Message ID | 20211120083953.GZ2646553@tucnak |
---|---|
State | New |
Headers | show |
Series | openacc: Fix up C++ #pragma acc routine handling [PR101731] | expand |
Hi Jakub! On 2021-11-20T09:39:53+0100, Jakub Jelinek via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > The following testcase ICEs because two function declarations are nested in > each other and the acc routine handling code isn't prepared to put the > pragma on both. Ha. Many things covered in 'c-c++-common/goacc/routine-5.c' -- but not that. > The fix is similar to what #pragma omp declare {simd,variant} does, > in particular set the fndecl_seen flag already in cp_parser_late_parsing* > when we encounter it rather than only after we finalize it. > > In cp_finalize_oacc_routine I had to move the fndecl_seen diagnostics to > non-FUNCTION_DECL block, because for FUNCTION_DECLs the flag is already > known to be set from cp_parser_late_parsing_oacc_routine, but can't be > removed altogether, because that regresses quality of 2 goacc/routine-5.c > diagnostics - we drop "a single " from the > '#pragma acc routine' not immediately followed by a single function declaration or definition > diagnostic say on > #pragma acc routine > int foo (), b; > if we drop it altogether. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? Thanks for looking into this. I now don't recall my exact thinking when reworking this code five years ago... Please push your change, fixing the ICE. Then, regarding the user-visible behavior: > +#pragma acc routine /* { dg-error "not immediately followed by a single function declaration or definition" "" { target c++ } } */ > +int foo (int bar ()); So in C++ we now refuse, but in C we do accept this. I suppose I shall look into making C behave the same way -- unless there is a reason for the different behavior? And/or, is it actually is useful to allow such nested usage? Per its associated clauses, an OpenACC 'routine' directive really is meant to apply to one function only, in contrast to OpenMP 'target declare'. But the question is whether we should raise an error for the example above, or whether the 'routine' shall just apply to 'foo' but not 'bar', but without an error diagnostic? OpenACC 3.2, 2.15.1 "Routine Directive" states that "the 'routine' directive without a name may appear immediately before a function definition, a C++ _lambda_, or just before a function prototype and applies to that immediately following function or prototype". Grüße Thomas > 2021-11-20 Jakub Jelinek <jakub@redhat.com> > > PR c++/101731 > * parser.c (cp_parser_late_parsing_oacc_routine): Set > parser->oacc_routine->fndecl_seen here, rather than ... > (cp_finalize_oacc_routine): ... here. Don't error if > parser->oacc_routine->fndecl_seen is set for FUNCTION_DECLs. > > * c-c++-common/goacc/routine-6.c: New test. > > --- gcc/cp/parser.c.jj 2021-11-19 16:39:51.534595887 +0100 > +++ gcc/cp/parser.c 2021-11-19 22:14:41.209591009 +0100 > @@ -46852,8 +46852,8 @@ cp_parser_late_parsing_oacc_routine (cp_ > emission easier. */ > parser->oacc_routine->clauses = nreverse (parser->oacc_routine->clauses); > cp_parser_pop_lexer (parser); > - /* Later, cp_finalize_oacc_routine will process the clauses, and then set > - fndecl_seen. */ > + /* Later, cp_finalize_oacc_routine will process the clauses. */ > + parser->oacc_routine->fndecl_seen = true; > > return attrs; > } > @@ -46871,16 +46871,17 @@ cp_finalize_oacc_routine (cp_parser *par > || fndecl == error_mark_node) > return; > > - if (parser->oacc_routine->fndecl_seen) > - { > - error_at (parser->oacc_routine->loc, > - "%<#pragma acc routine%> not immediately followed by" > - " a single function declaration or definition"); > - parser->oacc_routine = NULL; > - return; > - } > if (TREE_CODE (fndecl) != FUNCTION_DECL) > { > + if (parser->oacc_routine->fndecl_seen) > + { > + error_at (parser->oacc_routine->loc, > + "%<#pragma acc routine%> not immediately followed by" > + " a single function declaration or definition"); > + parser->oacc_routine = NULL; > + return; > + } > + > cp_ensure_no_oacc_routine (parser); > return; > } > @@ -46921,11 +46922,6 @@ cp_finalize_oacc_routine (cp_parser *par > parser->oacc_routine->clauses, > DECL_ATTRIBUTES (fndecl)); > } > - > - /* Don't unset parser->oacc_routine here: we may still need it to > - diagnose wrong usage. But, remember that we've used