[gcc r12-4860] Make sbitmap bitmap_set_bit and bitmap_clear_bit return changed state

[gcc r12-4860] Make sbitmap bitmap_set_bit and bitmap_clear_bit return changed state

[Richard Biener]

https://gcc.gnu.org/g:73658e70d9edfab77d7a50039b3ab7d2be3a41a0

commit r12-4860-g73658e70d9edfab77d7a50039b3ab7d2be3a41a0
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Nov 3 09:57:21 2021 +0100

    Make sbitmap bitmap_set_bit and bitmap_clear_bit return changed state
    
    The following adjusts the sbitmap bitmap_set_bit and bitmap_clear_bit
    APIs to match that of bitmap by returning a bool indicating whether
    the bitmap was changed.  I've also changed bitmap_bit_p to return
    a bool rather than an int and made use of the sbitmap bitmap_set_bit
    API change in one place.
    
    2021-11-03  Richard Biener  <rguenther@suse.de>
    
            * bitmap.h (bitmap_bit_p): Change the return type to bool.
            * bitmap.c (bitmap_bit_p): Likewise.
            * sbitmap.h (bitmap_bit_p): Likewise.
            (bitmap_set_bit): Return whether the bit changed.
            (bitmap_clear_bit): Likewise.
            * tree-ssa.c (verify_vssa): Make use of the changed state
            from bitmap_set_bit.

Diff:
---
 gcc/bitmap.c   |  2 +-
 gcc/bitmap.h   |  2 +-
 gcc/sbitmap.h  | 28 +++++++++++++++++++---------
 gcc/tree-ssa.c |  4 +---
 4 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/gcc/bitmap.c b/gcc/bitmap.c
index 98c6d0b9e05..1aa8e4b3134 100644
--- a/gcc/bitmap.c
+++ b/gcc/bitmap.c
@@ -983,7 +983,7 @@ bitmap_set_bit (bitmap head, int bit)
 
 /* Return whether a bit is set within a bitmap.  */
 
-int
+bool
 bitmap_bit_p (const_bitmap head, int bit)
 {
   unsigned int indx = bit / BITMAP_ELEMENT_ALL_BITS;
diff --git a/gcc/bitmap.h b/gcc/bitmap.h
index 1bddcdbfaee..fc33877c89d 100644
--- a/gcc/bitmap.h
+++ b/gcc/bitmap.h
@@ -436,7 +436,7 @@ extern bool bitmap_clear_bit (bitmap, int);
 extern bool bitmap_set_bit (bitmap, int);
 
 /* Return true if a bit is set in a bitmap.  */
-extern int bitmap_bit_p (const_bitmap, int);
+extern bool bitmap_bit_p (const_bitmap, int);
 
 /* Set and get multiple bit values in a sparse bitmap.  This allows a bitmap to
    function as a sparse array of bit patterns where the patterns are
diff --git a/gcc/sbitmap.h b/gcc/sbitmap.h
index 17660e5a65e..5fb0e005957 100644
--- a/gcc/sbitmap.h
+++ b/gcc/sbitmap.h
@@ -114,7 +114,7 @@ bitmap_check_sizes (const_sbitmap a, const_sbitmap b)
 }
 
 /* Test if bit number bitno in the bitmap is set.  */
-static inline SBITMAP_ELT_TYPE
+static inline bool
 bitmap_bit_p (const_sbitmap map, int bitno)
 {
   bitmap_check_index (map, bitno);
@@ -124,26 +124,36 @@ bitmap_bit_p (const_sbitmap map, int bitno)
   return (map->elms[i] >> s) & (SBITMAP_ELT_TYPE) 1;
 }
 
-/* Set bit number BITNO in the sbitmap MAP.  */
+/* Set bit number BITNO in the sbitmap MAP.
+   Return true if the bit changed.  */
 
-static inline void
+static inline bool
 bitmap_set_bit (sbitmap map, int bitno)
 {
   bitmap_check_index (map, bitno);
 
-  map->elms[bitno / SBITMAP_ELT_BITS]
-    |= (SBITMAP_ELT_TYPE) 1 << (bitno) % SBITMAP_ELT_BITS;
+  size_t i = bitno / SBITMAP_ELT_BITS;
+  unsigned int s = bitno % SBITMAP_ELT_BITS;
+  if (map->elms[i] & ((SBITMAP_ELT_TYPE) 1 << s))
+    return false;
+  map->elms[i] |= (SBITMAP_ELT_TYPE) 1 << s;
+  return true;
 }
 
-/* Reset bit number BITNO in the sbitmap MAP.  */
+/* Reset bit number BITNO in the sbitmap MAP.
+   Return true if the bit changed.  */
 
-static inline void
+static inline bool
 bitmap_clear_bit (sbitmap map, int bitno)
 {
   bitmap_check_index (map, bitno);
 
-  map->elms[bitno / SBITMAP_ELT_BITS]
-    &= ~((SBITMAP_ELT_TYPE) 1 << (bitno) % SBITMAP_ELT_BITS);
+  size_t i = bitno / SBITMAP_ELT_BITS;
+  unsigned int s = bitno % SBITMAP_ELT_BITS;
+  if (!(map->elms[i] & ((SBITMAP_ELT_TYPE) 1 << s)))
+    return false;
+  map->elms[i] &= ~((SBITMAP_ELT_TYPE) 1 << s);
+  return true;
 }
 
 /* The iterator for sbitmap.  */
diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index fde13defebf..3f25d654d3f 100644
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -649,11 +649,9 @@ verify_vssa (basic_block bb, tree current_vdef, sbitmap visited)
 {
   bool err = false;
 
-  if (bitmap_bit_p (visited, bb->index))
+  if (!bitmap_set_bit (visited, bb->index))
     return false;
 
-  bitmap_set_bit (visited, bb->index);
-
   /* Pick up the single virtual PHI def.  */
   gphi *phi = NULL;
   for (gphi_iterator si = gsi_start_phis (bb); !gsi_end_p (si);