PR c++/67557

	* expr.c (store_field): Call store_constructor directly when
	storing a CONSTRUCTOR into a target smaller than its type.
	Guard against unsafe bitwise copy.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@228704 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 17 insertions, 1 deletions

diff --git a/gcc/expr.c b/gcc/expr.c
index 6f6554d25c0..595324dc395 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -6616,7 +6616,11 @@ store_field (rtx target, HOST_WIDE_INT bitsize, HOST_WIDE_INT bitpos,
 	 operations.  */
       || (bitsize >= 0
 	  && TREE_CODE (TYPE_SIZE (TREE_TYPE (exp))) == INTEGER_CST
-	  && compare_tree_int (TYPE_SIZE (TREE_TYPE (exp)), bitsize) != 0)
+	  && compare_tree_int (TYPE_SIZE (TREE_TYPE (exp)), bitsize) != 0
+	  /* Except for initialization of full bytes from a CONSTRUCTOR, which
+	     we will handle specially below.  */
+	  && !(TREE_CODE (exp) == CONSTRUCTOR
+	       && bitsize % BITS_PER_UNIT == 0))
       /* If we are expanding a MEM_REF of a non-BLKmode non-addressable
          decl we must use bitfield operations.  */
       || (bitsize >= 0
@@ -6629,6 +6633,9 @@ store_field (rtx target, HOST_WIDE_INT bitsize, HOST_WIDE_INT bitpos,
       rtx temp;
       gimple *nop_def;
 
+      /* Using bitwise copy is not safe for TREE_ADDRESSABLE types.  */
+      gcc_assert (!TREE_ADDRESSABLE (TREE_TYPE (exp)));
+
       /* If EXP is a NOP_EXPR of precision less than its mode, then that
 	 implies a mask operation.  If the precision is the same size as
 	 the field we're storing into, that mask is redundant.  This is
@@ -6743,6 +6750,15 @@ store_field (rtx target, HOST_WIDE_INT bitsize, HOST_WIDE_INT bitpos,
       if (!MEM_KEEP_ALIAS_SET_P (to_rtx) && MEM_ALIAS_SET (to_rtx) != 0)
 	set_mem_alias_set (to_rtx, alias_set);
 
+      /* Above we avoided using bitfield operations for storing a CONSTRUCTOR
+	 into a target smaller than its type; handle that case now.  */
+      if (TREE_CODE (exp) == CONSTRUCTOR && bitsize >= 0)
+	{
+	  gcc_assert (bitsize % BITS_PER_UNIT == 0);
+	  store_constructor (exp, to_rtx, 0, bitsize/BITS_PER_UNIT);
+	  return to_rtx;
+	}
+
       return store_expr (exp, to_rtx, 0, nontemporal);
     }
 }