Reset root oracle from path_oracle::reset_path.

When we cross a backedge in the path solver, we reset the path
relations and nuke the root oracle.  However, we forget to reset it
for the next path.  This is causing us to miss threads because
subsequent paths will have no root oracle to use.

With this patch we get 201 more threads in the threadfull passes in my
.ii files and 118 more overall (DOM gets less because threadfull runs
before).

Normally, I'd recommend this for the GCC 12 branch, but considering
how sensitive other passes are to jump threading, and that there is no
PR associated with this, perhaps we should leave this out.  Up to the
release maintainers of course.

gcc/ChangeLog:

	* gimple-range-path.cc
	(path_range_query::compute_ranges_in_block): Remove
	set_root_oracle call.
	(path_range_query::compute_ranges): Pass ranger oracle to
	reset_path.
	* value-relation.cc (path_oracle::reset_path): Set root oracle.
	* value-relation.h (path_oracle::reset_path): Add root oracle
	argument.

diff --git a/gcc/gimple-range-path.cc b/gcc/gimple-range-path.cc
index c99d77dd340775e32981658a1e86529d041924e5..73e248b7e0be1ea9e1976d4fc27af094c4fcf1b4 100644 (file)
--- a/gcc/gimple-range-path.cc
+++ b/gcc/gimple-range-path.cc
@@ -435,11 +435,10 @@ path_range_query::compute_ranges_in_block (basic_block bb)
                 e->src->index, e->dest->index);
 
       path_oracle *p = get_path_oracle ();
-      p->reset_path ();
       // ?? Instead of nuking the root oracle altogether, we could
       // reset the path oracle to search for relations from the top of
       // the loop with the root oracle.  Something for future development.
-      p->set_root_oracle (nullptr);
+      p->reset_path ();
     }
 
   gori_compute &g = m_ranger->gori ();
@@ -615,7 +614,10 @@ path_range_query::compute_ranges (const vec<basic_block> &path,
     compute_exit_dependencies (m_exit_dependencies, m_path);
 
   if (m_resolve)
-    get_path_oracle ()->reset_path ();
+    {
+      path_oracle *p = get_path_oracle ();
+      p->reset_path (m_ranger->oracle ());
+    }
 
   if (DEBUG_SOLVER)
     {

diff --git a/gcc/value-relation.cc b/gcc/value-relation.cc
index 3f0957ccdd64d455466f2239626815b50b33c6da..7fc22d30126d89364557d2b00c3c96100ab7b2bd 100644 (file)
--- a/gcc/value-relation.cc
+++ b/gcc/value-relation.cc
@@ -1513,11 +1513,13 @@ path_oracle::query_relation (basic_block bb, tree ssa1, tree ssa2)
   return query_relation (bb, equiv_1, equiv_2);
 }
 
-// Reset any relations registered on this path.
+// Reset any relations registered on this path.  ORACLE is the root
+// oracle to use.
 
 void
-path_oracle::reset_path ()
+path_oracle::reset_path (relation_oracle *oracle)
 {
+  set_root_oracle (oracle);
   m_equiv.m_next = NULL;
   bitmap_clear (m_equiv.m_names);
   m_relations.m_head = NULL;

diff --git a/gcc/value-relation.h b/gcc/value-relation.h
index 77e12085eea521884a39187887b8dd207a268a65..64884a8eea20c9ea055379ad191656d0051db5e5 100644 (file)
--- a/gcc/value-relation.h
+++ b/gcc/value-relation.h
@@ -242,7 +242,7 @@ public:
   relation_kind query_relation (basic_block, tree, tree) final override;
   relation_kind query_relation (basic_block, const_bitmap, const_bitmap)
     final override;
-  void reset_path ();
+  void reset_path (relation_oracle *oracle = NULL);
   void set_root_oracle (relation_oracle *oracle) { m_root = oracle; }
   void dump (FILE *, basic_block) const final override;
   void dump (FILE *) const final override;