[gcc r15-357] [prange] Do not assume all pointers are the same size [PR115009]

[gcc r15-357] [prange] Do not assume all pointers are the same size [PR115009]

[Aldy Hernandez]

https://gcc.gnu.org/g:ac255c7afeb8a558bd6224ff77277eebcd849d6e

commit r15-357-gac255c7afeb8a558bd6224ff77277eebcd849d6e
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Thu May 9 23:37:30 2024 +0200

    [prange] Do not assume all pointers are the same size [PR115009]
    
    In a world with same sized pointers we can always reuse the storage
    slots, but since this is not always the case, we need to be more
    careful.  However, we can always store an undefined, because that
    requires no extra storage.
    
    gcc/ChangeLog:
    
            PR tree-optimization/115009
            * value-range-storage.cc (prange_storage::alloc): Do not assume
            all pointers are the same size.
            (prange_storage::prange_storage): Same.
            (prange_storage::fits_p): Same.

Diff:
---
 gcc/value-range-storage.cc | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/gcc/value-range-storage.cc b/gcc/value-range-storage.cc
index bbae0da4772d..8e8d61d59350 100644
--- a/gcc/value-range-storage.cc
+++ b/gcc/value-range-storage.cc
@@ -593,12 +593,12 @@ frange_storage::fits_p (const frange &) const
 prange_storage *
 prange_storage::alloc (vrange_internal_alloc &allocator, const prange &r)
 {
-  // Assume all pointers are the same size.
-  unsigned prec = TYPE_PRECISION (TREE_TYPE (null_pointer_node));
-  gcc_checking_assert (r.undefined_p () || TYPE_PRECISION (r.type ()) == prec);
-
-  typedef trailing_wide_ints<NINTS> twi;
-  size_t size = sizeof (prange_storage) + twi::extra_size (prec);
+  size_t size = sizeof (prange_storage);
+  if (!r.undefined_p ())
+    {
+      unsigned prec = TYPE_PRECISION (r.type ());
+      size += trailing_wide_ints<NINTS>::extra_size (prec);
+    }
   prange_storage *p = static_cast <prange_storage *> (allocator.alloc (size));
   new (p) prange_storage (r);
   return p;
@@ -610,8 +610,12 @@ prange_storage::prange_storage (const prange &r)
 {
   // It is the caller's responsibility to allocate enough space such
   // that the precision fits.
-  unsigned prec = TYPE_PRECISION (TREE_TYPE (null_pointer_node));
-  m_trailing_ints.set_precision (prec);
+  if (r.undefined_p ())
+    // Undefined ranges do not require any extra space for trailing
+    // wide ints.
+    m_trailing_ints.set_precision (0);
+  else
+    m_trailing_ints.set_precision (TYPE_PRECISION (r.type ()));
 
   set_prange (r);
 }
@@ -669,10 +673,14 @@ prange_storage::equal_p (const prange &r) const
 }
 
 bool
-prange_storage::fits_p (const prange &) const
+prange_storage::fits_p (const prange &r) const
 {
-  // All pointers are the same size.
-  return true;
+  // Undefined ranges always fit, because they don't store anything in
+  // the trailing wide ints.
+  if (r.undefined_p ())
+    return true;
+
+  return TYPE_PRECISION (r.type ()) <= m_trailing_ints.get_precision ();
 }