[patch] Don't insert pattern statements into the code (was Fix PR tree-optimization/49318)

[Richard Guenther]

On Mon, Jun 13, 2011 at 2:43 PM, Ira Rosen <ira.rosen@linaro.org> wrote:
> On 10 June 2011 12:14, Richard Guenther <richard.guenther@gmail.com> wrote:
>> In the end I think we should not generate the pattern stmt during
>> pattern matching but only mark the relevant statements with a
>> pattern kind.  Say, for each pattern we have a "main" statement
>> that has related stmts belonging to the pattern that define uses
>> of the "main" statement - mark those to refer to that "main" statement.
>> For that "main" statement simply record an enum value, like,
>> widening_mult.  Then only at vectorized statement
>> generation time actually generate the vectorized form of the
>> pattern statement.
>
> I ended up with the following: during pattern detection a new scalar
> pattern statement is created but not inserted into the code, it is
> only recorded as a related statement of the last statement in the
> detected pattern. Every time the last statement is being
> analyzed/transformed, we switch to the pattern statement instead. It
> is much more difficult just to mark the last stmt with an enum value,
> since we have to retrieve the relevant operands every time.
>
> I am not sure if we need to free the pattern stmt at the end.
>
> Bootstrapped and now testing on powerpc64-suse-linux (tested
> vectorizer testsuite on powerpc64-suse-linux and x86_64-suse-linux.
>
> What do you think?

   /* Mark the stmts that are involved in the pattern. */
-  gsi_insert_before (&si, pattern_stmt, GSI_SAME_STMT);
   set_vinfo_for_stmt (pattern_stmt,
 		      new_stmt_vec_info (pattern_stmt, loop_vinfo, NULL));
+  gimple_set_bb (pattern_stmt, gimple_bb (stmt));

do you really need this?  Otherwise it looks reasonable.  Btw,
we can probably remove the simple DCE done in
slpeel_tree_peel_loop_to_edge (remove_dead_stmts_from_loop)
with this patch.

Thanks,
Richard.

> Thanks,
> Ira
>
> ChangeLog:
>
>     * tree-vect-loop.c (vect_determine_vectorization_factor): Don't
>     remove irrelevant pattern statements.  For irrelevant statements
>     check if it is the last statement of a detected pattern, use
>     corresponding pattern statement instead.
>     (destroy_loop_vec_info): No need to remove pattern statements,
>     only free stmt_vec_info.
>     (vect_transform_loop): For irrelevant statements check if it is
>     the last statement of a detected pattern, use corresponding
>     pattern statement instead.
>     * tree-vect-patterns.c (vect_pattern_recog_1): Don't insert
>     pattern statements.  Set basic block for the new statement.
>     (vect_pattern_recog): Update documentation.
>     * tree-vect-stmts.c (vect_mark_stmts_to_be_vectorized): Scan
>     operands of pattern statements.
>     (vectorizable_call): Fix printing.  In case of a pattern statement
>     use the lhs of the original statement when creating a dummy
>     statement to replace the original call.
>     (vect_analyze_stmt): For irrelevant statements check if it is
>     the last statement of a detected pattern, use corresponding
>     pattern statement instead.
>     * tree-vect-slp.c (vect_schedule_slp_instance): For pattern
>     statements use gsi of the original statement.
>