Re: [RFC PATCH] ipa-cp: Speculatively call specialized functions

[Richard Biener <richard.guenther@gmail.com>]

On Sun, Nov 13, 2022 at 4:38 PM Christoph Muellner
<christoph.muellner@vrull.eu> wrote:
>
> From: mtsamis <manolis.tsamis@vrull.eu>
>
> The IPA CP pass offers a wide range of optimizations, where most of them
> lead to specialized functions that are called from a call site.
> This can lead to multiple specialized function clones, if more than
> one call-site allows such an optimization.
> If not all call-sites can be optimized, the program might end
> up with call-sites to the original function.
>
> This pass assumes that non-optimized call-sites (i.e. call-sites
> that don't call specialized functions) are likely to be called
> with arguments that would allow calling specialized clones.
> Since we cannot guarantee this (for obvious reasons), we can't
> replace the existing calls. However, we can introduce dynamic
> guards that test the arguments for the collected constants
> and calls the specialized function if there is a match.
>
> To demonstrate the effect, let's consider the following program part:
>
>   func_1()
>     myfunc(1)
>   func_2()
>     myfunc(2)
>   func_i(i)
>     myfunc(i)
>
> In this case the transformation would do the following:
>
>   func_1()
>     myfunc.constprop.1() // myfunc() with arg0 == 1
>   func_2()
>     myfunc.constprop.2() // myfunc() with arg0 == 2
>   func_i(i)
>     if (i == 1)
>       myfunc.constprop.1() // myfunc() with arg0 == 1
>     else if (i == 2)
>       myfunc.constprop.2() // myfunc() with arg0 == 2
>     else
>       myfunc(i)
>
> The pass consists of two main parts:
> * collecting all specialized functions and the argument/constant pair(s)
> * insertion of the guards during materialization
>
> The patch integrates well into ipa-cp and related IPA functionality.
> Given the nature of IPA, the changes are touching many IPA-related
> files as well as call-graph data structures.
>
> The impact of the dynamic guard is expected to be less than the speedup
> gained by enabled optimizations (e.g. inlining or constant propagation).

I don't see any limits on the number of callee candidates or the complexity
of the guard.  Is there any reason to not factor the guards into a wrapper
function to avoid bloating cold call sites and to allow inlining to decide
where the expansion is useful?

Skimming the patch I noticed an #if 0 commented assert with a comment
that this was to be temporary?

Thanks,
Richard.

> PR ipa/107667
> gcc/Changelog:
>
>         * cgraph.cc (cgraph_add_edge_to_call_site_hash): Add support for guarded specialized edges.
>         (cgraph_edge::set_call_stmt): Likewise.
>         (symbol_table::create_edge): Likewise.
>         (cgraph_edge::remove): Likewise.
>         (cgraph_edge::make_speculative): Likewise.
>         (cgraph_edge::make_specialized): Likewise.
>         (cgraph_edge::remove_specializations): Likewise.
>         (cgraph_edge::redirect_call_stmt_to_callee): Likewise.
>         (cgraph_edge::dump_edge_flags): Likewise.
>         (verify_speculative_call): Likewise.
>         (verify_specialized_call): Likewise.
>         (cgraph_node::verify_node): Likewise.
>         * cgraph.h (class GTY): Add new class that contains info of specialized edges.
>         * cgraphclones.cc (cgraph_edge::clone): Add support for guarded specialized edges.
>         (cgraph_node::set_call_stmt_including_clones): Likewise.
>         * ipa-cp.cc (want_remove_some_param_p): Likewise.
>         (create_specialized_node): Likewise.
>         (add_specialized_edges): Likewise.
>         (ipcp_driver): Likewise.
>         * ipa-fnsummary.cc (redirect_to_unreachable): Likewise.
>         (ipa_fn_summary_t::duplicate): Likewise.
>         (analyze_function_body): Likewise.
>         (estimate_edge_size_and_time): Likewise.
>         (remap_edge_summaries): Likewise.
>         * ipa-inline-transform.cc (inline_transform): Likewise.
>         * ipa-inline.cc (edge_badness): Likewise.
>          lto-cgraph.cc (lto_output_edge): Likewise.
>         (input_edge): Likewise.
>         * tree-inline.cc (copy_bb): Likewise.
>         * value-prof.cc (gimple_sc): Add function to create guarded specializations.
>         * value-prof.h (gimple_sc): Likewise.
>
> Signed-off-by: Manolis Tsamis <manolis.tsamis@vrull.eu>
> ---
>  gcc/cgraph.cc               | 316 +++++++++++++++++++++++++++++++++++-
>  gcc/cgraph.h                | 102 ++++++++++++
>  gcc/cgraphclones.cc         |  30 ++++
>  gcc/common.opt              |   4 +
>  gcc/ipa-cp.cc               | 105 ++++++++++++
>  gcc/ipa-fnsummary.cc        |  42 +++++
>  gcc/ipa-inline-transform.cc |  11 ++
>  gcc/ipa-inline.cc           |   5 +
>  gcc/lto-cgraph.cc           |  46 ++++++
>  gcc/tree-inline.cc          |  54 ++++++
>  gcc/value-prof.cc           | 214 ++++++++++++++++++++++++
>  gcc/value-prof.h            |   1 +
>  12 files changed, 923 insertions(+), 7 deletions(-)
>
> diff --git a/gcc/cgraph.cc b/gcc/cgraph.cc
> index 5851b2ffc6c..ee819c87261 100644
> --- a/gcc/cgraph.cc
> +++ b/gcc/cgraph.cc
> @@ -718,18 +718,24 @@ cgraph_add_edge_to_call_site_hash (cgraph_edge *e)
>       one indirect); always hash the direct one.  */
>    if (e->speculative && e->indirect_unknown_callee)
>      return;
> +  /* There are potentially multiple specialization edges for every
> +     specialized call; always hash the base egde.  */
> +  if (e->guarded_specialization_edge_p ())
> +    return;
>    cgraph_edge **slot = e->caller->call_site_hash->find_slot_with_hash
>        (e->call_stmt, cgraph_edge_hasher::hash (e->call_stmt), INSERT);
>    if (*slot)
>      {
> -      gcc_assert (((cgraph_edge *)*slot)->speculative);
> +      gcc_assert (((cgraph_edge *)*slot)->speculative
> +                 || ((cgraph_edge *)*slot)->specialized);
>        if (e->callee && (!e->prev_callee
>                         || !e->prev_callee->speculative
> +                       || !e->prev_callee->specialized
>                         || e->prev_callee->call_stmt != e->call_stmt))
>         *slot = e;
>        return;
>      }
> -  gcc_assert (!*slot || e->speculative);
> +  gcc_assert (!*slot || e->speculative || e->specialized);
>    *slot = e;
>  }
>
> @@ -800,6 +806,23 @@ cgraph_edge::set_call_stmt (cgraph_edge *e, gcall *new_stmt,
>        gcc_checking_assert (new_direct_callee);
>      }
>
> +  /* Update specialized first and do not return yet in case we're dealing
> +     with an edge that is both specialized and speculative.  */
> +  if (update_speculative && e->specialized)
> +    {
> +      cgraph_edge *next, *base = e->specialized_call_base_edge ();
> +      for (cgraph_edge *d = e->first_specialized_call_target (); d; d = next)
> +       {
> +         next = d->next_specialized_call_target ();
> +         cgraph_edge *d2 = set_call_stmt (d, new_stmt, false);
> +         gcc_assert (d2 == d);
> +       }
> +
> +      /* Don't update base for speculative edges.  The code below will.  */
> +      if (!e->speculative)
> +       set_call_stmt (base, new_stmt, false);
> +    }
> +
>    /* Speculative edges has three component, update all of them
