Re: move increase_alignment from simple to regular ipa pass

[Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>]

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On 2 June 2016 at 13:23, Richard Biener <rguenther@suse.de> wrote:
> On Thu, 2 Jun 2016, Prathamesh Kulkarni wrote:
>
>> On 1 June 2016 at 18:37, Richard Biener <rguenther@suse.de> wrote:
>> > On Wed, 1 Jun 2016, Prathamesh Kulkarni wrote:
>> >
>> >> Hi Richard,
>> >> This patch tries to move increase_alignment pass from small to regular ipa pass.
>> >> Does the patch look correct ?
>> >> Since we are only increasing alignment of varpool nodes, I am not sure
>> >> if any ipa
>> >> read/write hooks were necessary and passed NULL for them.
>> >> Cross-tested on arm*-*-*, aarch64*-*-*,
>> >> Bootstrap+test on aarch64-linux-gnu in progress.
>> >
>> > I think the patch looks sensible apart from the fact that both
>> > flag_section_anchors and flag_tree_vectorize can have different
>> > states for each function.  This would mean the pass should get
>> > its own non-Optimization flag initialized by targets where
>> > section anchors are usually used and it means you'd want to
>> > walk IPA refs to see whether variables are used in a function
>> > with both section anchors and vectorization enabled.
>> Hi,
>> I have attached patch (stage-1 built) that walks ipa-refs to determine
>> if function has flag_tree_loop_vectorize and flag_section_anchors set.
>> Does it look OK ?
>>
>> "This would mean the pass should get its own non-Optimization flag
>> initialized by targets where section anchors are usually used"
>> IIUC should we add a new option -fno-increase_alignment and gate the
>> pass on it ? Um sorry I didn't understand why targets
>> with section anchors (arm, aarch64, ppc) should initialize this option ?
>
> Currently the pass is only run for targets with section anchors (and there
> by default if they are enabled by default).  So it makes sense to
> run on those by default and the pass is not necessary on targets w/o
> section anchors as the vectorizer can easily adjust alignment itself on
> those.
Ah indeed, thanks for explanation. Does the attached patch look OK
(stage-1 built) ?
I added new option -fipa-increase_alignment which is disabled by default
and only enabled on arm, aarch64 and ppc.

Thanks,
Prathamesh
>
> Richard.
>
>> Thanks,
>> Prathamesh
>> >
>> > Honza may have further comments.
>> >
>> > Thanks,
>> > Richard.
>> >
>> >> Thanks,
>> >> Prathamesh
>> >>
>> >
>> > --
>> > Richard Biener <rguenther@suse.de>
>> > SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)
>>
>
> --
> Richard Biener <rguenther@suse.de>
> SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)

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diff --git a/gcc/common.opt b/gcc/common.opt
index fccd4b5..c964cf9 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1586,6 +1586,10 @@ fira-algorithm=
 Common Joined RejectNegative Enum(ira_algorithm) Var(flag_ira_algorithm) Init(IRA_ALGORITHM_CB) Optimization
 -fira-algorithm=[CB|priority] Set the used IRA algorithm.
 
+fipa-increase_alignment
+Common Report Var(flag_ipa_increase_alignment) Init(0) Optimization
+Option to gate increase_alignment ipa pass.
+
 Enum
 Name(ira_algorithm) Type(enum ira_algorithm) UnknownError(unknown IRA algorithm %qs)
 
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 51d2d50..f1c383f 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -8251,6 +8251,8 @@ aarch64_override_options (void)
 
   aarch64_register_fma_steering ();
 
+  /* Enable increase_alignment pass.  */
+  flag_ipa_increase_alignment = 1;
 }
 
 /* Implement targetm.override_options_after_change.  */
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 4e453fd..5aca5d0 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -3454,6 +3454,9 @@ arm_option_override (void)
 
