= 4) {
return "%edx";
}
return "%rdx";
}
case REG_SRC_IDX: {
if (bytes <= 1) {
return "%sil";
} else if (bytes <= 2) {
return "%si";
} else if (bytes <= 4) {
return "%esi";
}
return "%rsi";
}
case REG_DEST_IDX: {
if (bytes <= 1) {
return "%sil";
} else if (bytes <= 2) {
return "%di";
} else if (bytes <= 4) {
return "%edi";
}
return "%rdi";
}
case REG_STACK_PTR: {
if (bytes <= 1) {
return "%spl";
} else if (bytes <= 2) {
return "%sp";
} else if (bytes <= 4) {
return "%esp";
}
return "%rsp";
}
case REG_BASE_PTR: {
if (bytes <= 1) {
return "%bpl";
} else if (bytes <= 2) {
return "%bp";
} else if (bytes <= 4) {
return "%ebp";
}
return "%rbp";
}
case REG_R8: {
if (bytes <= 1) {
return "%r8b";
} else if (bytes <= 2) {
return "%r8w";
} else if (bytes <= 4) {
return "%r8d";
}
return "%r8";
}
case REG_R9: {
if (bytes <= 1) {
return "%r9b";
} else if (bytes <= 2) {
return "%r9w";
} else if (bytes <= 4) {
return "%r9d";
}
return "%r9";
}
case REG_R10: {
if (bytes <= 1) {
return "%r10b";
} else if (bytes <= 2) {
return "%r10w";
} else if (bytes <= 4) {
return "%r10d";
}
return "%r10";
}
case REG_R11: {
if (bytes <= 1) {
return "%r11b";
} else if (bytes <= 2) {
return "%r11w";
} else if (bytes <= 4) {
return "%r11d";
}
return "%r11";
}
case REG_R12: {
if (bytes <= 1) {
return "%r12b";
} else if (bytes <= 2) {
return "%r12w";
} else if (bytes <= 4) {
return "%r12d";
}
return "%r12";
}
case REG_R13: {
if (bytes <= 1) {
return "%r13b";
} else if (bytes <= 2) {
return "%r13w";
} else if (bytes <= 4) {
return "%r13d";
}
return "%r13";
}
case REG_R14: {
if (bytes <= 1) {
return "%r14b";
} else if (bytes <= 2) {
return "%r14w";
} else if (bytes <= 4) {
return "%r14d";
}
return "%r14";
}
case REG_R15: {
if (bytes <= 1) {
return "%r15b";
} else if (bytes <= 2) {
return "%r15w";
} else if (bytes <= 4) {
return "%r15d";
}
return "%r15";
}
}
assert(0 && "invalid register");
return NULL;
}