Do not convert a subtract of zero into an add of zero.

gas/ChangeLog

@@ -1,3 +1,8 @@
+2002-05-02  Nick Clifton  <nickc@cambridge.redhat.com>
+
+	* config/tc-arm.c (thumb_add_sub): Do not convert a subtract of
+	zero into an add of zero - it is not the same.
+
 2002-05-01  Arati Dikey <aratid@kpit.com>
 
 	* tc-sh.c (get_specific): Generate warning if the same

gas/config/tc-arm.c

@@ -7447,7 +7447,9 @@ thumb_add_sub (str, subtract)
 		  return;
 		}
 	    }
-	  else
+	  /* Note - you cannot convert a subtract of 0 into an
+	     add of 0 because the carry flag is set differently.  */
+	  else if (offset > 0)
 	    subtract = 0;
 
 	  if (Rd == REG_SP)

gas/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2002-05-02  Nick Clifton  <nickc@cambridge.redhat.com>
+
+	* gas/arm/arm7t.s: Add thumb mode "sub r?, #0" and "add r?, #0".
+	* gas/arm/arm7t.d: Add expected results.  (Make sure that the
+	subtract is not converted into an add).
+
 2002-04-23  H.J. Lu <hjl@gnu.org>
 
 	* gas/mips/elempic.d: Use empic.l.

gas/testsuite/gas/arm/arm7t.d

@@ -66,3 +66,5 @@ Disassembly of section .text:
 [		]*dc:.*fred
 0+e0 <[^>]*> 0000c0de ?	.*
 0+e4 <[^>]*> 0000dead ?	.*
+0+e8 <[^>]*> 3800      	sub	r0, #0
+0+ea <[^>]*> 3000      	add	r0, #0

gas/testsuite/gas/arm/arm7t.s

@@ -72,3 +72,11 @@ misc:
 	.align
 .L2:
 	.word	fred
+	
+	.ltorg
+	.thumb
+	.global thumb_tests
+	.thumb_func
+thumb_tests:	
+	sub	r0, #0
+	add	r0, #0