[PATCH] IRA: Fix % constraint modifier handling on disabled alternatives.

[Andreas Krebbel <krebbel@linux.vnet.ibm.com>]

Hi,

the constraint modifier % applies to all the alternatives of a pattern
and hence is mostly added to the first constraint of an operand.  IRA
currently ignores it if the alternative with the % gets disabled by
using the `enabled' attribute or if it is not among the preferred
alternatives.

Fixed with the attached patch by moving the % check to the first loop
which walks unconditionally over all the constraints.

Ok for mainline?

Bye,

-Andreas-

gcc/ChangeLog:

2015-12-14  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* ira.c (ira_setup_alts): Move the scan for commutative modifier
	to the first loop to make it work even with disabled alternatives.

diff --git a/gcc/ira.c b/gcc/ira.c
index 97edf8c..9824e4a 100644
--- a/gcc/ira.c
+++ b/gcc/ira.c
@@ -1800,7 +1800,13 @@ ira_setup_alts (rtx_insn *insn, HARD_REG_SET &alts)
 	    {
 	      insn_constraints[nop * recog_data.n_alternatives + nalt] = p;
 	      while (*p && *p != ',')
-		p++;
+		{
+		  /* We only support one commutative marker, the first
+		     one.  We already set commutative above.  */
+		  if (*p == '%' && commutative < 0)
+		    commutative = nop;
+		  p++;
+		}
 	      if (*p)
 		p++;
 	    }
@@ -1831,11 +1837,7 @@ ira_setup_alts (rtx_insn *insn, HARD_REG_SET &alts)
 		    break;
 		  
 		  case '%':
-		    /* We only support one commutative marker, the
-		       first one.  We already set commutative
-		       above.  */
-		    if (commutative < 0)
-		      commutative = nop;
+		    /* The commutative modifier is handled above.  */
 		    break;
 
 		  case '0':  case '1':  case '2':  case '3':  case '4':