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#include "ccc.h"
#include "codegen.h"
#include "scope.h"
#include <stdlib.h>
#include <stdio.h>
#define CGEN_PANIC(format, ...) {\
fprintf(\
stderr,\
"ccc: code gen error: " format "\n" __VA_OPT__(,)\
__VA_ARGS__);\
exit(1);\
}
static const struct storage_location RV_LOC = {
.type = REGISTER,
.label = "rax",
};
static struct scope* scope;
static void emit_storage_loc(
FILE* outfile,
const struct storage_location* loc
) {
switch (loc->type) {
case REGISTER:
case JMP_LABEL:
fprintf(outfile, "%s", loc->label);
break;
case BP_OFFSET:
if (loc->offset < 0)
fprintf(outfile, "[rbp + %lld]", -loc->offset);
else if (loc->offset > 0)
fprintf(outfile, "[rbp - %lld]", loc->offset);
else
fprintf(outfile, "[rbp]");
}
}
static void emit_int_lit(
FILE* outfile,
const struct int_lit_node* node,
const struct storage_location* storage
) {
if (storage != NULL) {
fprintf(outfile, "\tmov ");
emit_storage_loc(outfile, storage);
fprintf(outfile, ", %lld\n", node->val);
}
}
static void emit_expr(
FILE* outfile,
const struct expr_node* node,
const struct storage_location* storage
) {
switch (node->type) {
case EXPR_EMPTY:
break;
case EXPR_INT_LIT:
emit_int_lit(outfile, &node->as._int_lit, storage);
break;
}
}
static void emit_stmt(FILE* outfile, const struct stmt_node* node);
static struct type_def get_type_def(const char* type_name) {
struct type_def type_def;
if (!scope_get_type(scope, &type_def, type_name))
CGEN_PANIC("size of type %s is not known", type_name);
return type_def;
}
static void emit_var_decl(FILE* outfile, const struct var_decl_node* node) {
struct type_def type_def = get_type_def(node->type.type);
fprintf(outfile, "\tsub rsp, %llu\n", type_def.size);
scope->bp_offset += type_def.size;
scope_define_var(scope, (struct var_def) {
.name = node->ident,
.loc = {
.type = BP_OFFSET,
.offset = scope->bp_offset,
},
});
}
static void emit_return(FILE* outfile, const struct return_node* node) {
if (node->ret_val != NULL) emit_expr(outfile, node->ret_val, &RV_LOC);
fprintf(outfile, "\tmov rsp, rbp\n");
fprintf(outfile, "\tpop rbp\n");
fprintf(outfile, "\tret\n");
}
static void emit_group(FILE* outfile, const struct group_node* node) {
const struct stmt_node* body_node = node->body_head;
while (body_node != NULL) {
emit_stmt(outfile, body_node);
body_node = body_node->next;
}
}
static void emit_stmt_group(FILE* outfile, const struct group_node* node) {
scope_push(&scope);
scope->bp_offset = scope->next_out->bp_offset; /* don't reset bp */
emit_group(outfile, node);
scope_pop(&scope);
if (scope->bp_offset == 0)
fprintf(outfile, "\tmov rsp, rbp\n");
else {
fprintf(outfile, "\tlea rsp, ");
emit_storage_loc(outfile, &(struct storage_location) {
.type = BP_OFFSET,
.offset = scope->bp_offset,
});
fprintf(outfile, "\n");
}
}
static void emit_stmt(FILE* outfile, const struct stmt_node* node) {
switch (node->type) {
case STMT_VAR_DECL:
emit_var_decl(outfile, &node->as._var_decl);
break;
case STMT_RETURN:
emit_return(outfile, &node->as._return);
break;
case STMT_EXPR:
emit_expr(outfile, &node->as._expr, NULL);
break;
case STMT_GROUP:
emit_stmt_group(outfile, &node->as._group);
break;
}
}
static void emit_fn_decl(FILE* outfile, const struct fn_decl_node* node) {
fprintf(outfile, "%s:\n", node->name);
fprintf(outfile, "\tpush rbp\n");
fprintf(outfile, "\tmov rbp, rsp\n");
scope_push(&scope);
scope->bp_offset = 0;
struct var_decl_node* args_node = node->args_head;
long long arg_bp_offset = -8;
while (args_node != NULL) {
struct type_def type_def = get_type_def(args_node->type.type);
scope_define_var(scope, (struct var_def) {
.name = args_node->ident,
.loc = {
.type = BP_OFFSET,
.offset = arg_bp_offset,
},
});
arg_bp_offset -= type_def.size;
args_node = args_node->next;
}
emit_group(outfile, &node->body);
scope_pop(&scope);
fprintf(outfile, "\tmov rsp, rbp\n");
fprintf(outfile, "\tpop rbp\n");
fprintf(outfile, "\tret\n");
}
static void emit_root_node(FILE* outfile, const struct root_node* node) {
switch (node->type) {
case ROOT_FN_DECL:
emit_fn_decl(outfile, &node->as._fn_decl);
break;
}
}
void emit_code(const struct root_node* ast, const char* path) {
FILE* outfile = fopen(path, "w");
if (outfile == NULL) CCC_PANIC;
fprintf(outfile, "section .text\n");
scope_push(&scope);
/* TODO: register all basic types */
/* output all non-static function declarations as globals */
const struct root_node* node = ast;
while (node != NULL) {
if (node->type == ROOT_FN_DECL) {
const char* fn_name = node->as._fn_decl.name;
scope_define_var(scope, (struct var_def) {
.name = fn_name,
.loc = {
.type = JMP_LABEL,
.label = fn_name,
},
});
fprintf(outfile, "global %s\n", fn_name);
}
node = node->next;
}
fprintf(outfile, "\n");
/* actual code body */
node = ast;
while (node != NULL) {
emit_root_node(outfile, node);
fprintf(outfile, "\n");
node = node->next;
}
scope_pop(&scope);
fclose(outfile);
}
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