feat: partially implement bit-fields

5 files changed, 64 insertions, 149 deletions

diff --git a/src/ast.c b/src/ast.c
index 790eb81..4d30a66 100644
--- a/src/ast.c
+++ b/src/ast.c
@@ -662,8 +662,15 @@ int type_sizeof_struct(Type* ty) {
 
     for (int i = 0; i < members_of(ty)->as.list->len; ++i) {
         AstNode* member = &members_of(ty)->as.list->items[i];
-        int size = type_sizeof(member->ty);
-        int align = type_alignof(member->ty);
+        int size, align;
+        if (member->as.struct_member->is_bitfield) {
+            // TODO
+            size = member->as.struct_member->bitfield_width / 8;
+            align = 1;
+        } else {
+            size = type_sizeof(member->ty);
+            align = type_alignof(member->ty);
+        }
 
         next_offset = to_aligned(next_offset, align);
         next_offset += size;
@@ -734,11 +741,23 @@ int type_offsetof(Type* ty, const char* name) {
 
     for (int i = 0; i < members_of(ty)->as.list->len; ++i) {
         AstNode* member = &members_of(ty)->as.list->items[i];
-        int size = type_sizeof(member->ty);
-        int align = type_alignof(member->ty);
+        int size, align;
+        if (member->as.struct_member->is_bitfield) {
+            // TODO
+            size = member->as.struct_member->bitfield_width / 8;
+            align = 1;
+        } else {
+            size = type_sizeof(member->ty);
+            align = type_alignof(member->ty);
+        }
 
         next_offset = to_aligned(next_offset, align);
         if (strcmp(member->as.struct_member->name, name) == 0) {
+            if (member->as.struct_member->is_bitfield) {
+                // C23: 7.21.4
+                // if the specified member is a bit-field, the behavior is undefined.
+                fatal_error("type_offsetof: the result of offsetof(bit-field) is undefined");
+            }
             return next_offset;
         }
         next_offset += size;
diff --git a/src/ast.h b/src/ast.h
index f1405c6..f12fd83 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -311,6 +311,9 @@ typedef struct {
 
 typedef struct {
     const char* name;
+    bool is_bitfield;
+    int bitfield_offset;
+    int bitfield_width;
 } StructMemberNode;
 
 typedef struct {
diff --git a/src/parse.c b/src/parse.c
index 12d4fbf..308277f 100644
--- a/src/parse.c
+++ b/src/parse.c
@@ -1898,7 +1898,6 @@ static AstNode* parse_member_declaration_list(Parser* p) {
 static AstNode* parse_member_declaration(Parser* p) {
     Type* base_ty = parse_specifier_qualifier_list(p);
 
-    AstNode* decls = NULL;
     if (consume_token_if(p, TokenKind_semicolon)) {
         char* name = generate_anonymous_name(p);
         AstNode* decls = ast_new_list(1);
@@ -1909,16 +1908,8 @@ static AstNode* parse_member_declaration(Parser* p) {
         ast_append(decls, member);
         return decls;
     }
-    decls = parse_member_declarator_list(p, base_ty);
-
+    AstNode* decls = parse_member_declarator_list(p, base_ty);
     expect(p, TokenKind_semicolon);
-
-    for (int i = 0; i < decls->as.list->len; i++) {
-        const char* member_name = decls->as.list->items[i].as.declarator->name;
-        decls->as.list->items[i].kind = AstNodeKind_struct_member;
-        decls->as.list->items[i].as.struct_member = calloc(1, sizeof(StructMemberNode));
-        decls->as.list->items[i].as.struct_member->name = member_name;
-    }
     return decls;
 }
 
@@ -2104,9 +2095,37 @@ static AstNode* parse_member_declarator_list(Parser* p, Type* base_ty) {
 
