[gcc r12-6774] Only add equivalencies that are still valid.

[gcc r12-6774] Only add equivalencies that are still valid.

[Andrew Macleod]

https://gcc.gnu.org/g:6b73c07ec2e836a5cf7bacd6c7257fb8512c681e

commit r12-6774-g6b73c07ec2e836a5cf7bacd6c7257fb8512c681e
Author: Andrew MacLeod <amacleod@redhat.com>
Date:   Tue Jan 18 12:42:02 2022 -0500

    Only add equivalencies that are still valid.
    
    When equivalencies sets are merged, each member of the set should be queried
    to ensure its still valid rather than a bulk union.
    
            * value-relation.cc (relation_oracle::valid_equivs): Query and add
            if valid members of a set.
            (equiv_oracle::register_equiv): Call valid_equivs rather than
            bitmap direct operations.
            (path_oracle::register_equiv): Ditto.
            * value-relation.h (relation_oracle::valid_equivs): New prototype.

Diff:
---
 gcc/value-relation.cc | 41 +++++++++++++++++++++++++++++------------
 gcc/value-relation.h  |  2 ++
 2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/gcc/value-relation.cc b/gcc/value-relation.cc
index 32ca693c464..0134e0328ba 100644
--- a/gcc/value-relation.cc
+++ b/gcc/value-relation.cc
@@ -188,6 +188,23 @@ relation_transitive (relation_kind r1, relation_kind r2)
   return rr_transitive_table[r1 - VREL_FIRST][r2 - VREL_FIRST];
 }
 
+// Given an equivalence set EQUIV, set all the bits in B that are still valid
+// members of EQUIV in basic block BB.
+
+void
+relation_oracle::valid_equivs (bitmap b, const_bitmap equivs, basic_block bb)
+{
+  unsigned i;
+  bitmap_iterator bi;
+  EXECUTE_IF_SET_IN_BITMAP (equivs, 0, i, bi)
+    {
+      tree ssa = ssa_name (i);
+      const_bitmap ssa_equiv = equiv_set (ssa, bb);
+      if (ssa_equiv == equivs)
+	bitmap_set_bit (b, i);
+    }
+}
+
 // -------------------------------------------------------------------------
 
 // The very first element in the m_equiv chain is actually just a summary
@@ -364,7 +381,7 @@ equiv_oracle::register_equiv (basic_block bb, unsigned v, equiv_chain *equiv)
   // Otherwise create an equivalence for this block which is a copy
   // of equiv, the add V to the set.
   bitmap b = BITMAP_ALLOC (&m_bitmaps);
-  bitmap_copy (b, equiv->m_names);
+  valid_equivs (b, equiv->m_names, bb);
   bitmap_set_bit (b, v);
   return b;
 }
@@ -378,32 +395,32 @@ bitmap
 equiv_oracle::register_equiv (basic_block bb, equiv_chain *equiv_1,
 			      equiv_chain *equiv_2)
 {
-  // If equiv_1 is alreayd in BB, use it as the combined set.
+  // If equiv_1 is already in BB, use it as the combined set.
   if (equiv_1->m_bb == bb)
     {
-      bitmap_ior_into  (equiv_1->m_names, equiv_2->m_names);
+      valid_equivs (equiv_1->m_names, equiv_2->m_names, bb);
       // Its hard to delete from a single linked list, so
       // just clear the second one.
       if (equiv_2->m_bb == bb)
 	bitmap_clear (equiv_2->m_names);
       else
-	// Ensure equiv_2s names are in the summary for BB.
-	bitmap_ior_into (m_equiv[bb->index]->m_names, equiv_2->m_names);
+	// Ensure the new names are in the summary for BB.
+	bitmap_ior_into (m_equiv[bb->index]->m_names, equiv_1->m_names);
       return NULL;
     }
   // If equiv_2 is in BB, use it for the combined set.
   if (equiv_2->m_bb == bb)
     {
-      bitmap_ior_into (equiv_2->m_names, equiv_1->m_names);
-      // Add equiv_1 names into the summary.
-      bitmap_ior_into (m_equiv[bb->index]->m_names, equiv_1->m_names);
+      valid_equivs (equiv_2->m_names, equiv_1->m_names, bb);
+      // Ensure the new names are in the summary.
+      bitmap_ior_into (m_equiv[bb->index]->m_names, equiv_2->m_names);
       return NULL;
     }
 
   // At this point, neither equivalence is from this block.
   bitmap b = BITMAP_ALLOC (&m_bitmaps);
-  bitmap_copy (b, equiv_1->m_names);
-  bitmap_ior_into (b, equiv_2->m_names);
+  valid_equivs (b, equiv_1->m_names, bb);
+  valid_equivs (b, equiv_2->m_names, bb);
   return b;
 }
 
@@ -1289,8 +1306,8 @@ path_oracle::register_equiv (basic_block bb, tree ssa1, tree ssa2)
 
   // Don't mess around, simply create a new record and insert it first.
   bitmap b = BITMAP_ALLOC (&m_bitmaps);
-  bitmap_copy (b, equiv_1);
-  bitmap_ior_into (b, equiv_2);
+  valid_equivs (b, equiv_1, bb);
+  valid_equivs (b, equiv_2, bb);
 
   equiv_chain *ptr = (equiv_chain *) obstack_alloc (&m_chain_obstack,
 						    sizeof (equiv_chain));
diff --git a/gcc/value-relation.h b/gcc/value-relation.h
index 44d0796d939..d840234f355 100644
--- a/gcc/value-relation.h
+++ b/gcc/value-relation.h
@@ -96,6 +96,8 @@ public:
   virtual void dump (FILE *, basic_block) const = 0;
   virtual void dump (FILE *) const = 0;
   void debug () const;
+protected:
+  void valid_equivs (bitmap b, const_bitmap equivs, basic_block bb);
 };
 
 // This class represents an equivalency set, and contains a link to the next