From: Uros Bizjak <ubizjak@gmail.com>
Date: Wed, 21 Nov 2018 21:52:06 +0000 (+0100)
Subject: Revert the revert:
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=13986a58e723e4608ce0172d6713a7a9b06a4c30;p=gcc.git

Revert the revert:

	2013-10-26  Vladimir Makarov  <vmakarov@redhat.com>

	Revert:
	2013-10-25  Vladimir Makarov  <vmakarov@redhat.com>

	* lra-spills.c (lra_final_code_change): Remove useless move insns.

From-SVN: r266358
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5e09cd6d04f..ee5f1835b95 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2018-11-21  Uros Bizjak  <ubizjak@gmail.com>
+
+	Revert the revert:
+	2013-10-26  Vladimir Makarov  <vmakarov@redhat.com>
+
+	Revert:
+	2013-10-25  Vladimir Makarov  <vmakarov@redhat.com>
+
+	* lra-spills.c (lra_final_code_change): Remove useless move insns.
+
 2018-11-21  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR middle-end/88129
diff --git a/gcc/lra-spills.c b/gcc/lra-spills.c
index 33caf9f4564..008d7399687 100644
--- a/gcc/lra-spills.c
+++ b/gcc/lra-spills.c
@@ -740,6 +740,7 @@ lra_final_code_change (void)
   int i, hard_regno;
   basic_block bb;
   rtx_insn *insn, *curr;
+  rtx set;
   int max_regno = max_reg_num ();
 
   for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
@@ -818,5 +819,19 @@ lra_final_code_change (void)
 	      }
 	  if (insn_change_p)
 	    lra_update_operator_dups (id);
+
+	  if ((set = single_set (insn)) != NULL
+	      && REG_P (SET_SRC (set)) && REG_P (SET_DEST (set))
+	      && REGNO (SET_SRC (set)) == REGNO (SET_DEST (set)))
+	    {
+	      /* Remove an useless move insn.  IRA can generate move
+		 insns involving pseudos.  It is better remove them
+		 earlier to speed up compiler a bit.  It is also
+		 better to do it here as they might not pass final RTL
+		 check in LRA, (e.g. insn moving a control register
+		 into itself).  */
+	      lra_invalidate_insn_data (insn);
+	      delete_insn (insn);
+	    }
 	}
 }