[cris-decc0,2/14] cris: Define TARGET_FLAGS_REGNUM.
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Message ID 202002120650.01C6oBH5026343@ignucius.se.axis.com
State New
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Series
  • A set of compare-elimination-fixes.
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Commit Message

Hans-Peter Nilsson Feb. 12, 2020, 6:50 a.m. UTC
* config/cris/cris.c (TARGET_FLAGS_REGNUM): Define.

This made a whole lot of difference regarding regressions in the
delay-slot filling.  Before this, comparing __lshrdi3 for v10
before/after decc0ration and other nearby functions was worse by
several missing delay-slot fills; now down to 1.

Also, add a comment about *not* defining
TARGET_FIXED_CONDITION_CODE_REGS.
---
 gcc/config/cris/cris.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

Patch
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diff --git a/gcc/config/cris/cris.c b/gcc/config/cris/cris.c
index 9fdabe2ac..eecda8384 100644
--- a/gcc/config/cris/cris.c
+++ b/gcc/config/cris/cris.c
@@ -219,6 +219,16 @@  int cris_cpu_version = CRIS_DEFAULT_CPU_VERSION;
 #undef TARGET_PREFERRED_RELOAD_CLASS
 #define TARGET_PREFERRED_RELOAD_CLASS cris_preferred_reload_class
 
+/* We don't define TARGET_FIXED_CONDITION_CODE_REGS, as at the time of
+   this writing, it has an effect only on pre-reload CSE and when
+   scheduling (and for "macro fusion" at that).  Neither applies for
+   CRIS so don't waste compilation cycles on enabling a pass that does
+   nothing.  Beware of changes to its usage; it may make sense to enable
+   "later".  */
+
+#undef TARGET_FLAGS_REGNUM
+#define TARGET_FLAGS_REGNUM CRIS_CC0_REGNUM
+
 #undef TARGET_REGISTER_MOVE_COST
 #define TARGET_REGISTER_MOVE_COST cris_register_move_cost
 #undef TARGET_MEMORY_MOVE_COST