[arm] post_modify constraint failure (was Re: Patch ping)

[Paul Brook <paul@codesourcery.com>]

> /work/rearnsha/gnu/egcs/arm-elf/libstdc++-v3/include/complex:1455: error:
> insn d oes not satisfy its constraints:
> (insn:HI 2559 6401 6402 47
> /work/rearnsha/gnu/egcs/arm-elf/libstdc++-v3/include/ streambuf:187 (set
> (mem/s:SI (post_modify:SI (reg:SI 12 ip)
>                 (plus:SI (reg:SI 12 ip)
>                     (const_int 28 [0x1c]))) [9
> <variable>._vptr.basic_streambuf+ 0 S4 A32])
>         (reg/f:SI 3 r3 [314])) 140 {*arm_movsi_insn} (insn_list 2558 (nil))
>     (expr_list:REG_DEAD (reg/f:SI 3 r3 [314])
>         (expr_list:REG_INC (reg:SI 12 ip)
>             (nil))))
>
> Then I think this is because arm_legitimate_address_p is doing something
> wrong.  Probably this test:
>
>   else if ((GET_CODE (x) == POST_MODIFY || GET_CODE (x) == PRE_MODIFY)
> 	   && GET_MODE_SIZE (mode) <= 4
> 	   && arm_address_register_rtx_p (XEXP (x, 0), strict_p)
> 	   && GET_CODE (XEXP (x, 1)) == PLUS
> 	   && XEXP (XEXP (x, 1), 0) == XEXP (x, 0))
>
> That final equivalence should probably be using rtx_equal_p(), but I
> haven't tested that yet.

It does fix the problem. Patch below.

Tested with cross-compiler to arm-none-elf.
Ok?

Paul

2004-04-20  Paul Brook  <paul@codesourcery.com>

	* config/arm/arm.c (arm_legitimate_address_p): Use rtx_equal_p.

Index: config/arm/arm.c
===================================================================
RCS file: /var/cvsroot/gcc-cvs/gcc/gcc/config/arm/arm.c,v
retrieving revision 1.347
diff -u -p -r1.347 arm.c
--- a/config/arm/arm.c	20 Apr 2004 11:28:08 -0000	1.347
+++ b/config/arm/arm.c	20 Apr 2004 12:17:13 -0000
@@ -2994,7 +2994,7 @@ arm_legitimate_address_p (enum machine_m
 	   && GET_MODE_SIZE (mode) <= 4
 	   && arm_address_register_rtx_p (XEXP (x, 0), strict_p)
 	   && GET_CODE (XEXP (x, 1)) == PLUS
-	   && XEXP (XEXP (x, 1), 0) == XEXP (x, 0))
+	   && rtx_equal_p (XEXP (XEXP (x, 1), 0), XEXP (x, 0)))
     return arm_legitimate_index_p (mode, XEXP (XEXP (x, 1), 1), outer,
 				   strict_p);