>       when asked to.  */
>    if (update_speculative && e->speculative
> @@ -835,12 +858,16 @@ cgraph_edge::set_call_stmt (cgraph_edge *e, gcall *new_stmt,
>        return e_indirect ? indirect : direct;
>      }
>
> +  if (update_speculative && e->specialized)
> +    return e;
> +
>    if (new_direct_callee)
>      e = make_direct (e, new_direct_callee);
>
>    /* Only direct speculative edges go to call_site_hash.  */
>    if (e->caller->call_site_hash
>        && (!e->speculative || !e->indirect_unknown_callee)
> +      && (!e->specialized || e->spec_args == NULL)
>        /* It is possible that edge was previously speculative.  In this case
>          we have different value in call stmt hash which needs preserving.  */
>        && e->caller->get_edge (e->call_stmt) == e)
> @@ -854,11 +881,12 @@ cgraph_edge::set_call_stmt (cgraph_edge *e, gcall *new_stmt,
>    /* Update call stite hash.  For speculative calls we only record the first
>       direct edge.  */
>    if (e->caller->call_site_hash
> -      && (!e->speculative
> +      && ((!e->speculative && !e->specialized)
>           || (e->callee
>               && (!e->prev_callee || !e->prev_callee->speculative
>                   || e->prev_callee->call_stmt != e->call_stmt))
> -         || (e->speculative && !e->callee)))
> +         || (e->speculative && !e->callee)
> +         || e->base_specialization_edge_p ()))
>      cgraph_add_edge_to_call_site_hash (e);
>    return e;
>  }
> @@ -883,7 +911,8 @@ symbol_table::create_edge (cgraph_node *caller, cgraph_node *callee,
>          construction of call stmt hashtable.  */
>        cgraph_edge *e;
>        gcc_checking_assert (!(e = caller->get_edge (call_stmt))
> -                          || e->speculative);
> +                          || e->speculative
> +                          || e->specialized);
>
>        gcc_assert (is_gimple_call (call_stmt));
>      }
> @@ -909,6 +938,8 @@ symbol_table::create_edge (cgraph_node *caller, cgraph_node *callee,
>    edge->indirect_info = NULL;
>    edge->indirect_inlining_edge = 0;
>    edge->speculative = false;
> +  edge->specialized = false;
> +  edge->spec_args = NULL;
>    edge->indirect_unknown_callee = indir_unknown_callee;
>    if (call_stmt && caller->call_site_hash)
>      cgraph_add_edge_to_call_site_hash (edge);
> @@ -1066,6 +1097,11 @@ symbol_table::free_edge (cgraph_edge *e)
>  void
>  cgraph_edge::remove (cgraph_edge *edge)
>  {
> +  /* If we remove the base edge of a group of specialized
> +     edges then we must also remove all of its specializations.  */
> +  if (edge->base_specialization_edge_p ())
> +    cgraph_edge::remove_specializations (edge);
> +
>    /* Call all edge removal hooks.  */
>    symtab->call_edge_removal_hooks (edge);
>
> @@ -1109,6 +1145,8 @@ cgraph_edge::make_speculative (cgraph_node *n2, profile_count direct_count,
>    ipa_ref *ref = NULL;
>    cgraph_edge *e2;
>
> +  gcc_checking_assert (!specialized);
> +
>    if (dump_file)
>      fprintf (dump_file, "Indirect call -> speculative call %s => %s\n",
>              n->dump_name (), n2->dump_name ());
> @@ -1134,6 +1172,62 @@ cgraph_edge::make_speculative (cgraph_node *n2, profile_count direct_count,
>    return e2;
>  }
>
> +/* Mark this edge as specialized and add a new edge representing that N2
> +   is a specialized version of the CALLE of this edge, with the specialized
> +   arguments found in SPEC_ARGS.  */
> +cgraph_edge *
> +cgraph_edge::make_specialized (cgraph_node *n2,
> +                               vec<cgraph_specialization_info>* spec_args,
> +                               profile_count spec_count)
> +{
> +  if (speculative)
> +    {
> +      /* Because both speculative and specialized edges use CALL_STMT and
> +        LTO_STMT_UID to link edges together there is a limitation in
> +        specializing speculative edges.  Only one group of specialized
> +        edges can exist for a given group of speculative edges.  */
> +      for (cgraph_edge *direct = first_speculative_call_target ();
> +          direct; direct = direct->next_speculative_call_target ())
> +       if (direct != this && direct->specialized)
> +         return NULL;
> +    }
> +
> +  cgraph_node *n = caller;
> +  cgraph_edge *e2;
> +
> +  if (dump_file)
> +    fprintf (dump_file, "Creating guarded specialized edge %s -> %s "
> +                       "from%s callee %s\n",
> +                       caller->dump_name (), n2->dump_name (),
> +                       (speculative? " speculative" : ""),
> +                       callee->dump_name ());
> +  specialized = true;
> +  e2 = n->create_edge (n2, call_stmt, spec_count);
> +
> +  /* We don't want to inline the specialized edges seperately.  If the base
> +     specialized edge is inlined then we will drop the specializations.  */
> +  e2->inline_failed = CIF_UNSPECIFIED;
> +  if (TREE_NOTHROW (n2->decl))
> +    e2->can_throw_external = false;
> +  else
> +    e2->can_throw_external = can_throw_external;
> +
> +  e2->specialized = true;
> +
> +  unsigned i;
> +  cgraph_specialization_info* spec_info;
> +  vec_alloc (e2->spec_args, spec_args->length ());
> +
> +  FOR_EACH_VEC_ELT (*spec_args, i, spec_info)
> +    e2->spec_args->quick_push (*spec_info);
> +
> +  e2->lto_stmt_uid = lto_stmt_uid;
> +  e2->in_polymorphic_cdtor = in_polymorphic_cdtor;
> +  count -= e2->count;
> +  symtab->call_edge_duplication_hooks (this, e2);
> +  return e2;
> +}
> +
>  /* Speculative call consists of an indirect edge and one or more
>     direct edge+ref pairs.
>
> @@ -1364,6 +1458,39 @@ cgraph_edge::make_direct (cgraph_edge *edge, cgraph_node *callee)
>    return edge;
>  }
>
> +/* Given the base edge of a group of specialized edges remove all its
> +   specialized edges.  Essentially this can be used to undo the descision
> +   to specialize EDGE.  */
> +
> +void
> +cgraph_edge::remove_specializations (cgraph_edge *edge)
> +{
> +  if (!edge->specialized)
> +    return;
> +
> +  if (edge->base_specialization_edge_p ())
> +    {
> +      cgraph_edge *next;
> +      for (cgraph_edge *e2 = edge->caller->callees; e2; e2 = next)
> +       {
> +         next = e2->next_callee;
> +
> +         if (e2->guarded_specialization_edge_p ()
> +             && edge->call_stmt == e2->call_stmt
> +             && edge->lto_stmt_uid == e2->lto_stmt_uid)
> +           {
> +             edge->count += e2->count;
> +             if (e2->inline_failed)
> +               remove (e2);
> +             else
> +               e2->callee->remove_symbol_and_inline_clones ();
> +           }
> +       }
> +    }
> +  else
> +    gcc_checking_assert (false);
> +}
> +
>  /* Redirect callee of the edge to N.  The function does not update underlying
>     call expression.  */
>
> @@ -1411,6 +1538,7 @@ cgraph_edge::redirect_call_stmt_to_callee (cgraph_edge *e)
>  {
>    tree decl = gimple_call_fndecl (e->call_stmt);
>    gcall *new_stmt;
> +  bool remove_specializations_if_base = true;
>
>    if (e->speculative)
>      {
> @@ -1467,6 +1595,27 @@ cgraph_edge::redirect_call_stmt_to_callee (cgraph_edge *e)
>           /* Indirect edges are not both in the call site hash.
