Remove no_caller_save_reg_set

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