[gcc(refs/users/meissner/heads/work073)] If zero cycle move tuning, use absolute addresses in switch tables.

[gcc(refs/users/meissner/heads/work073)] If zero cycle move tuning, use absolute addresses in switch tables.

[Michael Meissner]

https://gcc.gnu.org/g:e25ccbc0c99daaeaf599eeb265e6fb975e548b46

commit e25ccbc0c99daaeaf599eeb265e6fb975e548b46
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Thu Nov 11 12:43:02 2021 -0500

    If zero cycle move tuning, use absolute addresses in switch tables.
    
    This option enables using absolute addresses in switch tables if the
    power10 zero cycle move tuning is turned on.  The combination of using
    absolute addresses in switch tables along with zero cycle moves seems to
    give the best performance.
    
    2021-11-11  Michael Meissner  <meissner@the-meissners.org>
    
            * config/rs6000/rs6000.c (rs6000_option_override_internal): Enable
            using absolute addresses if power10 zero cycle move fusion is
            enabled.

Diff:
---
 gcc/config/rs6000/rs6000.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 8531cef0337..dc942765828 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -4502,6 +4502,12 @@ rs6000_option_override_internal (bool global_init_p)
       && (rs6000_isa_flags_explicit & OPTION_MASK_P10_FUSION_ZERO_CYCLE) == 0)
     rs6000_isa_flags |= OPTION_MASK_P10_FUSION_ZERO_CYCLE;
 
+  /* If we enable zero cycle move fusion, also switch to absolute addresses in
+     switch tables.  */
+  if (TARGET_P10_FUSION && TARGET_P10_FUSION_ZERO_CYCLE
+      && !global_options_set.x_rs6000_relative_jumptables)
+    rs6000_relative_jumptables = 0;
+
   /* Turn off vector pair/mma options on non-power10 systems.  */
   else if (!TARGET_POWER10 && TARGET_MMA)
     {