PR 997

* frags.c (frag_offset_fixed_p): New function.
	* frags.h (frag_offset_fixed_p): Declare.
	* expr.c (expr): Use frag_offset_fixed_p when simplifying subtraction.
	(resolve_expression): Likewise.

gas/ChangeLog

@@ -1,3 +1,11 @@
+2006-04-04  Alan Modra  <amodra@bigpond.net.au>
+
+	PR 997
+	* frags.c (frag_offset_fixed_p): New function.
+	* frags.h (frag_offset_fixed_p): Declare.
+	* expr.c (expr): Use frag_offset_fixed_p when simplifying subtraction.
+	(resolve_expression): Likewise.
+
 2006-04-03  Sterling Augustine  <sterling@tensilica.com>
 
 	* config/tc-xtensa.c (init_op_placement_info_table): Check for formats

gas/expr.c

@@ -1,6 +1,6 @@
 /* expr.c -operands, expressions-
    Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-   1999, 2000, 2001, 2002, 2003, 2004, 2005
+   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
    Free Software Foundation, Inc.
 
    This file is part of GAS, the GNU Assembler.
@@ -1662,6 +1662,7 @@ expr (int rankarg,		/* Larger # is higher rank.  */
   while (op_left != O_illegal && op_rank[(int) op_left] > rank)
     {
       segT rightseg;
+      bfd_vma frag_off;
 
       input_line_pointer += op_chars;	/* -> after operator.  */
 
@@ -1741,12 +1742,15 @@ expr (int rankarg,		/* Larger # is higher rank.  */
       else if (op_left == O_subtract
 	       && right.X_op == O_symbol
 	       && resultP->X_op == O_symbol
-	       && (symbol_get_frag (right.X_add_symbol)
-		   == symbol_get_frag (resultP->X_add_symbol))
+	       && retval == rightseg
 	       && (SEG_NORMAL (rightseg)
-		   || right.X_add_symbol == resultP->X_add_symbol))
+		   || right.X_add_symbol == resultP->X_add_symbol)
+	       && frag_offset_fixed_p (symbol_get_frag (resultP->X_add_symbol),
+				       symbol_get_frag (right.X_add_symbol),
+				       &frag_off))
 	{
 	  resultP->X_add_number -= right.X_add_number;
+	  resultP->X_add_number -= frag_off / OCTETS_PER_BYTE;
 	  resultP->X_add_number += (S_GET_VALUE (resultP->X_add_symbol)
 				    - S_GET_VALUE (right.X_add_symbol));
 	  resultP->X_op = O_constant;
@@ -1900,6 +1904,7 @@ resolve_expression (expressionS *expressionP)
   valueT left, right;
   segT seg_left, seg_right;
   fragS *frag_left, *frag_right;
+  bfd_vma frag_off;
 
   switch (op)
     {
@@ -2002,13 +2007,15 @@ resolve_expression (expressionS *expressionP)
 	 on the input value.
 	 Otherwise, both operands must be absolute.  We already handled
 	 the case of addition or subtraction of a constant above.  */
+      frag_off = 0;
       if (!(seg_left == absolute_section
 	       && seg_right == absolute_section)
 	  && !(op == O_eq || op == O_ne)
 	  && !((op == O_subtract
 		|| op == O_lt || op == O_le || op == O_ge || op == O_gt)
 	       && seg_left == seg_right
-	       && (finalize_syms || frag_left == frag_right)
+	       && (finalize_syms
+		   || frag_offset_fixed_p (frag_left, frag_right, &frag_off))
 	       && (seg_left != reg_section || left == right)
 	       && (seg_left != undefined_section || add_symbol == op_symbol)))
 	{
@@ -2068,6 +2075,7 @@ resolve_expression (expressionS *expressionP)
 	    return 0;
 	}
 
+      right += frag_off / OCTETS_PER_BYTE;
       switch (op)
 	{
 	case O_add:			left += right; break;

gas/frags.c

@@ -1,6 +1,6 @@
 /* frags.c - manage frags -
    Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-   1999, 2000, 2001, 2003, 2004
+   1999, 2000, 2001, 2003, 2004, 2005, 2006
    Free Software Foundation, Inc.
 
    This file is part of GAS, the GNU Assembler.
@@ -383,3 +383,55 @@ frag_append_1_char (int datum)
     }
   obstack_1grow (&frchain_now->frch_obstack, datum);
 }
+
+/* Return TRUE if FRAG1 and FRAG2 have a fixed relationship between
+   their start addresses.  Set OFFSET to the difference in address
+   not already accounted for in the frag FR_ADDRESS.  */
+
+bfd_boolean
+frag_offset_fixed_p (fragS *frag1, fragS *frag2, bfd_vma *offset)
+{
+  fragS *frag;
+  bfd_vma off;
+
+  /* Start with offset initialised to difference between the two frags.
+     Prior to assigning frag addresses this will be zero.  */
+  off = frag1->fr_address - frag2->fr_address;
+  if (frag1 == frag2)
+    {
+      *offset = off;
+      return TRUE;
+    }
+
+  /* Maybe frag2 is after frag1.  */
+  frag = frag1;
+  while (frag->fr_type == rs_fill)
+    {
+      off += frag->fr_fix + frag->fr_offset * frag->fr_var;
+      frag = frag->fr_next;
+      if (frag == NULL)
+	break;
+      if (frag == frag2)
+	{
+	  *offset = off;
+	  return TRUE;
+	}
+    }
+
+  /* Maybe frag1 is after frag2.  */
+  frag = frag2;
+  while (frag->fr_type == rs_fill)
+    {
+      off -= frag->fr_fix + frag->fr_offset * frag->fr_var;
+      frag = frag->fr_next;
+      if (frag == NULL)
+	break;
+      if (frag == frag1)
+	{
+	  *offset = off;
+	  return TRUE;
+	}
+    }
+
+  return FALSE;
+}

gas/frags.h

@@ -1,6 +1,6 @@
 /* frags.h - Header file for the frag concept.
    Copyright 1987, 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000, 2001,
-   2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+   2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
 
    This file is part of GAS, the GNU Assembler.
 
@@ -148,4 +148,6 @@ char *frag_var (relax_stateT type,
 		offsetT offset,
 		char *opcode);
 
+bfd_boolean frag_offset_fixed_p (fragS *, fragS *, bfd_vma *);
+
 #endif /* FRAGS_H */