>              get it updated.  */
>           update_call_stmt_hash_for_removing_direct_edge (e, indirect);
> +
> +         if (e->specialized)
> +           {
> +             gcc_checking_assert (e->base_specialization_edge_p ());
> +
> +             /* If we're materializing a speculative and base specialized edge
> +                then we want to keep the specializations alive.  This amounts
> +                to changing the call statements of the guarded
> +                specializations.  */
> +             remove_specializations_if_base = false;
> +             cgraph_edge *next;
> +
> +             for (cgraph_edge *d = e->first_specialized_call_target ();
> +                  d; d = next)
> +               {
> +                 next = d->next_specialized_call_target ();
> +                 cgraph_edge *d2 = set_call_stmt (d, new_stmt, false);
> +                 gcc_assert (d2 == d);
> +               }
> +           }
> +
>           cgraph_edge::set_call_stmt (e, new_stmt, false);
>           e->count = gimple_bb (e->call_stmt)->count;
>
> @@ -1482,6 +1631,53 @@ cgraph_edge::redirect_call_stmt_to_callee (cgraph_edge *e)
>         }
>      }
>
> +  if (e->specialized)
> +    {
> +      if (e->spec_args != NULL)
> +       {
> +         /* Be sure we redirect all specialized targets before poking
> +            about base edge.  */
> +         cgraph_edge *base = e->specialized_call_base_edge ();
> +         gcall *new_stmt;
> +
> +         /* Expand specialization into GIMPLE code.  */
> +         if (dump_file)
> +           fprintf (dump_file,
> +                    "Expanding specialized call of %s -> %s\n",
> +                    e->caller->dump_name (), e->callee->dump_name ());
> +
> +         push_cfun (DECL_STRUCT_FUNCTION (e->caller->decl));
> +
> +         profile_count all = base->count;
> +         for (cgraph_edge *e2 = e->first_specialized_call_target ();
> +              e2; e2 = e2->next_specialized_call_target ())
> +           all = all + e2->count;
> +
> +         profile_probability prob = e->count.probability_in (all);
> +         if (!prob.initialized_p ())
> +           prob = profile_probability::even ();
> +
> +         new_stmt = gimple_sc (e, prob);
> +         e->specialized = false;
> +         e->spec_args = NULL;
> +         if (!base->first_specialized_call_target ())
> +           base->specialized = false;
> +
> +         cgraph_edge::set_call_stmt (e, new_stmt, false);
> +         e->count = gimple_bb (e->call_stmt)->count;
> +         /* Once we are done with expanding the sequence, update also base
> +            call probability.  Until then the basic block accounts for the
> +            sum of specialized edges and all non-expanded specializations.  */
> +         if (!base->specialized)
> +           base->count = gimple_bb (base->call_stmt)->count;
> +
> +         pop_cfun ();
> +       }
> +      else if (remove_specializations_if_base)
> +       /* The specialized edges are in part connected by CALL_STMT so if
> +          we change it for the base edge then remove all specializations.  */
> +       cgraph_edge::remove_specializations (e);
> +    }
>
>    if (e->indirect_unknown_callee
>        || decl == e->callee->decl)
> @@ -2069,6 +2265,10 @@ cgraph_edge::dump_edge_flags (FILE *f)
>  {
>    if (speculative)
>      fprintf (f, "(speculative) ");
> +  if (base_specialization_edge_p ())
> +    fprintf (f, "(specialized base) ");
> +  if (guarded_specialization_edge_p ())
> +    fprintf (f, "(guarded specialization) ");
>    if (!inline_failed)
>      fprintf (f, "(inlined) ");
>    if (call_stmt_cannot_inline_p)
> @@ -3313,6 +3513,10 @@ verify_speculative_call (struct cgraph_node *node, gimple *stmt,
>         direct = direct->next_callee)
>      if (direct->call_stmt == stmt && direct->lto_stmt_uid == lto_stmt_uid)
>        {
> +       /* Guarded specialized edges share the same CALL_STMT and LTO_STMT_UID
> +          but are handled separately.  */
> +       if (direct->guarded_specialization_edge_p ())
> +         continue;
>         if (!first_call)
>           first_call = direct;
>         if (prev_call && direct != prev_call->next_callee)
> @@ -3402,6 +3606,93 @@ verify_speculative_call (struct cgraph_node *node, gimple *stmt,
>    return false;
>  }
>
> +/* Verify consistency of specialized call in NODE corresponding to STMT
> +   and LTO_STMT_UID.  If BASE is set, assume that it is the base
> +   edge of call sequence.  Return true if error is found.
> +
> +   This function is called to every component of specialized call (base edge
> +   and specialized edges).  To save duplicated work, do full testing only
> +   when testing the base edge.  */
> +static bool
> +verify_specialized_call (struct cgraph_node *node, gimple *stmt,
> +                        unsigned int lto_stmt_uid,
> +                        struct cgraph_edge *base)
> +{
> +  if (base == NULL)
> +    {
> +      cgraph_edge *base;
> +      for (base = node->callees; base;
> +          base = base->next_callee)
> +       if (base->call_stmt == stmt
> +           && base->lto_stmt_uid == lto_stmt_uid
> +           && base->spec_args == NULL)
> +         break;
> +      if (!base)
> +       {
> +         error ("missing base call in specialized call sequence");
> +         return true;
> +       }
> +      if (!base->specialized)
> +       {
> +         error ("base call in specialized call sequence has no "
> +                "specialized flag");
> +         return true;
> +       }
> +      for (base = base->next_callee; base;
> +          base = base->next_callee)
> +       if (base->call_stmt == stmt
> +           && base->lto_stmt_uid == lto_stmt_uid
> +           && base->spec_args == NULL)
> +         {
> +           error ("cannot have more than one base edge in specialized "
> +                  "call sequence");
> +           return true;
> +         }
> +      return false;
> +    }
> +
> +  cgraph_edge *prev_call = NULL;
> +
> +  cgraph_node *origin_base = base->callee;
> +  while (origin_base->clone_of)
> +    origin_base = origin_base->clone_of;
> +
> +  for (cgraph_edge *spec = node->callees; spec;
> +       spec = spec->next_callee)
> +    if (spec->call_stmt == stmt
> +       && spec->lto_stmt_uid == lto_stmt_uid
> +       && spec->spec_args != NULL)
> +      {
> +       cgraph_node *origin_spec = spec->callee;
> +       while (origin_spec->clone_of)
> +         origin_spec = origin_spec->clone_of;
> +
> +       if (spec->callee->clone_of && origin_base != origin_spec)
> +         {
> +           error ("specialized call to %s in specialized call sequence has "
> +                  "different origin than base %s %s %s",
> +                  origin_spec->dump_name (), origin_base->dump_name (),
> +                  base->callee->dump_name (), spec->callee->dump_name ());
> +           return true;
> +         }
> +
> +       if (prev_call && spec != prev_call->next_callee)
> +         {
> +           error ("specialized edges are not adjacent");
> +           return true;
> +         }
> +       prev_call = spec;
> +       if (!spec->specialized)
> +         {
> +           error ("call to %s in specialized call sequence has no "
> +                  "specialized flag", spec->callee->dump_name ());
> +           return true;
> +         }
> +      }
> +
> +  return false;
> +}
> +
>  /* Verify cgraph nodes of given cgraph node.  */
>  DEBUG_FUNCTION void
>  cgraph_node::verify_node (void)
> @@ -3578,6 +3869,7 @@ cgraph_node::verify_node (void)
>        if (gimple_has_body_p (e->caller->decl)
>           && !e->caller->inlined_to
>           && !e->speculative
> +         && !e->specialized
>           /* Optimized out calls are redirected to __builtin_unreachable.  */
>           && (e->count.nonzero_p ()
>               || ! e->callee->decl
