Only use NO_REGS in cost calculation when !hard_regno_mode_ok for GENERAL_REGS and...

r14-172-g0368d169492017 replaces GENERAL_REGS with NO_REGS in cost
calculation when the preferred register class are not known yet.
It regressed powerpc PR109610 and PR109858, it looks too aggressive to use
NO_REGS when mode can be allocated with GENERAL_REGS.
The patch takes a step back, still use GENERAL_REGS when
hard_regno_mode_ok for mode and GENERAL_REGS, otherwise uses NO_REGS.

gcc/ChangeLog:

	PR target/109610
	PR target/109858
	* ira-costs.cc (scan_one_insn): Only use NO_REGS in cost
	calculation when !hard_regno_mode_ok for GENERAL_REGS and
	mode, otherwise still use GENERAL_REGS.

diff --git a/gcc/ira-costs.cc b/gcc/ira-costs.cc
index d2a801ab9b0cfe9e0b29db6a91544bf126287ca9..ae8304ff93836fac1fe2458b3ee653a12f40cfb2 100644 (file)
--- a/gcc/ira-costs.cc
+++ b/gcc/ira-costs.cc
@@ -1572,12 +1572,16 @@ scan_one_insn (rtx_insn *insn)
       && (! ira_use_lra_p || ! pic_offset_table_rtx
          || ! contains_symbol_ref_p (XEXP (note, 0))))
     {
-      /* Costs for NO_REGS are used in cost calculation on the
-        1st pass when the preferred register classes are not
-        known yet.  In this case we take the best scenario.  */
-      enum reg_class cl = NO_REGS;
+      enum reg_class cl = GENERAL_REGS;
       rtx reg = SET_DEST (set);
       int num = COST_INDEX (REGNO (reg));
+      /* Costs for NO_REGS are used in cost calculation on the
+        1st pass when the preferred register classes are not
+        known yet.  In this case we take the best scenario when
+        mode can't be put into GENERAL_REGS.  */
+      if (!targetm.hard_regno_mode_ok (ira_class_hard_regs[cl][0],
+                                      GET_MODE (reg)))
+       cl = NO_REGS;
 
       COSTS (costs, num)->mem_cost
        -= ira_memory_move_cost[GET_MODE (reg)][cl][1] * frequency;