tree-optimization/93946 - fix bogus redundant store removal in FRE, DSE and DOM

This fixes a common mistake in removing a store that looks redudnant but
is not because it changes the dynamic type of the memory and thus makes
a difference for following loads with TBAA.

2020-03-03  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/93946
	* alias.h (refs_same_for_tbaa_p): Declare.
	* alias.c (refs_same_for_tbaa_p): New function.
	* tree-ssa-alias.c (ao_ref_alias_set): For a NULL ref return
	zero.
	* tree-ssa-scopedtables.h
	(avail_exprs_stack::lookup_avail_expr): Add output argument
	giving access to the hashtable entry.
	* tree-ssa-scopedtables.c (avail_exprs_stack::lookup_avail_expr):
	Likewise.
	* tree-ssa-dom.c: Include alias.h.
	(dom_opt_dom_walker::optimize_stmt): Validate TBAA state before
	removing redundant store.
	* tree-ssa-sccvn.h (vn_reference_s::base_set): New member.
	(ao_ref_init_from_vn_reference): Adjust prototype.
	(vn_reference_lookup_pieces): Likewise.
	(vn_reference_insert_pieces): Likewise.
	* tree-ssa-sccvn.c: Track base alias set in addition to alias
	set everywhere.
	(eliminate_dom_walker::eliminate_stmt): Also check base alias
	set when removing redundant stores.
	(visit_reference_op_store): Likewise.
	* dse.c (record_store): Adjust valdity check for redundant
	store removal.

	* gcc.dg/torture/pr93946-1.c: New testcase.
	* gcc.dg/torture/pr93946-2.c: Likewise.

15 files changed, 305 insertions, 123 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 08ce80e25e4..b764b6152b1 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,30 @@
+2020-03-03  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/93946
+	* alias.h (refs_same_for_tbaa_p): Declare.
+	* alias.c (refs_same_for_tbaa_p): New function.
+	* tree-ssa-alias.c (ao_ref_alias_set): For a NULL ref return
+	zero.
+	* tree-ssa-scopedtables.h
+	(avail_exprs_stack::lookup_avail_expr): Add output argument
+	giving access to the hashtable entry.
+	* tree-ssa-scopedtables.c (avail_exprs_stack::lookup_avail_expr):
+	Likewise.
+	* tree-ssa-dom.c: Include alias.h.
+	(dom_opt_dom_walker::optimize_stmt): Validate TBAA state before
+	removing redundant store.
+	* tree-ssa-sccvn.h (vn_reference_s::base_set): New member.
+	(ao_ref_init_from_vn_reference): Adjust prototype.
+	(vn_reference_lookup_pieces): Likewise.
+	(vn_reference_insert_pieces): Likewise.
+	* tree-ssa-sccvn.c: Track base alias set in addition to alias
+	set everywhere.
+	(eliminate_dom_walker::eliminate_stmt): Also check base alias
+	set when removing redundant stores.
+	(visit_reference_op_store): Likewise.
+	* dse.c (record_store): Adjust valdity check for redundant
+	store removal.
+
 2020-03-03  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/26877
diff --git a/gcc/alias.c b/gcc/alias.c
index fe75e22cdb5..d38e386d0e8 100644
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -368,6 +368,26 @@ rtx_refs_may_alias_p (const_rtx x, const_rtx mem, bool tbaa_p)
 			     && MEM_ALIAS_SET (mem) != 0);
 }
 
+/* Return true if the ref EARLIER behaves the same as LATER with respect
+   to TBAA for every memory reference that might follow LATER.  */
+
+bool
+refs_same_for_tbaa_p (tree earlier, tree later)
+{
+  ao_ref earlier_ref, later_ref;
+  ao_ref_init (&earlier_ref, earlier);
+  ao_ref_init (&later_ref, later);
+  alias_set_type earlier_set = ao_ref_alias_set (&earlier_ref);
+  alias_set_type later_set = ao_ref_alias_set (&later_ref);
+  if (!(earlier_set == later_set
+	|| alias_set_subset_of (later_set, earlier_set)))
+    return false;
+  alias_set_type later_base_set = ao_ref_base_alias_set (&later_ref);
+  alias_set_type earlier_base_set = ao_ref_base_alias_set (&earlier_ref);
+  return (earlier_base_set == later_base_set
+	  || alias_set_subset_of (later_base_set, earlier_base_set));
+}
+
 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
    such an entry, or NULL otherwise.  */
 
diff --git a/gcc/alias.h b/gcc/alias.h
index 781b040fec1..4453d9723ce 100644
--- a/gcc/alias.h
+++ b/gcc/alias.h
@@ -38,6 +38,7 @@ extern void dump_alias_stats_in_alias_c (FILE *s);
 tree reference_alias_ptr_type (tree);
 bool alias_ptr_types_compatible_p (tree, tree);
 int compare_base_decls (tree, tree);
+bool refs_same_for_tbaa_p (tree, tree);
 
