feat: add memory loads via ^reg

5 files changed, 102 insertions, 25 deletions

diff --git a/src/codegen/nasm.c b/src/codegen/nasm.c
index e55c791..2f8de80 100644
--- a/src/codegen/nasm.c
+++ b/src/codegen/nasm.c
@@ -203,6 +203,7 @@ static bool emit_operand(struct Emitter* emitter, struct Expr* expr)
 			return true;
 		}
 		case EXPR_BINARY:
+		case EXPR_DEREF:
 			return false;
 	}
 
@@ -248,6 +249,7 @@ static bool expr_supported(struct Emitter* emitter, struct Expr* expr)
 	{
 		case EXPR_PRIMARY:
 		case EXPR_MEMBER:
+		case EXPR_DEREF:
 			return true;
 		case EXPR_BINARY:
 			if (expr->binary.right->kind != EXPR_PRIMARY &&
@@ -262,8 +264,41 @@ static bool expr_supported(struct Emitter* emitter, struct Expr* expr)
 	return false;
 }
 
+// dst = [address], zero-extending narrower loads into the full register
+static void emit_load(struct Emitter* emitter, const char* dst, struct DerefExpr* deref)
+{
+	FILE* out = emitter->out;
+	switch (deref->size)
+	{
+		case STORE_SIZE_BYTE:
+			fprintf(out, "\tmovzx %s, byte [", dst);
+			break;
+		case STORE_SIZE_WORD:
+			fprintf(out, "\tmovzx %s, word [", dst);
+			break;
+		case STORE_SIZE_DWORD:
+		{
+			const char* dword = sized_register(text_token(dst), STORE_SIZE_DWORD);
+			fprintf(out, "\tmov %s, [", dword != NULL ? dword : dst);
+			break;
+		}
+		default:
+			fprintf(out, "\tmov %s, [", dst);
+			break;
+	}
+
+	emit_operand(emitter, deref->address);
+	fprintf(out, "]\n");
+}
+
 static void emit_expr_into(struct Emitter* emitter, const char* dst, struct Expr* expr)
 {
+	if (expr->kind == EXPR_DEREF)
+	{
+		emit_load(emitter, dst, &expr->deref);
+		return;
+	}
+
 	if (expr->kind == EXPR_BINARY)
 	{
 		emit_expr_into(emitter, dst, expr->binary.left);
@@ -389,7 +424,8 @@ static void emit_assign(struct Emitter* emitter, struct AssignStatement* assign)
 	const char* mnemonic = assign_mnemonic(assign->op.type);
 	bool value_is_buffer = assign->value->kind == EXPR_PRIMARY 
 		                && is_buffer_name(emitter, assign->value->primary.token);
-	if (mnemonic == NULL || assign->value->kind == EXPR_BINARY || value_is_buffer)
+	if (mnemonic == NULL || assign->value->kind == EXPR_BINARY
+		|| assign->value->kind == EXPR_DEREF || value_is_buffer)
 	{
 		fprintf(emitter->out, "\t; TODO: unsupported assignment\n");
 		return;
@@ -458,7 +494,7 @@ static void emit_call(struct Emitter* emitter, struct CallStatement* call)
 
 	for (size_t i = 0; i < call->arg_count; i += 1)
 	{
-		if (call->args[i]->kind == EXPR_BINARY)
+		if (call->args[i]->kind == EXPR_BINARY || call->args[i]->kind == EXPR_DEREF)
 		{
 			fprintf(emitter->out, "\t; TODO: unsupported call argument\n");
 			continue;
@@ -478,7 +514,9 @@ static void emit_statement(struct Emitter* emitter, struct Statement* statement)
 static void emit_if(struct Emitter* emitter, struct IfStatement* branch)
 {
 	const char* jump = jump_if_false(branch->comparison.type);
-	if (jump == NULL || branch->left->kind == EXPR_BINARY || branch->right->kind == EXPR_BINARY)
+	if (jump == NULL
+		|| branch->left->kind == EXPR_BINARY || branch->left->kind == EXPR_DEREF
+		|| branch->right->kind == EXPR_BINARY || branch->right->kind == EXPR_DEREF)
 	{
 		fprintf(emitter->out, "\t; TODO: unsupported if\n");
 		return;
diff --git a/src/parser/ast.c b/src/parser/ast.c
index 96ee479..f9f857d 100644
--- a/src/parser/ast.c
+++ b/src/parser/ast.c
@@ -18,6 +18,9 @@ void free_expr(struct Expr* expr)
 		case EXPR_MEMBER:
 			free_expr(expr->member.object);
 			break;
+		case EXPR_DEREF:
+			free_expr(expr->deref.address);
+			break;
 	}
 
 	free(expr);
diff --git a/src/parser/ast.h b/src/parser/ast.h
index a98f43b..fc7af2b 100644
--- a/src/parser/ast.h
+++ b/src/parser/ast.h
@@ -24,11 +24,21 @@ struct Param
 	struct Token reg;
 };
 
