pkg/compiler: extend parent reference support in len

Earlier only len[parent, T] was supported and meant the size of the
whole structure.

Logically, len[parent:b, T] should be equivalent to just len[b, T].

Let len[parent:parent:a, T] refer to the structure that encloses the
current one.

Support len fields inside unions.

1 files changed, 31 insertions, 0 deletions

diff --git a/sys/test/test.txt b/sys/test/test.txt
index 1b63cd525..788eb8484 100644
--- a/sys/test/test.txt
+++ b/sys/test/test.txt
@@ -486,6 +486,37 @@ offsetof0 {
 	o7	offsetof[f7, int32]
 }
 
+parent_parent_helper {
+	f1	array[int32, 8]
+	f2	parent_parent_length
+	f3	ptr[in, parent_parent_length]
+}
+
+parent_parent_length {
+	f1	len[parent:parent:f1, int32]
+}
+
+test$length32(a0 ptr[in, parent_parent_helper])
+
+one_parent_length {
+	f1	array[int32, 4]
+	f2	len[parent:f1, int32]
+}
+
+test$length33(a0 ptr[in, one_parent_length])
+
+parent_union_struct {
+	f1	array[int32, 4]
+	f2	ptr[in, parent_union]
+}
+
+parent_union [
+	u1	len[parent:parent:f1, int32]
+	u2	int32
+]
+
+test$length34(a0 ptr[in, parent_union_struct])
+
 # Big endian
 
 test$end0(a0 ptr[in, syz_end_int_struct])