   /* Init initial mode for testing.  */
   thumb_flipper = TARGET_THUMB;
+
+  /* Enable increase_alignment pass.  */
+  flag_ipa_increase_alignment = 1;
 }
 
 static void
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index c6b2b6a..a046158 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -5011,6 +5011,9 @@ rs6000_option_override (void)
     = { pass_analyze_swaps, "cse1", 1, PASS_POS_INSERT_BEFORE };
 
   register_pass (&analyze_swaps_info);
+
+  /* Enable increase_alignment pass.  */
+  flag_ipa_increase_alignment = 1;
 }
 
 \f
diff --git a/gcc/passes.def b/gcc/passes.def
index 993ed28..a841183 100644
--- a/gcc/passes.def
+++ b/gcc/passes.def
@@ -138,12 +138,12 @@ along with GCC; see the file COPYING3.  If not see
   PUSH_INSERT_PASSES_WITHIN (pass_ipa_tree_profile)
       NEXT_PASS (pass_feedback_split_functions);
   POP_INSERT_PASSES ()
-  NEXT_PASS (pass_ipa_increase_alignment);
   NEXT_PASS (pass_ipa_tm);
   NEXT_PASS (pass_ipa_lower_emutls);
   TERMINATE_PASS_LIST (all_small_ipa_passes)
 
   INSERT_PASSES_AFTER (all_regular_ipa_passes)
+  NEXT_PASS (pass_ipa_increase_alignment);
   NEXT_PASS (pass_ipa_whole_program_visibility);
   NEXT_PASS (pass_ipa_profile);
   NEXT_PASS (pass_ipa_icf);
diff --git a/gcc/testsuite/gcc.dg/vect/section-anchors-vect-73.c b/gcc/testsuite/gcc.dg/vect/section-anchors-vect-73.c
new file mode 100644
index 0000000..74eaed8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/section-anchors-vect-73.c
@@ -0,0 +1,25 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target section_anchors } */
+/* { dg-require-effective-target vect_int } */
+
+#define N 32
+
+/* Clone of section-anchors-vect-70.c with foo() having -fno-tree-loop-vectorize.  */ 
+
+static struct A {
+  int p1, p2;
+  int e[N];
+} a, b, c;
+
+__attribute__((optimize("-fno-tree-loop-vectorize")))
+int foo(void)
+{
+  for (int i = 0; i < N; i++)
+    a.e[i] = b.e[i] + c.e[i];
+
+   return a.e[0];
+}
+
+/* { dg-final { scan-ipa-dump-times "Increasing alignment of decl" 0 "increase_alignment" { target aarch64*-*-* } } } */
+/* { dg-final { scan-ipa-dump-times "Increasing alignment of decl" 0 "increase_alignment" { target powerpc64*-*-* } } } */
+/* { dg-final { scan-ipa-dump-times "Increasing alignment of decl" 0 "increase_alignment" { target arm*-*-* } } } */
diff --git a/gcc/tree-pass.h b/gcc/tree-pass.h
index 66e103a..2d2e8fc 100644
--- a/gcc/tree-pass.h
+++ b/gcc/tree-pass.h
@@ -482,7 +482,7 @@ extern simple_ipa_opt_pass *make_pass_local_optimization_passes (gcc::context *c
 
 extern ipa_opt_pass_d *make_pass_ipa_whole_program_visibility (gcc::context
 							       *ctxt);
-extern simple_ipa_opt_pass *make_pass_ipa_increase_alignment (gcc::context
+extern ipa_opt_pass_d *make_pass_ipa_increase_alignment (gcc::context
 							      *ctxt);
 extern ipa_opt_pass_d *make_pass_ipa_inline (gcc::context *ctxt);
 extern simple_ipa_opt_pass *make_pass_ipa_free_lang_data (gcc::context *ctxt);
diff --git a/gcc/tree-vectorizer.c b/gcc/tree-vectorizer.c
index 2669813..ff9333e 100644
--- a/gcc/tree-vectorizer.c
+++ b/gcc/tree-vectorizer.c
@@ -899,6 +899,34 @@ get_vec_alignment_for_type (tree type)
   return (alignment > TYPE_ALIGN (type)) ? alignment : 0;
 }
 
