[PATCH 1/2] Allow folding all statements.

This patch allows users of the substitute_and_fold_engine to
enable folding all statements.  It is now enabled for VRP which
is needed for the match.pd pattern in patch 2/2.

The loop versioning pass was missing one case when
deconstructing addresses that would only be triggered after
this patch for me:
It could handle addition and subsequent convert/nop but not
a convert/nop directly.  This would cause the hash to be
calculated differently and, in turn, cause the pass to miss
a versioning opportunity.  Fixed this by adding the missing
case.

--

gcc/ChangeLog:

2019-08-26  Robin Dapp  <rdapp@linux.ibm.com>

        * gimple-loop-versioning.cc (loop_versioning::record_address_fragment):
        Add nop_convert case.
        * tree-ssa-propagate.c (substitute_and_fold_dom_walker::before_dom_children):
        Fold all statements if requested.
        * tree-ssa-propagate.h (class substitute_and_fold_engine):
        Allow to fold all statements.
        * tree-vrp.c (class vrp_folder):
        Let substitute_and_fold_engine fold all statements.

From-SVN: r274923

gcc/ChangeLog

@@ -1,3 +1,14 @@
+2019-08-26  Robin Dapp  <rdapp@linux.ibm.com>
+
+	* gimple-loop-versioning.cc (loop_versioning::record_address_fragment):
+	Add nop_convert case.
+	* tree-ssa-propagate.c (substitute_and_fold_dom_walker::before_dom_children):
+	Fold all statements if requested.
+	* tree-ssa-propagate.h (class substitute_and_fold_engine):
+	Allow to fold all statements.
+	* tree-vrp.c (class vrp_folder):
+	Let substitute_and_fold_engine fold all statements.
+
 2019-08-26  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/91526

gcc/gimple-loop-versioning.cc

@@ -1266,6 +1266,12 @@ loop_versioning::record_address_fragment (gimple *stmt,
 		  continue;
 		}
 	    }
+	  if (CONVERT_EXPR_CODE_P (code))
+	    {
+	      tree op1 = gimple_assign_rhs1 (assign);
+	      address->terms[i].expr = strip_casts (op1);
+	      continue;
+	    }
 	}
       i += 1;
     }

gcc/tree-ssa-propagate.c

@@ -814,7 +814,6 @@ ssa_propagation_engine::ssa_propagate (void)
   ssa_prop_fini ();
 }
 
-
 /* Return true if STMT is of the form 'mem_ref = RHS', where 'mem_ref'
    is a non-volatile pointer dereference, a structure reference or a
    reference to a single _DECL.  Ignore volatile memory references
@@ -1071,6 +1070,14 @@ substitute_and_fold_dom_walker::before_dom_children (basic_block bb)
 	  stmt = gsi_stmt (i);
 	  gimple_set_modified (stmt, true);
 	}
+      /* Also fold if we want to fold all statements.  */
+      else if (substitute_and_fold_engine->fold_all_stmts
+	  && fold_stmt (&i, follow_single_use_edges))
+	{
+	  did_replace = true;
+	  stmt = gsi_stmt (i);
+	  gimple_set_modified (stmt, true);
+	}
 
       /* Some statements may be simplified using propagator
 	 specific information.  Do this before propagating

gcc/tree-ssa-propagate.h

@@ -100,6 +100,8 @@ class ssa_propagation_engine
 class substitute_and_fold_engine
 {
  public:
+  substitute_and_fold_engine (bool fold_all_stmts = false)
+    : fold_all_stmts (fold_all_stmts) { }
   virtual ~substitute_and_fold_engine (void) { }
   virtual bool fold_stmt (gimple_stmt_iterator *) { return false; }
   virtual tree get_value (tree) { return NULL_TREE; }
@@ -107,6 +109,10 @@ class substitute_and_fold_engine
   bool substitute_and_fold (basic_block = NULL);
   bool replace_uses_in (gimple *);
   bool replace_phi_args_in (gphi *);
+
+  /* Users like VRP can set this when they want to perform
+     folding for every propagation.  */
+  bool fold_all_stmts;
 };
 
 #endif /* _TREE_SSA_PROPAGATE_H  */

gcc/tree-vrp.c

@@ -6415,6 +6415,7 @@ vrp_prop::visit_phi (gphi *phi)
 class vrp_folder : public substitute_and_fold_engine
 {
  public:
+  vrp_folder () : substitute_and_fold_engine (/* Fold all stmts.  */ true) {  }
   tree get_value (tree) FINAL OVERRIDE;
   bool fold_stmt (gimple_stmt_iterator *) FINAL OVERRIDE;
   bool fold_predicate_in (gimple_stmt_iterator *);