PR c++/69851

	* expr.c (store_field): Don't use bit-field path if exp is
	COMPONENT_REF with TREE_ADDRESSABLE type, where TYPE_SIZE is
	different from bitsize, but DECL_SIZE of FIELD_DECL is bitsize
	and the assignment can be performed by bitwise copy.  Formatting
	fix.

	* g++.dg/torture/pr69851.C: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@233566 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 51 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 587a53461cf..c39390c3eab 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,12 @@
 2016-02-19  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/69851
+	* expr.c (store_field): Don't use bit-field path if exp is
+	COMPONENT_REF with TREE_ADDRESSABLE type, where TYPE_SIZE is
+	different from bitsize, but DECL_SIZE of FIELD_DECL is bitsize
+	and the assignment can be performed by bitwise copy.  Formatting
+	fix.
+
 	PR middle-end/69838
 	* lra.c (lra_process_new_insns): If non-call exceptions are enabled,
 	call copy_reg_eh_region_note_forward on before and/or after sequences
diff --git a/gcc/expr.c b/gcc/expr.c
index 29e9356a31e..4ad76e10e27 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -6643,14 +6643,27 @@ store_field (rtx target, HOST_WIDE_INT bitsize, HOST_WIDE_INT bitpos,
 	  /* Except for initialization of full bytes from a CONSTRUCTOR, which
 	     we will handle specially below.  */
 	  && !(TREE_CODE (exp) == CONSTRUCTOR
-	       && bitsize % BITS_PER_UNIT == 0))
+	       && bitsize % BITS_PER_UNIT == 0)
+	  /* And except for bitwise copying of TREE_ADDRESSABLE types,
+	     where the FIELD_DECL has the right bitsize, but TREE_TYPE (exp)
+	     includes some extra padding.  store_expr / expand_expr will in
+	     that case call get_inner_reference that will have the bitsize
+	     we check here and thus the block move will not clobber the
+	     padding that shouldn't be clobbered.  */
+	  && (!TREE_ADDRESSABLE (TREE_TYPE (exp))
+	      || TREE_CODE (exp) != COMPONENT_REF
+	      || TREE_CODE (DECL_SIZE (TREE_OPERAND (exp, 1))) != INTEGER_CST
+	      || (bitsize % BITS_PER_UNIT != 0)
+	      || (bitpos % BITS_PER_UNIT != 0)
+	      || (compare_tree_int (DECL_SIZE (TREE_OPERAND (exp, 1)), bitsize)
+		  != 0)))
       /* If we are expanding a MEM_REF of a non-BLKmode non-addressable
          decl we must use bitfield operations.  */
       || (bitsize >= 0
 	  && TREE_CODE (exp) == MEM_REF
 	  && TREE_CODE (TREE_OPERAND (exp, 0)) == ADDR_EXPR
 	  && DECL_P (TREE_OPERAND (TREE_OPERAND (exp, 0), 0))
-	  && !TREE_ADDRESSABLE (TREE_OPERAND (TREE_OPERAND (exp, 0),0 ))
+	  && !TREE_ADDRESSABLE (TREE_OPERAND (TREE_OPERAND (exp, 0), 0))
 	  && DECL_MODE (TREE_OPERAND (TREE_OPERAND (exp, 0), 0)) != BLKmode))
     {
       rtx temp;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index adc10721b31..f753e7bdec8 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-02-19  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/69851
+	* g++.dg/torture/pr69851.C: New test.
+
 2016-02-19  Martin Sebor  <msebor@redhat.com>
 
 	PR testsuite/69573
diff --git a/gcc/testsuite/g++.dg/torture/pr69851.C b/gcc/testsuite/g++.dg/torture/pr69851.C
new file mode 100644
index 00000000000..17dbfa66b62
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr69851.C
@@ -0,0 +1,24 @@
+// PR c++/69851
+// { dg-do compile }
+// { dg-options "-std=c++11" }
+
+template <typename T>
+struct A { T a; };
+template <unsigned long, typename...>
+struct B;
+template <unsigned long N, typename T, typename... U>
+struct B<N, T, U...> : B<1, U...>, A<T>
+{
+  B (B &) = default;
+  B (B &&x) : B(x) {}
+};
+template <unsigned long N, typename T>
+struct B<N, T> {};
+struct C { C (C &); };
+struct D {};
+
+void
+foo (B<0, C, D, int, int> a)
+{
+  B<0, C, D, int, int> b (a);
+}