Re: [PATCH] Fix PTA info in IPA ICF (PR ipa/84658).

[Martin Liška <mliska at suse dot cz>]

On 03/12/2018 11:06 AM, Richard Biener wrote:
> On Mon, Mar 12, 2018 at 9:42 AM, Martin Liška <mliska@suse.cz> wrote:
> > Hi.
> >
> > This is what I was recommended in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84658#c18.
> > Patch can bootstrap on ppc64le-redhat-linux and survives regression tests.
> >
> > Ready to be installed?
>
> Please do not remove the DECL_PT_UID setting (set_alias_uids).   That's required
> to make followup PTA runs compute correct points-to sets.
>
> Otherwise...
>
> +       /* The above get's us to 99% I guess, at least catching the
> +         address compares.  Below also gets us aliasing correct
> +         but as said we're giving leeway to the situation with
> +         readonly vars anyway, so ... */
> +       basic_block bb;
> +       FOR_EACH_BB_FN (bb, DECL_STRUCT_FUNCTION (cnode->decl))
> +       for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);
> +            gsi_next (&gsi))
>
> so if you want to keep this (as the comment says I think it's not
> strictly necessary) then you can replace DECL_STRUCT_FUNCTION (cnode->decl)
> with 'fn' you compute earlier.
>
> Otherwise looks ok.

Good, done that. I'm attaching final version of patch I'm going to install.

Thanks for review,
Martin

> Thanks,
> Richard.
>
> > Martin
> >
> > gcc/ChangeLog:
> >
> > 2018-03-12  Martin Liska  <mliska@suse.cz>
> >
> >          PR ipa/84658.
> >          * ipa-icf.c (set_alias_uids): Remove.
> >          (sem_variable::merge): Remove usage.
> >          (sem_item_optimizer::sem_item_optimizer): Initialize new
> >          vector.
> >          (sem_item_optimizer::~sem_item_optimizer): Release it.
> >          (sem_item_optimizer::merge_classes): Register variable aliases.
> >          (sem_item_optimizer::fixup_pt_set): New function.
> >          (sem_item_optimizer::fixup_points_to_sets): Likewise.
> >          * ipa-icf.h: Declare new variables and functions.
> >
> > gcc/testsuite/ChangeLog:
> >
> > 2018-03-12  Martin Liska  <mliska@suse.cz>
> >
> >          PR ipa/84658.
> >          * g++.dg/ipa/pr84658.C: New test.
> > ---
> >   gcc/ipa-icf.c                      | 88 +++++++++++++++++++++++++++++---------
> >   gcc/ipa-icf.h                      | 10 +++++
> >   gcc/testsuite/g++.dg/ipa/pr84658.C | 30 +++++++++++++
> >   3 files changed, 108 insertions(+), 20 deletions(-)
> >   create mode 100644 gcc/testsuite/g++.dg/ipa/pr84658.C
>From 27acff689225028a262eec09c213be38eb323470 Mon Sep 17 00:00:00 2001
From: marxin <mliska@suse.cz>
Date: Fri, 9 Mar 2018 13:23:32 +0100
Subject: [PATCH] Fix PTA info in IPA ICF (PR ipa/84658).

gcc/ChangeLog:

2018-03-12  Martin Liska  <mliska@suse.cz>

	PR ipa/84658.
	* (sem_item_optimizer::sem_item_optimizer): Initialize new
	vector.
	(sem_item_optimizer::~sem_item_optimizer): Release it.
	(sem_item_optimizer::merge_classes): Register variable aliases.
	(sem_item_optimizer::fixup_pt_set): New function.
	(sem_item_optimizer::fixup_points_to_sets): Likewise.
	* ipa-icf.h: Declare new variables and functions.

gcc/testsuite/ChangeLog:

2018-03-12  Martin Liska  <mliska@suse.cz>

	PR ipa/84658.
	* g++.dg/ipa/pr84658.C: New test.
---
 gcc/ipa-icf.c                      | 112 ++++++++++++++++++++++++++++++-------
 gcc/ipa-icf.h                      |  12 ++++
 gcc/testsuite/g++.dg/ipa/pr84658.C |  30 ++++++++++
 3 files changed, 134 insertions(+), 20 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/ipa/pr84658.C

diff --git a/gcc/ipa-icf.c b/gcc/ipa-icf.c
index b9f2bf30744..1376a54e95e 100644
--- a/gcc/ipa-icf.c
+++ b/gcc/ipa-icf.c
@@ -2133,23 +2133,6 @@ sem_variable::get_hash (void)
   return m_hash;
 }
 
