Ping^3.

On Fri, 5 Aug 2022, Alexander Monakov wrote:

> Ping^2.
> 
> On Wed, 20 Jul 2022, Alexander Monakov wrote:
> 
> > 
> > Ping.
> > 
> > On Thu, 7 Jul 2022, Alexander Monakov via Gcc-patches wrote:
> > 
> > > From: Artem Klimov <jakmob...@gmail.com>
> > > 
> > > Fix PR99619, which asks to optimize TLS model based on visibility.
> > > The fix is implemented as an IPA optimization: this allows to take
> > > optimized visibility status into account (as well as avoid modifying
> > > all language frontends).
> > > 
> > > 2022-04-17  Artem Klimov  <jakmob...@gmail.com>
> > > 
> > > gcc/ChangeLog:
> > > 
> > >   * ipa-visibility.cc (function_and_variable_visibility): Promote
> > >   TLS access model afer visibility optimizations.
> > >   * varasm.cc (have_optimized_refs): New helper.
> > >   (optimize_dyn_tls_for_decl_p): New helper. Use it ...
> > >   (decl_default_tls_model): ... here in place of 'optimize' check.
> > > 
> > > gcc/testsuite/ChangeLog:
> > > 
> > >   * gcc.dg/tls/vis-attr-gd.c: New test.
> > >   * gcc.dg/tls/vis-attr-hidden-gd.c: New test.
> > >   * gcc.dg/tls/vis-attr-hidden.c: New test.
> > >   * gcc.dg/tls/vis-flag-hidden-gd.c: New test.
> > >   * gcc.dg/tls/vis-flag-hidden.c: New test.
> > >   * gcc.dg/tls/vis-pragma-hidden-gd.c: New test.
> > >   * gcc.dg/tls/vis-pragma-hidden.c: New test.
> > > 
> > > Co-Authored-By:  Alexander Monakov  <amona...@gcc.gnu.org>
> > > Signed-off-by: Artem Klimov <jakmob...@gmail.com>
> > > ---
> > > 
> > > v2: run the new loop in ipa-visibility only in the whole-program IPA pass;
> > >     in decl_default_tls_model, check if any referring function is 
> > > optimized
> > >     when 'optimize == 0' (when running in LTO mode)
> > > 
> > > 
> > > Note for reviewers: I noticed there's a place which tries to avoid TLS
> > > promotion, but the comment seems wrong and I could not find a testcase.
> > > I'd suggest we remove it. The compiler can only promote general-dynamic
> > > to local-dynamic and initial-exec to local-exec. The comment refers to
> > > promoting x-dynamic to y-exec, but that cannot happen AFAICT:
> > > https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=8e1ba78f1b8eedd6c65c6f0e6d6d09a801de5d3d
> > > 
> > > 
> > >  gcc/ipa-visibility.cc                         | 19 +++++++++++
> > >  gcc/testsuite/gcc.dg/tls/vis-attr-gd.c        | 12 +++++++
> > >  gcc/testsuite/gcc.dg/tls/vis-attr-hidden-gd.c | 13 ++++++++
> > >  gcc/testsuite/gcc.dg/tls/vis-attr-hidden.c    | 12 +++++++
> > >  gcc/testsuite/gcc.dg/tls/vis-flag-hidden-gd.c | 13 ++++++++
> > >  gcc/testsuite/gcc.dg/tls/vis-flag-hidden.c    | 12 +++++++
> > >  .../gcc.dg/tls/vis-pragma-hidden-gd.c         | 17 ++++++++++
> > >  gcc/testsuite/gcc.dg/tls/vis-pragma-hidden.c  | 16 ++++++++++
> > >  gcc/varasm.cc                                 | 32 ++++++++++++++++++-
> > >  9 files changed, 145 insertions(+), 1 deletion(-)
> > >  create mode 100644 gcc/testsuite/gcc.dg/tls/vis-attr-gd.c
> > >  create mode 100644 gcc/testsuite/gcc.dg/tls/vis-attr-hidden-gd.c
> > >  create mode 100644 gcc/testsuite/gcc.dg/tls/vis-attr-hidden.c
> > >  create mode 100644 gcc/testsuite/gcc.dg/tls/vis-flag-hidden-gd.c
> > >  create mode 100644 gcc/testsuite/gcc.dg/tls/vis-flag-hidden.c
> > >  create mode 100644 gcc/testsuite/gcc.dg/tls/vis-pragma-hidden-gd.c
> > >  create mode 100644 gcc/testsuite/gcc.dg/tls/vis-pragma-hidden.c
> > > 
> > > diff --git a/gcc/ipa-visibility.cc b/gcc/ipa-visibility.cc
> > > index 8a27e7bcd..3ed2b7cf6 100644
> > > --- a/gcc/ipa-visibility.cc
> > > +++ b/gcc/ipa-visibility.cc
> > > @@ -873,6 +873,25 @@ function_and_variable_visibility (bool whole_program)
> > >   }
> > >      }
> > >  
> > > +  if (symtab->state >= IPA_SSA)
> > > +    {
> > > +      FOR_EACH_VARIABLE (vnode)
> > > + {
> > > +   tree decl = vnode->decl;
> > > +
> > > +   /* Upgrade TLS access model based on optimized visibility status,
> > > +      unless it was specified explicitly or no references remain.  */