> @@ -3604,6 +3896,10 @@ cgraph_node::verify_node (void)
>           && verify_speculative_call (e->caller, e->call_stmt, e->lto_stmt_uid,
>                                       NULL))
>         error_found = true;
> +      if (e->specialized
> +         && verify_specialized_call (e->caller, e->call_stmt, e->lto_stmt_uid,
> +                                     e->spec_args == NULL? e : NULL))
> +       error_found = true;
>      }
>    for (e = indirect_calls; e; e = e->next_callee)
>      {
> @@ -3612,6 +3908,7 @@ cgraph_node::verify_node (void)
>        if (gimple_has_body_p (e->caller->decl)
>           && !e->caller->inlined_to
>           && !e->speculative
> +         && !e->specialized
>           && e->count.ipa_p ()
>           && count
>               == ENTRY_BLOCK_PTR_FOR_FN (DECL_STRUCT_FUNCTION (decl))->count
> @@ -3630,6 +3927,11 @@ cgraph_node::verify_node (void)
>           && verify_speculative_call (e->caller, e->call_stmt, e->lto_stmt_uid,
>                                       e))
>         error_found = true;
> +      if (e->specialized || e->spec_args != NULL)
> +       {
> +         error ("Cannot have specialized edges in indirect call");
> +         error_found = true;
> +       }
>      }
>    for (i = 0; iterate_reference (i, ref); i++)
>      {
> @@ -3824,7 +4126,7 @@ cgraph_node::verify_node (void)
>
>        for (e = callees; e; e = e->next_callee)
>         {
> -         if (!e->aux && !e->speculative)
> +         if (!e->aux && !e->speculative && !e->specialized)
>             {
>               error ("edge %s->%s has no corresponding call_stmt",
>                      identifier_to_locale (e->caller->name ()),
> @@ -3836,7 +4138,7 @@ cgraph_node::verify_node (void)
>         }
>        for (e = indirect_calls; e; e = e->next_callee)
>         {
> -         if (!e->aux && !e->speculative)
> +         if (!e->aux && !e->speculative && !e->specialized)
>             {
>               error ("an indirect edge from %s has no corresponding call_stmt",
>                      identifier_to_locale (e->caller->name ()));
> diff --git a/gcc/cgraph.h b/gcc/cgraph.h
> index 4be67e3cea9..4caed96e803 100644
> --- a/gcc/cgraph.h
> +++ b/gcc/cgraph.h
> @@ -1683,6 +1683,19 @@ public:
>    unsigned vptr_changed : 1;
>  };
>
> +class GTY (()) cgraph_specialization_info
> +{
> +public:
> +  unsigned arg_idx;
> +  int is_unsigned; /* Whether the specialization constant is unsigned.  */
> +  union
> +    {
> +      HOST_WIDE_INT GTY ((tag ("0"))) sval;
> +      unsigned HOST_WIDE_INT GTY ((tag ("1"))) uval;
> +    }
> +  GTY ((desc ("%1.is_unsigned"))) cst;
> +};
> +
>  class GTY((chain_next ("%h.next_caller"), chain_prev ("%h.prev_caller"),
>            for_user)) cgraph_edge
>  {
> @@ -1723,6 +1736,12 @@ public:
>     */
>    cgraph_edge *make_speculative (cgraph_node *n2, profile_count direct_count,
>                                  unsigned int speculative_id = 0);
> +  /* Mark that this edge represents a specialized call to N2.
> +     SPEC_ARGS represent the position and values of the CALL_STMT of this edge
> +     that are specialized in N2.  */
> +  cgraph_edge *make_specialized (cgraph_node *n2,
> +                                vec<cgraph_specialization_info> *spec_args,
> +                                profile_count spec_count);
>
>    /* Speculative call consists of an indirect edge and one or more
>       direct edge+ref pairs.  Speculative will expand to the following sequence:
> @@ -1802,6 +1821,66 @@ public:
>      gcc_unreachable ();
>    }
>
> +  /* Return the first edge that represents a specialization of the CALL_STMT
> +     of this edge if one exists or NULL otherwise.  */
> +  cgraph_edge *first_specialized_call_target ()
> +  {
> +    gcc_checking_assert (specialized && callee);
> +    for (cgraph_edge *e2 = caller->callees;
> +        e2; e2 = e2->next_callee)
> +      if (e2->guarded_specialization_edge_p ()
> +         && call_stmt == e2->call_stmt
> +         && lto_stmt_uid == e2->lto_stmt_uid)
> +       return e2;
> +
> +    return NULL;
> +  }
> +
> +  /* Return the next edge that represents a specialization of the CALL_STMT
> +     of this edge if one exists or NULL otherwise.  */
> +  cgraph_edge *next_specialized_call_target ()
> +  {
> +    cgraph_edge *e = this;
> +    gcc_checking_assert (specialized && callee);
> +
> +    if (e->next_callee
> +       && e->next_callee->guarded_specialization_edge_p ()
> +       && e->next_callee->call_stmt == e->call_stmt
> +       && e->next_callee->lto_stmt_uid == e->lto_stmt_uid)
> +      return e->next_callee;
> +    return NULL;
> +  }
> +
> +  /* When called on any edge in a specialized call return the (unique)
> +     edge that points to the non specialized function.  */
> +  cgraph_edge *specialized_call_base_edge ()
> +  {
> +    gcc_checking_assert (specialized && callee);
> +    for (cgraph_edge *e2 = caller->callees;
> +        e2; e2 = e2->next_callee)
> +      if (e2->base_specialization_edge_p ()
> +         && call_stmt == e2->call_stmt
> +         && lto_stmt_uid == e2->lto_stmt_uid)
> +       return e2;
> +
> +    return NULL;
> +  }
> +
> +  /* Return true iff this edge is part of specialized sequence and is the
> +     original edge for which other specialization edges potentially exist.  */
> +  bool base_specialization_edge_p () const
> +  {
> +    return specialized && spec_args == NULL;
> +  }
> +
> +  /* Return true iff this edge is part of specialized sequence and it
> +     represents a potential specialization target that canbe used instead
> +     of the base edge.  */
> +  bool guarded_specialization_edge_p () const
> +  {
> +    return specialized && spec_args != NULL;
> +  }
> +
>    /* Speculative call edge turned out to be direct call to CALLEE_DECL.  Remove
>       the speculative call sequence and return edge representing the call, the
>       original EDGE can be removed and deallocated.  It is up to caller to
> @@ -1820,6 +1899,11 @@ public:
>    static cgraph_edge *resolve_speculation (cgraph_edge *edge,
>                                            tree callee_decl = NULL);
>
> +  /* Given the base edge of a group of specialized edges remove all its
> +     specialized edges.  Essentially this can be used to undo the descision
> +     to specialize EDGE.  */
> +  static void remove_specializations (cgraph_edge *edge);
> +
>    /* If necessary, change the function declaration in the call statement
>       associated with edge E so that it corresponds to the edge callee.
>       Speculations can be resolved in the process and EDGE can be removed and
> @@ -1895,6 +1979,9 @@ public:
>    /* Additional information about an indirect call.  Not cleared when an edge
>       becomes direct.  */
>    cgraph_indirect_call_info *indirect_info;
> +  /* If this edge has a specialized function as a callee then this vector
> +     holds the indices and values of the specialized arguments.  */
> +  vec<cgraph_specialization_info>* GTY ((skip (""))) spec_args;
>    void *GTY ((skip (""))) aux;
>    /* When equal to CIF_OK, inline this call.  Otherwise, points to the
>       explanation why function was not inlined.  */
> @@ -1933,6 +2020,21 @@ public:
>       Optimizers may later redirect direct call to clone, so 1) and 3)
>       do not need to necessarily agree with destination.  */
>    unsigned int speculative : 1;
> +  /* Edges with SPECIALIZED flag represents calls that have additional
> +     specialized functions that can be used instead (as a result of ipa-cp).
> +     The final code sequence will have form:
> +
> +     if (specialized_arg_0 == specialized_const_0
> +        && ...
> +        && specialized_arg_i == specialized_const_i)
> +       call_target.constprop.N (non_specialized_arg_0, ...);
> +     ...
> +     more potential specializations
> +     ...
