[gcc r12-5517] Introduce REG_SET_EMPTY_P

[Richard Biener <rguenth@gcc.gnu.org>]

https://gcc.gnu.org/g:555b8cc39062d1e02ed9117883229c75e17a8871

commit r12-5517-g555b8cc39062d1e02ed9117883229c75e17a8871
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Nov 24 15:57:03 2021 +0100

    Introduce REG_SET_EMPTY_P
    
    This avoids a -Wunreachable-code diagnostic with EXECUTE_IF_*
    in case the first iteration will exit the loop.  For the case
    in thread_jump using bitmap_empty_p looks preferable so this
    adds REG_SET_EMPTY_P to make that available for register sets.
    
    2021-11-25  Richard Biener  <rguenther@suse.de>
    
            * regset.h (REG_SET_EMPTY_P): New macro.
            * cfgcleanup.c (thread_jump): Use REG_SET_EMPTY_P.

Diff:
---
 gcc/cfgcleanup.c | 3 +--
 gcc/regset.h     | 3 +++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/gcc/cfgcleanup.c b/gcc/cfgcleanup.c
index 82fc505ff50..67ae0597cee 100644
--- a/gcc/cfgcleanup.c
+++ b/gcc/cfgcleanup.c
@@ -256,7 +256,6 @@ thread_jump (edge e, basic_block b)
   unsigned i;
   regset nonequal;
   bool failed = false;
-  reg_set_iterator rsi;
 
   /* Jump threading may cause fixup_partitions to introduce new crossing edges,
      which is not allowed after reload.  */
@@ -379,7 +378,7 @@ thread_jump (edge e, basic_block b)
       goto failed_exit;
     }
 
-  EXECUTE_IF_SET_IN_REG_SET (nonequal, 0, i, rsi)
+  if (!REG_SET_EMPTY_P (nonequal))
     goto failed_exit;
 
   BITMAP_FREE (nonequal);
diff --git a/gcc/regset.h b/gcc/regset.h
index aee6d6f974f..997b4d2d827 100644
--- a/gcc/regset.h
+++ b/gcc/regset.h
@@ -49,6 +49,9 @@ typedef bitmap regset;
 /* Clear a register set by freeing up the linked list.  */
 #define CLEAR_REG_SET(HEAD) bitmap_clear (HEAD)
 
+/* True if the register set is empty.  */
+#define REG_SET_EMPTY_P(HEAD) bitmap_empty_p (HEAD)
+
 /* Copy a register set to another register set.  */
 #define COPY_REG_SET(TO, FROM) bitmap_copy (TO, FROM)