Fix volatile load/store of pointers. Consider this testcase:

Fix volatile load/store of pointers.  Consider this testcase:

void %test(int** %P) {
  %A = volatile load int** %P
  ret void
}

void %test2(int*** %Q) {
  %P = load int*** %Q
  volatile store int** %P, int*** %Q
  ret void
}

instead of emitting:

void test(int **l1_P) {
  int *l2_A;

  l2_A = (int **((volatile int **)l1_P));
  return;
}
void test2(int ***l2_Q) {
  int **l1_P;

  l1_P = *l2_Q;
  *((volatile int ***)l2_Q) = l1_P;
  return;
}

... which is loading/storing volatile pointers, not through volatile pointers,
emit this (which is right):

void test(int **l1_P) {
  int *l3_A;

  l3_A = *((int * volatile*)l1_P);
  return;
}
void test2(int ***l2_Q) {
  int **l1_P;

  l1_P = *l2_Q;
  *((int ** volatile*)l2_Q) = l1_P;
  return;
}

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20191 91177308-0d34-0410-b5e6-96231b3b80d8