> +     else
> +       call_target ();
> +  */
> +  unsigned int specialized : 1;
>    /* Set to true when caller is a constructor or destructor of polymorphic
>       type.  */
>    unsigned in_polymorphic_cdtor : 1;
> diff --git a/gcc/cgraphclones.cc b/gcc/cgraphclones.cc
> index bb4b3c5407d..9e12fa19180 100644
> --- a/gcc/cgraphclones.cc
> +++ b/gcc/cgraphclones.cc
> @@ -141,6 +141,20 @@ cgraph_edge::clone (cgraph_node *n, gcall *call_stmt, unsigned stmt_uid,
>    new_edge->can_throw_external = can_throw_external;
>    new_edge->call_stmt_cannot_inline_p = call_stmt_cannot_inline_p;
>    new_edge->speculative = speculative;
> +
> +  new_edge->specialized = specialized;
> +  new_edge->spec_args = NULL;
> +
> +  if (spec_args)
> +    {
> +      unsigned i;
> +      cgraph_specialization_info* spec_info;
> +      vec_alloc (new_edge->spec_args, spec_args->length ());
> +
> +      FOR_EACH_VEC_ELT (*spec_args, i, spec_info)
> +       new_edge->spec_args->quick_push (*spec_info);
> +    }
> +
>    new_edge->in_polymorphic_cdtor = in_polymorphic_cdtor;
>
>    /* Update IPA profile.  Local profiles need no updating in original.  */
> @@ -791,6 +805,22 @@ cgraph_node::set_call_stmt_including_clones (gimple *old_stmt,
>                   }
>                 indirect->speculative = false;
>               }
> +
> +           if (edge->specialized && !update_speculative)
> +             {
> +               cgraph_edge *base = edge->specialized_call_base_edge ();
> +
> +               for (cgraph_edge *next, *specialized
> +                       = edge->first_specialized_call_target ();
> +                    specialized;
> +                    specialized = next)
> +                 {
> +                   next = specialized->next_specialized_call_target ();
> +                   specialized->specialized = false;
> +                 }
> +               base->specialized = false;
> +             }
> +
>           }
>         if (node->clones)
>           node = node->clones;
> diff --git a/gcc/common.opt b/gcc/common.opt
> index bce3e514f65..437f2f4295b 100644
> --- a/gcc/common.opt
> +++ b/gcc/common.opt
> @@ -1933,6 +1933,10 @@ fipa-bit-cp
>  Common Var(flag_ipa_bit_cp) Optimization
>  Perform interprocedural bitwise constant propagation.
>
> +fipa-guarded-specialization
> +Common Var(flag_ipa_guarded_specialization) Optimization
> +Add speculative edges for existing specialized functions.
> +
>  fipa-modref
>  Common Var(flag_ipa_modref) Optimization
>  Perform interprocedural modref analysis.
> diff --git a/gcc/ipa-cp.cc b/gcc/ipa-cp.cc
> index d2bcd5e5e69..5a24f6987ac 100644
> --- a/gcc/ipa-cp.cc
> +++ b/gcc/ipa-cp.cc
> @@ -119,6 +119,7 @@ along with GCC; see the file COPYING3.  If not see
>  #include "symbol-summary.h"
>  #include "tree-vrp.h"
>  #include "ipa-prop.h"
> +#include "gimple-pretty-print.h"
>  #include "tree-pretty-print.h"
>  #include "tree-inline.h"
>  #include "ipa-fnsummary.h"
> @@ -5239,6 +5240,8 @@ want_remove_some_param_p (cgraph_node *node, vec<tree> known_csts)
>    return false;
>  }
>
> +static hash_map<cgraph_node*, vec<cgraph_node*>> *available_specializations;
> +
>  /* Create a specialized version of NODE with known constants in KNOWN_CSTS,
>     known contexts in KNOWN_CONTEXTS and known aggregate values in AGGVALS and
>     redirect all edges in CALLERS to it.  */
> @@ -5409,6 +5412,13 @@ create_specialized_node (struct cgraph_node *node,
>    new_info->known_csts = known_csts;
>    new_info->known_contexts = known_contexts;
>
> +  if (!info->ipcp_orig_node)
> +    {
> +      vec<cgraph_node*> &spec_nodes
> +       = available_specializations->get_or_insert (node);
> +      spec_nodes.safe_push (new_node);
> +    }
> +
>    ipcp_discover_new_direct_edges (new_node, known_csts, known_contexts,
>                                   aggvals);
>
> @@ -6538,6 +6548,96 @@ ipcp_store_vr_results (void)
>      }
>  }
>
> +/* Add new edges to the call graph to represent the available specializations
> +   of each specialized function.  */
> +static void
> +add_specialized_edges (void)
> +{
> +  cgraph_edge *e;
> +  cgraph_node *n, *spec_n;
> +  tree spec_v;
> +  unsigned i, j;
> +
> +  FOR_EACH_DEFINED_FUNCTION (n)
> +    {
> +      if (dump_file && n->callees)
> +       fprintf (dump_file,
> +                "Procesing function %s for specialization of edges.\n",
> +                n->dump_name ());
> +
> +      if (n->ipcp_clone)
> +       continue;
> +
> +      bool update = false;
> +      for (e = n->callees; e; e = e->next_callee)
> +       {
> +         if (!e->callee || e->recursive_p ())
> +           continue;
> +
> +         vec<cgraph_node*> *specialization_nodes
> +           = available_specializations->get (e->callee);
> +
> +         if (!specialization_nodes)
> +           continue;
> +
> +         FOR_EACH_VEC_ELT (*specialization_nodes, i, spec_n)
> +           {
> +             if (dump_file)
> +               fprintf (dump_file,
> +                        "Edge has available specialization %s.\n",
> +                        spec_n->dump_name ());
> +
> +             ipa_node_params *spec_params = ipa_node_params_sum->get (spec_n);
> +             vec<cgraph_specialization_info> replaced_args = vNULL;
> +             bool failed = false;
> +
> +             FOR_EACH_VEC_ELT (spec_params->known_csts, j, spec_v)
> +               {
> +                 if (spec_v != NULL_TREE)
> +                   {
> +                     if (TREE_CODE (spec_v) == INTEGER_CST
> +                         && TYPE_UNSIGNED (TREE_TYPE (spec_v))
> +                         && tree_fits_uhwi_p (spec_v))
> +                       {
> +                             cgraph_specialization_info spec_info;
> +                             spec_info.arg_idx = j;
> +                             spec_info.is_unsigned = 1;
> +                             spec_info.cst.uval = tree_to_uhwi (spec_v);
> +                             replaced_args.safe_push (spec_info);
> +                       }
> +                     else if (TREE_CODE (spec_v) == INTEGER_CST
> +                              && !TYPE_UNSIGNED (TREE_TYPE (spec_v))
> +                              && tree_fits_shwi_p (spec_v))
> +                       {
> +                             cgraph_specialization_info spec_info;
> +                             spec_info.arg_idx = j;
> +                             spec_info.is_unsigned = 0;
> +                             spec_info.cst.uval = tree_to_shwi (spec_v);
> +                             replaced_args.safe_push (spec_info);
> +                       }
> +                     else
> +                       {
> +                         failed = true;
> +                         break;
> +                       }
> +                   }
> +               }
> +
> +             if (!failed && replaced_args.length () > 0)
> +               {
> +                 if (e->make_specialized (spec_n,
> +                                          &replaced_args,
> +                                          e->count.apply_scale (1, 10)))
> +                   update = true;
> +               }
> +           }
> +       }
> +
> +      if (update)
> +       ipa_update_overall_fn_summary (n);
> +    }
> +}
> +
>  /* The IPCP driver.  */
>
>  static unsigned int
> @@ -6551,6 +6651,7 @@ ipcp_driver (void)
>    ipa_check_create_node_params ();
>    ipa_check_create_edge_args ();
>    clone_num_suffixes = new hash_map<const char *, unsigned>;
> +  available_specializations = new hash_map<cgraph_node*, vec<cgraph_node*>>;
>
>    if (dump_file)
>      {
> @@ -6570,8 +6671,12 @@ ipcp_driver (void)
>    ipcp_store_bits_results ();
>    /* Store results of value range propagation.  */
>    ipcp_store_vr_results ();
> +  /* Add new edges for specializations.  */
> +  if (flag_ipa_guarded_specialization)
> +    add_specialized_edges ();
>
>    /* Free all IPCP structures.  */
> +  delete available_specializations;
>    delete clone_num_suffixes;
>    free_toporder_info (&topo);
>    delete edge_clone_summaries;
> diff --git a/gcc/ipa-fnsummary.cc b/gcc/ipa-fnsummary.cc
> index fd3d7d6c5e8..a1f219a056e 100644
> --- a/gcc/ipa-fnsummary.cc
> +++ b/gcc/ipa-fnsummary.cc
> @@ -257,6 +257,13 @@ redirect_to_unreachable (struct cgraph_edge *e)
>      e = cgraph_edge::resolve_speculation (e, target->decl);
>    else if (!e->callee)
>      e = cgraph_edge::make_direct (e, target);
> +  else if (e->base_specialization_edge_p ())
> +    {
> +      /* If the base edge becomes unreachable there's no reason to
> +        keep the specializations around.  */
> +      cgraph_edge::remove_specializations (e);
> +      e->redirect_callee (target);
> +    }
>    else
>      e->redirect_callee (target);
>    class ipa_call_summary *es = ipa_call_summaries->get (e);
> @@ -866,6 +873,7 @@ ipa_fn_summary_t::duplicate (cgraph_node *src,
>           ipa_predicate new_predicate;
>           class ipa_call_summary *es = ipa_call_summaries->get (edge);
>           next = edge->next_callee;
> +         bool update_next = edge->specialized;
>
>           if (!edge->inline_failed)
>             inlined_to_p = true;
> @@ -876,6 +884,9 @@ ipa_fn_summary_t::duplicate (cgraph_node *src,
>           if (new_predicate == false && *es->predicate != false)
>             optimized_out_size += es->call_stmt_size * ipa_fn_summary::size_scale;
>           edge_set_predicate (edge, &new_predicate);
> +         /* NEXT may be invalidated for specialized calls.  */
> +         if (update_next)
> +           next = edge->next_callee;
>         }
>
>        /* Remap indirect edge predicates with the same simplification as above.
