Re: Tweak BB analysis for dr_analyze_innermost

["Bin.Cheng" <amker dot cheng at gmail dot com>]

On Wed, Jun 28, 2017 at 2:36 PM, Richard Sandiford
<richard.sandiford@linaro.org> wrote:
> Index: gcc/tree-data-ref.c
> ===================================================================
> --- gcc/tree-data-ref.c 2017-06-28 14:33:41.294720044 +0100
> +++ gcc/tree-data-ref.c 2017-06-28 14:35:30.475155670 +0100
> @@ -749,15 +749,29 @@ canonicalize_base_object_address (tree a
>    return build_fold_addr_expr (TREE_OPERAND (addr, 0));
>  }
>
> -/* Analyzes the behavior of the memory reference DR in the innermost loop or
> -   basic block that contains it.  Returns true if analysis succeed or false
> -   otherwise.  */
> +/* Analyze the behavior of memory reference DR.  There are two modes:
> +
> +   - BB analysis.  In this case we simply split the address into base,
> +     init and offset components, without reference to any containing loop.
> +     The resulting base and offset are general expressions and they can
> +     vary arbitrarily from one iteration of the containing loop to the next.
> +     The step is always zero.
> +
> +   - loop analysis.  In this case we analyze the reference both wrt LOOP
> +     and on the basis that the reference occurs (is "used") in LOOP;
> +     see the comment above analyze_scalar_evolution_in_loop for more
> +     information about this distinction.  The base, init, offset and
> +     step fields are all invariant in LOOP.
> +
> +   Perform BB analysis if LOOP is null, or if LOOP is the function's
> +   dummy outermost loop.  In other cases perform loop analysis.
> +
> +   Return true if the analysis succeeded and store the results in DR if so.
> +   BB analysis can only fail for bitfield or reversed-storage accesses.  */
>
>  bool
> -dr_analyze_innermost (struct data_reference *dr, struct loop *nest)
> +dr_analyze_innermost (struct data_reference *dr, struct loop *loop)
>  {
> -  gimple *stmt = DR_STMT (dr);
> -  struct loop *loop = loop_containing_stmt (stmt);
>    tree ref = DR_REF (dr);
>    HOST_WIDE_INT pbitsize, pbitpos;
>    tree base, poffset;
> @@ -806,22 +820,11 @@ dr_analyze_innermost (struct data_refere
>
>    if (in_loop)
A nit.  No need to use bool variable now?  We can check loop != NULL instead.

Thanks,
bin