re PR rtl-optimization/56178 (Miscompilation of Ada front-end with profiled bootstrap)

	PR rtl-optimization/56178
	* cse.c (cse_insn): Do not create a REG_EQUAL note if the source is a
	SUBREG of a register.  Tidy up related block of code.
	* fwprop.c (forward_propagate_and_simplify): Do not create a REG_EQUAL
	note if the source is a register or a SUBREG of a register.

From-SVN: r195841

gcc/ChangeLog

+2013-02-07  Eric Botcazou  <ebotcazou@adacore.com>
+
+	PR rtl-optimization/56178
+	* cse.c (cse_insn): Do not create a REG_EQUAL note if the source is a
+	SUBREG of a register.  Tidy up related block of code.
+	* fwprop.c (forward_propagate_and_simplify): Do not create a REG_EQUAL
+	note if the source is a register or a SUBREG of a register.
+
 2013-02-07  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/56228

gcc/cse.c

@@ -5311,33 +5311,33 @@ cse_insn (rtx insn)
 	}
 
       /* If this is a single SET, we are setting a register, and we have an
-	 equivalent constant, we want to add a REG_NOTE.   We don't want
-	 to write a REG_EQUAL note for a constant pseudo since verifying that
-	 that pseudo hasn't been eliminated is a pain.  Such a note also
-	 won't help anything.
+	 equivalent constant, we want to add a REG_EQUAL note if the constant
+	 is different from the source.  We don't want to do it for a constant
+	 pseudo since verifying that this pseudo hasn't been eliminated is a
+	 pain; moreover such a note won't help anything.
 
 	 Avoid a REG_EQUAL note for (CONST (MINUS (LABEL_REF) (LABEL_REF)))
 	 which can be created for a reference to a compile time computable
 	 entry in a jump table.  */
-
-      if (n_sets == 1 && src_const && REG_P (dest)
+      if (n_sets == 1
+	  && REG_P (dest)
+	  && src_const
 	  && !REG_P (src_const)
-	  && ! (GET_CODE (src_const) == CONST
-		&& GET_CODE (XEXP (src_const, 0)) == MINUS
-		&& GET_CODE (XEXP (XEXP (src_const, 0), 0)) == LABEL_REF
-		&& GET_CODE (XEXP (XEXP (src_const, 0), 1)) == LABEL_REF))
+	  && !(GET_CODE (src_const) == SUBREG
+	       && REG_P (SUBREG_REG (src_const)))
+	  && !(GET_CODE (src_const) == CONST
+	       && GET_CODE (XEXP (src_const, 0)) == MINUS
+	       && GET_CODE (XEXP (XEXP (src_const, 0), 0)) == LABEL_REF
+	       && GET_CODE (XEXP (XEXP (src_const, 0), 1)) == LABEL_REF)
+	  && !rtx_equal_p (src, src_const))
 	{
-	  /* We only want a REG_EQUAL note if src_const != src.  */
-	  if (! rtx_equal_p (src, src_const))
-	    {
-	      /* Make sure that the rtx is not shared.  */
-	      src_const = copy_rtx (src_const);
+	  /* Make sure that the rtx is not shared.  */
+	  src_const = copy_rtx (src_const);
 
-	      /* Record the actual constant value in a REG_EQUAL note,
-		 making a new one if one does not already exist.  */
-	      set_unique_reg_note (insn, REG_EQUAL, src_const);
-	      df_notes_rescan (insn);
-	    }
+	  /* Record the actual constant value in a REG_EQUAL note,
+	     making a new one if one does not already exist.  */
+	  set_unique_reg_note (insn, REG_EQUAL, src_const);
+	  df_notes_rescan (insn);
 	}
 
       /* Now deal with the destination.  */

gcc/fwprop.c

@@ -1316,10 +1316,16 @@ forward_propagate_and_simplify (df_ref use, rtx def_insn, rtx def_set)
 	 separately try plugging the definition in the note and simplifying.
 	 And only install a REQ_EQUAL note when the destination is a REG
 	 that isn't mentioned in USE_SET, as the note would be invalid
-	 otherwise.  */
-      set_reg_equal = (note == NULL_RTX && REG_P (SET_DEST (use_set))
-		       && ! reg_mentioned_p (SET_DEST (use_set),
-					     SET_SRC (use_set)));
+	 otherwise.  We also don't want to install a note if we are merely
+	 propagating a pseudo since verifying that this pseudo isn't dead
+	 is a pain; moreover such a note won't help anything.  */
+      set_reg_equal = (note == NULL_RTX
+		       && REG_P (SET_DEST (use_set))
+		       && !REG_P (src)
+		       && !(GET_CODE (src) == SUBREG
+			    && REG_P (SUBREG_REG (src)))
+		       && !reg_mentioned_p (SET_DEST (use_set),
+					    SET_SRC (use_set)));
     }
 
   if (GET_MODE (*loc) == VOIDmode)