(expand_assignment): When offset is zero, make new MEM

before setting MEM_VOLATILE_P.

From-SVN: r9167

diff --git a/gcc/expr.c b/gcc/expr.c
index bd08fe9c5d2df10f57e92e8bca02b53461395d44..76e497f4178d4830d8cea1007a4d223780d89043 100644 (file)
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -2508,7 +2508,14 @@ expand_assignment (to, from, want_value, suggest_reg)
       if (volatilep)
        {
          if (GET_CODE (to_rtx) == MEM)
-           MEM_VOLATILE_P (to_rtx) = 1;
+           {
+             /* When the offset is zero, to_rtx is the address of the
+                structure we are storing into, and hence may be shared.
+                We must make a new MEM before setting the volatile bit.  */
+             if (offset == 0)
+               to_rtx = change_address (to_rtx, VOIDmode, XEXP (to_rtx, 0));
+             MEM_VOLATILE_P (to_rtx) = 1;
+           }
 #if 0  /* This was turned off because, when a field is volatile
          in an object which is not volatile, the object may be in a register,
          and then we would abort over here.  */