[PATCH] ira: Cap callee-saved register cost scale to 300

[H.J. Lu]

Don't increase callee-saved register cost by 1000x, which leads to that
callee-saved registers aren't used to preserve local variable values
across calls, by capping the scale to 300.

        PR rtl-optimization/111673
        PR rtl-optimization/115932
        PR rtl-optimization/116028
        PR rtl-optimization/117081
        PR rtl-optimization/118497
        * ira-color.cc (assign_hard_reg): Cap callee-saved register cost
        scale to 300.

Signed-off-by: H.J. Lu <hjl.to...@gmail.com>
---
 gcc/ira-color.cc | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/gcc/ira-color.cc b/gcc/ira-color.cc
index 0699b349a1a..707ff188250 100644
--- a/gcc/ira-color.cc
+++ b/gcc/ira-color.cc
@@ -2175,13 +2175,25 @@ assign_hard_reg (ira_allocno_t a, bool retry_p)
          /* We need to save/restore the hard register in
             epilogue/prologue.  Therefore we increase the cost.  */
          {
+           int scale;
+           if (optimize_size)
+             scale = 1;
+           else
+             {
+               scale = REG_FREQ_FROM_BB (ENTRY_BLOCK_PTR_FOR_FN (cfun));
+               /* Don't increase callee-saved register cost by 1000x,
+                  which leads to that callee-saved registers aren't
+                  used to preserve local variable values across calls,
+                  by capping the scale to 300.  */
+               if (REG_FREQ_MAX == 1000 && scale == REG_FREQ_MAX)
+                 scale = 300;
+             }
            rclass = REGNO_REG_CLASS (hard_regno);
            add_cost = ((ira_memory_move_cost[mode][rclass][0]
                         + ira_memory_move_cost[mode][rclass][1])
                        * saved_nregs / hard_regno_nregs (hard_regno,
                                                          mode) - 1)
-                      * (optimize_size ? 1 :
-                         REG_FREQ_FROM_BB (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
+                      * scale;
            cost += add_cost;
            full_cost += add_cost;
          }
-- 
2.48.1