a lra patch

[Vladimir Makarov <vmakarov at redhat dot com>]

The following patch is Shiva Chen's patch to fix a LRA bug on some 
experimental target.  The bug occurs when one insn requires many reloads 
and they are done on different passes.  I evaluate the probability of 
this bug for other targets as quite tiny.

  The patch was approved by me.

  Successfully bootstrapped on x86/x86-64.

  Committed as rev. 198204.

2013-04-23  Shiva Chen<shiva0217@gmail.com>

        * lra-assigns.c (find_hard_regno_for): Use lra_reg_val_equal_p
        to check the register content is equal or not.
        * lra-constraints.c (match_reload): Use lra_assign_reg_val
        to assign register content record.
        * lra-eliminations.c (update_reg_eliminate): Use lra_set_up_reg_val
        to update register content offset.
        * lra-int.h (struct lra_reg): Add offset member.
        (lra_reg_val_equal_p): New static inline function.
        (lra_set_up_reg_val): New static inline function.
        (lra_assign_reg_val): New static inline function.
        * lra.c (lra_create_new_reg): Use lra_assign_reg_val
        to assign register content record.
        (initialize_lra_reg_info_element): Initial offset to zero


Index: lra-assigns.c
===================================================================
--- lra-assigns.c	(revision 198200)
+++ lra-assigns.c	(working copy)
@@ -448,7 +448,7 @@ find_hard_regno_for (int regno, int *cos
   int hr, conflict_hr, nregs;
   enum machine_mode biggest_mode;
   unsigned int k, conflict_regno;
-  int val, biggest_nregs, nregs_diff;
+  int offset, val, biggest_nregs, nregs_diff;
   enum reg_class rclass;
   bitmap_iterator bi;
   bool *rclass_intersect_p;
@@ -508,9 +508,10 @@ find_hard_regno_for (int regno, int *cos
 #endif
   sparseset_clear_bit (conflict_reload_and_inheritance_pseudos, regno);
   val = lra_reg_info[regno].val;
+  offset = lra_reg_info[regno].offset;
   CLEAR_HARD_REG_SET (impossible_start_hard_regs);
   EXECUTE_IF_SET_IN_SPARSESET (live_range_hard_reg_pseudos, conflict_regno)
-    if (val == lra_reg_info[conflict_regno].val)
+    if (lra_reg_val_equal_p (conflict_regno, val, offset))
       {
 	conflict_hr = live_pseudos_reg_renumber[conflict_regno];
 	nregs = (hard_regno_nregs[conflict_hr]
@@ -538,7 +539,7 @@ find_hard_regno_for (int regno, int *cos
       }
   EXECUTE_IF_SET_IN_SPARSESET (conflict_reload_and_inheritance_pseudos,
 			       conflict_regno)
-    if (val != lra_reg_info[conflict_regno].val)
+    if (!lra_reg_val_equal_p (conflict_regno, val, offset))
       {
 	lra_assert (live_pseudos_reg_renumber[conflict_regno] < 0);
 	if ((hard_regno
@@ -1007,7 +1008,7 @@ setup_live_pseudos_and_spill_after_risky
 {
   int p, i, j, n, regno, hard_regno;
   unsigned int k, conflict_regno;
-  int val;
+  int val, offset;
   HARD_REG_SET conflict_set;
   enum machine_mode mode;
   lra_live_range_t r;
@@ -1050,8 +1051,9 @@ setup_live_pseudos_and_spill_after_risky
       COPY_HARD_REG_SET (conflict_set, lra_no_alloc_regs);
       IOR_HARD_REG_SET (conflict_set, lra_reg_info[regno].conflict_hard_regs);
       val = lra_reg_info[regno].val;
+      offset = lra_reg_info[regno].offset;
       EXECUTE_IF_SET_IN_SPARSESET (live_range_hard_reg_pseudos, conflict_regno)
-	if (val != lra_reg_info[conflict_regno].val
+	if (!lra_reg_val_equal_p (conflict_regno, val, offset)
 	    /* If it is multi-register pseudos they should start on
 	       the same hard register.	*/
 	    || hard_regno != reg_renumber[conflict_regno])
Index: lra-constraints.c
===================================================================
--- lra-constraints.c	(revision 198200)
+++ lra-constraints.c	(working copy)
@@ -704,7 +704,7 @@ match_reload (signed char out, signed ch
 	     pseudos still live where reload pseudos dies.  */
 	  if (REG_P (in_rtx) && (int) REGNO (in_rtx) < lra_new_regno_start
 	      && find_regno_note (curr_insn, REG_DEAD, REGNO (in_rtx)))
-	    lra_reg_info[REGNO (reg)].val = lra_reg_info[REGNO (in_rtx)].val;
+	    lra_assign_reg_val (REGNO (in_rtx), REGNO (reg));
 	}
       else
 	{
@@ -733,8 +733,7 @@ match_reload (signed char out, signed ch
 		  && GET_MODE (subreg_reg) == outmode
 		  && SUBREG_BYTE (in_rtx) == SUBREG_BYTE (new_in_reg)
 		  && find_regno_note (curr_insn, REG_DEAD, REGNO (subreg_reg)))
-		lra_reg_info[REGNO (reg)].val
-		  = lra_reg_info[REGNO (subreg_reg)].val;
+		lra_assign_reg_val (REGNO (subreg_reg), REGNO (reg));
 	    }
 	}
     }
Index: lra-eliminations.c
===================================================================
--- lra-eliminations.c	(revision 198200)
+++ lra-eliminations.c	(working copy)
@@ -1124,8 +1124,15 @@ update_reg_eliminate (bitmap insns_with_
   setup_elimination_map ();
   for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
     if (elimination_map[ep->from] == ep && ep->previous_offset != ep->offset)
-      bitmap_ior_into (insns_with_changed_offsets,
-		       &lra_reg_info[ep->from].insn_bitmap);
+      {
+	bitmap_ior_into (insns_with_changed_offsets,
+			 &lra_reg_info[ep->from].insn_bitmap);
+
+	/* Update offset when the eliminate offset have been
+	   changed.  */
+	lra_update_reg_val_offset (lra_reg_info[ep->from].val,
+				   ep->offset - ep->previous_offset);
+      }
 }
 
