RFA: patch to fix broken FRV target

[Vladimir Makarov]

Currently, FRV port is broken.  It crashes on assertion in IRA because
the right pressure register classes can not be found.
I started work on this and found that register move cost for moving
between GPR_REGS (or QUAD_REGS) is too costly (40) although FRV
machine dependent code reports it cheap explicitly.

The cost is changed to the big value by the following code in 
reginfo.c::init_move_cost

          cost = last_move_cost[i][j];

          for (p2 = &reg_class_subclasses[j][0];
           *p2 != LIM_REG_CLASSES; p2++)
        if (*p2 != i && contains_reg_of_mode[*p2][m])
          cost = MAX (cost, move_cost[m][i][*p2]);

          for (p1 = &reg_class_subclasses[i][0];
           *p1 != LIM_REG_CLASSES; p1++)
        if (*p1 != j && contains_reg_of_mode[*p1][m])
          cost = MAX (cost, move_cost[m][*p1][j]);

when i==GPR_REGS and *p2 == GR8_REGS for example.  That happens
because moves from/to GR8_REGS, GR9_REGS, and other classes which are
subsets of GPR_REGS are treated too costly in frv_register_move_cost.

I could modify a code in init_move_cost ignoring costly subclasses when 
moves inside the superclass i s less costly than memory.  But I think it 
is wrong thing to do because it affects other targets in unknown now way 
and because I think we still need the right costs for GR8_REGS, ...

So I think the following patch is the right way to fix frv target.

Nick, is the patch ok for you?


2011-07-19  Vladimir Makarov <vmaka...@redhat.com>

    * config/frv/frv.c (frv_register_move_cost): Define explicitly
    costs for subclasses of GR_REGS.


Index: config/frv/frv.c
===================================================================
--- config/frv/frv.c    (revision 176462)
+++ config/frv/frv.c    (working copy)
@@ -6818,6 +6818,13 @@ frv_register_move_cost (enum machine_mod

     case QUAD_REGS:
     case GPR_REGS:
+    case GR8_REGS:
+    case GR9_REGS:
+    case GR89_REGS:
+    case FDPIC_REGS:
+    case FDPIC_FPTR_REGS:
+    case FDPIC_CALL_REGS:
+
       switch (to)
     {
     default:
@@ -6825,6 +6832,13 @@ frv_register_move_cost (enum machine_mod

     case QUAD_REGS:
     case GPR_REGS:
+    case GR8_REGS:
+    case GR9_REGS:
+    case GR89_REGS:
+    case FDPIC_REGS:
+    case FDPIC_FPTR_REGS:
+    case FDPIC_CALL_REGS:
+
       return LOW_COST;

     case FPR_REGS:
@@ -6844,6 +6858,13 @@ frv_register_move_cost (enum machine_mod

     case QUAD_REGS:
     case GPR_REGS:
+    case GR8_REGS:
+    case GR9_REGS:
+    case GR89_REGS:
+    case FDPIC_REGS:
+    case FDPIC_FPTR_REGS:
+    case FDPIC_CALL_REGS:
+
     case QUAD_ACC_REGS:
     case ACCG_REGS:
       return MEDIUM_COST;
@@ -6862,6 +6883,13 @@ frv_register_move_cost (enum machine_mod

     case QUAD_REGS:
     case GPR_REGS:
+    case GR8_REGS:
+    case GR9_REGS:
+    case GR89_REGS:
+    case FDPIC_REGS:
+    case FDPIC_FPTR_REGS:
+    case FDPIC_CALL_REGS:
+
       return MEDIUM_COST;
     }