Make SRA less strict with memcpy performing MEM_REFs

2019-03-10  Martin Jambor  <mjambor@suse.cz>

	PR tree-optimization/85762
	PR tree-optimization/87008
	PR tree-optimization/85459
	* tree-sra.c (contains_vce_or_bfcref_p): New parameter, set the bool
	it points to if there is a type changing MEM_REF.  Adjust all callers.
	(build_accesses_from_assign): Disable total scalarization if
	contains_vce_or_bfcref_p returns true through the new parameter, for
	both rhs and lhs.

	testsuite/
	* g++.dg/tree-ssa/pr87008.C: New test.
	* gcc.dg/guality/pr54970.c: Xfail tests querying a[0] everywhere.

From-SVN: r269556

gcc/ChangeLog

+2019-03-10  Martin Jambor  <mjambor@suse.cz>
+
+	PR tree-optimization/85762
+	PR tree-optimization/87008
+	PR tree-optimization/85459
+	* tree-sra.c (contains_vce_or_bfcref_p): New parameter, set the bool
+	it points to if there is a type changing MEM_REF.  Adjust all callers.
+	(build_accesses_from_assign): Disable total scalarization if
+	contains_vce_or_bfcref_p returns true through the new parameter, for
+	both rhs and lhs.
+
 2019-03-09  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c/88568

gcc/testsuite/ChangeLog

+2019-03-10  Martin Jambor  <mjambor@suse.cz>
+
+	PR tree-optimization/85762
+	PR tree-optimization/87008
+	PR tree-optimization/85459
+	* g++.dg/tree-ssa/pr87008.C: New test.
+	* gcc.dg/guality/pr54970.c: Xfail tests querying a[0] everywhere.
+
 2019-03-10  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	PR fortran/66089

gcc/testsuite/g++.dg/tree-ssa/pr87008.C

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+extern void dontcallthis();
+
+struct A { long a, b; };
+struct B : A {};
+template<class T>void cp(T&a,T const&b){a=b;}
+long f(B x){
+  B y; cp<A>(y,x);
+  B z; cp<A>(z,x);
+  if (y.a - z.a)
+    dontcallthis ();
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-not "dontcallthis" "optimized" } } */

gcc/testsuite/gcc.dg/guality/pr54970.c

@@ -8,17 +8,17 @@
 int
 main ()
 {
-  int a[] = { 1, 2, 3 };	/* { dg-final { gdb-test .+4 "a\[0\]" "1" } } */
+  int a[] = { 1, 2, 3 };	/* { dg-final { gdb-test .+4 "a\[0\]" "1" { xfail { *-*-* } } } } */
   int *p = a + 2;		/* { dg-final { gdb-test .+3 "a\[1\]" "2" } } */
   int *q = a + 1;		/* { dg-final { gdb-test .+2 "a\[2\]" "3" } } */
 				/* { dg-final { gdb-test .+1 "*p" "3" } } */
   asm volatile (NOP);		/* { dg-final { gdb-test . "*q" "2" } } */
-  *p += 10;			/* { dg-final { gdb-test .+4 "a\[0\]" "1" } } */
+  *p += 10;			/* { dg-final { gdb-test .+4 "a\[0\]" "1" { xfail { *-*-* } } } } */
 				/* { dg-final { gdb-test .+3 "a\[1\]" "2" } } */
 				/* { dg-final { gdb-test .+2 "a\[2\]" "13" } } */
 				/* { dg-final { gdb-test .+1 "*p" "13" } } */
   asm volatile (NOP);		/* { dg-final { gdb-test . "*q" "2" } } */
-  *q += 10;			/* { dg-final { gdb-test .+4 "a\[0\]" "1" } } */
+  *q += 10;			/* { dg-final { gdb-test .+4 "a\[0\]" "1" { xfail { *-*-* } } } } */
 				/* { dg-final { gdb-test .+3 "a\[1\]" "12" } } */
 				/* { dg-final { gdb-test .+2 "a\[2\]" "13" } } */
 				/* { dg-final { gdb-test .+1 "*p" "13" } } */

gcc/tree-sra.c

@@ -1150,29 +1150,36 @@ contains_view_convert_expr_p (const_tree ref)
   return false;
 }
 
-/* Return true if REF contains a VIEW_CONVERT_EXPR or a MEM_REF that performs
-   type conversion or a COMPONENT_REF with a bit-field field declaration.  */
+/* Return true if REF contains a VIEW_CONVERT_EXPR or a COMPONENT_REF with a
+   bit-field field declaration.  If TYPE_CHANGING_P is non-NULL, set the bool
+   it points to will be set if REF contains any of the above or a MEM_REF
+   expression that effectively performs type conversion.  */
 
 static bool
-contains_vce_or_bfcref_p (const_tree ref)
+contains_vce_or_bfcref_p (const_tree ref, bool *type_changing_p = NULL)
 {
   while (handled_component_p (ref))
     {
       if (TREE_CODE (ref) == VIEW_CONVERT_EXPR
 	  || (TREE_CODE (ref) == COMPONENT_REF
 	      && DECL_BIT_FIELD (TREE_OPERAND (ref, 1))))
-	return true;
+	{
+	  if (type_changing_p)
+	    *type_changing_p = true;
+	  return true;
+	}
       ref = TREE_OPERAND (ref, 0);
     }
 
-  if (TREE_CODE (ref) != MEM_REF
+  if (!type_changing_p
+      || TREE_CODE (ref) != MEM_REF
       || TREE_CODE (TREE_OPERAND (ref, 0)) != ADDR_EXPR)
     return false;
 
   tree mem = TREE_OPERAND (TREE_OPERAND (ref, 0), 0);
   if (TYPE_MAIN_VARIANT (TREE_TYPE (ref))
       != TYPE_MAIN_VARIANT (TREE_TYPE (mem)))
-    return true;
+    *type_changing_p = true;
 
   return false;
 }
@@ -1368,15 +1375,26 @@ build_accesses_from_assign (gimple *stmt)
       lacc->grp_assignment_write = 1;
       if (storage_order_barrier_p (rhs))
 	lacc->grp_unscalarizable_region = 1;
+
+      if (should_scalarize_away_bitmap && !is_gimple_reg_type (lacc->type))
+	{
+	  bool type_changing_p = false;
+	  contains_vce_or_bfcref_p (lhs, &type_changing_p);
+	  if (type_changing_p)
+	    bitmap_set_bit (cannot_scalarize_away_bitmap,
+			    DECL_UID (lacc->base));
+	}
     }
 
   if (racc)
     {
       racc->grp_assignment_read = 1;
-      if (should_scalarize_away_bitmap && !gimple_has_volatile_ops (stmt)
-	  && !is_gimple_reg_type (racc->type))
+      if (should_scalarize_away_bitmap && !is_gimple_reg_type (racc->type))
 	{
-	  if (contains_vce_or_bfcref_p (rhs))
+	  bool type_changing_p = false;
+	  contains_vce_or_bfcref_p (rhs, &type_changing_p);
+
+	  if (type_changing_p || gimple_has_volatile_ops (stmt))
 	    bitmap_set_bit (cannot_scalarize_away_bitmap,
 			    DECL_UID (racc->base));
 	  else