1 files changed, 8 insertions, 3 deletions
diff --git a/gcc/expr.c b/gcc/expr.c
index 1adea93..7cf812d 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -10270,10 +10270,15 @@ expand_expr_real_1 (tree exp, rtx target, enum machine_mode tmode,
 	{
 	  enum insn_code icode;
 
-	  op0 = copy_rtx (op0);
-
 	  if (TYPE_ALIGN_OK (type))
-	    set_mem_align (op0, MAX (MEM_ALIGN (op0), TYPE_ALIGN (type)));
+	    {
+	      /* ??? Copying the MEM without substantially changing it might
+		 run afoul of the code handling volatile memory references in
+		 store_expr, which assumes that TARGET is returned unmodified
+		 if it has been used.  */
+	      op0 = copy_rtx (op0);
+	      set_mem_align (op0, MAX (MEM_ALIGN (op0), TYPE_ALIGN (type)));
+	    }
 	  else if (mode != BLKmode
 		   && MEM_ALIGN (op0) < GET_MODE_ALIGNMENT (mode)
 		   /* If the target does have special handling for unaligned