> > > +   if (DECL_THREAD_LOCAL_P (decl)
> > > +       && !lookup_attribute ("tls_model", DECL_ATTRIBUTES (decl))
> > > +       && vnode->ref_list.referring.length ())
> > > +     {
> > > +       enum tls_model new_model = decl_default_tls_model (decl);
> > > +       gcc_checking_assert (new_model >= decl_tls_model (decl));
> > > +       set_decl_tls_model (decl, new_model);
> > > +     }
> > > + }
> > > +    }
> > > +
> > >    if (dump_file)
> > >      {
> > >        fprintf (dump_file, "\nMarking local functions:");
> > > diff --git a/gcc/varasm.cc b/gcc/varasm.cc
> > > index 4db8506b1..de149e82c 100644
> > > --- a/gcc/varasm.cc
> > > +++ b/gcc/varasm.cc
> > > @@ -6679,6 +6679,36 @@ init_varasm_once (void)
> > >  #endif
> > >  }
> > >  
> > > +/* Determine whether SYMBOL is used in any optimized function.  */
> > > +
> > > +static bool
> > > +have_optimized_refs (struct symtab_node *symbol)
> > > +{
> > > +  struct ipa_ref *ref;
> > > +
> > > +  for (int i = 0; symbol->iterate_referring (i, ref); i++)
> > > +    {
> > > +      cgraph_node *cnode = dyn_cast <cgraph_node *> (ref->referring);
> > > +
> > > +      if (cnode && opt_for_fn (cnode->decl, optimize))
> > > + return true;
> > > +    }
> > > +
> > > +  return false;
> > > +}
> > > +
> > > +/* Check if promoting general-dynamic TLS access model to local-dynamic 
> > > is
> > > +   desirable for DECL.  */
> > > +
> > > +static bool
> > > +optimize_dyn_tls_for_decl_p (const_tree decl)
> > > +{
> > > +  if (optimize)
> > > +    return true;
> > > +  return symtab->state >= IPA && have_optimized_refs (symtab_node::get 
> > > (decl));
> > > +}
> > > +
> > > +
> > >  enum tls_model
> > >  decl_default_tls_model (const_tree decl)
> > >  {
> > > @@ -6696,7 +6726,7 @@ decl_default_tls_model (const_tree decl)
> > >  
> > >    /* Local dynamic is inefficient when we're not combining the
> > >       parts of the address.  */
> > > -  else if (optimize && is_local)
> > > +  else if (is_local && optimize_dyn_tls_for_decl_p (decl))
> > >      kind = TLS_MODEL_LOCAL_DYNAMIC;
> > >    else
> > >      kind = TLS_MODEL_GLOBAL_DYNAMIC;
> > > diff --git a/gcc/testsuite/gcc.dg/tls/vis-attr-gd.c 
> > > b/gcc/testsuite/gcc.dg/tls/vis-attr-gd.c
> > > new file mode 100644
> > > index 000000000..89a248a80
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.dg/tls/vis-attr-gd.c
> > > @@ -0,0 +1,12 @@
> > > +/* { dg-do compile } */
> > > +/* { dg-require-effective-target fpic } */
> > > +/* { dg-require-effective-target tls } */
> > > +/* { dg-options "-O2 -fPIC -fdump-ipa-whole-program" } */
> > > +
> > > +// tls_model should be global-dynamic due to explicitly specified 
> > > attribute
> > > +__attribute__((tls_model("global-dynamic")))
> > > +__thread int x;
> > > +
> > > +void reference() { x++; }
> > > +
> > > +/* { dg-final { scan-ipa-dump "Varpool flags: tls-global-dynamic" 
> > > "whole-program" } } */
> > > diff --git a/gcc/testsuite/gcc.dg/tls/vis-attr-hidden-gd.c 
> > > b/gcc/testsuite/gcc.dg/tls/vis-attr-hidden-gd.c
> > > new file mode 100644
> > > index 000000000..e32565588
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.dg/tls/vis-attr-hidden-gd.c
> > > @@ -0,0 +1,13 @@
> > > +/* { dg-do compile } */
> > > +/* { dg-require-effective-target fpic } */
> > > +/* { dg-require-effective-target tls } */
> > > +/* { dg-options "-O2 -fPIC -fdump-ipa-whole-program" } */
> > > +
> > > +// tls_model should be global-dynamic due to explicitly specified 
> > > attribute
> > > +__attribute__((visibility("hidden")))
> > > +__attribute__((tls_model("global-dynamic")))
> > > +__thread int x;
> > > +
> > > +void reference() { x++; }
> > > +
> > > +/* { dg-final { scan-ipa-dump "Varpool flags: tls-global-dynamic" 
> > > "whole-program" } } */
> > > diff --git a/gcc/testsuite/gcc.dg/tls/vis-attr-hidden.c 
> > > b/gcc/testsuite/gcc.dg/tls/vis-attr-hidden.c
> > > new file mode 100644
> > > index 000000000..0d43fc565
