tree-predcom.c: Revise general description of the pass.

	* tree-predcom.c: Revise general description of the pass.
	(enum chain_type): New enum type for store elimination.
	(struct chain): New field supporting store elimination.
	(struct component): Ditto.
	(dump_chain): Dump store-stores chain.
	(release_chain): Release resources.
	(split_data_refs_to_components): Compute and create component
	contains only stores for elimination.
	(get_chain_last_ref_at): New function.
	(make_invariant_chain): Initialization.
	(make_rooted_chain): Specify chain type in parameter and record it.
	(add_looparound_copies): Skip for store-stores chain.
	(determine_roots_comp): Compute type of chain and pass it to
	make_rooted_chain.
	(initialize_root_vars_store_elim_2): New function.
	(finalize_eliminated_stores): New function.
	(remove_stmt): Handle store for elimination.
	(execute_pred_commoning_chain): Execute predictive commoning on
	store-store chains.
	(determine_unroll_factor): Skip unroll for store-stores chain.
	(prepare_initializers_chain_store_elim): New function.
	(prepare_initializers_chain): Hanlde store-store chain.
	(prepare_finalizers_chain, prepare_finalizers): New function.
	(tree_predictive_commoning_loop): Return integer value indicating
	if loop is unrolled or lcssa form is corrupted.
	(tree_predictive_commoning): Rewrite for lcssa form if necessary.

	gcc/testsuite
	* gcc.dg/tree-ssa/predcom-dse-1.c: New test.
	* gcc.dg/tree-ssa/predcom-dse-2.c: New test.
	* gcc.dg/tree-ssa/predcom-dse-3.c: New test.
	* gcc.dg/tree-ssa/predcom-dse-4.c: New test.
	* gcc.dg/tree-ssa/predcom-dse-5.c: New test.
	* gcc.dg/tree-ssa/predcom-dse-6.c: New test.
	* gcc.dg/tree-ssa/predcom-dse-7.c: New test.
	* gcc.dg/tree-ssa/predcom-dse-8.c: New test.
	* gcc.dg/tree-ssa/predcom-dse-9.c: New test.
	* gcc.dg/tree-ssa/predcom-dse-10.c: New test.
	* gcc.dg/tree-ssa/predcom-dse-11.c: New test.

From-SVN: r250669

gcc/ChangeLog

 2017-07-28  Bin Cheng  <bin.cheng@arm.com>
 
+	* tree-predcom.c: Revise general description of the pass.
+	(enum chain_type): New enum type for store elimination.
+	(struct chain): New field supporting store elimination.
+	(struct component): Ditto.
+	(dump_chain): Dump store-stores chain.
+	(release_chain): Release resources.
+	(split_data_refs_to_components): Compute and create component
+	contains only stores for elimination.
+	(get_chain_last_ref_at): New function.
+	(make_invariant_chain): Initialization.
+	(make_rooted_chain): Specify chain type in parameter and record it.
+	(add_looparound_copies): Skip for store-stores chain.
+	(determine_roots_comp): Compute type of chain and pass it to
+	make_rooted_chain.
+	(initialize_root_vars_store_elim_2): New function.
+	(finalize_eliminated_stores): New function.
+	(remove_stmt): Handle store for elimination.
+	(execute_pred_commoning_chain): Execute predictive commoning on
+	store-store chains.
+	(determine_unroll_factor): Skip unroll for store-stores chain.
+	(prepare_initializers_chain_store_elim): New function.
+	(prepare_initializers_chain): Hanlde store-store chain.
+	(prepare_finalizers_chain, prepare_finalizers): New function.
+	(tree_predictive_commoning_loop): Return integer value indicating
+	if loop is unrolled or lcssa form is corrupted.
+	(tree_predictive_commoning): Rewrite for lcssa form if necessary.
+
+2017-07-28  Bin Cheng  <bin.cheng@arm.com>
+
 	* tree-predcom.c (initialize_root): Delete.
 	(execute_pred_commoning_chain): Initialize root vars and replace
 	reference of non-combined chain directly, rather than call above

