Remove no_caller_save_reg_set

Reusing the reasoning from the call_fixed_reg_set patch:

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    for (j = 1; j <= MOVE_MAX_WORDS; j++)
      if (reg_save_code (i,regno_save_mode[i][j]) == -1)

should be true whenever regno_save_mode[i][j] == VOIDmode,
which it is for:

  ~call_used_reg_set | ~have_save_mode

So this condition amounts to:

  ~call_used_reg_set | ~have_save_mode | ~have_save_insn
  == ~call_used_reg_set | ~savable_regs

no_caller_save_reg_set is then set if call_used_regs[i], so
no_caller_save_reg_set is:

  call_used_reg_set & (~call_used_reg_set | ~savable_regs)
  == call_used_reg_set & ~savable_regs

This patch expands its single user accordingly.

Note that ~savable_regs is always empty on LRA targets.

2019-09-10  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* hard-reg-set.h (target_hard_regs::x_no_caller_save_reg_set): Delete.
	(no_caller_save_reg_set): Delete.
	* caller-save.c (init_caller_save): Don't initialize it.
	* ira-conflicts.c (ira_build_conflicts): Calculate
	no_caller_save_reg_set locally from call_used_reg_set and savable_regs.

From-SVN: r275599

gcc/ChangeLog

 2019-09-10  Richard Sandiford  <richard.sandiford@arm.com>
 
+	* hard-reg-set.h (target_hard_regs::x_no_caller_save_reg_set): Delete.
+	(no_caller_save_reg_set): Delete.
+	* caller-save.c (init_caller_save): Don't initialize it.
+	* ira-conflicts.c (ira_build_conflicts): Calculate
+	no_caller_save_reg_set locally from call_used_reg_set and savable_regs.
+
+2019-09-10  Richard Sandiford  <richard.sandiford@arm.com>
+
 	* hard-reg-set.h (target_hard_regs::x_call_fixed_reg_set): Delete.
 	(target_hard_regs::x_savable_regs): New field.
 	(call_fixed_reg_set): Delete.

gcc/caller-save.c

@@ -192,7 +192,6 @@ init_caller_save (void)
 
   caller_save_initialized_p = true;
 
-  CLEAR_HARD_REG_SET (no_caller_save_reg_set);
   /* First find all the registers that we need to deal with and all
      the modes that they can have.  If we can't find a mode to use,
      we can't have the register live over calls.  */
@@ -264,11 +263,7 @@ init_caller_save (void)
 	{
 	  regno_save_mode[i][j] = VOIDmode;
 	  if (j == 1)
-	    {
-	      CLEAR_HARD_REG_BIT (savable_regs, i);
-	      if (call_used_regs[i])
-		SET_HARD_REG_BIT (no_caller_save_reg_set, i);
-	    }
+	    CLEAR_HARD_REG_BIT (savable_regs, i);
 	}
 }
 

gcc/hard-reg-set.h

@@ -424,10 +424,6 @@ struct target_hard_regs {
      with the local stack frame are safe, but scant others.  */
   HARD_REG_SET x_regs_invalidated_by_call;
 
-  /* Call used hard registers which cannot be saved because there is no
-     insn for this.  */
-  HARD_REG_SET x_no_caller_save_reg_set;
-
   /* Table of register numbers in the order in which to try to use them.  */
   int x_reg_alloc_order[FIRST_PSEUDO_REGISTER];
 
@@ -490,8 +486,6 @@ extern struct target_hard_regs *this_target_hard_regs;
   (this_target_hard_regs->x_savable_regs)
 #define regs_invalidated_by_call \
   (this_target_hard_regs->x_regs_invalidated_by_call)
-#define no_caller_save_reg_set \
-  (this_target_hard_regs->x_no_caller_save_reg_set)
 #define reg_alloc_order \
   (this_target_hard_regs->x_reg_alloc_order)
 #define inv_reg_alloc_order \

gcc/ira-conflicts.c

@@ -765,6 +765,8 @@ ira_build_conflicts (void)
 	    }
 	  else if (ALLOCNO_CALLS_CROSSED_NUM (a) != 0)
 	    {
+	      HARD_REG_SET no_caller_save_reg_set
+		= (call_used_reg_set & ~savable_regs);
 	      OBJECT_TOTAL_CONFLICT_HARD_REGS (obj) |= no_caller_save_reg_set;
 	      OBJECT_TOTAL_CONFLICT_HARD_REGS (obj) |= temp_hard_reg_set;
 	      OBJECT_CONFLICT_HARD_REGS (obj) |= no_caller_save_reg_set;