 /* This alias set can be used to force a memory to conflict with all
    other memories, creating a barrier across which no memory reference
diff --git a/gcc/dse.c b/gcc/dse.c
index fe1181b502f..0d96bd43457 100644
--- a/gcc/dse.c
+++ b/gcc/dse.c
@@ -1540,9 +1540,12 @@ record_store (rtx body, bb_info_t bb_info)
 					 width)
 	      /* We can only remove the later store if the earlier aliases
 		 at least all accesses the later one.  */
-	      && (MEM_ALIAS_SET (mem) == MEM_ALIAS_SET (s_info->mem)
-		  || alias_set_subset_of (MEM_ALIAS_SET (mem),
-					  MEM_ALIAS_SET (s_info->mem))))
+	      && ((MEM_ALIAS_SET (mem) == MEM_ALIAS_SET (s_info->mem)
+		   || alias_set_subset_of (MEM_ALIAS_SET (mem),
+					   MEM_ALIAS_SET (s_info->mem)))
+		  && (!MEM_EXPR (s_info->mem)
+		      || refs_same_for_tbaa_p (MEM_EXPR (s_info->mem),
+					       MEM_EXPR (mem)))))
 	    {
 	      if (GET_MODE (mem) == BLKmode)
 		{
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c4aa9102460..3990df0166f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2020-03-03  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/93946
+	* gcc.dg/torture/pr93946-1.c: New testcase.
+	* gcc.dg/torture/pr93946-2.c: Likewise.
+
 2020-03-03  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/94002
diff --git a/gcc/testsuite/gcc.dg/torture/pr93946-1.c b/gcc/testsuite/gcc.dg/torture/pr93946-1.c
new file mode 100644
index 00000000000..d7cfc91f95c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr93946-1.c
@@ -0,0 +1,27 @@
+/* { dg-do run } */
+
+union U { long long i; long f; };
+struct a {union U u;};
+struct aa {struct a a;};
+struct b {union U u;};
+struct bb {struct b b;};
+
+long __attribute__((noipa))
+foo (struct bb *bv, void *ptr)
+{
+  struct aa *a = ptr;
+  struct bb *b = ptr;
+  bv->b.u.f = 1;
+  a->a.u.i = 0;
+  b->b.u.f = 0;
+  return bv->b.u.f;
+}
+
+int
+main ()
+{
+  union C {struct aa aa; struct bb bb;} v;
+  if (foo (&v.bb, &v) != 0)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/torture/pr93946-2.c b/gcc/testsuite/gcc.dg/torture/pr93946-2.c
new file mode 100644
index 00000000000..4c73e58f407
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr93946-2.c
@@ -0,0 +1,28 @@
+/* { dg-do run } */
+/* { dg-additional-options "-fno-tree-dse" } */
+
+union U { long long i; long f; };
+struct a {union U u;};
+struct aa {struct a a;};
+struct b {union U u;};
+struct bb {struct b b;};
+
+long __attribute__((noipa))
+foo (struct bb *bv, void *ptr)
+{
+  struct aa *a = ptr;
+  struct bb *b = ptr;
+  bv->b.u.f = 1;
+  a->a.u.i = 0;
+  b->b.u.f = 0;
+  return bv->b.u.f;
+}
+
+int
+main ()
+{
+  union C {struct aa aa; struct bb bb;} v;
+  if (foo (&v.bb, &v) != 0)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 2e8290f35d5..df9ba0de0d6 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -697,6 +697,8 @@ ao_ref_alias_set (ao_ref *ref)
 {
   if (ref->ref_alias_set != -1)
     return ref->ref_alias_set;
+  if (!ref->ref)
+    return 0;
   ref->ref_alias_set = get_alias_set (ref->ref);
   return ref->ref_alias_set;
 }
diff --git a/gcc/tree-ssa-dom.c b/gcc/tree-ssa-dom.c
index 1dbfb3840f7..eea494c8a96 100644
--- a/gcc/tree-ssa-dom.c
+++ b/gcc/tree-ssa-dom.c
@@ -49,6 +49,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-vrp.h"
 #include "vr-values.h"
 #include "gimple-ssa-evrp-analyze.h"
+#include "alias.h"
 
 /* This file implements optimizations on the dominator tree.  */
 
@@ -2155,9 +2156,14 @@ dom_opt_dom_walker::optimize_stmt (basic_block bb, gimple_stmt_iterator *si,
 	  else
 	    new_stmt = gimple_build_assign (rhs, lhs);
 	  gimple_set_vuse (new_stmt, gimple_vuse (stmt));
+	  expr_hash_elt *elt = NULL;
 	  cached_lhs = m_avail_exprs_stack->lookup_avail_expr (new_stmt, false,
-							       false);
-	  if (cached_lhs && operand_equal_p (rhs, cached_lhs, 0))
+							       false, &elt);
+	  if (cached_lhs
+	      && operand_equal_p (rhs, cached_lhs, 0)
+	      && refs_same_for_tbaa_p (elt->expr ()->kind == EXPR_SINGLE
+				       ? elt->expr ()->ops.single.rhs
+				       : NULL_TREE, lhs))
 	    {
 	      basic_block bb = gimple_bb (stmt);
 	      unlink_stmt_vdef (stmt);
diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
index 374143e5785..f2a4ed97a36 100644
--- a/gcc/tree-ssa-dse.c
+++ b/gcc/tree-ssa-dse.c
@@ -658,6 +658,17 @@ dse_optimize_redundant_stores (gimple *stmt)
 {
   int cnt = 0;
 
+  /* TBAA state of STMT, if it is a call it is effectively alias-set zero.  */
+  alias_set_type earlier_set = 0;
+  alias_set_type earlier_base_set = 0;
+  if (is_gimple_assign (stmt))
+    {
+      ao_ref lhs_ref;
+      ao_ref_init (&lhs_ref, gimple_assign_lhs (stmt));
+      earlier_set = ao_ref_alias_set (&lhs_ref);
+      earlier_base_set = ao_ref_base_alias_set (&lhs_ref);
+    }
+
   /* We could do something fairly complex and look through PHIs
      like DSE_CLASSIFY_STORE, but it doesn't seem to be worth
      the effort.
@@ -698,10 +709,27 @@ dse_optimize_redundant_stores (gimple *stmt)
 	    {
 	      gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
 	      if (is_gimple_assign (use_stmt))
-		delete_dead_or_redundant_assignment (&gsi, "redundant",
-						     need_eh_cleanup);
+		{
+		  ao_ref lhs_ref;
+		  ao_ref_init (&lhs_ref, gimple_assign_lhs (use_stmt));
+		  if ((earlier_set == ao_ref_alias_set (&lhs_ref)
+		       || alias_set_subset_of (ao_ref_alias_set (&lhs_ref),
+					       earlier_set))
+		      && (earlier_base_set == ao_ref_base_alias_set (&lhs_ref)
+			  || alias_set_subset_of
+			       (ao_ref_base_alias_set (&lhs_ref),
+						  earlier_base_set)))
+		    delete_dead_or_redundant_assignment (&gsi, "redundant",
+							 need_eh_cleanup);
+		}
 	      else if (is_gimple_call (use_stmt))
-		delete_dead_or_redundant_call (&gsi, "redundant");
+		{
+		  if ((earlier_set == 0
+		       || alias_set_subset_of (0, earlier_set))
+		      && (earlier_base_set == 0
+			  || alias_set_subset_of (0, earlier_base_set)))
+		  delete_dead_or_redundant_call (&gsi, "redundant");
+		}
 	      else
 		gcc_unreachable ();
 	    }
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index eaed4b16ed8..29987d840fd 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -1140,7 +1140,8 @@ fully_constant_expression (pre_expr e)
 