-/* Set all points-to UIDs of aliases pointing to node N as UID.  */
-
-static void
-set_alias_uids (symtab_node *n, int uid)
-{
-  ipa_ref *ref;
-  FOR_EACH_ALIAS (n, ref)
-    {
-      if (dump_file)
-	fprintf (dump_file, "  Setting points-to UID of [%s] as %d\n",
-		 xstrdup_for_dump (ref->referring->asm_name ()), uid);
-
-      SET_DECL_PT_UID (ref->referring->decl, uid);
-      set_alias_uids (ref->referring, uid);
-    }
-}
-
 /* Merges instance with an ALIAS_ITEM, where alias, thunk or redirection can
    be applied.  */
 
@@ -2276,7 +2259,6 @@ sem_variable::merge (sem_item *alias_item)
       if (dump_file)
 	fprintf (dump_file, "Unified; Variable alias has been created.\n");
 
-      set_alias_uids (original, DECL_UID (original->decl));
       return true;
     }
 }
@@ -2296,7 +2278,7 @@ unsigned int sem_item_optimizer::class_id = 0;
 
 sem_item_optimizer::sem_item_optimizer ()
 : worklist (0), m_classes (0), m_classes_count (0), m_cgraph_node_hooks (NULL),
-  m_varpool_node_hooks (NULL)
+  m_varpool_node_hooks (NULL), m_merged_variables ()
 {
   m_items.create (0);
   bitmap_obstack_initialize (&m_bmstack);
@@ -2321,6 +2303,7 @@ sem_item_optimizer::~sem_item_optimizer ()
   m_items.release ();
 
   bitmap_obstack_release (&m_bmstack);
+  m_merged_variables.release ();
 }
 
 /* Write IPA ICF summary for symbols.  */
@@ -3572,13 +3555,102 @@ sem_item_optimizer::merge_classes (unsigned int prev_class_count)
 	      }
 
 	    if (dbg_cnt (merged_ipa_icf))
-	      merged_p |= source->merge (alias);
+	      {
+		bool merged = source->merge (alias);
+		merged_p |= merged;
+
+		if (merged && alias->type == VAR)
+		  {
+		    symtab_pair p = symtab_pair (source->node, alias->node);
+		    m_merged_variables.safe_push (p);
+		  }
+	      }
 	  }
       }
 
+  if (!m_merged_variables.is_empty ())
+    fixup_points_to_sets ();
+
   return merged_p;
 }
 
+/* Fixup points to set PT.  */
+
+void
+sem_item_optimizer::fixup_pt_set (struct pt_solution *pt)
+{
+  if (pt->vars == NULL)
+    return;
+
+  unsigned i;
+  symtab_pair *item;
+  FOR_EACH_VEC_ELT (m_merged_variables, i, item)
+    if (bitmap_bit_p (pt->vars, DECL_UID (item->second->decl)))
+      bitmap_set_bit (pt->vars, DECL_UID (item->first->decl));
+}
+
+/* Set all points-to UIDs of aliases pointing to node N as UID.  */
+
+static void
+set_alias_uids (symtab_node *n, int uid)
+{
+  ipa_ref *ref;
+  FOR_EACH_ALIAS (n, ref)
+    {
+      if (dump_file)
+	fprintf (dump_file, "  Setting points-to UID of [%s] as %d\n",
+		 xstrdup_for_dump (ref->referring->asm_name ()), uid);
+
+      SET_DECL_PT_UID (ref->referring->decl, uid);
+      set_alias_uids (ref->referring, uid);
+    }
+}
+
+/* Fixup points to analysis info.  */
+
+void
+sem_item_optimizer::fixup_points_to_sets (void)
+{
+  /* TODO: remove in GCC 9 and trigger PTA re-creation after IPA passes.  */
+
+  cgraph_node *cnode;
+  return;
+
+  FOR_EACH_DEFINED_FUNCTION (cnode)
+    {
+      tree name;
+      unsigned i;
+      function *fn = DECL_STRUCT_FUNCTION (cnode->decl);
+      FOR_EACH_SSA_NAME (i, name, fn)
+	if (POINTER_TYPE_P (TREE_TYPE (name))
+	    && SSA_NAME_PTR_INFO (name))
+	  fixup_pt_set (&SSA_NAME_PTR_INFO (name)->pt);
+      fixup_pt_set (&fn->gimple_df->escaped);
+
+       /* The above get's us to 99% I guess, at least catching the
+	  address compares.  Below also gets us aliasing correct
+	  but as said we're giving leeway to the situation with
+	  readonly vars anyway, so ... */
+       basic_block bb;
+       FOR_EACH_BB_FN (bb, fn)
+	for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);
+	     gsi_next (&gsi))
+	  {
+	    gcall *call = dyn_cast<gcall *> (gsi_stmt (gsi));
+	    if (call)
+	      {
+		fixup_pt_set (gimple_call_use_set (call));
+		fixup_pt_set (gimple_call_clobber_set (call));
+	      }
+	  }
+    }
+
+  unsigned i;
+  symtab_pair *item;
+  FOR_EACH_VEC_ELT (m_merged_variables, i, item)
+    set_alias_uids (item->first, DECL_UID (item->first->decl));
+}
+
 /* Dump function prints all class members to a FILE with an INDENT.  */
 