> @@ -2825,6 +2836,29 @@ analyze_function_body (struct cgraph_node *node, bool early)
>                                                      es, es3);
>                     }
>                 }
> +             if (edge->specialized)
> +               {
> +                 cgraph_edge *base
> +                       = edge->specialized_call_base_edge ();
> +                 ipa_call_summary *es2
> +                        = ipa_call_summaries->get_create (base);
> +                 ipa_call_summaries->duplicate (edge, base,
> +                                                es, es2);
> +
> +                 /* Edge is the first direct call.
> +                    create and duplicate call summaries for multiple
> +                    speculative call targets.  */
> +                 for (cgraph_edge *specialization
> +                        = edge->next_specialized_call_target ();
> +                      specialization; specialization
> +                        = specialization->next_specialized_call_target ())
> +                   {
> +                     ipa_call_summary *es3
> +                       = ipa_call_summaries->get_create (specialization);
> +                     ipa_call_summaries->duplicate (edge, specialization,
> +                                                    es, es3);
> +                   }
> +               }
>             }
>
>           /* TODO: When conditional jump or switch is known to be constant, but
> @@ -3275,6 +3309,9 @@ estimate_edge_size_and_time (struct cgraph_edge *e, int *size, int *min_size,
>                              sreal *time, ipa_call_arg_values *avals,
>                              ipa_hints *hints)
>  {
> +  if (e->guarded_specialization_edge_p ())
> +    return;
> +
>    class ipa_call_summary *es = ipa_call_summaries->get (e);
>    int call_size = es->call_stmt_size;
>    int call_time = es->call_stmt_time;
> @@ -4050,6 +4087,7 @@ remap_edge_summaries (struct cgraph_edge *inlined_edge,
>      {
>        ipa_predicate p;
>        next = e->next_callee;
> +      bool update_next = e->specialized;
>
>        if (e->inline_failed)
>         {
> @@ -4073,6 +4111,10 @@ remap_edge_summaries (struct cgraph_edge *inlined_edge,
>                               params_summary, callee_info,
>                               operand_map, offset_map, possible_truths,
>                               toplev_predicate);
> +
> +      /* NEXT may be invalidated for specialized calls.  */
> +      if (update_next)
> +       next = e->next_callee;
>      }
>    for (e = node->indirect_calls; e; e = next)
>      {
> diff --git a/gcc/ipa-inline-transform.cc b/gcc/ipa-inline-transform.cc
> index 07288e57c73..d0b9cd9e599 100644
> --- a/gcc/ipa-inline-transform.cc
> +++ b/gcc/ipa-inline-transform.cc
> @@ -775,11 +775,22 @@ inline_transform (struct cgraph_node *node)
>      }
>
>    maybe_materialize_called_clones (node);
> +  /* Perform call statement redirection in two steps.  In the first step
> +     only consider speculative edges and then process the rest in a separate
> +     step.  This is required due to the potential existance of edges that are
> +     both speculative and specialized, in which case we need to process them
> +     in this order.  */
>    for (e = node->callees; e; e = next)
>      {
>        if (!e->inline_failed)
>         has_inline = true;
>        next = e->next_callee;
> +      if (e->speculative)
> +       cgraph_edge::redirect_call_stmt_to_callee (e);
> +    }
> +  for (e = node->callees; e; e = next)
> +    {
> +      next = e->next_callee;
>        cgraph_edge::redirect_call_stmt_to_callee (e);
>      }
>    node->remove_all_references ();
> diff --git a/gcc/ipa-inline.cc b/gcc/ipa-inline.cc
> index 14969198cde..c6cd2b92f6e 100644
> --- a/gcc/ipa-inline.cc
> +++ b/gcc/ipa-inline.cc
> @@ -1185,12 +1185,17 @@ edge_badness (struct cgraph_edge *edge, bool dump)
>    edge_time = estimate_edge_time (edge, &unspec_edge_time);
>    hints = estimate_edge_hints (edge);
>    gcc_checking_assert (edge_time >= 0);
> +
> +  /* Temporarily disabled due to the way time is calculated
> +     with specialized edges.  */
> +#if 0
>    /* Check that inlined time is better, but tolerate some roundoff issues.
