Re: [GOOGLE] Fix LIPO resolved node reference fixup

[Xinliang David Li <davidxl at google dot com>]

ok.

thanks,

David


On Mon, Oct 27, 2014 at 7:33 AM, Teresa Johnson <tejohnson@google.com> wrote:
> Here is the new patch that walks op looking for the reference to addr.
>
> Passes internal benchmarks and regression tests. Ok for google/4_9?
>
> Thanks,
> Teresa
>
> 2014-10-27  Teresa Johnson  <tejohnson@google.com>
>
>         Google ref b/18110567.
>         * cgraphbuild.c (fixup_all_refs_1): New function.
>         (fixup_all_refs): Ditto.
>         (fixup_ref): Walk tree to find and replace ref.
>
> Index: cgraphbuild.c
> ===================================================================
> --- cgraphbuild.c       (revision 216735)
> +++ cgraphbuild.c       (working copy)
> @@ -665,6 +665,45 @@ record_references_in_initializer (tree decl, bool
>    pointer_set_destroy (visited_nodes);
>  }
>
> +typedef struct _fixup_decl_info {
> +  tree orig_decl;
> +  tree new_decl;
> +} fixup_decl_info;
> +
> +/* Check the tree at TP to see if it contains the original decl stored in
> +   DATA and if so replace it with the new decl. If original decl is
> +   found set WALK_SUBTREES to 0 so the subtree under TP is not traversed.
> +   Returns the updated parent tree T or NULL if no update performed.  */
> +
> +static tree
> +fixup_all_refs_1 (tree *tp, int *walk_subtrees, void *data)
> +{
> +  tree t = *tp;
> +  fixup_decl_info *info = (fixup_decl_info *) data;
> +
> +  /* The original function decl is always the first tree operand.  */
> +  if (TREE_OPERAND (t,0) == info->orig_decl)
> +    {
> +      TREE_OPERAND (t,0) = info->new_decl;
> +      *walk_subtrees = 0;
> +      return t;
> +    }
> +  return NULL_TREE;
> +}
> +
> +/* Walk the whole tree rooted at TP and invoke fixup_all_refs_1 to
> +   replace any references to the original decl with the new decl
> +   stored in INFO.  */
> +
> +static inline void
> +fixup_all_refs (tree *tp, fixup_decl_info *info)
> +{
> +  tree t = walk_tree (tp, fixup_all_refs_1, info, NULL);
> +  /* This is invoked when we found the original decl, so we expect
> +     to have replaced a reference.  */
> +  gcc_assert (t != NULL_TREE);
> +}
> +
>  /* Update any function decl references in base ADDR of operand OP to refer to
>     the resolved node.  */
>
> @@ -674,13 +713,16 @@ fixup_ref (gimple, tree addr, tree op)
>    addr = get_base_address (addr);
>    if (addr && TREE_CODE (addr) == FUNCTION_DECL)
>      {
> -      gcc_assert (TREE_CODE (op) == ADDR_EXPR);
> -      gcc_assert (TREE_OPERAND (op,0) == addr);
>        struct cgraph_node *real_callee;
>        real_callee = cgraph_lipo_get_resolved_node (addr);
>        if (addr == real_callee->decl)
>          return false;
> -      TREE_OPERAND (op,0) = real_callee->decl;
> +      /* We need to locate and update the tree operand within OP
> +         that contains ADDR and update it to the real callee's decl.  */
> +      fixup_decl_info info;
> +      info.orig_decl = addr;
> +      info.new_decl = real_callee->decl;
> +      fixup_all_refs (&op, &info);
>      }
>    return false;
>  }
>
>
> On Fri, Oct 24, 2014 at 11:46 AM, Teresa Johnson <tejohnson@google.com> wrote:
>> On Fri, Oct 24, 2014 at 10:55 AM, Xinliang David Li <davidxl@google.com> wrote:
>>> When orgin_addr == addr, is there a guarantee that this assert:
>>>
>>>  gcc_assert (TREE_OPERAND (op,0) == addr);
>>>
>>> is always true?
>>
>> It should be, that is the assumption of the code that we are trying to
>> enforce with the assert.
>>
>> Teresa
>>
>>>
>>> David
>>>
>>>
>>>
>>> On Fri, Oct 24, 2014 at 10:21 AM, Teresa Johnson <tejohnson@google.com> wrote:
>>>> This patch makes a fix to the reference fixups performed after LIPO
>>>> node resolution, to better handle the case where we are updating the
>>>> base address of a reference.
>>>>
>>>> Fixes google benchmark and passes regression tests. Ok for google/4_9?
>>>>
>>>> Thanks,
>>>> Teresa
>>>>
>>>> 2014-10-24  Teresa Johnson  <tejohnson@google.com>
>>>>
>>>>         Google ref b/18110567.
>>>>         * cgraphbuild.c (get_base_address_expr): New function.
>>>>         (fixup_ref): Update the op expression for new base address.
>>>>
>>>> Index: cgraphbuild.c
>>>> ===================================================================
>>>> --- cgraphbuild.c       (revision 216667)
>>>> +++ cgraphbuild.c       (working copy)
>>>> @@ -665,13 +665,35 @@ record_references_in_initializer (tree decl, bool
>>>>    pointer_set_destroy (visited_nodes);
>>>>  }
>>>>
>>>> +/* Similar to get_base_address but returns the ADDR_EXPR pointing
>>>> +   to the base address corresponding to T.  */
>>>> +
>>>> +static tree
>>>> +get_base_address_expr (tree t)
>>>> +{
>>>> +  while (handled_component_p (t))
>>>> +    t = TREE_OPERAND (t, 0);
>>>> +
>>>> +  if ((TREE_CODE (t) == MEM_REF
>>>> +       || TREE_CODE (t) == TARGET_MEM_REF)
>>>> +      && TREE_CODE (TREE_OPERAND (t, 0)) == ADDR_EXPR)
>>>> +    return TREE_OPERAND (t, 0);
>>>> +
>>>> +  return NULL_TREE;
>>>> +}
>>>> +
>>>>  /* Update any function decl references in base ADDR of operand OP to refer to
>>>>     the resolved node.  */
>>>>
>>>>  static bool
>>>>  fixup_ref (gimple, tree addr, tree op)
>>>>  {
>>>> +  tree orig_addr = addr;
>>>>    addr = get_base_address (addr);
>>>> +  /* If the address was changed, update the operand OP to be the
>>>> +     ADDR_EXPR pointing to the new base address.  */
>>>> +  if (orig_addr != addr)
>>>> +    op = get_base_address_expr (orig_addr);
>>>>    if (addr && TREE_CODE (addr) == FUNCTION_DECL)
>>>>      {
>>>>        gcc_assert (TREE_CODE (op) == ADDR_EXPR);
>>>>
>>>>
>>>> --
>>>> Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413
>>
>>
>>
>> --
>> Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413
>
>
>
> --
> Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413