os

commit 5ebdcce90ba41520880d8e5270f1ca4275c0103a
parent c46ccba8c2ad085e053b47b694551a1a6b1b7744
Author: erai <erai@omiltem.net>
Date:   Wed, 20 Nov 2024 23:23:39 -0500

add nil

Diffstat:
M
cc1.om
 | 
12
++++++++++--
M
cc3.peg
 | 
4
++--
M
cout.om
 | 
2
++
M
node.om
 | 
2
++
M
parse2.om
 | 
11
+++++++++++
M
type.om
 | 
5
+++++

6 files changed, 32 insertions(+), 4 deletions(-)
diff --git a/cc1.om b/cc1.om
@@ -266,7 +266,7 @@ func mark_expr_used(c: *compiler, d: *decl, n: *node) {
 		mark_expr_used(c, d, n.a);
 		return;
 	} else if kind == N_SIZEOF || kind == N_STR || kind == N_NUM
-		|| kind == N_CHAR {
+		|| kind == N_CHAR || kind == N_NIL {
 		return;
 	} else {
 		cdie(c, "not an expression");
@@ -647,6 +647,12 @@ func typecheck_expr(c: *compiler, d: *decl, n: *node, rhs: int) {
 		}
 
 		n.t = mktype1(c, TY_PTR, mktype0(c, TY_BYTE));
+	} else if (kind == N_NIL) {
+		if (!rhs) {
+			cdie(c, "nil is not an lexpr");
+		}
+
+		n.t = mktype0(c, TY_NIL);
 	} else if (kind == N_NUM) {
 		if (!rhs) {
 			cdie(c, "num is not an lexpr");
@@ -1334,6 +1340,8 @@ func compile_expr(c: *compiler, d: *decl, n: *node, rhs: int) {
 	kind = n.kind;
 	if (kind == N_STR) {
 		emit_str(c.s, n.s);
+	} else if (kind == N_NIL) {
+		emit_num(c.s, 0);
 	} else if (kind == N_NUM) {
 		emit_num(c.s, n.n);
 	} else if (kind == N_CHAR) {
@@ -1635,7 +1643,7 @@ func call_check(c: *compiler, n: *node): int {
 		// Possible side effect in the first position
 		result = call_check(c, n.a);
 	} else if n.kind == N_STR || n.kind == N_NUM || n.kind == N_CHAR
-		|| n.kind == N_IDENT || n.kind == N_SIZEOF {
+		|| n.kind == N_IDENT || n.kind == N_SIZEOF || n.kind == N_NIL {
 		// No side effects
 	} else {
 		fdputd(2, n.kind);
diff --git a/cc3.peg b/cc3.peg
@@ -93,7 +93,7 @@ cast_expr <- 'as' sp type
 post_expr <- primary (index_expr / call_expr / member_expr / cast_expr)*
 
 primary <- ident sp / hex sp / dec sp / str sp / char sp
-         / sizeof_expr / '(' sp expr ')' sp
+         / sizeof_expr / nil sp / '(' sp expr ')' sp
 
 sizeof_expr <- sizeof sp '(' sp expr ')' sp
 
@@ -103,7 +103,7 @@ str <- ["] ([\\] . / !["] .)* ["]
 char <- ['] ([\\] . / !['] .)+ [']
 
 reserved <- return / break / sizeof / if / else / loop / continue / goto
-          / var / enum / struct / union / byte / int / void / func / as
+          / var / enum / struct / union / byte / int / void / func / as / nil
 
 return <- 'return' ![a-zA-Z0-9_]
 break <- 'break' ![a-zA-Z0-9_]
diff --git a/cout.om b/cout.om
@@ -317,6 +317,8 @@ func ctranslate_expr(c: *compiler, n: *node) {
 	} else if n.kind == N_NUM {
 		fputd(c.cout, n.n);
 		fputs(c.cout, "UL");
+	} else if n.kind == N_NIL {
+		fputs(c.cout, "(void *)0");
 	} else if n.kind == N_CHAR {
 		fputd(c.cout, n.n);
 	} else if n.kind == N_CALL {
diff --git a/node.om b/node.om
@@ -15,6 +15,7 @@ enum {
 	N_NUM,
 	N_CHAR,
 	N_STR,
+	N_NIL,
 	N_STMTLIST,
 	N_EXPRLIST,
 	N_CALL,
@@ -126,6 +127,7 @@ func node_to_str(kind: int): *byte {
 	if kind == N_NUM { return "N_NUM"; }
 	if kind == N_CHAR { return "N_CHAR"; }
 	if kind == N_STR { return "N_STR"; }
+	if kind == N_NIL { return "N_NIL"; }
 	if kind == N_STMTLIST { return "N_STMTLIST"; }
 	if kind == N_EXPRLIST { return "N_EXPRLIST"; }
 	if kind == N_CALL { return "N_CALL"; }
diff --git a/parse2.om b/parse2.om
@@ -610,6 +610,8 @@ func reconstruct_primary(c: *parser, pn: *peg_node): *node {
 		return reconstruct_char(c, pn);
 	} else if pn.tag == P_sizeof_expr {
 		return reconstruct_sizeof(c, pn);
+	} else if pn.tag == P_nil {
+		return reconstruct_nil(c, pn);
 	} else if pn.tag == P_expr {
 		return reconstruct_expr(c, pn);
 	} else {
@@ -694,6 +696,15 @@ func reconstruct_char(c: *parser, pn: *peg_node): *node {
 	n.n = x;
 	return n;
 }
+
+func reconstruct_nil(c: *parser, pn: *peg_node): *node {
+	var n: *node;
+	assert(pn.tag == P_nil, "nil");
+	n = mknode0(c, N_NIL);
+	copypos(n, pn);
+	return n;
+}
+
 func reconstruct_sizeof(c: *parser, pn: *peg_node): *node {
 	var n: *node;
 	var a: *node;
diff --git a/type.om b/type.om
@@ -6,6 +6,7 @@ struct type {
 }
 
 enum {
+	TY_NIL,
 	TY_VOID,
 	TY_INT,
 	TY_BYTE,
@@ -47,6 +48,10 @@ func unify(c: *compiler, a: *type, b: *type) {
 		return;
 	}
 
+	if a && b && ((a.kind == TY_NIL && b.kind == TY_PTR) || (a.kind == TY_PTR && b.kind == TY_NIL)) {
+		return;
+	}
+
 	if ((a && !b) || (b && !a) || a.kind != b.kind) {
 		cdie(c, "type error");
 	}