gcc/testsuite/ChangeLog

+2017-07-28  Bin Cheng  <bin.cheng@arm.com>
+
+	* gcc.dg/tree-ssa/predcom-dse-1.c: New test.
+	* gcc.dg/tree-ssa/predcom-dse-2.c: New test.
+	* gcc.dg/tree-ssa/predcom-dse-3.c: New test.
+	* gcc.dg/tree-ssa/predcom-dse-4.c: New test.
+	* gcc.dg/tree-ssa/predcom-dse-5.c: New test.
+	* gcc.dg/tree-ssa/predcom-dse-6.c: New test.
+	* gcc.dg/tree-ssa/predcom-dse-7.c: New test.
+	* gcc.dg/tree-ssa/predcom-dse-8.c: New test.
+	* gcc.dg/tree-ssa/predcom-dse-9.c: New test.
+	* gcc.dg/tree-ssa/predcom-dse-10.c: New test.
+	* gcc.dg/tree-ssa/predcom-dse-11.c: New test.
+
 2017-07-28  Martin Liska  <mliska@suse.cz>
 
 	PR sanitizer/81340

gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-1.c

+/* { dg-do run } */
+/* { dg-options "-O2 -fno-inline -fpredictive-commoning -fdump-tree-pcom-details" } */
+
+int arr[105] = {2, 3, 5, 7, 11};
+int result0[10] = {2, 3, 5, 7, 11};
+int result1[10] = {0, -1, 5, -2, 11, 0};
+int result2[10] = {0, 0, -1, -2, -2, 0};
+int result3[10] = {0, 0, 0, -1, -2, -2, 0};
+int result4[10] = {0, 0, 0, 0, -1, -2, -2, 0};
+int result100[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -2, -2, 0};
+
+extern void abort (void);
+
+void __attribute__((noinline)) foo (int *a, int len)
+{
+  int i;
+  for (i = 0; i < len; i++)
+    {
+      a[i] = 0;
+      a[i + 1] = -1;
+      a[i + 3] = -2;
+    }
+}
+
+void check (int *a, int *res, int len)
+{
+  int i;
+
+  for (i = 0; i < len; i++)
+    if (a[i] != res[i])
+      abort ();
+}
+
+int main (void)
+{
+  foo (arr, 0);
+  check (arr, result0, 10);
+
+  foo (arr, 1);
+  check (arr, result1, 10);
+
+  foo (arr, 2);
+  check (arr, result2, 10);
+
+  foo (arr, 3);
+  check (arr, result3, 10);
+
+  foo (arr, 4);
+  check (arr, result4, 10);
+
+  foo (arr, 100);
+  check (arr, result100, 105);
+
+  return 0;
+}
+/* { dg-final { scan-tree-dump "Store-stores chain" "pcom"} } */

gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-10.c

+/* { dg-do run } */
+/* { dg-options "-O2 -fno-inline -fpredictive-commoning -fdump-tree-pcom-details" } */
+
+int arr[105] = {2, 3, 5, 7, 11};
+int result0[10] = {2, 3, 5, 7, 11};
+int result1[10] = {0, 3, 5, -2, 11, 0};
+
+extern void abort (void);
+
+void __attribute__((noinline)) foo (int *a, int len, int flag)
+{
+  int i;
+  for (i = 0; i < len; i++)
+    {
+      a[i] = 0;
+      if (flag)
+        a[i + 1] = -1;
+      a[i + 3] = -2;
+    }
+}
+
+void check (int *a, int *res, int len)
+{
+  int i;
+
+  for (i = 0; i < len; i++)
+    if (a[i] != res[i])
+      abort ();
+}
+
+int main (void)
+{
+  int i;
+
+  foo (arr, 0, 0);
+  check (arr, result0, 10);
+
+  foo (arr, 1, 0);
+  check (arr, result1, 10);
+
+  return 0;
+}
+/* { dg-final { scan-tree-dump-not "Store-stores chain" "pcom"} } */
+

gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-11.c

+/* { dg-do run } */
+/* { dg-options "-O2 -fno-inline -fpredictive-commoning -fdump-tree-pcom-details" } */
+
+int arr[105] = {2, 3, 5, 7, 11};
+int x[105] = {2, 3, 5, 7, 11};
+int result0[10] = {2, 3, 5, 7, 11};
+int result1[10] = {0, 0, 0, 0, 0, 0, -1, -2, -2};
+
+extern void abort (void);
+
+int __attribute__((noinline)) foo (int * __restrict__ a, int * __restrict__ b, int len, int flag)
+{
+  int i, sum = 0;
+  for (i = 0; i < len; i++)
+    {
+      a[i] = 0;
+      b[i + 2] = i;
+      a[i + 1] = -1;
+      sum += b[i];
+      a[i + 3] = -2;
+    }
+  return sum;
+}
+
+void check (int *a, int *res, int len, int sum, int val)
+{
+  int i;
+
+  if (sum != val)
+    abort ();
+
+  for (i = 0; i < len; i++)
+    if (a[i] != res[i])
+      abort ();
+}
+
+int main (void)
+{
+  int i, sum;
+
+  sum = foo (arr, x, 0, 0);
+  check (arr, result0, 10, sum, 0);
+
+  sum = foo (arr, x, 6, 0);
+  check (arr, result1, 10, sum, 11);
+
+  return 0;
+}
+/* { dg-final { scan-tree-dump "Store-stores chain" "pcom"} } */
+/* { dg-final { scan-tree-dump "Store-loads chain" "pcom"} } */
+

gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-2.c

+/* { dg-do run } */
+/* { dg-options "-O2 -fno-inline -fpredictive-commoning -fdump-tree-pcom-details" } */
+
+int arr[105] = {2, 3, 5, 7, 11};
+int result0[10] = {2, 3, 5, 7, 11};
+int result1[10] = {0, 3, -1, -2, 11, 0};
+int result2[10] = {0, 0, -1, -1, -2, 0};
+int result3[10] = {0, 0, 0, -1, -1, -2, 0};
+int result4[10] = {0, 0, 0, 0, -1, -1, -2, 0};
+int result100[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, -2, 0};
+
+extern void abort (void);
+
+void __attribute__((noinline)) foo (int *a, int len)
+{
+  int i;
+  for (i = 0; i < len; i++)
+    {
+      a[i] = 0;
+      a[i + 2] = -1;
+      a[i + 3] = -2;
+    }
+}
+
+void check (int *a, int *res, int len)
+{
+  int i;
+
+  for (i = 0; i < len; i++)
+    if (a[i] != res[i])
+      abort ();
+}
+
+int main (void)
+{
+  foo (arr, 0);
+  check (arr, result0, 10);
+
+  foo (arr, 1);
+  check (arr, result1, 10);
+
+  foo (arr, 2);
+  check (arr, result2, 10);
+
+  foo (arr, 3);
+  check (arr, result3, 10);
+
+  foo (arr, 4);
+  check (arr, result4, 10);
+
+  foo (arr, 100);
+  check (arr, result100, 105);
+
+  return 0;
+}
+/* { dg-final { scan-tree-dump "Store-stores chain" "pcom"} } */

gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-3.c

+/* { dg-do run } */
+/* { dg-options "-O2 -fno-inline -fpredictive-commoning -fdump-tree-pcom-details" } */
+
+int arr1[105] = {2, 3, 5, 7, 11, 13, 0};
+int arr2[105] = {2, 3, 5, 7, 11, 13, 0};
+int arr3[105] = {2, 3, 5, 7, 11, 13, 0};
+int arr4[105] = {2, 3, 5, 7, 11, 13, 0};
+int result1[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -2, -3, 0};
+int result2[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, -2, 0};
+int result3[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -2, -2, 0};
+int result4[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, 0};
+
+extern void abort (void);
+
+void check (int *a, int *res, int len)
+{
+  int i;
+
+  for (i = 0; i < len; i++)
+    if (a[i] != res[i])
+      abort ();
+}
+
+void __attribute__((noinline)) foo1 (int *a)
+{
+  int i;
+  for (i = 0; i < 100; i++)
+    {
+      a[i] = 0;
+      a[i + 1] = -1;
+      a[i + 2] = -2;
+      a[i + 3] = -3;
+    }
+}
+
+void __attribute__((noinline)) foo2 (int *a)
+{
+  int i;
+  for (i = 0; i < 100; i++)
+    {
+      a[i] = 0;
+      a[i + 2] = -1;
+      a[i + 3] = -2;
+    }
+}
+
+void __attribute__((noinline)) foo3 (int *a)
+{
+  int i;
+  for (i = 0; i < 100; i++)
+    {
+      a[i] = 0;
+      a[i + 1] = -1;
+      a[i + 3] = -2;
+    }
+}
+
+void __attribute__((noinline)) foo4 (int *a)
+{
+  int i;
+  for (i = 0; i < 100; i++)
+    {
+      a[i] = 0;
+      a[i + 3] = -1;
+    }
+}
+
+int main (void)
+{
+  foo1 (arr1);
+  check (arr1, result1, 105);
+
+  foo2 (arr2);
+  check (arr2, result2, 105);
+
+  foo3 (arr3);
+  check (arr3, result3, 105);
+
+  foo4 (arr4);
+  check (arr4, result4, 105);
+
+  return 0;
+}
+/* { dg-final { scan-tree-dump-times "Store-stores chain" 4 "pcom"} } */

gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-4.c

+/* { dg-do run } */
+/* { dg-options "-O2 -fno-inline -fpredictive-commoning -fdump-tree-pcom-details" } */
+
+int arr[105] = {2, 3, 5, 7, 11};
+int result0[10] = {2, 3, 5, 7, 11};
+int result1[10] = {0, 3, 5, -1, 11, 0};
+int result2[10] = {0, 0, 5, -1, -1, 0};
+int result3[10] = {0, 0, 0, -1, -1, -1, 0};
+int result4[10] = {0, 0, 0, 0, -1, -1, -1, 0};
+int result100[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, 0};
+
+extern void abort (void);
+
+void __attribute__((noinline)) foo (int *a, int len)
+{
+  int i;
+  for (i = 0; i < len; i++)
+    {
+      a[i] = 0;
+      a[i + 3] = -1;
+    }
+}
+
+void check (int *a, int *res, int len)
+{
+  int i;
+
+  for (i = 0; i < len; i++)
+    if (a[i] != res[i])
+      abort ();
+}
+
+int main (void)
+{
+  foo (arr, 0);
+  check (arr, result0, 10);
+
+  foo (arr, 1);
+  check (arr, result1, 10);
+
+  foo (arr, 2);
+  check (arr, result2, 10);
+
+  foo (arr, 3);
+  check (arr, result3, 10);
+
+  foo (arr, 4);
+  check (arr, result4, 10);
+
+  foo (arr, 100);
+  check (arr, result100, 105);
+
+  return 0;
+}
+/* { dg-final { scan-tree-dump "Store-stores chain" "pcom"} } */

gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-5.c

+/* { dg-do run } */
+/* { dg-options "-O2 -fno-inline -fpredictive-commoning -fdump-tree-pcom-details" } */
+
+int arr[105] = {2, 3, 5, 7, 11};
+int result0[10] = {2, 3, 5, 7, 11};
+int result1[10] = {0, -1, -2, -3, 11, 0};
+int result2[10] = {0, 0, -1, -2, -3, 0};
+int result3[10] = {0, 0, 0, -1, -2, -3, 0};
+int result4[10] = {0, 0, 0, 0, -1, -2, -3, 0};
+int result100[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -2, -3, 0};
+
+extern void abort (void);
+
+void __attribute__((noinline)) foo (int *a, int len)
+{
+  int i;
+  for (i = 0; i < len; i++)
+    {
+      a[i] = 0;
+      a[i + 1] = -1;
+      a[i + 2] = -2;
+      a[i + 3] = -3;
+    }
+}
+
+void check (int *a, int *res, int len)
+{
+  int i;
+
+  for (i = 0; i < len; i++)
+    if (a[i] != res[i])
+      abort ();
+}
+
+int main (void)
+{
+  foo (arr, 0);
+  check (arr, result0, 10);
+
+  foo (arr, 1);
+  check (arr, result1, 10);
+
+  foo (arr, 2);
+  check (arr, result2, 10);
+
+  foo (arr, 3);
+  check (arr, result3, 10);
+
+  foo (arr, 4);
+  check (arr, result4, 10);
+
+  foo (arr, 100);
+  check (arr, result100, 105);
+
+  return 0;
+}
+/* { dg-final { scan-tree-dump "Store-stores chain" "pcom"} } */

gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-6.c

+/* { dg-do run } */
+/* { dg-options "-O2 -fno-inline -fpredictive-commoning -fdump-tree-pcom-details" } */
+
+int arr[105] = {2, 3, 5, 7, 11, 13, 17, 19};
+int result0[10] = {2, 3, 5, 7, 11, 13, 17, 19};
+int result1[10] = {0, -1, -2, -3, -4, -5, 17, 19};
+int result2[10] = {0, 0, -1, -2, -3, -4, -5, 19};
+int result3[10] = {0, 0, 0, -1, -2, -3, -4, -5};
+int result4[10] = {0, 0, 0, 0, -1, -2, -3, -4, -5};
+int result100[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -2, -3, -4, -5};
+
+extern void abort (void);
+
+void __attribute__((noinline)) foo (int *a, int len)
+{
+  int i;
+  for (i = 0; i < len; i++)
+    {
+      a[i] = 0;
+      a[i + 1] = -1;
+      a[i + 2] = -2;
+      a[i + 3] = -3;
+      a[i + 4] = -4;
+      a[i + 5] = -5;
+    }
+}
+
+void check (int *a, int *res, int len)
+{
+  int i;
+
+  for (i = 0; i < len; i++)
+    if (a[i] != res[i])
+      abort ();
+}
+
+int main (void)
+{
+  foo (arr, 0);
+  check (arr, result0, 10);
+
+  foo (arr, 1);
+  check (arr, result1, 10);
+
+  foo (arr, 2);
+  check (arr, result2, 10);
+
+  foo (arr, 3);
+  check (arr, result3, 10);
+
+  foo (arr, 4);
+  check (arr, result4, 10);
+
+  foo (arr, 100);
+  check (arr, result100, 105);
+
+  return 0;
+}
+/* { dg-final { scan-tree-dump "Store-stores chain" "pcom"} } */

gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-7.c

+/* { dg-do run } */
+/* { dg-options "-O2 -fno-inline -fpredictive-commoning -fdump-tree-pcom-details" } */
+
+int arr[105] = {2, 3, 5, 7, 11, 13, 17, 19};
+int result0[10] = {2, 3, 5, 7, 11, 13, 17, 19};
+int result1[10] = {0, -1, 5, -3, 11, -5, 17, 19};
+int result2[10] = {0, 0, -1, -3, -3, -5, -5, 19};
+int result3[10] = {0, 0, 0, -1, -3, -3, -5, -5};
+int result4[10] = {0, 0, 0, 0, -1, -3, -3, -5, -5};
+int result100[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -3, -3, -5, -5};
+
+extern void abort (void);
+
+void __attribute__((noinline)) foo (int *a, int len)
+{
+  int i;
+  for (i = 0; i < len; i++)
+    {
+      a[i] = 0;
+      a[i + 1] = -1;
+      a[i + 3] = -3;
+      a[i + 5] = -5;
+    }
+}
+
+void check (int *a, int *res, int len)
+{
+  int i;
+
+  for (i = 0; i < len; i++)
+    if (a[i] != res[i])
+      abort ();
+}
+
+int main (void)
+{
+  foo (arr, 0);
+  check (arr, result0, 10);
+
+  foo (arr, 1);
+  check (arr, result1, 10);
+
+  foo (arr, 2);
+  check (arr, result2, 10);
+
+  foo (arr, 3);
+  check (arr, result3, 10);
+
+  foo (arr, 4);
+  check (arr, result4, 10);
+
+  foo (arr, 100);
+  check (arr, result100, 105);
+
+  return 0;
+}
+/* { dg-final { scan-tree-dump "Store-stores chain" "pcom"} } */

gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-8.c

+/* { dg-do run } */
+/* { dg-options "-O2 -fno-inline -fpredictive-commoning -fdump-tree-pcom-details" } */
+
+int arr[105] = {2, 3, 5, 7, 11, 13, 17, 19};
+int result0[10] = {2, 3, 5, 7, 11, 13, 17, 19};
+int result1[10] = {0, 3, 5, 7, 11, -5, 17, 19};
+int result2[10] = {0, 0, 5, 7, 11, -5, -5, 19};
+int result3[10] = {0, 0, 0, 7, 11, -5, -5, -5};
+int result4[10] = {0, 0, 0, 0, 11, -5, -5, -5, -5};
+int result100[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -5, -5, -5, -5, -5};
+
+extern void abort (void);
+
+void __attribute__((noinline)) foo (int *a, int len)
+{
+  int i;
+  for (i = 0; i < len; i++)
+    {
+      a[i] = 0;
+      a[i + 5] = -5;
+    }
+}
+
+void check (int *a, int *res, int len)
+{
+  int i;
+
+  for (i = 0; i < len; i++)
+    if (a[i] != res[i])
+      abort ();
+}
+
+int main (void)
+{
+  foo (arr, 0);
+  check (arr, result0, 10);
+
+  foo (arr, 1);
+  check (arr, result1, 10);
+
+  foo (arr, 2);
+  check (arr, result2, 10);
+
+  foo (arr, 3);
+  check (arr, result3, 10);
+
+  foo (arr, 4);
+  check (arr, result4, 10);
+
+  foo (arr, 100);
+  check (arr, result100, 105);
+
+  return 0;
+}

gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-9.c

+/* { dg-do run } */
+/* { dg-options "-O2 -fno-inline -fpredictive-commoning -fdump-tree-pcom-details" } */
+
+int arr1[105] = {2, 3, 5, 7, 11, 13, 17, 19};
+int arr2[105] = {2, 3, 5, 7, 11, 13, 17, 19};
+int arr3[105] = {2, 3, 5, 7, 11, 13, 17, 19};
+
+int result1[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -2, -3, -4, -5};
+int result2[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -3, -3, -5, -5};
+int result3[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -5, -5, -5, -5, -5};
+
+extern void abort (void);
+
+void __attribute__((noinline)) foo1 (int *a)
+{
+  int i;
+  for (i = 0; i < 100; i++)
+    {
+      a[i] = 0;
+      a[i + 1] = -1;
+      a[i + 2] = -2;
+      a[i + 3] = -3;
+      a[i + 4] = -4;
+      a[i + 5] = -5;
+    }
+}
+
+void __attribute__((noinline)) foo2 (int *a)
+{
+  int i;
+  for (i = 0; i < 100; i++)
+    {
+      a[i] = 0;
+      a[i + 1] = -1;
+      a[i + 3] = -3;
+      a[i + 5] = -5;
+    }
+}
+
+void __attribute__((noinline)) foo3 (int *a)
+{
+  int i;
+  for (i = 0; i < 100; i++)
+    {
+      a[i] = 0;
+      a[i + 5] = -5;
+    }
+}
+
+void check (int *a, int *res, int len)
+{
+  int i;
+
+  for (i = 0; i < len; i++)
+    if (a[i] != res[i])
+      abort ();
+}
+
+int main (void)
+{
+  foo1 (arr1);
+  check (arr1, result1, 10);
+
+  foo2 (arr2);
+  check (arr2, result2, 10);
+
+  foo3 (arr3);
+  check (arr3, result3, 10);
+
+  return 0;
+}
+/* { dg-final { scan-tree-dump "Store-stores chain" "pcom"} } */