Handle copy cycles in pass_cprop_hardreg

2014-10-17  Tom de Vries  <tom@codesourcery.com>

	PR rtl-optimization/61605
	* regcprop.c (copyprop_hardreg_forward_1): Add copy_p and noop_p.  Don't
	notice stores for noops.  Don't regard noops as copies.

From-SVN: r216364

gcc/ChangeLog

+2014-10-17  Tom de Vries  <tom@codesourcery.com>
+
+	PR rtl-optimization/61605
+	* regcprop.c (copyprop_hardreg_forward_1): Add copy_p and noop_p.  Don't
+	notice stores for noops.  Don't regard noops as copies.
+
 2014-10-17  Uros Bizjak  <ubizjak@gmail.com>
 
 	* config/i386/cpuid.h (__cpuid): Remove definitions that handle %ebx

gcc/regcprop.c

@@ -1047,12 +1047,21 @@ copyprop_hardreg_forward_1 (basic_block bb, struct value_data *vd)
 	    }
 	}
 
-      /* Notice stores.  */
-      note_stores (PATTERN (insn), kill_set_value, &ksvd);
+      bool copy_p = (set
+		     && REG_P (SET_DEST (set))
+		     && REG_P (SET_SRC (set)));
+      bool noop_p = (copy_p
+		     && rtx_equal_p (SET_DEST (set), SET_SRC (set)));
 
-      /* Notice copies.  */
-      if (set && REG_P (SET_DEST (set)) && REG_P (SET_SRC (set)))
-	copy_value (SET_DEST (set), SET_SRC (set), vd);
+      if (!noop_p)
+	{
+	  /* Notice stores.  */
+	  note_stores (PATTERN (insn), kill_set_value, &ksvd);
+
+	  /* Notice copies.  */
+	  if (copy_p)
+	    copy_value (SET_DEST (set), SET_SRC (set), vd);
+	}
 
       if (insn == BB_END (bb))
 	break;