mostly there except need to implement one more hash map

7 files changed, 225 insertions, 19 deletions

diff --git a/.gitignore b/.gitignore
index 85a7886..e19039e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 ccc
+*.s
 *.o
 *.out
 build/**
diff --git a/codegen.c b/codegen.c
index 37c7a91..cfb4cca 100644
--- a/codegen.c
+++ b/codegen.c
@@ -1,42 +1,95 @@
 #include "ccc.h"
-#include "ast.h"
+#include "codegen.h"
+#include "scope.h"
 #include <stdlib.h>
 #include <stdio.h>
 
-static void emit_stmt(FILE* outfile, const struct stmt_node* node);
-static void emit_expr(
+#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 expr_node* node,
-    const char* reg);
+    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 char* reg
+    const struct storage_location* storage
 ) {
-   fprintf(outfile, "\tmov %s, %lld\n", reg, node->val); 
+    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 char* reg
+    const struct storage_location* storage
 ) {
     switch (node->type) {
         case EXPR_EMPTY:
             break;
         case EXPR_INT_LIT:
-            emit_int_lit(outfile, &node->as._int_lit, reg);
+            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) {
-    /* TODO: make do smth */
+    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, "rax");
+    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");
 }
 
@@ -48,6 +101,25 @@ static void emit_group(FILE* outfile, const struct group_node* node) {
     }
 }
 
+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:
@@ -60,15 +132,41 @@ static void emit_stmt(FILE* outfile, const struct stmt_node* node) {
             emit_expr(outfile, &node->as._expr, NULL);
             break;
         case STMT_GROUP:
-            emit_group(outfile, &node->as._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);
-    /* TODO: probably something to map the args to temporaries lol */
+    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) {
@@ -84,12 +182,22 @@ void emit_code(const struct root_node* ast, const char* path) {
     if (outfile == NULL) CCC_PANIC;
 
     fprintf(outfile, "section .text\n");
+    scope_push(&scope);
 
     /* output all non-static function declarations as globals */
     const struct root_node* node = ast;
     while (node != NULL) {
-        if (node->type == ROOT_FN_DECL)
-            fprintf(outfile, "global %s\n", node->as._fn_decl.name);
+        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;
     }
@@ -104,5 +212,6 @@ void emit_code(const struct root_node* ast, const char* path) {
         node = node->next;
     }
 
+    scope_pop(&scope);
     fclose(outfile);
 }
diff --git a/codegen.h b/codegen.h
new file mode 100644
index 0000000..50bb105
--- /dev/null
+++ b/codegen.h
@@ -0,0 +1,8 @@
+#ifndef CODEGEN_H
+#define CODEGEN_H
+
+#include "ast.h"
+
+void emit_code(const struct root_node* ast, const char* path);
+
+#endif
diff --git a/main.c b/main.c
index c86efdd..e2aca11 100644
--- a/main.c
+++ b/main.c
@@ -1,5 +1,6 @@
 #include "lexer.h"
 #include "parser.h"
+#include "codegen.h"
 #include <stdlib.h>
 #include <stdio.h>
 
@@ -35,8 +36,6 @@ void test_lexer(int argc, char** argv) {
     }
 }
 
-void gdb_break_here() {}
-
 void test_parser(int argc, char** argv) {
     struct root_node* root;
     struct root_node** p_cur = &root;
@@ -44,7 +43,8 @@ void test_parser(int argc, char** argv) {
         *p_cur = parse(argv[i]);
         p_cur = &((*p_cur)->next);
     }
-    gdb_break_here();
+
+    emit_code(root, "test/simple.s");
     ast_destroy(root);
 }
 
diff --git a/scope.c b/scope.c
new file mode 100644
index 0000000..076f1a6
--- /dev/null
+++ b/scope.c
@@ -0,0 +1,42 @@
+#include "scope.h"
+#include <stdlib.h>
+
+static void scope_init(struct scope* scope) {}
+
+static void scope_destroy(struct scope* scope) {}
+
+unsigned long long hash_name(const char* name) {
+    unsigned long long hash = 0, i = 0;
+    while (name[i] != 0) hash = (hash << 5) - hash + name[i++];
+    return hash;
+}
+
+void scope_push(struct scope** p_scope) {
+    struct scope* inner_scope = calloc(1, sizeof(struct scope));
+    scope_init(inner_scope);
+    inner_scope->next_out = *p_scope;
+    *p_scope = inner_scope;
+}
+
+void scope_pop(struct scope** p_scope) {
+    struct scope* discarded_scope = *p_scope;
+    *p_scope = (*p_scope)->next_out;
+    scope_destroy(discarded_scope);
+    free(discarded_scope);
+}
+
+bool scope_get_type(
+    const struct scope* scope,
+    struct type_def* p_entry,
+    const char* name
+) {}
+
+void scope_define_type(struct scope* scope, struct type_def type) {}
+
+bool scope_get_var(
+    const struct scope* scope,
+    struct var_def* p_entry,
+    const char* name
+) {}
+
+void scope_define_var(struct scope* scope, struct var_def var) {}
diff --git a/scope.h b/scope.h
new file mode 100644
index 0000000..b469476
--- /dev/null
+++ b/scope.h
@@ -0,0 +1,46 @@
+#ifndef VARS_H
+#define VARS_H
+
+struct storage_location {
+    enum {
+        REGISTER,
+        JMP_LABEL,
+        BP_OFFSET,
+    } type;
+    union {
+        long long offset;
+        const char* label;
+    };
+};
+
+struct type_def {
+    const char* name;
+    unsigned long long size;
+};
+
+struct var_def {
+    const char* name;
+    struct storage_location loc;
+};
+
+struct scope {
+    struct type_def* types;
+    struct var_def* vars;
+    struct scope* next_out;
+    unsigned long long bp_offset;
+};
+
+void scope_push(struct scope** p_scope);
+void scope_pop(struct scope** p_scope);
+bool scope_get_type(
+    const struct scope* scope,
+    struct type_def* p_entry,
+    const char* name);
+void scope_define_type(struct scope* scope, struct type_def type);
+bool scope_get_var(
+    const struct scope* scope,
+    struct var_def* p_entry,
+    const char* name);
+void scope_define_var(struct scope* scope, struct var_def var);
+
+#endif
\ No newline at end of file
diff --git a/test/simple.c b/test/simple.c
index 33c14ce..99d86c4 100644
--- a/test/simple.c
+++ b/test/simple.c
@@ -1,3 +1,3 @@
 int main() {
-    return 0;
+    return 16;
 }