From: Alexander Monakov <amonakov@ispras.ru>
To: gcc-patches@gcc.gnu.org
Cc: Jan Hubicka <hubicka@kam.mff.cuni.cz>,
Artem Klimov <jakmobius@gmail.com>
Subject: Re: [PATCH v2] ipa-visibility: Optimize TLS access [PR99619]
Date: Fri, 5 Aug 2022 17:03:33 +0300 (MSK) [thread overview]
Message-ID: <355431a0-e218-48a4-4414-97d67c7c8c8e@ispras.ru> (raw)
In-Reply-To: <4f83b8e1-60dd-ed50-3d3e-fa15a6d571e1@ispras.ru>
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 <jakmobius@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 <jakmobius@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 <amonakov@gcc.gnu.org>
> > Signed-off-by: Artem Klimov <jakmobius@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" } } */
> >
>
next prev parent reply other threads:[~2022-08-05 14:03 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-17 18:51 [PATCH] " Artem Klimov
2022-05-02 8:51 ` Alexander Monakov
2022-05-02 16:04 ` Martin Jambor
2022-05-02 16:43 ` Alexander Monakov
2022-05-09 16:06 ` Alexander Monakov
2022-05-09 16:47 ` Jan Hubicka
2022-05-09 17:15 ` Alexander Monakov
2022-05-16 15:50 ` Alexander Monakov
2022-05-23 10:56 ` Alexander Monakov
2022-05-25 9:04 ` Jan Hubicka
2022-07-07 15:53 ` [PATCH v2] " Alexander Monakov
2022-07-20 13:04 ` Alexander Monakov
2022-08-05 14:03 ` Alexander Monakov [this message]
2022-08-23 15:27 ` Alexander Monakov
2022-08-26 11:32 ` Martin Jambor
2022-08-26 13:35 ` Alexander Monakov
2022-08-30 11:44 ` Martin Jambor
2022-08-30 13:19 ` Alexander Monakov
2022-08-30 14:03 ` Alexander Monakov
2022-09-05 10:39 ` Martin Jambor
2022-05-02 19:28 ` [PATCH] " Martin Liška
2022-05-05 10:50 ` Jan Hubicka
2022-05-05 11:50 ` Alexander Monakov
2022-05-05 11:56 ` Jan Hubicka
2022-05-05 14:41 ` Alexander Monakov
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