 static tree
 translate_vuse_through_block (vec<vn_reference_op_s> operands,
-			      alias_set_type set, tree type, tree vuse,
+			      alias_set_type set, alias_set_type base_set,
+			      tree type, tree vuse,
 			      basic_block phiblock,
 			      basic_block block, bool *same_valid)
 {
@@ -1156,7 +1157,8 @@ translate_vuse_through_block (vec<vn_reference_op_s> operands,
     return vuse;
 
   unsigned int cnt = param_sccvn_max_alias_queries_per_access;
-  use_oracle = ao_ref_init_from_vn_reference (&ref, set, type, operands);
+  use_oracle = ao_ref_init_from_vn_reference (&ref, set, base_set,
+					      type, operands);
 
   /* Use the alias-oracle to find either the PHI node in this block,
      the first VUSE used in this block that is equivalent to vuse or
@@ -1535,7 +1537,8 @@ phi_translate_1 (bitmap_set_t dest,
 	  {
 	    newvuse = translate_vuse_through_block (newoperands.exists ()
 						    ? newoperands : operands,
-						    ref->set, ref->type,
+						    ref->set, ref->base_set,
+						    ref->type,
 						    vuse, phiblock, pred,
 						    changed
 						    ? NULL : &same_valid);
@@ -1551,6 +1554,7 @@ phi_translate_1 (bitmap_set_t dest,
 	    unsigned int new_val_id;
 
 	    tree result = vn_reference_lookup_pieces (newvuse, ref->set,
+						      ref->base_set,
 						      ref->type,
 						      newoperands.exists ()
 						      ? newoperands : operands,
@@ -1608,7 +1612,7 @@ phi_translate_1 (bitmap_set_t dest,
 		if (!newoperands.exists ())
 		  newoperands = operands.copy ();
 		newref = vn_reference_insert_pieces (newvuse, ref->set,
-						     ref->type,
+						     ref->base_set, ref->type,
 						     newoperands,
 						     result, new_val_id);
 		newoperands = vNULL;
@@ -1827,8 +1831,8 @@ value_dies_in_block_x (pre_expr expr, basic_block block)
 
       /* Init ref only if we really need it.  */
       if (ref.base == NULL_TREE
-	  && !ao_ref_init_from_vn_reference (&ref, refx->set, refx->type,
-					     refx->operands))
+	  && !ao_ref_init_from_vn_reference (&ref, refx->set, refx->base_set,
+					     refx->type, refx->operands))
 	{
 	  res = true;
 	  break;
@@ -3914,12 +3918,16 @@ compute_avail (void)
 		  case VN_REFERENCE:
 		    {
 		      tree rhs1 = gimple_assign_rhs1 (stmt);
-		      alias_set_type set = get_alias_set (rhs1);
+		      ao_ref rhs1_ref;
+		      ao_ref_init (&rhs1_ref, rhs1);
+		      alias_set_type set = ao_ref_alias_set (&rhs1_ref);
+		      alias_set_type base_set
+			= ao_ref_base_alias_set (&rhs1_ref);
 		      vec<vn_reference_op_s> operands
 			= vn_reference_operands_for_lookup (rhs1);
 		      vn_reference_t ref;
 		      vn_reference_lookup_pieces (gimple_vuse (stmt), set,
-						  TREE_TYPE (rhs1),
+						  base_set, TREE_TYPE (rhs1),
 						  operands, &ref, VN_WALK);
 		      if (!ref)
 			{
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index e260ca4eed1..1015875591c 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -367,7 +367,8 @@ static void init_vn_nary_op_from_pieces (vn_nary_op_t, unsigned int,
 					 enum tree_code, tree, tree *);
 static tree vn_lookup_simplify_result (gimple_match_op *);
 static vn_reference_t vn_reference_lookup_or_insert_for_pieces
-	  (tree, alias_set_type, tree, vec<vn_reference_op_s, va_heap>, tree);
+	  (tree, alias_set_type, alias_set_type, tree,
+	   vec<vn_reference_op_s, va_heap>, tree);
 
 /* Return whether there is value numbering information for a given SSA name.  */
 
@@ -982,8 +983,8 @@ copy_reference_ops_from_ref (tree ref, vec<vn_reference_op_s> *result)
 
 bool
 ao_ref_init_from_vn_reference (ao_ref *ref,
-			       alias_set_type set, tree type,
-			       vec<vn_reference_op_s> ops)
+			       alias_set_type set, alias_set_type base_set,
+			       tree type, vec<vn_reference_op_s> ops)
 {
   vn_reference_op_t op;
   unsigned i;
@@ -993,7 +994,6 @@ ao_ref_init_from_vn_reference (ao_ref *ref,
   poly_offset_int max_size;
   poly_offset_int size = -1;
   tree size_tree = NULL_TREE;
-  alias_set_type base_alias_set = -1;
 
   /* First get the final access size from just the outermost expression.  */
   op = &ops[0];
@@ -1050,7 +1050,6 @@ ao_ref_init_from_vn_reference (ao_ref *ref,
 
