On 22/05/15 14:40, Jason Merrill wrote:
On 05/22/2015 07:23 AM, Ramana Radhakrishnan wrote:
+  /* Load the guard value only through an atomic acquire load.  */
+  guard = build_atomic_load (guard, MEMMODEL_ACQUIRE);
+
    /* Check to see if the GUARD is zero.  */
    guard = get_guard_bits (guard);

I wonder if these calls should be reversed, to express that we're only
trying to atomically load a byte (on non-ARM targets)?


I'm not sure about the impact on other non-ARM targets without some more investigation.

+  tree orig_src = src;
+  tree t, addr, val;
+  unsigned int size;
+  int fncode;
+
+  size = tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (src)));
+
+  fncode = BUILT_IN_ATOMIC_LOAD_N + exact_log2 (size) + 1;
+  t = builtin_decl_implicit ((enum built_in_function) fncode);
+
+  addr = build1 (ADDR_EXPR, ptr_type, src);
+  val = build_call_expr (t, 2, addr, mem_model);
+
+  /* First reinterpret the loaded bits in the original type of the load,
+     then convert to the expected result type.  */
+  t = fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (src), val);
+  return convert (TREE_TYPE (orig_src), t);

I don't see anything that changes src here.

Sorry 'bout that. Will fix in the next spin depending on comments from others.

I take it that you are happy with the patch otherwise ...

regards
Ramana


Jason

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