From patchwork Tue Oct 23 20:06:34 2012
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Subject: [lra] patch to prevent ASHIFT exchange and dead early clobber operand
Date: Tue, 23 Oct 2012 10:06:34 -0000
From: Vladimir Makarov <vmakarov@redhat.com>
X-Patchwork-Id: 193564
Message-Id: <5086F8CA.3060801@redhat.com>
To: gcc-patches <gcc-patches@gcc.gnu.org>

The following patch prevents mistaken ASHIFT exchange found by 
Richard Sandiford and removes check early_clobber matching operand.

   The patch was successfully bootstrap on x86-64.

   Committed as rev. 192742.

2012-10-23  Vladimir Makarov  <vmakarov@redhat.com>

     * lra-constraints.c (extract_loc_address_regs): Don't swap ASHIFT
     operands.
     (process_alt_operands): Remove code for checking DEAD note for
     early clobber.


Index: lra-constraints.c
===================================================================
--- lra-constraints.c	(revision 192702)
+++ lra-constraints.c	(working copy)
@@ -639,7 +639,7 @@ extract_loc_address_regs (bool top_p, en
 	rtx *arg0_loc = &XEXP (x, 0);
 	enum rtx_code code0 = GET_CODE (*arg0_loc);
 	
-	if (code0 == CONST_INT)
+	if (code0 == CONST_INT && code == MULT)
 	  arg0_loc = &XEXP (x, 1);
 	extract_loc_address_regs (false, mode, as, arg0_loc, true,
 				  outer_code, code, modify_p, ad);
@@ -1781,17 +1781,7 @@ process_alt_operands (int only_alternati
 		    match_p = false;
 		    if (operands_match_p (*curr_id->operand_loc[nop],
 					  *curr_id->operand_loc[m], m_hregno))
-		      {
-			/* We should reject matching of an early
-			   clobber operand if the matching operand is
-			   not dying in the insn.  */
-			if (! curr_static_id->operand[m].early_clobber
-			    || operand_reg[nop] == NULL_RTX
-			    || (find_regno_note (curr_insn, REG_DEAD,
-						 REGNO (operand_reg[nop]))
-						 != NULL_RTX))
-			  match_p = true;
-		      }
+		      match_p = true;
 		    if (match_p)
 		      {
 			/* If we are matching a non-offsettable