 	/* Record the base objects.  */
 	case MEM_REF:
-	  base_alias_set = get_deref_alias_set (op->op0);
 	  *op0_p = build2 (MEM_REF, op->type,
 			   NULL_TREE, op->op0);
 	  MR_DEPENDENCE_CLIQUE (*op0_p) = op->clique;
@@ -1140,10 +1139,7 @@ ao_ref_init_from_vn_reference (ao_ref *ref,
   ref->ref = NULL_TREE;
   ref->base = base;
   ref->ref_alias_set = set;
-  if (base_alias_set != -1)
-    ref->base_alias_set = base_alias_set;
-  else
-    ref->base_alias_set = get_alias_set (base);
+  ref->base_alias_set = base_set;
   /* We discount volatiles from value-numbering elsewhere.  */
   ref->volatile_p = false;
 
@@ -1689,15 +1685,17 @@ struct vn_walk_cb_data
 		   vn_lookup_kind vn_walk_kind_, bool tbaa_p_)
     : vr (vr_), last_vuse_ptr (last_vuse_ptr_), last_vuse (NULL_TREE),
       vn_walk_kind (vn_walk_kind_), tbaa_p (tbaa_p_),
-      saved_operands (vNULL), first_set (-2), known_ranges (NULL)
+      saved_operands (vNULL), first_set (-2), first_base_set (-2),
+      known_ranges (NULL)
    {
      if (!last_vuse_ptr)
        last_vuse_ptr = &last_vuse;
      ao_ref_init (&orig_ref, orig_ref_);
    }
   ~vn_walk_cb_data ();
-  void *finish (alias_set_type, tree);
-  void *push_partial_def (const pd_data& pd, alias_set_type, HOST_WIDE_INT);
+  void *finish (alias_set_type, alias_set_type, tree);
+  void *push_partial_def (const pd_data& pd,
+			  alias_set_type, alias_set_type, HOST_WIDE_INT);
 
   vn_reference_t vr;
   ao_ref orig_ref;
@@ -1712,6 +1710,7 @@ struct vn_walk_cb_data
   /* The first defs range to avoid splay tree setup in most cases.  */
   pd_range first_range;
   alias_set_type first_set;
+  alias_set_type first_base_set;
   splay_tree known_ranges;
   obstack ranges_obstack;
 };
@@ -1727,12 +1726,15 @@ vn_walk_cb_data::~vn_walk_cb_data ()
 }
 
 void *
-vn_walk_cb_data::finish (alias_set_type set, tree val)
+vn_walk_cb_data::finish (alias_set_type set, alias_set_type base_set, tree val)
 {
   if (first_set != -2)
-    set = first_set;
+    {
+      set = first_set;
+      base_set = first_base_set;
+    }
   return vn_reference_lookup_or_insert_for_pieces
-      (last_vuse, set, vr->type,
+      (last_vuse, set, base_set, vr->type,
        saved_operands.exists () ? saved_operands : vr->operands, val);
 }
 
@@ -1769,7 +1771,8 @@ pd_tree_dealloc (void *, void *)
 
 void *
 vn_walk_cb_data::push_partial_def (const pd_data &pd,
-				   alias_set_type set, HOST_WIDE_INT maxsizei)
+				   alias_set_type set, alias_set_type base_set,
+				   HOST_WIDE_INT maxsizei)
 {
   const HOST_WIDE_INT bufsize = 64;
   /* We're using a fixed buffer for encoding so fail early if the object
@@ -1794,6 +1797,7 @@ vn_walk_cb_data::push_partial_def (const pd_data &pd,
       first_range.offset = pd.offset;
       first_range.size = pd.size;
       first_set = set;
+      first_base_set = base_set;
       last_vuse_ptr = NULL;
       /* Continue looking for partial defs.  */
       return NULL;
@@ -2062,7 +2066,7 @@ vn_walk_cb_data::push_partial_def (const pd_data &pd,
 		 "Successfully combined %u partial definitions\n", ndefs);
       /* We are using the alias-set of the first store we encounter which
 	 should be appropriate here.  */
-      return finish (first_set, val);
+      return finish (first_set, first_base_set, val);
     }
   else
     {
@@ -2107,7 +2111,7 @@ vn_reference_lookup_2 (ao_ref *op ATTRIBUTE_UNUSED, tree vuse, void *data_)
   if (slot)
     {
       if ((*slot)->result && data->saved_operands.exists ())
-	return data->finish (vr->set, (*slot)->result);
+	return data->finish (vr->set, vr->base_set, (*slot)->result);
       return *slot;
     }
 
@@ -2121,6 +2125,7 @@ vn_reference_lookup_2 (ao_ref *op ATTRIBUTE_UNUSED, tree vuse, void *data_)
 static vn_reference_t
 vn_reference_lookup_or_insert_for_pieces (tree vuse,
 					  alias_set_type set,
+					  alias_set_type base_set,
 					  tree type,
 					  vec<vn_reference_op_s,
 					        va_heap> operands,
@@ -2133,6 +2138,7 @@ vn_reference_lookup_or_insert_for_pieces (tree vuse,
   vr1.operands = operands;
   vr1.type = type;
   vr1.set = set;
+  vr1.base_set = base_set;
   vr1.hashcode = vn_reference_compute_hash (&vr1);
   if (vn_reference_lookup_1 (&vr1, &result))
     return result;
@@ -2140,7 +2146,7 @@ vn_reference_lookup_or_insert_for_pieces (tree vuse,
     value_id = VN_INFO (value)->value_id;
   else
     value_id = get_or_alloc_constant_value_id (value);
-  return vn_reference_insert_pieces (vuse, set, type,
+  return vn_reference_insert_pieces (vuse, set, base_set, type,
 				     operands.copy (), value, value_id);
 }
 
