On Wed, Jun 03, 2009 at 07:49:29PM +0200, Stelian Pop wrote:
> I'm doing a port of gcc 4.3.3 on a custom architecture and I'm having trouble
> when initializing the bit fields of a structure.
Ok, after further analysis, it looks like a genuine bug in gcc,
in store_bit_field_1(): when a field is bigger than a word, the
rvalue is splitted in several words, after being placed in a
smallest_mode_for_size() operand.
But the logic for adressing the words of this operand is buggy
in the WORDS_BIG_ENDIAN case, the most signficant words being
used instead of the least significant ones.
The following patch corrects this, and makes the
gcc.c-torture/execute/991118-1.c testcase work correctly on my platform.
Stelian.
diff --git a/gcc/expmed.c b/gcc/expmed.c
index dc61de7..03c60a8 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -582,7 +582,10 @@ store_bit_field_1 (rtx str_rtx, unsigned HOST_WIDE_INT
bitsize,
{
/* If I is 0, use the low-order word in both field and target;
if I is 1, use the next to lowest word; and so on. */
- unsigned int wordnum = (backwards ? nwords - i - 1 : i);
+ unsigned int wordnum = (backwards
+ ? GET_MODE_SIZE(fieldmode) / UNITS_PER_WORD
+ - i - 1
+ : i);
unsigned int bit_offset = (backwards
? MAX ((int) bitsize - ((int) i + 1)
* BITS_PER_WORD,
--
Stelian Pop <[email protected]>