>       FIXME: When callee profile drops to 0 we account calls more.  This
>       should be fixed by never doing that.  */
>    gcc_checking_assert ((edge_time * 100
>                         - callee_info->time * 101).to_int () <= 0
>                         || callee->count.ipa ().initialized_p ());
> +#endif
>    gcc_checking_assert (growth <= ipa_size_summaries->get (callee)->size);
>
>    if (dump)
> diff --git a/gcc/lto-cgraph.cc b/gcc/lto-cgraph.cc
> index 350195d86db..c8250f7b73c 100644
> --- a/gcc/lto-cgraph.cc
> +++ b/gcc/lto-cgraph.cc
> @@ -271,6 +271,8 @@ lto_output_edge (struct lto_simple_output_block *ob, struct cgraph_edge *edge,
>    bp_pack_value (&bp, edge->speculative_id, 16);
>    bp_pack_value (&bp, edge->indirect_inlining_edge, 1);
>    bp_pack_value (&bp, edge->speculative, 1);
> +  bp_pack_value (&bp, edge->specialized, 1);
> +  bp_pack_value (&bp, edge->spec_args != NULL, 1);
>    bp_pack_value (&bp, edge->call_stmt_cannot_inline_p, 1);
>    gcc_assert (!edge->call_stmt_cannot_inline_p
>               || edge->inline_failed != CIF_BODY_NOT_AVAILABLE);
> @@ -295,7 +297,27 @@ lto_output_edge (struct lto_simple_output_block *ob, struct cgraph_edge *edge,
>        bp_pack_value (&bp, edge->indirect_info->num_speculative_call_targets,
>                      16);
>      }
> +
>    streamer_write_bitpack (&bp);
> +
> +  if (edge->spec_args != NULL)
> +    {
> +      cgraph_specialization_info *spec_info;
> +      unsigned len = edge->spec_args->length (), i;
> +      streamer_write_uhwi_stream (ob->main_stream, len);
> +
> +      FOR_EACH_VEC_ELT (*edge->spec_args, i, spec_info)
> +       {
> +         unsigned idx = spec_info->arg_idx;
> +         streamer_write_uhwi_stream (ob->main_stream, idx);
> +         streamer_write_hwi_stream (ob->main_stream, spec_info->is_unsigned);
> +
> +         if (spec_info->is_unsigned)
> +           streamer_write_uhwi_stream (ob->main_stream, spec_info->cst.uval);
> +         else
> +           streamer_write_hwi_stream (ob->main_stream, spec_info->cst.sval);
> +       }
> +    }
>  }
>
>  /* Return if NODE contain references from other partitions.  */
> @@ -1517,6 +1539,8 @@ input_edge (class lto_input_block *ib, vec<symtab_node *> nodes,
>
>    edge->indirect_inlining_edge = bp_unpack_value (&bp, 1);
>    edge->speculative = bp_unpack_value (&bp, 1);
> +  edge->specialized = bp_unpack_value (&bp, 1);
> +  bool has_edge_spec_args = bp_unpack_value (&bp, 1);
>    edge->lto_stmt_uid = stmt_id;
>    edge->speculative_id = speculative_id;
>    edge->inline_failed = inline_failed;
> @@ -1542,6 +1566,28 @@ input_edge (class lto_input_block *ib, vec<symtab_node *> nodes,
>        edge->indirect_info->num_speculative_call_targets
>         = bp_unpack_value (&bp, 16);
>      }
> +
> +  if (has_edge_spec_args)
> +    {
> +      unsigned len = streamer_read_uhwi (ib);
> +      vec_alloc (edge->spec_args, len);
> +
> +      for (unsigned i = 0; i < len; i++)
> +       {
> +         cgraph_specialization_info spec_info;
> +         spec_info.arg_idx = streamer_read_uhwi (ib);
> +         spec_info.is_unsigned = streamer_read_hwi (ib);
> +
> +         if (spec_info.is_unsigned)
> +           spec_info.cst.uval = streamer_read_uhwi (ib);
> +         else
> +           spec_info.cst.sval = streamer_read_hwi (ib);
> +
> +         edge->spec_args->quick_push (spec_info);
> +      }
> +    }
> +  else
> +    edge->spec_args = NULL;
>  }
>
>
> diff --git a/gcc/tree-inline.cc b/gcc/tree-inline.cc
> index 8091ba8f13b..26657f7c017 100644
> --- a/gcc/tree-inline.cc
> +++ b/gcc/tree-inline.cc
> @@ -2307,6 +2307,60 @@ copy_bb (copy_body_data *id, basic_block bb,
>                           indirect->count
>                              = copy_basic_block->count.apply_probability (prob);
>                         }
> +                     /* A specialized call is consist of multiple
> +                        edges - a base edge and one or more specialized edges.
> +                        Duplicate and distribute frequencies in a way similar
> +                        to the speculative edges.  */
> +                     else if (edge->specialized)
> +                       {
> +                         int n = 0;
> +                         cgraph_edge *first
> +                                = old_edge->first_specialized_call_target ();
> +                         profile_count spec_cnt
> +                                = profile_count::zero ();
> +
> +                         /* First figure out the distribution of counts
> +                            so we can re-scale BB profile accordingly.  */
> +                         for (cgraph_edge *e = first; e;
> +                              e = e->next_specialized_call_target ())
> +                           spec_cnt = spec_cnt + e->count;
> +
> +                         cgraph_edge *base
> +                                = old_edge->specialized_call_base_edge ();
> +                         profile_count base_cnt = base->count;
> +
> +                         /* Next iterate all specializations, clone them
> +                            and update the profile.  */
> +                         for (cgraph_edge *e = first; e;
> +                              e = e->next_specialized_call_target ())
> +                           {
> +                             profile_count cnt = e->count;
> +
> +                             edge = e->clone (id->dst_node, call_stmt,
> +                                              gimple_uid (stmt), num, den,
> +                                              true);
> +                             profile_probability prob
> +                                = cnt.probability_in (spec_cnt
> +                                                      + base_cnt);
> +                             edge->count
> +                                = copy_basic_block->count.apply_probability
> +                                        (prob);
> +                             n++;
> +                           }
> +
> +                         /* Duplicate the base edge after all specialized
> +                            edges cloned.  */
> +                         base = base->clone (id->dst_node, call_stmt,
> +                                                     gimple_uid (stmt),
> +                                                     num, den,
> +                                                     true);
> +
> +                         profile_probability prob
> +                            = base_cnt.probability_in (spec_cnt
> +                                                        + base_cnt);
> +                         base->count
> +                            = copy_basic_block->count.apply_probability (prob);
> +                       }
>                       else
>                         {
>                           edge = edge->clone (id->dst_node, call_stmt,
> diff --git a/gcc/value-prof.cc b/gcc/value-prof.cc
> index 9656ce5870d..3db0070bcbf 100644
> --- a/gcc/value-prof.cc
> +++ b/gcc/value-prof.cc
> @@ -42,6 +42,8 @@ along with GCC; see the file COPYING3.  If not see
>  #include "gimple-pretty-print.h"
>  #include "dumpfile.h"
>  #include "builtins.h"
> +#include "tree-cfg.h"
> +#include "tree-dfa.h"
>
>  /* In this file value profile based optimizations are placed.  Currently the
>     following optimizations are implemented (for more detailed descriptions
> @@ -1434,6 +1436,218 @@ gimple_ic (gcall *icall_stmt, struct cgraph_node *direct_call,
>    return dcall_stmt;
>  }
>
> +/* Do transformation
> +
> +  if (arg_i == spec_args[y] && ...)