@@ -2407,22 +2413,16 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	  lhs_ops = valueize_refs_1 (lhs_ops, &valueized_anything, true);
 	}
       vn_context_bb = saved_rpo_bb;
-      if (valueized_anything)
+      ao_ref_init (&lhs_ref, lhs);
+      lhs_ref_ok = true;
+      if (valueized_anything
+	  && ao_ref_init_from_vn_reference
+	       (&lhs_ref, ao_ref_alias_set (&lhs_ref),
+		ao_ref_base_alias_set (&lhs_ref), TREE_TYPE (lhs), lhs_ops)
+	  && !refs_may_alias_p_1 (ref, &lhs_ref, data->tbaa_p))
 	{
-	  lhs_ref_ok = ao_ref_init_from_vn_reference (&lhs_ref,
-						      get_alias_set (lhs),
-						      TREE_TYPE (lhs), lhs_ops);
-	  if (lhs_ref_ok
-	      && !refs_may_alias_p_1 (ref, &lhs_ref, data->tbaa_p))
-	    {
-	      *disambiguate_only = TR_VALUEIZE_AND_DISAMBIGUATE;
-	      return NULL;
-	    }
-	}
-      else
-	{
-	  ao_ref_init (&lhs_ref, lhs);
-	  lhs_ref_ok = true;
+	  *disambiguate_only = TR_VALUEIZE_AND_DISAMBIGUATE;
+	  return NULL;
 	}
 
       /* Besides valueizing the LHS we can also use access-path based
@@ -2673,7 +2673,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	      if (!val)
 		return (void *)-1;
 	    }
-	  return data->finish (0, val);
+	  return data->finish (0, 0, val);
 	}
       /* For now handle clearing memory with partial defs.  */
       else if (known_eq (ref->size, maxsize)
@@ -2691,7 +2691,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	  pd.rhs = build_constructor (NULL_TREE, NULL);
 	  pd.offset = offset2i - offseti;
 	  pd.size = leni << LOG2_BITS_PER_UNIT;
-	  return data->push_partial_def (pd, 0, maxsizei);
+	  return data->push_partial_def (pd, 0, 0, maxsizei);
 	}
     }
 
@@ -2701,22 +2701,14 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	   && gimple_assign_rhs_code (def_stmt) == CONSTRUCTOR
 	   && CONSTRUCTOR_NELTS (gimple_assign_rhs1 (def_stmt)) == 0)
     {
-      tree lhs = gimple_assign_lhs (def_stmt);
       tree base2;
       poly_int64 offset2, size2, maxsize2;
       HOST_WIDE_INT offset2i, size2i;
-      bool reverse;
-      if (lhs_ref_ok)
-	{
-	  base2 = ao_ref_base (&lhs_ref);
-	  offset2 = lhs_ref.offset;
-	  size2 = lhs_ref.size;
-	  maxsize2 = lhs_ref.max_size;
-	  reverse = reverse_storage_order_for_component_p (lhs);
-	}
-      else
-	base2 = get_ref_base_and_extent (lhs,
-					 &offset2, &size2, &maxsize2, &reverse);
+      gcc_assert (lhs_ref_ok);
+      base2 = ao_ref_base (&lhs_ref);
+      offset2 = lhs_ref.offset;
+      size2 = lhs_ref.size;
+      maxsize2 = lhs_ref.max_size;
       if (known_size_p (maxsize2)
 	  && known_eq (maxsize2, size2)
 	  && adjust_offsets_for_equal_base_address (base, &offset,
@@ -2730,7 +2722,8 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	      if (gimple_clobber_p (def_stmt))
 		return (void *)-1;
 	      tree val = build_zero_cst (vr->type);
-	      return data->finish (get_alias_set (lhs), val);
+	      return data->finish (ao_ref_alias_set (&lhs_ref),
+				   ao_ref_base_alias_set (&lhs_ref), val);
 	    }
 	  else if (known_eq (ref->size, maxsize)
 		   && maxsize.is_constant (&maxsizei)
@@ -2747,7 +2740,9 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	      pd.rhs = gimple_assign_rhs1 (def_stmt);
 	      pd.offset = offset2i - offseti;
 	      pd.size = size2i;
-	      return data->push_partial_def (pd, get_alias_set (lhs), maxsizei);
+	      return data->push_partial_def (pd, ao_ref_alias_set (&lhs_ref),
+					     ao_ref_base_alias_set (&lhs_ref),
+					     maxsizei);
 	    }
 	}
     }
@@ -2774,17 +2769,12 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
       poly_int64 offset2, size2, maxsize2;
       HOST_WIDE_INT offset2i, size2i;
       bool reverse;
-      if (lhs_ref_ok)
-	{
-	  base2 = ao_ref_base (&lhs_ref);
-	  offset2 = lhs_ref.offset;
-	  size2 = lhs_ref.size;
-	  maxsize2 = lhs_ref.max_size;
-	  reverse = reverse_storage_order_for_component_p (lhs);
-	}
-      else
-	base2 = get_ref_base_and_extent (lhs,
-					 &offset2, &size2, &maxsize2, &reverse);
+      gcc_assert (lhs_ref_ok);
+      base2 = ao_ref_base (&lhs_ref);
+      offset2 = lhs_ref.offset;
+      size2 = lhs_ref.size;
+      maxsize2 = lhs_ref.max_size;
+      reverse = reverse_storage_order_for_component_p (lhs);
       if (base2
 	  && !reverse
 	  && !storage_order_barrier_p (lhs)
@@ -2887,7 +2877,8 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 		    }
 