 /* Initialize the table of hard registers to eliminate.
Index: lra-int.h
===================================================================
--- lra-int.h	(revision 198200)
+++ lra-int.h	(working copy)
@@ -118,6 +118,8 @@ struct lra_reg
   /* Value holding by register.	 If the pseudos have the same value
      they do not conflict.  */
   int val;
+  /* Offset from relative eliminate register to pesudo reg.  */
+  int offset;
   /* These members are set up in lra-lives.c and updated in
      lra-coalesce.c.  */
   /* The biggest size mode in which each pseudo reg is referred in
@@ -443,6 +445,37 @@ lra_get_insn_recog_data (rtx insn)
   return lra_set_insn_recog_data (insn);
 }
 
+/* Update offset from pseudos with VAL by INCR.  */
+static inline void
+lra_update_reg_val_offset (int val, int incr)
+{
+  int i;
+
+  for (i = FIRST_PSEUDO_REGISTER; i < max_reg_num (); i++)
+    {
+      if (lra_reg_info[i].val == val)
+        lra_reg_info[i].offset += incr;
+    }
+}
+
+/* Return true if register content is equal to VAL with OFFSET.  */
+static inline bool
+lra_reg_val_equal_p (int regno, int val, int offset)
+{
+  if (lra_reg_info[regno].val == val
+      && lra_reg_info[regno].offset == offset)
+    return true;
+
+  return false;
+}
+
+/* Assign value of register FROM to TO.  */
+static inline void
+lra_assign_reg_val (int from, int to)
+{
+  lra_reg_info[to].val = lra_reg_info[from].val;
+  lra_reg_info[to].offset = lra_reg_info[from].offset;
+}
 
 
 struct target_lra_int
Index: lra.c
===================================================================
--- lra.c	(revision 198200)
+++ lra.c	(working copy)
@@ -194,7 +194,7 @@ lra_create_new_reg (enum machine_mode md
   new_reg
     = lra_create_new_reg_with_unique_value (md_mode, original, rclass, title);
   if (original != NULL_RTX && REG_P (original))
-    lra_reg_info[REGNO (new_reg)].val = lra_reg_info[REGNO (original)].val;
+    lra_assign_reg_val (REGNO (original), REGNO (new_reg));
   return new_reg;
 }
 
@@ -1392,6 +1392,7 @@ initialize_lra_reg_info_element (int i)
   lra_reg_info[i].last_reload = 0;
   lra_reg_info[i].restore_regno = -1;
   lra_reg_info[i].val = get_new_reg_value ();
+  lra_reg_info[i].offset = 0;
   lra_reg_info[i].copies = NULL;
 }