From: Alan Modra <amodra@gmail.com>
Date: Tue, 3 May 2016 14:43:35 +0000 (+0930)
Subject: PR70890, stage2 miscompilation
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=fcc861d975cf423c23c1eb62508afffb7d9e2221;p=gcc.git

PR70890, stage2 miscompilation

	PR rtl-optimization/70890
	* ira.c (combine_and_move_insns): When moving def_insn, remove
	equivs on use_insn.

From-SVN: r235825
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 095e502adfa..7cd0bd4f73d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-05-03  Alan Modra  <amodra@gmail.com>
+
+	PR rtl-optimization/70890
+	* ira.c (combine_and_move_insns): When moving def_insn, remove
+	equivs on use_insn.
+
 2016-05-03  Dominik Vogt  <vogt@linux.vnet.ibm.com>
 
 	* config/s390/s390.md ("*r<noxa>sbg_<mode>_sll")
diff --git a/gcc/ira.c b/gcc/ira.c
index d383a551370..55b4bd700be 100644
--- a/gcc/ira.c
+++ b/gcc/ira.c
@@ -3742,6 +3742,22 @@ combine_and_move_insns (void)
 	  if (use_insn == BB_HEAD (use_bb))
 	    BB_HEAD (use_bb) = new_insn;
 
+	  /* We know regno dies in use_insn, but inside a loop
+	     REG_DEAD notes might be missing when def_insn was in
+	     another basic block.  However, when we move def_insn into
+	     this bb we'll definitely get a REG_DEAD note and reload
+	     will see the death.  It's possible that update_equiv_regs
+	     set up an equivalence referencing regno for a reg set by
+	     use_insn, when regno was seen as non-local.  Now that
+	     regno is local to this block, and dies, such an
+	     equivalence is invalid.  */
+	  if (find_reg_note (use_insn, REG_EQUIV, NULL_RTX))
+	    {
+	      rtx set = single_set (use_insn);
+	      if (set && REG_P (SET_DEST (set)))
+		no_equiv (SET_DEST (set), set, NULL);
+	    }
+
 	  ira_reg_equiv[regno].init_insns
 	    = gen_rtx_INSN_LIST (VOIDmode, new_insn, NULL_RTX);
 	  bitmap_set_bit (cleared_regs, regno);