round up the array element size to byte align

When layout the array element, the element size should
round up to byte align.

Signed-off-by: Christopher Li <sparse@chrisli.org>

3 files changed, 11 insertions, 2 deletions

diff --git a/evaluate.c b/evaluate.c
index 7ce8c555..03992d03 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -2302,7 +2302,7 @@ static struct expression *check_designators(struct expression *e,
 			}
 			type = ctype->ctype.base_type;
 			if (ctype->bit_size >= 0 && type->bit_size >= 0) {
-				unsigned offset = e->idx_to * type->bit_size;
+				unsigned offset = array_element_offset(type->bit_size, e->idx_to);
 				if (offset >= ctype->bit_size) {
 					err = "index out of bounds in";
 					break;
diff --git a/symbol.c b/symbol.c
index 1a3df636..a6976279 100644
--- a/symbol.c
+++ b/symbol.c
@@ -234,7 +234,8 @@ static struct symbol * examine_array_type(struct symbol *sym)
 		return sym;
 
 	if (array_size) {	
-		bit_size = base_type->bit_size * get_expression_value_silent(array_size);
+		bit_size = array_element_offset(base_type->bit_size,
+						get_expression_value_silent(array_size));
 		if (array_size->type != EXPR_VALUE) {
 			if (Wvla)
 				warning(array_size->pos, "Variable length array is used.");
diff --git a/target.h b/target.h
index 140df3c1..78c85cf7 100644
--- a/target.h
+++ b/target.h
@@ -57,4 +57,12 @@ static inline int bytes_to_bits(int bytes)
 	return bytes * bits_in_char;
 }
 
+static inline unsigned long array_element_offset(unsigned long base_bits, int idx)
+{
+	int fragment = base_bits % bits_in_char;
+	if (fragment)
+		base_bits += bits_in_char - fragment;
+	return base_bits * idx;
+}
+
 #endif