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From: "jakub at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/26457] -fstack-protector leaks the upper bits of RAX
Date: Thu, 02 Mar 2006 14:48:00 -0000	[thread overview]
Message-ID: <20060302144851.23657.qmail@sourceware.org> (raw)
In-Reply-To: <bug-26457-12259@http.gcc.gnu.org/bugzilla/>



------- Comment #5 from jakub at gcc dot gnu dot org  2006-03-02 14:48 -------
(define_insn "*movdi_xor_rex64"
  [(set (match_operand:DI 0 "register_operand" "=r")
        (match_operand:DI 1 "const0_operand" "i"))
   (clobber (reg:CC FLAGS_REG))]
  "TARGET_64BIT && (!TARGET_USE_MOV0 || optimize_size)
   && reload_completed"
  "xor{l}\t{%k0, %k0|%k0, %k0}"
  [(set_attr "type" "alu1")
   (set_attr "mode" "SI")
   (set_attr "length_immediate" "0")])

and say:
long foo (void) { return 0; }
with -m64 -O2 gives:
        xorl    %eax, %eax
        ret
If xorl %eax, %eax did not zero extend to 64-bits, GCC compiled code wouldn't
really work.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26457


      parent reply	other threads:[~2006-03-02 14:48 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-02-24 15:08 [Bug c/26457] New: " arjan at linux dot intel dot com
2006-02-24 15:12 ` [Bug target/26457] " jakub at gcc dot gnu dot org
2006-02-24 15:20 ` pinskia at gcc dot gnu dot org
2006-03-02 14:00 ` pinskia at gcc dot gnu dot org
2006-03-02 14:32 ` pluto at agmk dot net
2006-03-02 14:48 ` jakub at gcc dot gnu dot org [this message]

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