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Re: ALIGN directive showing different behavior than documented
- From: Alan Modra <amodra at gmail dot com>
- To: Andre Vieira <Andre dot SimoesDiasVieira at arm dot com>
- Cc: binutils at sourceware dot org
- Date: Wed, 8 Jul 2015 22:31:28 +0930
- Subject: Re: ALIGN directive showing different behavior than documented
- Authentication-results: sourceware.org; auth=none
- References: <559BD727 dot 20802 at arm dot com>
On Tue, Jul 07, 2015 at 02:41:59PM +0100, Andre Vieira wrote:
> After some digging I found that the unary operator uses the expression
> 'expld.dot' whereas the binary operator uses 'lhs.value'. The first gives an
> absolute value, whereas the second seems to hold a relative value to the
> section start.
Right, lhs.value is evaluated from fold_name case NAME here:
else if (tree->name.name[0] == '.' && tree->name.name[1] == 0)
new_rel_from_abs (expld.dot);
So the difference is that the unary operator is missing a conversion
from absolute to relative. I think that is a bug since we say the
value of dot inside a section is relative to the start of the section.
I wonder how many scripts rely on the old behaviour? If I don't hear
any objections to this change, I'll install the following in a day or
two.
* ldexp.c (align_dot_val): New function.
(fold_unary <ALIGN_K, NEXT>): Use it.
diff --git a/ld/ldexp.c b/ld/ldexp.c
index a5192b1..2c0fe5a 100644
--- a/ld/ldexp.c
+++ b/ld/ldexp.c
@@ -257,6 +257,14 @@ new_rel_from_abs (bfd_vma value)
expld.result.section = s;
}
+static void
+align_dot_val (bfd_vma align)
+{
+ bfd_vma base = expld.section->vma;
+
+ new_rel_from_abs (base + align_n (expld.dot - base, align));
+}
+
/* New-function for the definedness hash table. */
static struct bfd_hash_entry *
@@ -335,7 +343,7 @@ fold_unary (etree_type *tree)
{
case ALIGN_K:
if (expld.phase != lang_first_phase_enum)
- new_rel_from_abs (align_n (expld.dot, expld.result.value));
+ align_dot_val (expld.result.value);
else
expld.result.valid_p = FALSE;
break;
@@ -365,7 +373,7 @@ fold_unary (etree_type *tree)
if (expld.phase != lang_first_phase_enum)
{
make_abs ();
- expld.result.value = align_n (expld.dot, expld.result.value);
+ align_dot_val (expld.result.value);
}
else
expld.result.valid_p = FALSE;
--
Alan Modra
Australia Development Lab, IBM