re PR tree-optimization/83518 (Missing optimization: useless instructions should be dropped)

2019-07-08  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/83518
	* tree-ssa-sccvn.c: Include splay-tree.h.
	(struct pd_range, struct pd_data): New.
	(struct vn_walk_cb_data): Add data to track partial definitions.
	(vn_walk_cb_data::~vn_walk_cb_data): New.
	(vn_walk_cb_data::push_partial_def): New.
	(pd_tree_alloc, pd_tree_dealloc, pd_range_compare): New.
	(vn_reference_lookup_2): When partial defs are registered give up.
	(vn_reference_lookup_3): Track partial defs for memset and
	constructor zeroing and for defs from constants.

	* gcc.dg/tree-ssa/ssa-fre-73.c: New testcase.
	* gcc.dg/tree-ssa/ssa-fre-74.c: Likewise.
	* gcc.dg/tree-ssa/ssa-fre-75.c: Likewise.
	* gcc.dg/tree-ssa/ssa-fre-76.c: Likewise.
	* g++.dg/tree-ssa/pr83518.C: Likewise.

From-SVN: r273194

gcc/ChangeLog

+2019-07-08  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/83518
+	* tree-ssa-sccvn.c: Include splay-tree.h.
+	(struct pd_range, struct pd_data): New.
+	(struct vn_walk_cb_data): Add data to track partial definitions.
+	(vn_walk_cb_data::~vn_walk_cb_data): New.
+	(vn_walk_cb_data::push_partial_def): New.
+	(pd_tree_alloc, pd_tree_dealloc, pd_range_compare): New.
+	(vn_reference_lookup_2): When partial defs are registered give up.
+	(vn_reference_lookup_3): Track partial defs for memset and
+	constructor zeroing and for defs from constants.
+
 2019-07-08  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* doc/install.texi (bootstrap-Og): Document.

gcc/testsuite/ChangeLog

+2019-07-08  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/83518
+	* gcc.dg/tree-ssa/ssa-fre-73.c: New testcase.
+	* gcc.dg/tree-ssa/ssa-fre-74.c: Likewise.
+	* gcc.dg/tree-ssa/ssa-fre-75.c: Likewise.
+	* gcc.dg/tree-ssa/ssa-fre-76.c: Likewise.
+	* g++.dg/tree-ssa/pr83518.C: Likewise.
+
 2019-07-08  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* gcc.dg/guality/guality.h: Include <sys/prctl.h> on Linux targets.

gcc/testsuite/g++.dg/tree-ssa/pr83518.C

+/* { dg-do compile } */
+/* { dg-options "-O3 -fdump-tree-optimized" } */
+
+unsigned test()
+{
+  int arr[] = {5,4,3,2,1};
+  int sum = 0;
+
+  for(int i = 0;i < 5;++i)
+    {
+      for(int j = 0; j < 5; ++j)
+	{
+	  int t = arr[i];
+	  arr[i] = arr[j];
+	  arr[j] = t;
+	}
+    }
+
+  for(int i = 0; i < 5; ++i)
+    {
+      sum += arr[i];
+    }
+
+  return sum;
+}
+
+/* { dg-final { scan-tree-dump "return 15;" "optimized" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-73.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-fre1" } */
+
+typedef int v2si __attribute__((vector_size(__SIZEOF_INT__ * 2)));
+int foo (int *a)
+{
+  a[0] = 1;
+  a[1] = 2;
+  v2si x = *(v2si *)a;
+  *(v2si *)&a[2] = x;
+  return a[3];
+}
+
+/* { dg-final { scan-tree-dump "return 2;" "fre1" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-74.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-fre1" } */
+
+typedef int v4si __attribute__((vector_size(__SIZEOF_INT__ * 4)));
+int foo (int *a)
+{
+  a[2] = 2;
+  a[0] = 0;
+  a[1] = 1;
+  a[3] = 4;
+  v4si x = *(v4si *)a;
+  *(v4si *)&a[4] = x;
+  return a[4] + a[7];
+}
+
+/* { dg-final { scan-tree-dump "return 4;" "fre1" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-75.c

+/* { dg-do compile } */
+/* { dg-require-effective-target int32plus } */
+/* { dg-options "-O -fgimple -fdump-tree-fre1" } */
+
+typedef int v4si __attribute__((vector_size(__SIZEOF_INT__ * 4)));
+#if __SIZEOF_INT__ == 4
+__GIMPLE (ssa) int foo (int *a)
+{
+  v4si _2;
+  int _3;
+  int _4;
+  int _5;
+  int _6;
+  int _7;
+  int _8;
+  int _9;
+
+__BB(2):
+  __MEM <unsigned char[3 * __SIZEOF_INT__]> ((char *)a_1(D) + 4) = _Literal (unsigned char[3 * __SIZEOF_INT__]) {};
+  __MEM <int> (a_1(D) + 8) = 2;
+  __MEM <int> (a_1(D)) = 1;
+  _2 = __MEM <v4si> (a_1(D));
+  _3 = __BIT_FIELD_REF <int> (_2, 32, 0);
+  _4 = __BIT_FIELD_REF <int> (_2, 32, 32);
+  _5 = __BIT_FIELD_REF <int> (_2, 32, 64);
+  _6 = __BIT_FIELD_REF <int> (_2, 32, 96);
+  _7 = _3 + _4;
+  _8 = _7 + _5;
+  _9 = _8 + _6;
+  return _9;
+}
+#endif
+
+/* { dg-final { scan-tree-dump "return 3;" "fre1" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-76.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-fre1" } */
+
+typedef int v4si __attribute__((vector_size(__SIZEOF_INT__ * 4)));
+int foo (int *a)
+{
+  __builtin_memset (a, 0, 2 * __SIZEOF_INT__);
+  a[2] = 2;
+  a[0] = 1;
+  a[3] = 3;
+  v4si x = *(v4si *)a;
+  *(v4si *)&a[4] = x;
+  return a[4] + a[5] + a[7];
+}
+
+/* { dg-final { scan-tree-dump "return 4;" "fre1" } } */