 		  if (val)
-		    return data->finish (get_alias_set (lhs), val);
+		    return data->finish (ao_ref_alias_set (&lhs_ref),
+					 ao_ref_base_alias_set (&lhs_ref), val);
 		}
 	    }
 	  else if (ranges_known_overlap_p (offseti, maxsizei, offset2i,
@@ -2900,7 +2891,9 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	      pd.rhs = rhs;
 	      pd.offset = offset2i - offseti;
 	      pd.size = size2i;
-	      return data->push_partial_def (pd, get_alias_set (lhs), maxsizei);
+	      return data->push_partial_def (pd, ao_ref_alias_set (&lhs_ref),
+					     ao_ref_base_alias_set (&lhs_ref),
+					     maxsizei);
 	    }
 	}
     }
@@ -2918,17 +2911,12 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
       poly_int64 offset2, size2, maxsize2;
       HOST_WIDE_INT offset2i, size2i, offseti;
       bool reverse;
-      if (lhs_ref_ok)
-	{
-	  base2 = ao_ref_base (&lhs_ref);
-	  offset2 = lhs_ref.offset;
-	  size2 = lhs_ref.size;
-	  maxsize2 = lhs_ref.max_size;
-	  reverse = reverse_storage_order_for_component_p (lhs);
-	}
-      else
-	base2 = get_ref_base_and_extent (lhs,
-					 &offset2, &size2, &maxsize2, &reverse);
+      gcc_assert (lhs_ref_ok);
+      base2 = ao_ref_base (&lhs_ref);
+      offset2 = lhs_ref.offset;
+      size2 = lhs_ref.size;
+      maxsize2 = lhs_ref.max_size;
+      reverse = reverse_storage_order_for_component_p (lhs);
       tree def_rhs = gimple_assign_rhs1 (def_stmt);
       if (!reverse
 	  && !storage_order_barrier_p (lhs)
@@ -2968,7 +2956,8 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	      if (val
 		  && (TREE_CODE (val) != SSA_NAME
 		      || ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val)))
-		return data->finish (get_alias_set (lhs), val);
+		return data->finish (ao_ref_alias_set (&lhs_ref),
+				     ao_ref_base_alias_set (&lhs_ref), val);
 	    }
 	  else if (maxsize.is_constant (&maxsizei)
 		   && offset.is_constant (&offseti)
@@ -2980,7 +2969,9 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	      pd.rhs = SSA_VAL (def_rhs);
 	      pd.offset = offset2i - offseti;
 	      pd.size = size2i;
-	      return data->push_partial_def (pd, get_alias_set (lhs), maxsizei);
+	      return data->push_partial_def (pd, ao_ref_alias_set (&lhs_ref),
+					     ao_ref_base_alias_set (&lhs_ref),
+					     maxsizei);
 	    }
 	}
     }
@@ -2993,15 +2984,13 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	       || TREE_CODE (gimple_assign_rhs1 (def_stmt)) == MEM_REF
 	       || handled_component_p (gimple_assign_rhs1 (def_stmt))))
     {
-      tree lhs = gimple_assign_lhs (def_stmt);
       tree base2;
       int i, j, k;
       auto_vec<vn_reference_op_s> rhs;
       vn_reference_op_t vro;
       ao_ref r;
 
-      if (!lhs_ref_ok)
-	return (void *)-1;
+      gcc_assert (lhs_ref_ok);
 
       /* See if the assignment kills REF.  */
       base2 = ao_ref_base (&lhs_ref);
@@ -3104,7 +3093,8 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
       if (val)
 	{
 	  if (data->partial_defs.is_empty ())
-	    return data->finish (get_alias_set (lhs), val);
+	    return data->finish (ao_ref_alias_set (&lhs_ref),
+				 ao_ref_base_alias_set (&lhs_ref), val);
 	  /* This is the only interesting case for partial-def handling
 	     coming from targets that like to gimplify init-ctors as
 	     aggregate copies from constant data like aarch64 for
@@ -3115,7 +3105,8 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	      pd.rhs = val;
 	      pd.offset = 0;
 	      pd.size = maxsizei;
-	      return data->push_partial_def (pd, get_alias_set (lhs),
+	      return data->push_partial_def (pd, ao_ref_alias_set (&lhs_ref),
+					     ao_ref_base_alias_set (&lhs_ref),
 					     maxsizei);
 	    }
 	}
@@ -3127,7 +3118,10 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	return (void *)-1;
 
       /* Adjust *ref from the new operands.  */
-      if (!ao_ref_init_from_vn_reference (&r, get_alias_set (rhs1),
+      ao_ref rhs1_ref;
+      ao_ref_init (&rhs1_ref, rhs1);
+      if (!ao_ref_init_from_vn_reference (&r, ao_ref_alias_set (&rhs1_ref),
+					  ao_ref_base_alias_set (&rhs1_ref),
 					  vr->type, vr->operands))
 	return (void *)-1;
       /* This can happen with bitfields.  */
@@ -3142,7 +3136,10 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
       data->orig_ref.ref = NULL_TREE;
       /* Use the alias-set of this LHS for recording an eventual result.  */
       if (data->first_set == -2)
-	data->first_set = get_alias_set (lhs);
+	{
+	  data->first_set = ao_ref_alias_set (&lhs_ref);
+	  data->first_base_set = ao_ref_base_alias_set (&lhs_ref);
+	}
 
       /* Keep looking for the adjusted *REF / VR pair.  */
       return NULL;
@@ -3302,10 +3299,10 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
       /* Try folding the new reference to a constant.  */
       tree val = fully_constant_vn_reference_p (vr);
       if (val)
-	return data->finish (0, val);
+	return data->finish (0, 0, val);
 
       /* Adjust *ref from the new operands.  */
-      if (!ao_ref_init_from_vn_reference (&r, 0, vr->type, vr->operands))
+      if (!ao_ref_init_from_vn_reference (&r, 0, 0, vr->type, vr->operands))
 	return (void *)-1;
       /* This can happen with bitfields.  */
       if (maybe_ne (ref->size, r.size))
@@ -3319,7 +3316,10 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
       data->orig_ref.ref = NULL_TREE;
       /* Use the alias-set of this stmt for recording an eventual result.  */
       if (data->first_set == -2)
-	data->first_set = 0;
+	{
+	  data->first_set = 0;
+	  data->first_base_set = 0;
+	}
 