 void
diff --git a/gcc/ipa-icf.h b/gcc/ipa-icf.h
index e3dcde2b4d1..622aebc00c0 100644
--- a/gcc/ipa-icf.h
+++ b/gcc/ipa-icf.h
@@ -141,6 +141,8 @@ public:
   unsigned int index;
 };
 
+typedef std::pair<symtab_node *, symtab_node *> symtab_pair;
+
 /* Semantic item is a base class that encapsulates all shared functionality
    for both semantic function and variable items.  */
 class sem_item
@@ -563,6 +565,12 @@ private:
      processed.  */
   bool merge_classes (unsigned int prev_class_count);
 
+  /* Fixup points to analysis info.  */
+  void fixup_points_to_sets (void);
+
+  /* Fixup points to set PT.  */
+  void fixup_pt_set (struct pt_solution *pt);
+
   /* Adds a newly created congruence class CLS to worklist.  */
   void worklist_push (congruence_class *cls);
 
@@ -632,6 +640,10 @@ private:
 
   /* Bitmap stack.  */
   bitmap_obstack m_bmstack;
+
+  /* Vector of merged variables.  Needed for fixup of points-to-analysis
+     info.  */
+  vec <symtab_pair> m_merged_variables;
 }; // class sem_item_optimizer
 
 } // ipa_icf namespace
diff --git a/gcc/testsuite/g++.dg/ipa/pr84658.C b/gcc/testsuite/g++.dg/ipa/pr84658.C
new file mode 100644
index 00000000000..6846e1832bd
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ipa/pr84658.C
@@ -0,0 +1,30 @@
+/* PR ipa/84658 */
+/* { dg-do run } */
+/* { dg-options "-O2 -fmerge-all-constants -std=c++11" } */
+
+const int kTestCasesFoo[] = { 0, 1, 2, 3, 4, 5, 8, 15, 16, 17, 512, 1020, 1021, 1022, 1023, 1024 };
+const int kTestCasesBar[] = { 0, 1, 2, 3, 4, 5, 8, 15, 16, 17, 512, 1020, 1021, 1022, 1023, 1024 };
+
+void Foo() {
+    __builtin_printf("foo:");
+    for (int count : kTestCasesFoo) {
+        __builtin_printf("%d,", count);
+    }
+    __builtin_printf(";\n");
+}
+
+void Bar() {
+    __builtin_printf("bar:");
+    for (int count : kTestCasesBar) {
+        __builtin_printf("%d,", count);
+    }
+    __builtin_printf(";\n");
+}
+
+int main() {
+    Foo();
+    Bar();
+}
+
+/* { dg-output "foo:0,1,2,3,4,5,8,15,16,17,512,1020,1021,1022,1023,1024,;(\n|\n\r|\r)*" } */
+/* { dg-output "bar:0,1,2,3,4,5,8,15,16,17,512,1020,1021,1022,1023,1024,;(\n|\n\r|\r)*" } */
-- 
2.16.2