[gcc r15-79] Fix ranger when called from SCEV.

[Andrew Macleod via Gcc-cvs]

https://gcc.gnu.org/g:e8ae56a7dc46e39a48017bb5159e4dc672ec7fad

commit r15-79-ge8ae56a7dc46e39a48017bb5159e4dc672ec7fad
Author: Andrew MacLeod <amacl...@redhat.com>
Date:   Wed Mar 13 14:10:41 2024 -0400

    Fix ranger when called from SCEV.
    
    Do not pre-evaluate PHIs in the cache, and allow fill_block_cache to
    be re-entrant.  This allows SCEV to call into ranger with a context
    and not produce cycles or loops.
    
            * gimple-range-cache.cc (ranger_cache::get_global_range): Do not
            pre-evaluate PHI nodes from the cache.
            (ranger_cache::fill_block_cache): Make re-entrant.

Diff:
---
 gcc/gimple-range-cache.cc | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/gcc/gimple-range-cache.cc b/gcc/gimple-range-cache.cc
index a33b7a73872..72ac2552311 100644
--- a/gcc/gimple-range-cache.cc
+++ b/gcc/gimple-range-cache.cc
@@ -1047,7 +1047,9 @@ ranger_cache::get_global_range (vrange &r, tree name, 
bool &current_p)
       if (r.varying_p () && !cfun->after_inlining)
        {
          gimple *s = SSA_NAME_DEF_STMT (name);
-         if (gimple_get_lhs (s) == name)
+         // Do not process PHIs as SCEV may be in use and it can
+         // spawn cyclic lookups.
+         if (gimple_get_lhs (s) == name && !is_a<gphi *> (s))
            {
              if (!fold_range (r, s, get_global_range_query ()))
                gimple_range_global (r, name);
@@ -1413,7 +1415,7 @@ ranger_cache::fill_block_cache (tree name, basic_block 
bb, basic_block def_bb)
 
   // At this point we shouldn't be looking at the def, entry block.
   gcc_checking_assert (bb != def_bb && bb != ENTRY_BLOCK_PTR_FOR_FN (cfun));
-  gcc_checking_assert (m_workback.length () == 0);
+  unsigned start_length = m_workback.length ();
 
   // If the block cache is set, then we've already visited this block.
   if (m_on_entry.bb_range_p (name, bb))
@@ -1500,7 +1502,7 @@ ranger_cache::fill_block_cache (tree name, basic_block 
bb, basic_block def_bb)
        }
 
       m_on_entry.set_bb_range (name, bb, block_result);
-      gcc_checking_assert (m_workback.length () == 0);
+      gcc_checking_assert (m_workback.length () == start_length);
       return;
     }
 
@@ -1512,7 +1514,7 @@ ranger_cache::fill_block_cache (tree name, basic_block 
bb, basic_block def_bb)
   m_on_entry.set_bb_range (name, bb, undefined);
   gcc_checking_assert (m_update->empty_p ());
 
-  while (m_workback.length () > 0)
+  while (m_workback.length () > start_length)
     {
       basic_block node = m_workback.pop ();
       if (DEBUG_RANGE_CACHE)