re PR rtl-optimization/72778 (internal compiler error: in create_pre_exit, at mode-switching.c:451)

2016-08-02  Vladimir Makarov  <vmakarov@redhat.com>

	PR middle-end/72778
	* lra-spills.c (regno_in_use_p): New.
	(lra_final_code_change): Use it.

From-SVN: r239000

gcc/ChangeLog

 2016-08-02  Vladimir Makarov  <vmakarov@redhat.com>
 
+	PR middle-end/72778
+	* lra-spills.c (regno_in_use_p): New.
+	(lra_final_code_change): Use it.
+
+2016-08-02  Vladimir Makarov  <vmakarov@redhat.com>
+
 	PR rtl-optimization/69847
 	* lra-int.h (struct lra-reg): Use restore_rtx instead of
 	restore_regno.

gcc/lra-spills.c

@@ -686,6 +686,20 @@ return_regno_p (unsigned int regno)
   return false;
 }
 
+/* Return true if REGNO is one of subsequent USE after INSN.  */
+static bool
+regno_in_use_p (rtx_insn *insn, unsigned int regno)
+{
+  while ((insn = next_nondebug_insn (insn)) != NULL_RTX
+	 && INSN_P (insn) && GET_CODE (PATTERN (insn)) == USE)
+    {
+      if (REG_P (XEXP (PATTERN (insn), 0))
+	  && regno == REGNO (XEXP (PATTERN (insn), 0)))
+	return TRUE;
+    }
+  return false;
+}
+
 /* Final change of pseudos got hard registers into the corresponding
    hard registers and removing temporary clobbers.  */
 void
@@ -693,7 +707,7 @@ lra_final_code_change (void)
 {
   int i, hard_regno;
   basic_block bb;
-  rtx_insn *insn, *curr, *next_insn;
+  rtx_insn *insn, *curr;
   int max_regno = max_reg_num ();
 
   for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
@@ -728,11 +742,7 @@ lra_final_code_change (void)
 	      && REG_P (SET_SRC (pat)) && REG_P (SET_DEST (pat))
 	      && REGNO (SET_SRC (pat)) == REGNO (SET_DEST (pat))
 	      && (! return_regno_p (REGNO (SET_SRC (pat)))
-		  || (next_insn = next_nondebug_insn (insn)) == NULL_RTX
-		  || ! INSN_P (next_insn)
-		  || GET_CODE (PATTERN (next_insn)) != USE
-		  || ! REG_P (XEXP (PATTERN (next_insn), 0))
-		  || REGNO (SET_SRC (pat)) != REGNO (XEXP (PATTERN (next_insn), 0))))
+		  || ! regno_in_use_p (insn, REGNO (SET_SRC (pat)))))
 	    {
 	      lra_invalidate_insn_data (insn);
 	      delete_insn (insn);