+enum StoreSize
+{
+	STORE_SIZE_NONE,
+	STORE_SIZE_BYTE,
+	STORE_SIZE_WORD,
+	STORE_SIZE_DWORD,
+	STORE_SIZE_QWORD,
+};
+
 enum ExprKind
 {
 	EXPR_PRIMARY,
 	EXPR_BINARY,
 	EXPR_MEMBER,
+	EXPR_DEREF,
 };
 
 struct PrimaryExpr
@@ -49,6 +59,12 @@ struct MemberExpr
 	struct Token member;
 };
 
+struct DerefExpr
+{
+	enum StoreSize size;
+	struct Expr* address;
+};
+
 struct Expr
 {
 	enum ExprKind kind;
@@ -57,18 +73,10 @@ struct Expr
 		struct PrimaryExpr primary;
 		struct BinaryExpr binary;
 		struct MemberExpr member;
+		struct DerefExpr deref;
 	};
 };
 
-enum StoreSize
-{
-	STORE_SIZE_NONE,
-	STORE_SIZE_BYTE,
-	STORE_SIZE_WORD,
-	STORE_SIZE_DWORD,
-	STORE_SIZE_QWORD,
-};
-
 enum StatementKind
 {
 	STATEMENT_ASSIGN,
diff --git a/src/parser/parser.c b/src/parser/parser.c
index beb6b04..969ed86 100644
--- a/src/parser/parser.c
+++ b/src/parser/parser.c
@@ -133,8 +133,35 @@ static struct Expr* alloc_expr(enum ExprKind kind)
 	return expr;
 }
 
+static enum StoreSize parse_store_size(struct Parser* parser)
+{
+	if (match_token(parser, TOKEN_BYTE))
+		return STORE_SIZE_BYTE;
+	if (match_token(parser, TOKEN_WORD))
+		return STORE_SIZE_WORD;
+	if (match_token(parser, TOKEN_DWORD))
+		return STORE_SIZE_DWORD;
+	if (match_token(parser, TOKEN_QWORD))
+		return STORE_SIZE_QWORD;
+	return STORE_SIZE_NONE;
+}
+
 static struct Expr* parse_primary(struct Parser* parser)
 {
+	if (match_token(parser, TOKEN_CARET))
+	{
+		enum StoreSize size = parse_store_size(parser);
+
+		struct Expr* address = parse_primary(parser);
+		if (address == NULL)
+			return NULL;
+
+		struct Expr* deref = alloc_expr(EXPR_DEREF);
+		deref->deref.size = size;
+		deref->deref.address = address;
+		return deref;
+	}
+
 	if (check(parser, TOKEN_IDENTIFIER) || check(parser, TOKEN_INTEGER) || check(parser, TOKEN_CHAR))
 	{
 		advance_parser(parser);
@@ -350,19 +377,7 @@ static bool parse_statement(struct Parser* parser, struct Statement* out)
 	}
 
 	bool deref = match_token(parser, TOKEN_CARET);
-
-	enum StoreSize store_size = STORE_SIZE_NONE;
-	if (deref)
-	{
-		if (match_token(parser, TOKEN_BYTE))
-			store_size = STORE_SIZE_BYTE;
-		else if (match_token(parser, TOKEN_WORD))
-			store_size = STORE_SIZE_WORD;
-		else if (match_token(parser, TOKEN_DWORD))
-			store_size = STORE_SIZE_DWORD;
-		else if (match_token(parser, TOKEN_QWORD))
-			store_size = STORE_SIZE_QWORD;
-	}
+	enum StoreSize store_size = deref ? parse_store_size(parser) : STORE_SIZE_NONE;
 
 	if (!consume(parser, TOKEN_IDENTIFIER, "expected a statement"))
 		return false;
diff --git a/src/sema/sema.c b/src/sema/sema.c
index ad2b12a..fb53bbf 100644
--- a/src/sema/sema.c
+++ b/src/sema/sema.c
@@ -227,6 +227,19 @@ static void check_expr(struct RefCheck* check, struct Expr* expr)
 			check_expr(check, expr->binary.left);
 			check_expr(check, expr->binary.right);
 			break;
+		case EXPR_DEREF:
+		{
+			struct Expr* address = expr->deref.address;
+			if (address->kind == EXPR_PRIMARY
+				&& (is_register(check, address->primary.token) || is_param(check, address->primary.token)))
+				break;
+
+			if (address->kind == EXPR_PRIMARY)
+				ref_error(check, address->primary.token, "dereference address must be a register");
+			else
+				check_expr(check, address);
+			break;
+		}
 		case EXPR_MEMBER:
 		{
 			struct Expr* object = expr->member.object;