fix peephole bug (communative(phi(a,b), phi(a,b)) =/= communative(a,b))

1 files changed, 46 insertions, 7 deletions

diff --git a/ir.c b/ir.c
index 125e882..b0b90f5 100644
--- a/ir.c
+++ b/ir.c
@@ -4,8 +4,6 @@
 #include "ir.h"
 #include "strio.h"
 
-extern int no_opt;
-
 /* nodes */
 
 const char *node_type_name(NodeType t) {
@@ -361,13 +359,54 @@ static int type_ok(Node *n) {
 	}
 }
 
-void type_check(Node *n, Lexer *l) {
+/* TODO: make it so
+ * func foo(a, b i64) i64 {
+ * 	let x i64
+ * 	if a < b {
+ * 		return 0
+ * 	} else {
+ * 		x := 3
+ * 	}
+ * 	return x
+ * }
+ * doesn't throw warnings (e.g. don't generate phi nodes if one scope is
+ * guaranteed to return early)
+ */
+
+int node_uninit(Node *n) {
+	return n->op == N_UNINIT;
+}
+
+int node_maybe_uninit(Node *n) {
+	if (node_uninit(n)) return 1;
 	for (int i = 0; i < n->in.len; i++) {
-		if (IN(n,i) && IN(n,i)->op == N_UNINIT) {
-			lex_error_at(l, n->src_pos, LE_ERROR,
-					str_fmt(&l->arena, "attempt to use uninitialized %S value",
-						type_desc(&IN(n,i)->type, &l->arena)));
+		if (IN(n,i) && node_maybe_uninit(IN(n,i))) {
+			return 1;
 		}
 	}
+	return 0;
+}
+
+void uninit_check(Node *n, Lexer *l) {
+	if (NMASK(n->op) & ~NM_PHI) {
+		for (int i = 0; i < n->in.len; i++) {
+			Node *o = IN(n, i);
+			if (!o) continue;
+			if (node_uninit(o)) {
+				fprintf(stderr, "%s\n", node_type_name(n->op));
+				lex_error_at(l, o->src_pos, LE_WARN,
+						str_fmt(&l->arena, "uninitialized %S",
+							type_desc(&IN(n,i)->type, &l->arena)));
+			} else if (node_maybe_uninit(o)) {
+				lex_error_at(l, o->src_pos, LE_WARN,
+						str_fmt(&l->arena, "possibly uninitialized %S",
+							type_desc(&o->type, &l->arena)));
+			}
+		}
+	}
+}
+
+void type_check(Node *n, Lexer *l) {
+	uninit_check(n, l);
 	if (!type_ok(n)) type_err(n, l);
 }