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From: "Kong, Lingling" <lingling.kong@intel.com>
To: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Cc: "Liu, Hongtao" <hongtao.liu@intel.com>, Uros Bizjak <ubizjak@gmail.com>
Subject: [PATCH] i386: fix ix86_hardreg_mov_ok with lra_in_progress
Date: Mon, 6 May 2024 07:39:39 +0000	[thread overview]
Message-ID: <DM4PR11MB5487F8160B8087A569EE5A45EC1C2@DM4PR11MB5487.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20240506071557.2072799-1-lingling.kong@intel.com>

Hi,
Originally eliminate_regs_in_insn will transform 
(parallel [
  (set (reg:QI 130)
    (plus:QI (subreg:QI (reg:DI 19 frame) 0)
      (const_int 96)))
  (clobber (reg:CC 17 flag))]) {*addqi_1} 
to 
(set (reg:QI 130) 
  (subreg:QI (reg:DI 19 frame) 0)) {*movqi_internal}
when verify_changes.

But with No Flags add, it transforms
(set (reg:QI 5 di)
  (plus:QI (subreg:QI (reg:DI 19 frame) 0)
   (const_int 96))) {*addqi_1_nf}
to
(set (reg:QI 5 di)
 (subreg:QI (reg:DI 19 frame) 0)) {*addqi_1_nf}.
there is no extra clobbers at the end, and its dest reg just is a hardreg. For ix86_hardreg_mov_ok, it returns false. So it fails to update insn and causes the ICE when transform to movqi_internal.

But actually it is ok and safe for ix86_hardreg_mov_ok when lra_in_progress.

And tested the spec2017, the performance was not affected.
Bootstrapped and regtested on x86_64-pc-linux-gnu. OK for trunk?

gcc/ChangeLog:

	* config/i386/i386.cc (ix86_hardreg_mov_ok): Relax
	hard reg mov restriction when lra in progress.
---
 gcc/config/i386/i386.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc index 4d6b2b98761..ca4348a18bf 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -20357,7 +20357,8 @@ ix86_hardreg_mov_ok (rtx dst, rtx src)
 	   ? standard_sse_constant_p (src, GET_MODE (dst))
 	   : x86_64_immediate_operand (src, GET_MODE (dst)))
       && ix86_class_likely_spilled_p (REGNO_REG_CLASS (REGNO (dst)))
-      && !reload_completed)
+      && !reload_completed
+      && !lra_in_progress)
     return false;
   return true;
 }
--
2.31.1


       reply	other threads:[~2024-05-06  7:39 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20240506071557.2072799-1-lingling.kong@intel.com>
2024-05-06  7:39 ` Kong, Lingling [this message]
2024-05-08  2:08   ` Hongtao Liu

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