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/*
* Copyright (C) 2023 Johnny Richard
*
* 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 <https://www.gnu.org/licenses/>.
*/
#include "gas_assembly_generator.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
static void
gas_assembly_generator_visit_function(ast_visitor_t *visitor, ast_function_declaration_t *func);
static void
gas_assembly_generator_visit_return_stmt(ast_visitor_t *visitor, ast_return_stmt_t *return_stmt);
static void
gas_assembly_generator_visit_literal(ast_visitor_t *visitor, ast_literal_t *literal);
static void
gas_assembly_generator_binary_operation(ast_visitor_t *visitor, ast_binary_operation_t *binary_operation);
void
gas_assembly_generator_init(gas_assembly_generator_t *gen, FILE *out)
{
assert(gen && out);
gen->super = (ast_visitor_t){ .visit_function = &gas_assembly_generator_visit_function,
.visit_literal = &gas_assembly_generator_visit_literal,
.visit_return_stmt = &gas_assembly_generator_visit_return_stmt,
.visit_binary_operation = &gas_assembly_generator_binary_operation };
gen->out = out;
}
static void
gas_assembly_generator_visit_function(ast_visitor_t *visitor, ast_function_declaration_t *func)
{
assert(visitor && func);
if (!string_view_eq(func->name, string_view_from_str("main"))) {
fprintf(stderr, "[ERROR]: no main function has been defined!\n");
exit(EXIT_FAILURE);
}
gas_assembly_generator_t *gen = (gas_assembly_generator_t *)visitor;
fprintf(gen->out, ".global _start\n");
fprintf(gen->out, ".text\n");
fprintf(gen->out, "_start:\n");
for (size_t i = 0; i < func->body->size; i++) {
ast_visitor_visit(visitor, vector_at(func->body, i));
}
}
static void
gas_assembly_generator_visit_return_stmt(ast_visitor_t *visitor, ast_return_stmt_t *return_stmt)
{
assert(visitor && return_stmt);
gas_assembly_generator_t *gen = (gas_assembly_generator_t *)visitor;
ast_visitor_visit(visitor, return_stmt->argument);
fprintf(gen->out, " mov %%rax, %%rbx\n");
fprintf(gen->out, " mov $1, %%al\n");
fprintf(gen->out, " int $0x80\n");
}
static void
gas_assembly_generator_visit_literal(ast_visitor_t *visitor, ast_literal_t *literal)
{
gas_assembly_generator_t *gen = (gas_assembly_generator_t *)visitor;
switch (literal->kind) {
case AST_LITERAL_INTEGER:
fprintf(gen->out, " mov $%d, %%rax\n", literal->value.integer);
return;
default:
assert(false && "no code generation strategy.");
}
}
static void
gas_assembly_generator_binary_operation(ast_visitor_t *visitor, ast_binary_operation_t *binary_operation)
{
gas_assembly_generator_t *gen = (gas_assembly_generator_t *)visitor;
ast_visitor_visit(visitor, binary_operation->right);
fprintf(gen->out, " push %%rax\n");
ast_visitor_visit(visitor, binary_operation->left);
fprintf(gen->out, " pop %%rcx\n");
if (string_view_eq(binary_operation->op, string_view_from_str("+"))) {
fprintf(gen->out, " add %%rcx, %%rax\n");
return;
}
if (string_view_eq(binary_operation->op, string_view_from_str("-"))) {
fprintf(gen->out, " sub %%rcx, %%rax\n");
return;
}
if (string_view_eq(binary_operation->op, string_view_from_str("*"))) {
fprintf(gen->out, " mul %%rcx\n");
return;
}
if (string_view_eq(binary_operation->op, string_view_from_str("/"))) {
fprintf(gen->out, " xor %%rdx, %%rdx\n");
fprintf(gen->out, " div %%rcx\n");
return;
}
fprintf(stderr, "no strategy defined for: " SVFMT "\n", SVARG(&binary_operation->op));
assert(false);
}
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