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From: "amodra at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/52107] IBM 128bit long double constant loaded inefficiently
Date: Fri, 03 Feb 2012 23:18:00 -0000	[thread overview]
Message-ID: <bug-52107-4-zlSm60XY3l@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-52107-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52107

--- Comment #2 from Alan Modra <amodra at gmail dot com> 2012-02-03 23:17:36 UTC ---
.tc generates an 8-byte word in both cases, so no space saved in the toc.  This
bit of code in rs6000_emit_move does the loads in DImode, then cse1 shows the
toc load being converted to a load immediate and it all goes downhill from
there.

  /* 128-bit constant floating-point values on Darwin should really be
     loaded as two parts.  */
  if (!TARGET_IEEEQUAD && TARGET_LONG_DOUBLE_128
      && mode == TFmode && GET_CODE (operands[1]) == CONST_DOUBLE)
    {
      /* DImode is used, not DFmode, because simplify_gen_subreg doesn't
     know how to get a DFmode SUBREG of a TFmode.  */


  parent reply	other threads:[~2012-02-03 23:18 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-03 13:05 [Bug target/52107] New: " amodra at gmail dot com
2012-02-03 13:34 ` [Bug target/52107] " rguenth at gcc dot gnu.org
2012-02-03 23:18 ` amodra at gmail dot com [this message]
2012-02-03 23:21 ` amodra at gmail dot com
2012-02-06 22:09 ` amodra at gcc dot gnu.org
2012-02-06 23:42 ` amodra at gcc dot gnu.org
2012-02-06 23:43 ` amodra at gmail dot com
2012-02-06 23:46 ` amodra at gmail dot com

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