       /* Keep looking for the adjusted *REF / VR pair.  */
       return NULL;
@@ -3346,7 +3346,8 @@ vn_reference_operands_for_lookup (tree op)
    vn_reference_t stored in the hashtable if something is found.  */
 
 tree
-vn_reference_lookup_pieces (tree vuse, alias_set_type set, tree type,
+vn_reference_lookup_pieces (tree vuse, alias_set_type set,
+			    alias_set_type base_set, tree type,
 			    vec<vn_reference_op_s> operands,
 			    vn_reference_t *vnresult, vn_lookup_kind kind)
 {
@@ -3369,6 +3370,7 @@ vn_reference_lookup_pieces (tree vuse, alias_set_type set, tree type,
     = valueize_refs (shared_lookup_references);
   vr1.type = type;
   vr1.set = set;
+  vr1.set = base_set;
   vr1.hashcode = vn_reference_compute_hash (&vr1);
   if ((cst = fully_constant_vn_reference_p (&vr1)))
     return cst;
@@ -3381,7 +3383,7 @@ vn_reference_lookup_pieces (tree vuse, alias_set_type set, tree type,
       ao_ref r;
       unsigned limit = param_sccvn_max_alias_queries_per_access;
       vn_walk_cb_data data (&vr1, NULL_TREE, NULL, kind, true);
-      if (ao_ref_init_from_vn_reference (&r, set, type, vr1.operands))
+      if (ao_ref_init_from_vn_reference (&r, set, base_set, type, vr1.operands))
 	*vnresult =
 	  (vn_reference_t)walk_non_aliased_vuses (&r, vr1.vuse, true,
 						  vn_reference_lookup_2,
@@ -3420,7 +3422,10 @@ vn_reference_lookup (tree op, tree vuse, vn_lookup_kind kind,
   vr1.operands = operands
     = valueize_shared_reference_ops_from_ref (op, &valuezied_anything);
   vr1.type = TREE_TYPE (op);
-  vr1.set = get_alias_set (op);
+  ao_ref op_ref;
+  ao_ref_init (&op_ref, op);
+  vr1.set = ao_ref_alias_set (&op_ref);
+  vr1.base_set = ao_ref_base_alias_set (&op_ref);
   vr1.hashcode = vn_reference_compute_hash (&vr1);
   if ((cst = fully_constant_vn_reference_p (&vr1)))
     return cst;
@@ -3434,8 +3439,8 @@ vn_reference_lookup (tree op, tree vuse, vn_lookup_kind kind,
       /* Make sure to use a valueized reference if we valueized anything.
          Otherwise preserve the full reference for advanced TBAA.  */
       if (!valuezied_anything
-	  || !ao_ref_init_from_vn_reference (&r, vr1.set, vr1.type,
-					     vr1.operands))
+	  || !ao_ref_init_from_vn_reference (&r, vr1.set, vr1.base_set,
+					     vr1.type, vr1.operands))
 	ao_ref_init (&r, op);
       vn_walk_cb_data data (&vr1, r.ref ? NULL_TREE : op,
 			    last_vuse_ptr, kind, tbaa_p);
@@ -3476,6 +3481,7 @@ vn_reference_lookup_call (gcall *call, vn_reference_t *vnresult,
   vr->operands = valueize_shared_reference_ops_from_call (call);
   vr->type = gimple_expr_type (call);
   vr->set = 0;
+  vr->base_set = 0;
   vr->hashcode = vn_reference_compute_hash (vr);
   vn_reference_lookup_1 (vr, vnresult);
 }
@@ -3497,7 +3503,10 @@ vn_reference_insert (tree op, tree result, tree vuse, tree vdef)
   vr1->vuse = vuse_ssa_val (vuse);
   vr1->operands = valueize_shared_reference_ops_from_ref (op, &tem).copy ();
   vr1->type = TREE_TYPE (op);
-  vr1->set = get_alias_set (op);
+  ao_ref op_ref;
+  ao_ref_init (&op_ref, op);
+  vr1->set = ao_ref_alias_set (&op_ref);
+  vr1->base_set = ao_ref_base_alias_set (&op_ref);
   vr1->hashcode = vn_reference_compute_hash (vr1);
   vr1->result = TREE_CODE (result) == SSA_NAME ? SSA_VAL (result) : result;
   vr1->result_vdef = vdef;
@@ -3539,7 +3548,8 @@ vn_reference_insert (tree op, tree result, tree vuse, tree vdef)
    structure we created.  */
 
 vn_reference_t
-vn_reference_insert_pieces (tree vuse, alias_set_type set, tree type,
+vn_reference_insert_pieces (tree vuse, alias_set_type set,
+			    alias_set_type base_set, tree type,
 			    vec<vn_reference_op_s> operands,
 			    tree result, unsigned int value_id)
 
