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Re: [gomp4 simd, RFC] Simple fix to override vectorization cost estimation.


Thanks for comments, hope I got all of em.
Note: I used a LOOP_VINFO_LOC (loop_vinfo) to print the loop location
but it appears to be 0, so the output is somewhat lousy. The global
vect_location points somewhere inside the loop, which is not that better.
Shall we address this separately?

Sergos

        * common.opt: Added new option -fsimd-cost-model.
        * tree-vectorizer.h (unlimited_cost_model): Interface update
        to rely on particular loop info.
        * tree-vect-data-refs.c (vect_peeling_hash_insert): Update to
        unlimited_cost_model call according to new interface.
        (vect_peeling_hash_choose_best_peeling): Ditto.
        (vect_enhance_data_refs_alignment): Ditto.
        * tree-vect-slp.c: Ditto.
        * tree-vect-loop.c (vect_estimate_min_profitable_iters): Ditto,
        plus issue a warning in case cost model overrides users' directive.
        * c-family/c.opt: add openmp-simd warning.
        * fortran/lang.opt: Ditto.
        * doc/invoke.texi: Added new openmp-simd warning.



diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 0026683..a85a8ad 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -592,6 +592,10 @@ Wold-style-definition
 C ObjC Var(warn_old_style_definition) Warning
 Warn if an old-style parameter definition is used

+Wopenmp-simd
+C C++ Var(openmp_simd) Warning EnabledBy(Wall)
+Warn about simd directive is overridden by vectorizer cost model
+
 Woverlength-strings
 C ObjC C++ ObjC++ Var(warn_overlength_strings) Warning
LangEnabledBy(C ObjC C++ ObjC++,Wpedantic)
 Warn if a string is longer than the maximum portable length specified
by the standard
diff --git a/gcc/common.opt b/gcc/common.opt
index d5971df..2b0e9e6 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2296,6 +2296,10 @@ fvect-cost-model=
 Common Joined RejectNegative Enum(vect_cost_model)
Var(flag_vect_cost_model) Init(VECT_COST_MODEL_DEFAULT)
 Specifies the cost model for vectorization

+fsimd-cost-model=
+Common Joined RejectNegative Enum(vect_cost_model)
Var(flag_simd_cost_model) Init(VECT_COST_MODEL_UNLIMITED)
+Specifies the vectorization cost model for code marked with simd directive
+
 Enum
 Name(vect_cost_model) Type(enum vect_cost_model) UnknownError(unknown
vectorizer cost model %qs)

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index c250385..050bd44 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -256,7 +256,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wlogical-op -Wlong-long @gol
 -Wmain -Wmaybe-uninitialized -Wmissing-braces
-Wmissing-field-initializers @gol
 -Wmissing-include-dirs @gol
--Wno-multichar  -Wnonnull  -Wno-overflow @gol
+-Wno-multichar  -Wnonnull  -Wno-overflow -Wopenmp-simd @gol
 -Woverlength-strings  -Wpacked  -Wpacked-bitfield-compat  -Wpadded @gol
 -Wparentheses  -Wpedantic-ms-format -Wno-pedantic-ms-format @gol
 -Wpointer-arith  -Wno-pointer-to-int-cast @gol
@@ -3318,6 +3318,7 @@ Options} and @ref{Objective-C and Objective-C++
Dialect Options}.
 -Wmaybe-uninitialized @gol
 -Wmissing-braces @r{(only for C/ObjC)} @gol
 -Wnonnull  @gol
+-Wopenmp-simd @gol
 -Wparentheses  @gol
 -Wpointer-sign  @gol
 -Wreorder   @gol
@@ -4804,6 +4805,10 @@ attribute.
 @opindex Woverflow
 Do not warn about compile-time overflow in constant expressions.

+@item -Wopenmp-simd
+@opindex Wopenm-simd
+Warn if vectorizer cost model overrides simd directive from user.
+
 @item -Woverride-init @r{(C and Objective-C only)}
 @opindex Woverride-init
 @opindex Wno-override-init
diff --git a/gcc/fortran/lang.opt b/gcc/fortran/lang.opt
index 5e09cbd..b43c48c 100644
--- a/gcc/fortran/lang.opt
+++ b/gcc/fortran/lang.opt
@@ -257,6 +257,10 @@ Wintrinsics-std
 Fortran Warning
 Warn on intrinsics not part of the selected standard

+Wopenmp-simd
+Fortran Warning
+; Documented in C
+
 Wreal-q-constant
 Fortran Warning
 Warn about real-literal-constants with 'q' exponent-letter
diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index 83d1f45..977db43 100644
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -1090,7 +1090,8 @@ vect_peeling_hash_insert (loop_vec_info
loop_vinfo, struct data_reference *dr,
       *new_slot = slot;
     }

-  if (!supportable_dr_alignment && unlimited_cost_model ())
+  if (!supportable_dr_alignment
+      && unlimited_cost_model (LOOP_VINFO_LOOP (loop_vinfo)))
     slot->count += VECT_MAX_COST;
 }

@@ -1200,7 +1201,7 @@ vect_peeling_hash_choose_best_peeling
(loop_vec_info loop_vinfo,
    res.peel_info.dr = NULL;
    res.body_cost_vec = stmt_vector_for_cost ();

