Start to handle overlapping initializers

5 files changed, 56 insertions, 24 deletions

diff --git a/init.c b/init.c
index 590fbc9..1b0c5e0 100644
--- a/init.c
+++ b/init.c
@@ -46,29 +46,24 @@ mkinit(uint64_t start, uint64_t end, struct expr *expr)
 static void
 initadd(struct init **init, struct init *new)
 {
-	struct init *next, *sub, *last;
-	uint64_t offset;
+	struct init *old;
 
-	while (*init && new->start >= (*init)->end)
-		init = &(*init)->next;
-	next = *init;
-	if (next && next->start <= new->start && new->end < next->end) {
-		initadd(&next->subinit, new);
-		last = NULL;  /* silence gcc, we know that next->subinit has at least one member */
-		for (offset = next->start, sub = next->subinit; sub; offset = sub->end, last = sub, sub = sub->next) {
-			if (sub->start != offset)
-				return;
-		}
-		if (offset == next->end) {
-			*init = next->subinit;
-			last->next = next->next;
+	for (; old = *init; init = &old->next) {
+		if (new->start >= old->end)
+			continue;
+		/* no overlap, insert before `old` */
+		if (new->end <= old->start)
+			break;
+		/* replace any initializers that `new` covers */
+		if (new->end >= old->end) {
+			do old = old->next;
+			while (old && new->end >= old->end);
+			break;
 		}
-	} else {
-		*init = new;
-		while (next && next->start < (*init)->end)
-			next = next->next;
-		(*init)->next = next;
+		/* `old` covers `new`, keep looking */
 	}
+	new->next = old;
+	*init = new;
 }
 
 static void
diff --git a/init.h b/init.h
index 9e50515..410b4d7 100644
--- a/init.h
+++ b/init.h
@@ -1,7 +1,7 @@
 struct init {
 	uint64_t start, end;
 	struct expr *expr;
-	struct init *next, *subinit;
+	struct init *next;
 };
 
 struct scope;
diff --git a/qbe.c b/qbe.c
index 63e0039..a40540a 100644
--- a/qbe.c
+++ b/qbe.c
@@ -892,7 +892,7 @@ void
 funcinit(struct func *func, struct decl *d, struct init *init)
 {
 	struct value *src, *dst;
-	uint64_t offset = 0;
+	uint64_t offset = 0, max = 0;
 	size_t i;
 
 	funcalloc(func, d);
@@ -912,8 +912,10 @@ funcinit(struct func *func, struct decl *d, struct init *init)
 			funcstore(func, init->expr->type, dst, src);
 			offset = init->end;
 		}
+		if (max < offset)
+			max = offset;
 	}
-	zero(func, d->value, d->type->align, offset, d->type->size);
+	zero(func, d->value, d->type->align, max, d->type->size);
 }
 
 static void
@@ -1203,12 +1205,15 @@ emitdata(struct decl *d, struct init *init)
 	emitvalue(d->value);
 	printf(" = align %d { ", d->align);
 
-	for (; init; offset = init->end, init = init->next) {
+	for (; init; init = init->next) {
+		if (init->start < offset)  /* XXX: sub-initializer may overlap */
+			continue;
 		if (offset < init->start)
 			printf("z %" PRIu64 ", ", init->start - offset);
 		printf("%c ", init->expr->type->kind == TYPEARRAY ? init->expr->type->base->repr->ext : init->expr->type->repr->ext);
 		dataitem(init->expr, init->end - init->start);
 		fputs(", ", stdout);
+		offset = init->end;
 	}
 	assert(offset <= d->type->size);
 	if (offset < d->type->size)
diff --git a/tests/initializer-replace.c b/tests/initializer-replace.c
new file mode 100644
index 0000000..8b93ef2
--- /dev/null
+++ b/tests/initializer-replace.c
@@ -0,0 +1,10 @@
+void f(void) {
+	struct {
+		char s[6];
+	} x = {
+		.s[0] = 'x',
+		.s[4] = 'y',
+		.s = "hello",
+		.s[1] = 'a',
+	};
+}
diff --git a/tests/initializer-replace.qbe b/tests/initializer-replace.qbe
new file mode 100644
index 0000000..72ad90a
--- /dev/null
+++ b/tests/initializer-replace.qbe
@@ -0,0 +1,22 @@
+export
+function $f() {
+@start.1
+	%.1 =l alloc4 6
+@body.2
+	%.2 =l add %.1, 0
+	storeb 104, %.2
+	%.3 =l add %.1, 1
+	storeb 101, %.3
+	%.4 =l add %.1, 2
+	storeb 108, %.4
+	%.5 =l add %.1, 3
+	storeb 108, %.5
+	%.6 =l add %.1, 4
+	storeb 111, %.6
+	%.7 =l add %.1, 1
+	%.8 =w copy 97
+	storeb %.8, %.7
+	%.9 =l add %.1, 5
+	storeb 0, %.9
+	ret
+}