this "#pragma acc > - routine". */ > - parser->oacc_routine->fndecl_seen = true; > } > } > > --- gcc/testsuite/c-c++-common/goacc/routine-6.c.jj 2021-11-19 22:13:11.150864445 +0100 > +++ gcc/testsuite/c-c++-common/goacc/routine-6.c 2021-11-19 22:13:11.150864445 +0100 > @@ -0,0 +1,4 @@ > +/* PR c++/101731 */ > + > +#pragma acc routine /* { dg-error "not immediately followed by a single function declaration or definition" "" { target c++ } } */ > +int foo (int bar ()); > > Jakub ----------------- Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstraße 201, 80634 München; Gesellschaft mit beschränkter Haftung; Geschäftsführer: Thomas Heurung, Frank Thürauf; Sitz der Gesellschaft: München; Registergericht München, HRB 106955
On Mon, Nov 22, 2021 at 03:49:42PM +0100, Thomas Schwinge wrote: > Then, regarding the user-visible behavior: > > > +#pragma acc routine /* { dg-error "not immediately followed by a single function declaration or definition" "" { target c++ } } */ > > +int foo (int bar ()); > > So in C++ we now refuse, but in C we do accept this. I suppose I shall > look into making C behave the same way -- unless there is a reason for > the different behavior? And/or, is it actually is useful to allow such > nested usage? Per its associated clauses, an OpenACC 'routine' directive > really is meant to apply to one function only, in contrast to OpenMP > 'target declare'. But the question is whether we should raise an error > for the example above, or whether the 'routine' shall just apply to 'foo' > but not 'bar', but without an error diagnostic? All I've verified is that our OpenMP code handles it the same way, i.e. #pragma omp declare simd int foo (int bar ()); is accepted in C and rejected in C++. I guess one question is to check if it is in both languages actually the same thing. If we want to accept it in C++ and let the pragma apply only to the outer declaration, I guess we'd need to temporarily set to NULL parser->omp_declare_simd and parser->oacc_routine while parsing the parameters of a function declaration or definition. At least OpenMP is fairly fuzzy here, the reason we error on #pragma omp declare simd int foo (), i; has been mainly some discussions in the lang committee and the fact that it talks about a single declaration, not all affected declarations. Whether int foo (int bar ()); should be in that light treated as two function declarations or one with another one nested in it and irrelevant for it is unclear. Jakub
--- gcc/cp/parser.c.jj 2021-11-19 16:39:51.534595887 +0100 +++ gcc/cp/parser.c 2021-11-19 22:14:41.209591009 +0100 @@ -46852,8 +46852,8 @@ cp_parser_late_parsing_oacc_routine (cp_ emission easier. */ parser->oacc_routine->clauses = nreverse (parser->oacc_routine->clauses); cp_parser_pop_lexer (parser); - /* Later, cp_finalize_oacc_routine will process the clauses, and then set - fndecl_seen. */ + /* Later, cp_finalize_oacc_routine will process the clauses. */ + parser->oacc_routine->fndecl_seen = true; return attrs; } @@ -46871,16 +46871,17 @@ cp_finalize_oacc_routine (cp_parser *par || fndecl == error_mark_node) return; - if (parser->oacc_routine->fndecl_seen) - { - error_at (parser->oacc_routine->loc, - "%<#pragma acc routine%> not immediately followed by" - " a single function declaration or definition"); - parser->oacc_routine = NULL; - return; - } if (TREE_CODE (fndecl) != FUNCTION_DECL) { + if (parser->oacc_routine->fndecl_seen) + { + error_at (parser->oacc_routine->loc, + "%<#pragma acc routine%> not immediately followed by" + " a single function declaration or definition"); + parser->oacc_routine = NULL; + return; + } + cp_ensure_no_oacc_routine (parser); return; } @@ -46921,11 +46922,6 @@ cp_finalize_oacc_routine (cp_parser *par parser->oacc_routine->clauses, DECL_ATTRIBUTES (fndecl)); } - - /* Don't unset parser->oacc_routine here: we may still need it to - diagnose wrong usage. But, remember that we've used this "#pragma acc - routine". */ - parser->oacc_routine->fndecl_seen = true; } } --- gcc/testsuite/c-c++-common/goacc/routine-6.c.jj 2021-11-19 22:13:11.150864445 +0100 +++ gcc/testsuite/c-c++-common/goacc/routine-6.c 2021-11-19 22:13:11.150864445 +0100 @@ -0,0 +1,4 @@ +/* PR c++/101731 */ + +#pragma acc routine /* { dg-error "not immediately followed by a single function declaration or definition" "" { target c++ } } */ +int foo (int bar ());