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.dg/tls/vis-attr-hidden.c
> > > @@ -0,0 +1,12 @@
> > > +/* { dg-do compile } */
> > > +/* { dg-require-effective-target fpic } */
> > > +/* { dg-require-effective-target tls } */
> > > +/* { dg-options "-O2 -fPIC -fdump-ipa-whole-program" } */
> > > +
> > > +//tls_model should be local-dynamic due to visibility("hidden")
> > > +__attribute__((visibility("hidden")))
> > > +__thread int x;
> > > +
> > > +void reference() { x++; }
> > > +
> > > +/* { dg-final { scan-ipa-dump "Varpool flags: tls-local-dynamic" 
> > > "whole-program" } } */
> > > diff --git a/gcc/testsuite/gcc.dg/tls/vis-flag-hidden-gd.c 
> > > b/gcc/testsuite/gcc.dg/tls/vis-flag-hidden-gd.c
> > > new file mode 100644
> > > index 000000000..cad41e0c8
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.dg/tls/vis-flag-hidden-gd.c
> > > @@ -0,0 +1,13 @@
> > > +/* { dg-do compile } */
> > > +/* { dg-require-effective-target fpic } */
> > > +/* { dg-require-effective-target tls } */
> > > +/* { dg-options "-O2 -fPIC -fdump-ipa-whole-program -fvisibility=hidden" 
> > > } */
> > > +
> > > +
> > > +// tls_model should be global-dynamic due to explicitly specified 
> > > attribute
> > > +__attribute__((tls_model("global-dynamic")))
> > > +__thread int x;
> > > +
> > > +void reference() { x++; }
> > > +
> > > +/* { dg-final { scan-ipa-dump "Varpool flags: tls-global-dynamic" 
> > > "whole-program" } } */
> > > diff --git a/gcc/testsuite/gcc.dg/tls/vis-flag-hidden.c 
> > > b/gcc/testsuite/gcc.dg/tls/vis-flag-hidden.c
> > > new file mode 100644
> > > index 000000000..a15df092d
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.dg/tls/vis-flag-hidden.c
> > > @@ -0,0 +1,12 @@
> > > +/* { dg-do compile } */
> > > +/* { dg-require-effective-target fpic } */
> > > +/* { dg-require-effective-target tls } */
> > > +/* { dg-options "-O2 -fPIC -fdump-ipa-whole-program -fvisibility=hidden" 
> > > } */
> > > +
> > > +
> > > +// tls_model should be local-dynamic due to -fvisibility=hidden
> > > +__thread int x;
> > > +
> > > +void reference() { x++; }
> > > +
> > > +/* { dg-final { scan-ipa-dump "Varpool flags: tls-local-dynamic" 
> > > "whole-program" } } */
> > > diff --git a/gcc/testsuite/gcc.dg/tls/vis-pragma-hidden-gd.c 
> > > b/gcc/testsuite/gcc.dg/tls/vis-pragma-hidden-gd.c
> > > new file mode 100644
> > > index 000000000..3b3598134
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.dg/tls/vis-pragma-hidden-gd.c
> > > @@ -0,0 +1,17 @@
> > > +/* { dg-do compile } */
> > > +/* { dg-require-effective-target fpic } */
> > > +/* { dg-require-effective-target tls } */
> > > +/* { dg-options "-O2 -fPIC -fdump-ipa-whole-program" } */
> > > +
> > > +
> > > +#pragma GCC visibility push(hidden)
> > > +
> > > +// tls_model should be global-dynamic due to explicitly specified 
> > > attribute
> > > +__attribute__((tls_model("global-dynamic")))
> > > +__thread int x;
> > > +
> > > +#pragma GCC visibility pop
> > > +
> > > +void reference() { x++; }
> > > +
> > > +/* { dg-final { scan-ipa-dump "Varpool flags: tls-global-dynamic" 
> > > "whole-program" } } */
> > > diff --git a/gcc/testsuite/gcc.dg/tls/vis-pragma-hidden.c 
> > > b/gcc/testsuite/gcc.dg/tls/vis-pragma-hidden.c
> > > new file mode 100644
> > > index 000000000..1be976442
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.dg/tls/vis-pragma-hidden.c
> > > @@ -0,0 +1,16 @@
> > > +/* { dg-do compile } */
> > > +/* { dg-require-effective-target fpic } */
> > > +/* { dg-require-effective-target tls } */
> > > +/* { dg-options "-O2 -fPIC -fdump-ipa-whole-program" } */
> > > +
> > > +
> > > +#pragma GCC visibility push(hidden)
> > > +
> > > +// tls_model should be local-dynamic due to a pragma
> > > +__thread int x;
> > > +
> > > +#pragma GCC visibility pop
> > > +
> > > +void reference() { x++; }
> > > +
> > > +/* { dg-final { scan-ipa-dump "Varpool flags: tls-local-dynamic" 
> > > "whole-program" } } */
> > > 
> > 
> 

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