patch to fix mips16 LRA register shuffling

patch to fix mips16 LRA register shuffling

[Vladimir Makarov]

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  The following patch fixes a problem reported by Matt Fortune.  LRA
generated additional moves for frame pointer eliminated into stack pointer.

  LRA uses register number of the elimination result when matching
constraints.  But it did not substitute RTL operand itself and that
resulted in EXTRA_CONSTRAINT hooks failure and worse code generation.

  The patch was bootstrapped on x86/x86-64 and ppc64 (with LRA).

  Committed as rev. 204267.

2013-10-31  Vladimir Makarov  <vmakarov@redhat.com>

        * lra-constraints (process_alt_operands): Use the result
        elimination register for operand when matching constraints.



[-- Attachment #2: mips16.patch --]
[-- Type: text/x-patch, Size: 1704 bytes --]

Index: lra-constraints.c
===================================================================
--- lra-constraints.c	(revision 204245)
+++ lra-constraints.c	(working copy)
@@ -1466,23 +1466,32 @@
      function.	*/
   for (nop = 0; nop < n_operands; nop++)
     {
+      rtx reg;
+
       op = no_subreg_reg_operand[nop] = *curr_id->operand_loc[nop];
       /* The real hard regno of the operand after the allocation.  */
       hard_regno[nop] = get_hard_regno (op);
 
-      operand_reg[nop] = op;
-      biggest_mode[nop] = GET_MODE (operand_reg[nop]);
-      if (GET_CODE (operand_reg[nop]) == SUBREG)
+      operand_reg[nop] = reg = op;
+      biggest_mode[nop] = GET_MODE (op);
+      if (GET_CODE (op) == SUBREG)
 	{
-	  operand_reg[nop] = SUBREG_REG (operand_reg[nop]);
+	  operand_reg[nop] = reg = SUBREG_REG (op);
 	  if (GET_MODE_SIZE (biggest_mode[nop])
-	      < GET_MODE_SIZE (GET_MODE (operand_reg[nop])))
-	    biggest_mode[nop] = GET_MODE (operand_reg[nop]);
+	      < GET_MODE_SIZE (GET_MODE (reg)))
+	    biggest_mode[nop] = GET_MODE (reg);
 	}
-      if (REG_P (operand_reg[nop]))
-	no_subreg_reg_operand[nop] = operand_reg[nop];
+      if (! REG_P (reg))
+	operand_reg[nop] = NULL_RTX;
+      else if (REGNO (reg) >= FIRST_PSEUDO_REGISTER
+	       || ((int) REGNO (reg)
+		   == lra_get_elimination_hard_regno (REGNO (reg))))
+	no_subreg_reg_operand[nop] = reg;
       else
-	operand_reg[nop] = NULL_RTX;
+	operand_reg[nop] = no_subreg_reg_operand[nop]
+	  /* Just use natural mode for elimination result.  It should
+	     be enough for extra constraints hooks.  */
+	  = regno_reg_rtx[hard_regno[nop]];
     }
 
   /* The constraints are made of several alternatives.	Each operand's