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" } } */ >