 // member-declarator:
 //     declarator
-//     TODO declarator? ':' constant-expr
+//     declarator ':' constant-expr
+//     TODO ':' constant-expr
 static AstNode* parse_member_declarator(Parser* p, Type* base_ty) {
-    return parse_declarator(p, base_ty);
+    AstNode* decl = parse_declarator(p, base_ty);
+
+    const char* name = decl->as.declarator->name;
+    decl->kind = AstNodeKind_struct_member;
+    decl->as.struct_member = calloc(1, sizeof(StructMemberNode));
+    decl->as.struct_member->name = name;
+
+    if (consume_token_if(p, TokenKind_colon)) {
+        AstNode* bit_width_node = parse_constant_expr(p);
+        InitData* bit_width_evaluated = eval_init_expr(bit_width_node, type_new(TypeKind_int));
+        if (bit_width_evaluated->len != 1)
+            fatal_error("parse_member_declarator: invalid bit-field");
+        if (bit_width_evaluated->blocks[0].kind != InitDataBlockKind_bytes)
+            fatal_error("parse_member_declarator: invalid bit-field");
+        if (bit_width_evaluated->blocks[0].as.bytes.len != sizeof(int))
+            fatal_error("parse_member_declarator: invalid bit-field");
+        int bit_width;
+        memcpy(&bit_width, bit_width_evaluated->blocks[0].as.bytes.buf, sizeof(int));
+        if (bit_width < 0)
+            fatal_error("parse_member_declarator: invalid bit-field");
+        if (bit_width % 8 != 0)
+            fatal_error("parse_member_declarator: unimplemented");
+        decl->as.struct_member->is_bitfield = true;
+        decl->as.struct_member->bitfield_offset = -1; // TODO
+        decl->as.struct_member->bitfield_width = bit_width;
+    }
+
+    return decl;
 }
 
 // enum-specifier:
diff --git a/tests/examples.sh b/tests/examples.sh
index 6b15ed8..39bf15c 100644
--- a/tests/examples.sh
+++ b/tests/examples.sh
@@ -111,136 +111,4 @@ EOF
 
 test_example fizzbuzz
 
-# example programs
-cat <<'EOF' > expected
-1
-2
-Fizz
-4
-Buzz
-Fizz
-7
-8
-Fizz
-Buzz
-11
-Fizz
-13
-14
-FizzBuzz
-16
-17
-Fizz
-19
-Buzz
-Fizz
-22
-23
-Fizz
-Buzz
-26
-Fizz
-28
-29
-FizzBuzz
-31
-32
-Fizz
-34
-Buzz
-Fizz
-37
-38
-Fizz
-Buzz
-41
-Fizz
-43
-44
-FizzBuzz
-46
-47
-Fizz
-49
-Buzz
-Fizz
-52
-53
-Fizz
-Buzz
-56
-Fizz
-58
-59
-FizzBuzz
-61
-62
-Fizz
-64
-Buzz
-Fizz
-67
-68
-Fizz
-Buzz
-71
-Fizz
-73
-74
-FizzBuzz
-76
-77
-Fizz
-79
-Buzz
-Fizz
-82
-83
-Fizz
-Buzz
-86
-Fizz
-88
-89
-FizzBuzz
-91
-92
-Fizz
-94
-Buzz
-Fizz
-97
-98
-Fizz
-Buzz
-EOF
-test_diff <<'EOF'
-int printf();
-
-int main() {
-    int i;
-    for (i = 1; i <= 100; i = i + 1) {
-        if (i % 15 == 0) {
-            printf("FizzBuzz\n");
-        } else if (i % 3 == 0) {
-            printf("Fizz\n");
-        } else if (i % 5 == 0) {
-            printf("Buzz\n");
-        } else {
-            printf("%d\n", i);
-        }
-    }
-    return 0;
-}
-EOF
-
-cat <<'EOF' > expected
-hello, world
-EOF
-test_diff <<'EOF'
-int printf();
-int main() {
-    printf("hello, world\n");
-    return 0;
-}
-EOF
+test_example_compile_only 2048
diff --git a/tests/helpers.sh b/tests/helpers.sh
index b8de8a9..09de3df 100644
--- a/tests/helpers.sh
+++ b/tests/helpers.sh
@@ -74,3 +74,9 @@ function test_example() {
 
     diff -u expected output
 }
+
+function test_example_compile_only() {
+    filename="../../../examples/$1.c"
+
+    "$ducc" "${CFLAGS:-}" -I ../../../tests -o a.out "$filename"
+}