-   if (!unlimited_cost_model ())
+   if (!unlimited_cost_model (LOOP_VINFO_LOOP (loop_vinfo)))
      {
        res.inside_cost = INT_MAX;
        res.outside_cost = INT_MAX;
@@ -1429,7 +1430,7 @@ vect_enhance_data_refs_alignment (loop_vec_info
loop_vinfo)
                  vectorization factor.
                  We do this automtically for cost model, since we
calculate cost
                  for every peeling option.  */
-              if (unlimited_cost_model ())
+              if (unlimited_cost_model (LOOP_VINFO_LOOP (loop_vinfo)))
                 possible_npeel_number = vf /nelements;

               /* Handle the aligned case. We may decide to align some other
@@ -1437,7 +1438,7 @@ vect_enhance_data_refs_alignment (loop_vec_info
loop_vinfo)
               if (DR_MISALIGNMENT (dr) == 0)
                 {
                   npeel_tmp = 0;
-                  if (unlimited_cost_model ())
+                  if (unlimited_cost_model (LOOP_VINFO_LOOP (loop_vinfo)))
                     possible_npeel_number++;
                 }

diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index 86ebbd2..1fd28e3 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -2696,7 +2696,7 @@ vect_estimate_min_profitable_iters
(loop_vec_info loop_vinfo,
   void *target_cost_data = LOOP_VINFO_TARGET_COST_DATA (loop_vinfo);

   /* Cost model disabled.  */
-  if (unlimited_cost_model ())
+  if (unlimited_cost_model (LOOP_VINFO_LOOP (loop_vinfo)))
     {
       dump_printf_loc (MSG_NOTE, vect_location, "cost model disabled.\n");
       *ret_min_profitable_niters = 0;
@@ -2929,6 +2929,13 @@ vect_estimate_min_profitable_iters
(loop_vec_info loop_vinfo,
   /* vector version will never be profitable.  */
   else
     {
+      if (LOOP_VINFO_LOOP (loop_vinfo)->force_vect)
+        {
+          warning_at (LOOP_VINFO_LOC (loop_vinfo), OPT_Wopenmp_simd,
+                      "Vectorization did not happen for "
+                      "the loop labeled as simd.");
+        }
+
       if (dump_enabled_p ())
         dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
  "cost model: the vector iteration cost = %d "
diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index 247bdfd..4b25964 100644
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -2171,7 +2171,7 @@ vect_slp_analyze_bb_1 (basic_block bb)
     }

   /* Cost model: check if the vectorization is worthwhile.  */
-  if (!unlimited_cost_model ()
+  if (!unlimited_cost_model (NULL)
       && !vect_bb_vectorization_profitable_p (bb_vinfo))
     {
       if (dump_enabled_p ())
diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index a6c5b59..fd255db 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -919,9 +919,12 @@ known_alignment_for_access_p (struct
data_reference *data_ref_info)

 /* Return true if the vect cost model is unlimited.  */
 static inline bool
-unlimited_cost_model ()
+unlimited_cost_model (loop_p loop)
 {
-  return flag_vect_cost_model == VECT_COST_MODEL_UNLIMITED;
+  return (flag_vect_cost_model == VECT_COST_MODEL_UNLIMITED
+          || (loop != NULL
+              && loop->force_vect
+              && flag_simd_cost_model == VECT_COST_MODEL_UNLIMITED));
 }

 /* Source location */


On Wed, Nov 20, 2013 at 12:14 AM, Tobias Burnus <burnus@net-b.de> wrote:
> I have some small comments to the patch:
>
> * You should also update gcc/doc/invoke.texi
>
>
> Sergey Ostanevich wrote:
>>
>> index 0026683..84911a0 100644
>> --- a/gcc/c-family/c.opt
>> +++ b/gcc/c-family/c.opt
>
> ...
>
>> +Wopenmp-simd
>> +C C++ Var(openmp_simd) Warning
>> +Warn about omp simd construct is overridden by cost model
>
>
>> --- a/gcc/fortran/lang.opt
>> +++ b/gcc/fortran/lang.opt
>
> ...
>
>> +Wopenmp-simd
>> +Fortran Warning
>> +Warn about omp simd construct is overridden by cost model
>
>
> As the option files get merged, using
>
> Wopenmp-simd
> Fortran
> ; Documented in C
>
> is sufficient.
>
>
>
>> +fsimd-cost-model=
>> +Common Joined RejectNegative Enum(vect_cost_model)
>> Var(flag_simd_cost_model) Init(VECT_COST_MODEL_DEFAULT)
>> +Specifies the cost model for vectorization in loops marked with omp simd
>
>
> I wonder whether we need to care about Cilk Plus' "#pragma simd" in this
> summary.
>
>
>
>
>> +      if (LOOP_VINFO_LOOP (loop_vinfo)->force_vect)
>> +        {
>> +          warning (OPT_Wopenmp_simd, "Vectorization did not happen
>> for the loop ",
>> +                   "labeled as simd");
>> +        }
>> +
>
>
> The warning line is too long.
>
>
> Tobias


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