lra: Handle register filters

This patch makes LRA apply register filters.  This plus the recog
change is enough for correct code generation, but a follow-on IRA
patch improves the allocation.

All the new code should be optimised away on targets that don't
use register filters.  That's because get_register_filter just
wraps "return nullptr" on those targets.

gcc/
	* lra-constraints.cc (process_alt_operands): Check register filters.

diff --git a/gcc/lra-constraints.cc b/gcc/lra-constraints.cc
index 0607c8be7cbb698234eaa47a698756513cd9ba03..9b6a2af5b7552a96fc2054b758b89ea0d603e04e 100644 (file)
--- a/gcc/lra-constraints.cc
+++ b/gcc/lra-constraints.cc
@@ -2149,6 +2149,7 @@ process_alt_operands (int only_alternative)
   int reload_nregs, reload_sum;
   bool costly_p;
   enum reg_class cl;
+  const HARD_REG_SET *cl_filter;
 
   /* Calculate some data common for all alternatives to speed up the
      function. */
@@ -2514,6 +2515,7 @@ process_alt_operands (int only_alternative)
                      || spilled_pseudo_p (op))
                    win = true;
                  cl = GENERAL_REGS;
+                 cl_filter = nullptr;
                  goto reg;
 
                default:
@@ -2523,7 +2525,10 @@ process_alt_operands (int only_alternative)
                    case CT_REGISTER:
                      cl = reg_class_for_constraint (cn);
                      if (cl != NO_REGS)
-                       goto reg;
+                       {
+                         cl_filter = get_register_filter (cn);
+                         goto reg;
+                       }
                      break;
 
                    case CT_CONST_INT:
@@ -2567,6 +2572,7 @@ process_alt_operands (int only_alternative)
                        win = true;
                      cl = base_reg_class (VOIDmode, ADDR_SPACE_GENERIC,
                                           ADDRESS, SCRATCH);
+                     cl_filter = nullptr;
                      badop = false;
                      goto reg;
 
@@ -2600,6 +2606,8 @@ process_alt_operands (int only_alternative)
                    this_alternative_exclude_start_hard_regs
                      |= ira_exclude_class_mode_regs[cl][mode];
                  this_alternative_set |= reg_class_contents[cl];
+                 if (cl_filter)
+                   this_alternative_exclude_start_hard_regs |= ~*cl_filter;
                  if (costly_p)
                    {
                      this_costly_alternative
@@ -2613,6 +2621,9 @@ process_alt_operands (int only_alternative)
                      if (hard_regno[nop] >= 0
                          && in_hard_reg_set_p (this_alternative_set,
                                                mode, hard_regno[nop])
+                         && (!cl_filter
+                             || TEST_HARD_REG_BIT (*cl_filter,
+                                                   hard_regno[nop]))
                          && ((REG_ATTRS (op) && (decl = REG_EXPR (op)) != NULL
                               && VAR_P (decl) && DECL_HARD_REGISTER (decl))
                              || !(TEST_HARD_REG_BIT