+/* Return true if alignment should be increased for this vnode.
+   This is done if every function that references/referring to vnode
+   has flag_tree_loop_vectorize and flag_section_anchors set.  */
+
+static bool
+increase_alignment_p (varpool_node *vnode)
+{
+  ipa_ref *ref;
+
+  for (int i = 0; vnode->iterate_reference (i, ref); i++)
+    if (cgraph_node *cnode = dyn_cast<cgraph_node *> (ref->referred))
+      {
+	struct cl_optimization *opts = opts_for_fn (cnode->decl);
+	if (! (opts->x_flag_tree_vectorize && opts->x_flag_section_anchors))
+	  return false;
+      }
+
+  for (int i = 0; vnode->iterate_referring (i, ref); i++)
+    if (cgraph_node *cnode = dyn_cast<cgraph_node *> (ref->referring))
+      {
+	struct cl_optimization *opts = opts_for_fn (cnode->decl);
+	if (! (opts->x_flag_tree_loop_vectorize && opts->x_flag_section_anchors))
+	  return false;
+      }
+
+  return true;
+}
+
 /* Entry point to increase_alignment pass.  */
 static unsigned int
 increase_alignment (void)
@@ -916,7 +944,8 @@ increase_alignment (void)
 
       if ((decl_in_symtab_p (decl)
 	  && !symtab_node::get (decl)->can_increase_alignment_p ())
-	  || DECL_USER_ALIGN (decl) || DECL_ARTIFICIAL (decl))
+	  || DECL_USER_ALIGN (decl) || DECL_ARTIFICIAL (decl)
+	  || !increase_alignment_p (vnode))
 	continue;
 
       alignment = get_vec_alignment_for_type (TREE_TYPE (decl));
@@ -938,7 +967,7 @@ namespace {
 
 const pass_data pass_data_ipa_increase_alignment =
 {
-  SIMPLE_IPA_PASS, /* type */
+  IPA_PASS, /* type */
   "increase_alignment", /* name */
   OPTGROUP_LOOP | OPTGROUP_VEC, /* optinfo_flags */
   TV_IPA_OPT, /* tv_id */
@@ -949,17 +978,26 @@ const pass_data pass_data_ipa_increase_alignment =
   0, /* todo_flags_finish */
 };
 
-class pass_ipa_increase_alignment : public simple_ipa_opt_pass
+class pass_ipa_increase_alignment : public ipa_opt_pass_d
 {
 public:
   pass_ipa_increase_alignment (gcc::context *ctxt)
-    : simple_ipa_opt_pass (pass_data_ipa_increase_alignment, ctxt)
+    : ipa_opt_pass_d (pass_data_ipa_increase_alignment, ctxt,
+			   NULL, /* generate_summary  */
+			   NULL, /* write summary  */
+			   NULL, /* read summary  */
+			   NULL, /* write optimization summary  */
+			   NULL, /* read optimization summary  */
+			   NULL, /* stmt fixup  */
+			   0, /* function_transform_todo_flags_start  */
+			   NULL, /* transform function  */
+			   NULL )/* variable transform  */
   {}
 
   /* opt_pass methods: */
   virtual bool gate (function *)
     {
-      return flag_section_anchors && flag_tree_loop_vectorize;
+      return flag_ipa_increase_alignment != 0; 
     }
 
   virtual unsigned int execute (function *) { return increase_alignment (); }
@@ -968,7 +1006,7 @@ public:
 
 } // anon namespace
 
-simple_ipa_opt_pass *
+ipa_opt_pass_d *
 make_pass_ipa_increase_alignment (gcc::context *ctxt)
 {
   return new pass_ipa_increase_alignment (ctxt);