Bug 13509

Seen better if .align 4 or larger alignment is used rather than .align 3

(In reply to comment #1)
> Seen better if .align 4 or larger alignment is used rather than .align 3

Sorry for the poor bug report at the time.  I was going to fix up later in the evening as I knew I forgot the target.  Anyways I am looking into fixing this bug.

   The MIPS assembler also automatically adjusts any preceding
   label.  */

The reason why GCC emits "LABEL = ." is because of the following reason:
* Print debug labels as "foo = ." rather than "foo:" because they should
   represent a byte pointer rather than an ISA-encoded address.
...

The .uleb128 requies $LFBxxx to match the FDE start address, which is
   likewise a byte pointer rather than an ISA-encoded address.

So I think we should just delete the code in the assembler which moves the labels since they don't move "= ." based labels.

Or maybe I should add support to mips_record_label for recording the "= ." based labels.

Looks like this version of the mips patch:
http://sourceware.org/ml/binutils/2010-10/msg00512.html
Would have fixed it also.  But it was rejected and only a fake labels were added rather than all cases where the "symbol = ." .

Actually the code does not do what the comment says it does, it only moves one previous label.  Moving all labels allows the code to be correct.

Something like:
Index: config/tc-mips.c
===================================================================
RCS file: /cvs/src/src/gas/config/tc-mips.c,v
retrieving revision 1.500
diff -u -p -r1.500 tc-mips.c
--- config/tc-mips.c	8 Dec 2011 20:47:25 -0000	1.500
+++ config/tc-mips.c	17 Dec 2011 00:38:28 -0000
@@ -15633,7 +15633,7 @@ get_symbol (void)
    label.  */
 
 static void
-mips_align (int to, int *fill, symbolS *label)
+mips_align (int to, int *fill, struct insn_label_list *labels)
 {
   mips_emit_delays ();
   mips_record_compressed_mode ();
@@ -15642,11 +15642,13 @@ mips_align (int to, int *fill, symbolS *
   else
     frag_align (to, fill ? *fill : 0, 0);
   record_alignment (now_seg, to);
-  if (label != NULL)
+ while (labels != NULL)
     {
+      symbolS *label = labels->label;
       gas_assert (S_GET_SEGMENT (label) == now_seg);
       symbol_set_frag (label, frag_now);
       S_SET_VALUE (label, (valueT) frag_now_fix ());
+      labels = labels->next;
     }
 }
 
@@ -15689,7 +15691,7 @@ s_align (int x ATTRIBUTE_UNUSED)
       struct insn_label_list *l = si->label_list;
       /* Auto alignment should be switched on by next section change.  */
       auto_align = 1;
-      mips_align (temp, fill_ptr, l != NULL ? l->label : NULL);
+      mips_align (temp, fill_ptr, l);
     }
   else
     {
@@ -15859,12 +15861,10 @@ s_cons (int log_size)
 {
   segment_info_type *si = seg_info (now_seg);
   struct insn_label_list *l = si->label_list;
-  symbolS *label;
 
-  label = l != NULL ? l->label : NULL;
   mips_emit_delays ();
   if (log_size > 0 && auto_align)
-    mips_align (log_size, 0, label);
+    mips_align (log_size, 0, l);
   cons (1 << log_size);
   mips_clear_insn_labels ();
 }
@@ -15874,18 +15874,15 @@ s_float_cons (int type)
 {
   segment_info_type *si = seg_info (now_seg);
   struct insn_label_list *l = si->label_list;
-  symbolS *label;
-
-  label = l != NULL ? l->label : NULL;
 
   mips_emit_delays ();
 
   if (auto_align)
     {
       if (type == 'd')
-	mips_align (3, 0, label);
+	mips_align (3, 0, l);
       else
-	mips_align (2, 0, label);
+	mips_align (2, 0, l);
     }
 
   float_cons (type);
@@ -16653,7 +16650,6 @@ s_gpword (int ignore ATTRIBUTE_UNUSED)
 {
   segment_info_type *si;
   struct insn_label_list *l;
-  symbolS *label;
   expressionS ex;
   char *p;
 
@@ -16666,10 +16662,9 @@ s_gpword (int ignore ATTRIBUTE_UNUSED)
 
   si = seg_info (now_seg);
   l = si->label_list;
-  label = l != NULL ? l->label : NULL;
   mips_emit_delays ();
   if (auto_align)
-    mips_align (2, 0, label);
+    mips_align (2, 0, l);
 
   expression (&ex);
   mips_clear_insn_labels ();
@@ -16693,7 +16688,6 @@ s_gpdword (int ignore ATTRIBUTE_UNUSED)
 {
   segment_info_type *si;
   struct insn_label_list *l;
-  symbolS *label;
   expressionS ex;
   char *p;
 
@@ -16706,10 +16700,9 @@ s_gpdword (int ignore ATTRIBUTE_UNUSED)
 
   si = seg_info (now_seg);
   l = si->label_list;
-  label = l != NULL ? l->label : NULL;
   mips_emit_delays ();
   if (auto_align)
-    mips_align (3, 0, label);
+    mips_align (3, 0, l);
 
   expression (&ex);
   mips_clear_insn_labels ();