> +    do call to specialized target callee
> +  else
> +    old call
> + */
> +
> +gcall *
> +gimple_sc (struct cgraph_edge *edg, profile_probability prob)
> +{
> +  /* The call statement we're modifying.  */
> +  gcall *call_stmt = edg->call_stmt;
> +  /* The cgraph_node of the specialized function.  */
> +  cgraph_node *callee = edg->callee;
> +  vec<cgraph_specialization_info> *spec_args = edg->spec_args;
> +
> +  /* CALL_STMT should be the call_stmt of the generic function.  */
> +  gcc_checking_assert (edg->specialized_call_base_edge ()->call_stmt
> +                     == call_stmt);
> +
> +  gcall *spec_call_stmt = NULL;
> +  tree cond_tree = NULL_TREE;
> +  gcond *cond_stmt = NULL;
> +  basic_block cond_bb, dcall_bb, icall_bb, join_bb = NULL;
> +  edge e_cd, e_ci, e_di, e_dj = NULL, e_ij;
> +  gimple_stmt_iterator gsi;
> +  int lp_nr, dflags;
> +  edge e_eh, e;
> +  edge_iterator ei;
> +
> +  cond_bb = gimple_bb (call_stmt);
> +  gsi = gsi_for_stmt (call_stmt);
> +
> +  /* To call the specialized function we need to build a guard conditional
> +     with the specialized arguments and constants.  */
> +  unsigned nargs = gimple_call_num_args (call_stmt);
> +  unsigned cur_spec = 0;
> +  bool dump_first = true;
> +
> +  if (dump_file)
> +    {
> +      fprintf (dump_file, "Creating specialization guard for edge %s -> %s:\n",
> +                        edg->caller->dump_name (), edg->callee->dump_name ());
> +      fprintf (dump_file, "if (");
> +    }
> +
> +  for (unsigned arg_idx = 0; arg_idx < nargs; arg_idx++)
> +    {
> +      tree cur_arg = gimple_call_arg (call_stmt, arg_idx);
> +      bool cur_arg_specialized_p = cur_spec < spec_args->length ()
> +       && arg_idx == (*spec_args)[cur_spec].arg_idx;
> +
> +      if (cur_arg_specialized_p)
> +       {
> +         gcc_checking_assert (!cond_stmt);
> +
> +         cgraph_specialization_info spec_info = (*spec_args)[cur_spec];
> +         cur_spec++;
> +
> +         tree spec_v;
> +         if (spec_info.is_unsigned)
> +           spec_v = build_int_cstu (integer_type_node, spec_info.cst.uval);
> +         else
> +           spec_v = build_int_cst (integer_type_node, spec_info.cst.sval);
> +
> +         tree cmp_const = fold_convert (TREE_TYPE (cur_arg), spec_v);
> +
> +         tree cur_arg_eq_spec = build2 (EQ_EXPR, boolean_type_node,
> +                                             cur_arg, cmp_const);
> +
> +         if (dump_file)
> +           {
> +             if (!dump_first)
> +               fprintf (dump_file, " && ");
> +             print_generic_expr (dump_file, cur_arg_eq_spec);
> +             dump_first = false;
> +           }
> +
> +         tree tmp1 = make_temp_ssa_name (boolean_type_node, NULL, "SPEC");
> +         gassign* load_stmt1 = gimple_build_assign (tmp1, cur_arg_eq_spec);
> +         gsi_insert_before (&gsi, load_stmt1, GSI_SAME_STMT);
> +
> +         if (!cond_tree)
> +           cond_tree = tmp1;
> +         else
> +           {
> +             tree cur_and_prev_true = fold_build2 (BIT_AND_EXPR,
> +                                        boolean_type_node,
> +                                        cond_tree,
> +                                        tmp1);
> +
> +             tree tmp2 = make_temp_ssa_name (boolean_type_node, NULL, "SPEC");
> +             gassign* load_stmt2
> +               = gimple_build_assign (tmp2, cur_and_prev_true);
> +             gsi_insert_before (&gsi, load_stmt2, GSI_SAME_STMT);
> +             cond_tree = tmp2;
> +           }
> +       }
> +    }
> +
> +  cond_stmt = gimple_build_cond (EQ_EXPR, cond_tree, boolean_true_node,
> +                                NULL_TREE, NULL_TREE);
> +
> +  gsi_insert_before (&gsi, cond_stmt, GSI_SAME_STMT);
> +
> +  if (gimple_vdef (call_stmt)
> +      && TREE_CODE (gimple_vdef (call_stmt)) == SSA_NAME)
> +    {
> +      unlink_stmt_vdef (call_stmt);
> +      release_ssa_name (gimple_vdef (call_stmt));
> +    }
> +  gimple_set_vdef (call_stmt, NULL_TREE);
> +  gimple_set_vuse (call_stmt, NULL_TREE);
> +  update_stmt (call_stmt);
> +  spec_call_stmt = as_a <gcall *> (gimple_copy (call_stmt));
> +  gimple_call_set_fndecl (spec_call_stmt, callee->decl);
> +  dflags = flags_from_decl_or_type (callee->decl);
> +
> +  if ((dflags & ECF_NORETURN) != 0
> +      && should_remove_lhs_p (gimple_call_lhs (spec_call_stmt)))
> +    gimple_call_set_lhs (spec_call_stmt, NULL_TREE);
> +  gsi_insert_before (&gsi, spec_call_stmt, GSI_SAME_STMT);
> +
> +  if (dump_file)
> +    {
> +      fprintf (dump_file, ")\n  ");
> +      print_gimple_stmt (dump_file, spec_call_stmt, 0);
> +    }
> +
> +  e_cd = split_block (cond_bb, cond_stmt);
> +  dcall_bb = e_cd->dest;
> +  dcall_bb->count = cond_bb->count.apply_probability (prob);
> +
> +  e_di = split_block (dcall_bb, spec_call_stmt);
> +  icall_bb = e_di->dest;
> +  icall_bb->count = cond_bb->count - dcall_bb->count;
> +
> +  if (!stmt_ends_bb_p (call_stmt))
> +    e_ij = split_block (icall_bb, call_stmt);
> +  else
> +    {
> +      e_ij = find_fallthru_edge (icall_bb->succs);
> +      if (e_ij != NULL)
> +       {
> +         e_ij->probability = profile_probability::always ();
> +         e_ij = single_pred_edge (split_edge (e_ij));
> +       }
> +    }
> +  if (e_ij != NULL)
> +    {
> +      join_bb = e_ij->dest;
> +      join_bb->count = cond_bb->count;
> +    }
> +
> +  e_cd->flags = (e_cd->flags & ~EDGE_FALLTHRU) | EDGE_TRUE_VALUE;
> +  e_cd->probability = prob;
> +
> +  e_ci = make_edge (cond_bb, icall_bb, EDGE_FALSE_VALUE);
> +  e_ci->probability = prob.invert ();
> +
> +  remove_edge (e_di);
> +
> +  if (e_ij != NULL)
> +    {
> +      if ((dflags & ECF_NORETURN) == 0)
> +       {
> +         e_dj = make_edge (dcall_bb, join_bb, EDGE_FALLTHRU);
> +         e_dj->probability = profile_probability::always ();
> +       }
> +      e_ij->probability = profile_probability::always ();
> +    }
> +
> +  if (gimple_call_lhs (call_stmt)
> +      && TREE_CODE (gimple_call_lhs (call_stmt)) == SSA_NAME
> +      && (dflags & ECF_NORETURN) == 0)
> +    {
> +      tree result = gimple_call_lhs (call_stmt);
> +      gphi *phi = create_phi_node (result, join_bb);
> +      gimple_call_set_lhs (call_stmt,
> +                          duplicate_ssa_name (result, call_stmt));
> +      add_phi_arg (phi, gimple_call_lhs (call_stmt), e_ij, UNKNOWN_LOCATION);
> +      gimple_call_set_lhs (spec_call_stmt,
> +                          duplicate_ssa_name (result, spec_call_stmt));
> +      add_phi_arg (phi, gimple_call_lhs (spec_call_stmt), e_dj,
> +                  UNKNOWN_LOCATION);
> +    }
> +
> +  lp_nr = lookup_stmt_eh_lp (call_stmt);
> +  if (lp_nr > 0 && stmt_could_throw_p (cfun, spec_call_stmt))
> +    {
> +      add_stmt_to_eh_lp (spec_call_stmt, lp_nr);
> +    }
> +
> +  FOR_EACH_EDGE (e_eh, ei, icall_bb->succs)
> +    if (e_eh->flags & (EDGE_EH | EDGE_ABNORMAL))
> +      {
> +       e = make_edge (dcall_bb, e_eh->dest, e_eh->flags);
> +       e->probability = e_eh->probability;
> +       for (gphi_iterator psi = gsi_start_phis (e_eh->dest);
> +            !gsi_end_p (psi); gsi_next (&psi))
> +         {
> +           gphi *phi = psi.phi ();
> +           SET_USE (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e),
> +                    PHI_ARG_DEF_FROM_EDGE (phi, e_eh));
> +         }
> +       }
> +  if (!stmt_could_throw_p (cfun, spec_call_stmt))
> +    gimple_purge_dead_eh_edges (dcall_bb);
> +  return spec_call_stmt;
> +}
> +
>  /* Dump info about indirect call profile.  */
>
>  static void
> diff --git a/gcc/value-prof.h b/gcc/value-prof.h
> index d852c41f33f..7d8be5920b9 100644
> --- a/gcc/value-prof.h
> +++ b/gcc/value-prof.h
> @@ -89,6 +89,7 @@ void verify_histograms (void);
>  void free_histograms (function *);
>  void stringop_block_profile (gimple *, unsigned int *, HOST_WIDE_INT *);
>  gcall *gimple_ic (gcall *, struct cgraph_node *, profile_probability);
> +gcall *gimple_sc (struct cgraph_edge *, profile_probability);
>  bool get_nth_most_common_value (gimple *stmt, const char *counter_type,
>                                 histogram_value hist, gcov_type *value,
>                                 gcov_type *count, gcov_type *all,
> --
> 2.38.1
>