@@ -3553,6 +3563,7 @@ vn_reference_insert_pieces (tree vuse, alias_set_type set, tree type,
   vr1->operands = valueize_refs (operands);
   vr1->type = type;
   vr1->set = set;
+  vr1->base_set = base_set;
   vr1->hashcode = vn_reference_compute_hash (vr1);
   if (result && TREE_CODE (result) == SSA_NAME)
     result = SSA_VAL (result);
@@ -4735,6 +4746,7 @@ visit_reference_op_call (tree lhs, gcall *stmt)
       vr2->operands = vr1.operands.copy ();
       vr2->type = vr1.type;
       vr2->set = vr1.set;
+      vr2->base_set = vr1.base_set;
       vr2->hashcode = vr1.hashcode;
       vr2->result = lhs;
       vr2->result_vdef = vdef_val;
@@ -4839,9 +4851,14 @@ visit_reference_op_store (tree lhs, tree op, gimple *stmt)
 	{
 	  /* If the TBAA state isn't compatible for downstream reads
 	     we cannot value-number the VDEFs the same.  */
-	  alias_set_type set = get_alias_set (lhs);
-	  if (vnresult->set != set
-	      && ! alias_set_subset_of (set, vnresult->set))
+	  ao_ref lhs_ref;
+	  ao_ref_init (&lhs_ref, lhs);
+	  alias_set_type set = ao_ref_alias_set (&lhs_ref);
+	  alias_set_type base_set = ao_ref_base_alias_set (&lhs_ref);
+	  if ((vnresult->set != set
+	       && ! alias_set_subset_of (set, vnresult->set))
+	      || (vnresult->base_set != base_set
+		  && ! alias_set_subset_of (base_set, vnresult->base_set)))
 	    resultsame = false;
 	}
     }
@@ -5915,10 +5932,15 @@ eliminate_dom_walker::eliminate_stmt (basic_block b, gimple_stmt_iterator *gsi)
 	  /* We can only remove the later store if the former aliases
 	     at least all accesses the later one does or if the store
 	     was to readonly memory storing the same value.  */
-	  alias_set_type set = get_alias_set (lhs);
+	  ao_ref lhs_ref;
+	  ao_ref_init (&lhs_ref, lhs);
+	  alias_set_type set = ao_ref_alias_set (&lhs_ref);
+	  alias_set_type base_set = ao_ref_base_alias_set (&lhs_ref);
 	  if (! vnresult
-	      || vnresult->set == set
-	      || alias_set_subset_of (set, vnresult->set))
+	      || ((vnresult->set == set
+		   || alias_set_subset_of (set, vnresult->set))
+		  && (vnresult->base_set == base_set
+		      || alias_set_subset_of (base_set, vnresult->base_set))))
 	    {
 	      if (dump_file && (dump_flags & TDF_DETAILS))
 		{
diff --git a/gcc/tree-ssa-sccvn.h b/gcc/tree-ssa-sccvn.h
index 68e8764b807..2042df118d7 100644
--- a/gcc/tree-ssa-sccvn.h
+++ b/gcc/tree-ssa-sccvn.h
@@ -143,6 +143,7 @@ typedef struct vn_reference_s
   hashval_t hashcode;
   tree vuse;
   alias_set_type set;
+  alias_set_type base_set;
   tree type;
   vec<vn_reference_op_s> operands;
   tree result;
@@ -249,17 +250,17 @@ tree vn_nary_op_lookup_pieces (unsigned int, enum tree_code,
 			       tree, tree *, vn_nary_op_t *);
 vn_nary_op_t vn_nary_op_insert_pieces (unsigned int, enum tree_code,
 				       tree, tree *, tree, unsigned int);
-bool ao_ref_init_from_vn_reference (ao_ref *, alias_set_type, tree,
-				    vec<vn_reference_op_s> );
+bool ao_ref_init_from_vn_reference (ao_ref *, alias_set_type, alias_set_type,
+				    tree, vec<vn_reference_op_s> );
 vec<vn_reference_op_s> vn_reference_operands_for_lookup (tree);
-tree vn_reference_lookup_pieces (tree, alias_set_type, tree,
+tree vn_reference_lookup_pieces (tree, alias_set_type, alias_set_type, tree,
 				 vec<vn_reference_op_s> ,
 				 vn_reference_t *, vn_lookup_kind);
 tree vn_reference_lookup (tree, tree, vn_lookup_kind, vn_reference_t *, bool,
 			  tree * = NULL);
 void vn_reference_lookup_call (gcall *, vn_reference_t *, vn_reference_t);
-vn_reference_t vn_reference_insert_pieces (tree, alias_set_type, tree,
-					   vec<vn_reference_op_s> ,
+vn_reference_t vn_reference_insert_pieces (tree, alias_set_type, alias_set_type,
+					   tree, vec<vn_reference_op_s>,
 					   tree, unsigned int);
 
 bool vn_nary_op_eq (const_vn_nary_op_t const vno1,
diff --git a/gcc/tree-ssa-scopedtables.c b/gcc/tree-ssa-scopedtables.c
index b680db41241..c1aa59f65d5 100644
--- a/gcc/tree-ssa-scopedtables.c
+++ b/gcc/tree-ssa-scopedtables.c
@@ -223,7 +223,8 @@ avail_exprs_stack::simplify_binary_operation (gimple *stmt,
    we finish processing this block and its children.  */
 
 tree
-avail_exprs_stack::lookup_avail_expr (gimple *stmt, bool insert, bool tbaa_p)
+avail_exprs_stack::lookup_avail_expr (gimple *stmt, bool insert, bool tbaa_p,
+				      expr_hash_elt **elt)
 {
   expr_hash_elt **slot;
   tree lhs;
@@ -317,6 +318,8 @@ avail_exprs_stack::lookup_avail_expr (gimple *stmt, bool insert, bool tbaa_p)
   /* Extract the LHS of the assignment so that it can be used as the current
      definition of another variable.  */
   lhs = (*slot)->lhs ();
+  if (elt)
+    *elt = *slot;
 
   /* Valueize the result.  */
   if (TREE_CODE (lhs) == SSA_NAME)
diff --git a/gcc/tree-ssa-scopedtables.h b/gcc/tree-ssa-scopedtables.h
index 463a5aa4e9d..ecb3b97eebf 100644
--- a/gcc/tree-ssa-scopedtables.h
+++ b/gcc/tree-ssa-scopedtables.h
@@ -148,7 +148,7 @@ class avail_exprs_stack
 
   /* Lookup and conditionally insert an expression into the table,
      recording enough information to unwind as needed.  */
-  tree lookup_avail_expr (gimple *, bool, bool);
+  tree lookup_avail_expr (gimple *, bool, bool, expr_hash_elt ** = NULL);
 
   void record_cond (cond_equivalence *);