From 4fe34cdcc80ac225b80670eabc38ac5e31ce8a5a Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Fri, 28 Oct 2022 14:40:25 +0000 Subject: c: tree: target: C2x (...) function prototypes and va_start relaxation C2x allows function prototypes to be given as (...), a prototype meaning a variable-argument function with no named arguments. To allow such functions to access their arguments, requirements for va_start calls are relaxed so it ignores all but its first argument (i.e. subsequent arguments, if any, can be arbitrary pp-token sequences). Implement this feature accordingly. The va_start relaxation in is itself easy: __builtin_va_start already supports a second argument of 0 instead of a parameter name, and calls get converted internally to the form using 0 for that argument, so just needs changing to use a variadic macro that passes 0 as the second argument of __builtin_va_start. (This is done only in C2x mode, on the expectation that users of older standard would expect unsupported uses of va_start to be diagnosed.) For the (...) functions, it's necessary to distinguish these from unprototyped functions, whereas previously C++ (...) functions and unprototyped functions both used NULL TYPE_ARG_TYPES. A flag is added to tree_type_common to mark the (...) functions; as discussed on gcc@, doing things this way is likely to be safer for unchanged code in GCC than adding a different form of representation in TYPE_ARG_TYPES, or adding a flag that instead signals that the function is unprototyped. There was previously an option -fallow-parameterless-variadic-functions to enable support for (...) prototypes. The support was incomplete - it treated the functions as unprototyped, and only parsed some declarations, not e.g. "int g (int (...));". This option is changed into a no-op ignored option; (...) is always accepted syntactically, with a pedwarn_c11 call to given required diagnostics when appropriate. The peculiarity of a parameter list with __attribute__ followed by '...' being accepted with that option is removed. Interfaces in tree.cc that create function types are adjusted to set this flag as appropriate. It is of course possible that some existing users of the functions to create variable-argument functions actually wanted unprototyped functions in the no-named-argument case, rather than functions with a (...) prototype; some such cases in c-common.cc (for built-in functions and implicit function declarations) turn out to need updating for that reason. I didn't do anything to change how the C++ front end creates (...) function types. It's very likely there are unchanged places in the compiler that in fact turn out to need changes to work properly with (...) function prototypes. Target setup_incoming_varargs hooks, where they used the information passed about the last named argument, needed updating to avoid using that information in the (...) case. Note that apart from the x86 changes, I haven't done any testing of those target changes beyond building cc1 to check for syntax errors. It's possible further target-specific fixes will be needed; target maintainers should watch out for failures of c2x-stdarg-4.c or c2x-stdarg-split-1a.c, the execution tests, which would indicate that this feature is not working correctly. Those tests also verify the case where there are named arguments but the last named argument has a declaration that results in undefined behavior in previous C standard versions, such as a type changed by the default argument promotions. Bootstrapped with no regressions for x86_64-pc-linux-gnu. gcc/ * config/aarch64/aarch64.cc (aarch64_setup_incoming_varargs): Check TYPE_NO_NAMED_ARGS_STDARG_P. * config/alpha/alpha.cc (alpha_setup_incoming_varargs): Likewise. * config/arc/arc.cc (arc_setup_incoming_varargs): Likewise. * config/arm/arm.cc (arm_setup_incoming_varargs): Likewise. * config/csky/csky.cc (csky_setup_incoming_varargs): Likewise. * config/epiphany/epiphany.cc (epiphany_setup_incoming_varargs): Likewise. * config/fr30/fr30.cc (fr30_setup_incoming_varargs): Likewise. * config/frv/frv.cc (frv_setup_incoming_varargs): Likewise. * config/ft32/ft32.cc (ft32_setup_incoming_varargs): Likewise. * config/i386/i386.cc (ix86_setup_incoming_varargs): Likewise. * config/ia64/ia64.cc (ia64_setup_incoming_varargs): Likewise. * config/loongarch/loongarch.cc (loongarch_setup_incoming_varargs): Likewise. * config/m32r/m32r.cc (m32r_setup_incoming_varargs): Likewise. * config/mcore/mcore.cc (mcore_setup_incoming_varargs): Likewise. * config/mips/mips.cc (mips_setup_incoming_varargs): Likewise. * config/mmix/mmix.cc (mmix_setup_incoming_varargs): Likewise. * config/nds32/nds32.cc (nds32_setup_incoming_varargs): Likewise. * config/nios2/nios2.cc (nios2_setup_incoming_varargs): Likewise. * config/riscv/riscv.cc (riscv_setup_incoming_varargs): Likewise. * config/rs6000/rs6000-call.cc (setup_incoming_varargs): Likewise. * config/sh/sh.cc (sh_setup_incoming_varargs): Likewise. * config/visium/visium.cc (visium_setup_incoming_varargs): Likewise. * config/vms/vms-c.cc (vms_c_common_override_options): Do not set flag_allow_parameterless_variadic_functions. * doc/invoke.texi (-fallow-parameterless-variadic-functions): Do not document option. * function.cc (assign_parms): Call assign_parms_setup_varargs for TYPE_NO_NAMED_ARGS_STDARG_P case. * ginclude/stdarg.h [__STDC_VERSION__ > 201710L] (va_start): Make variadic macro. Pass second argument of 0 to __builtin_va_start. * target.def (setup_incoming_varargs): Update documentation. * doc/tm.texi: Regenerate. * tree-core.h (struct tree_type_common): Add no_named_args_stdarg_p. * tree-streamer-in.cc (unpack_ts_type_common_value_fields): Unpack TYPE_NO_NAMED_ARGS_STDARG_P. * tree-streamer-out.cc (pack_ts_type_common_value_fields): Pack TYPE_NO_NAMED_ARGS_STDARG_P. * tree.cc (type_cache_hasher::equal): Compare TYPE_NO_NAMED_ARGS_STDARG_P. (build_function_type): Add argument no_named_args_stdarg_p. (build_function_type_list_1, build_function_type_array_1) (reconstruct_complex_type): Update calls to build_function_type. (stdarg_p, prototype_p): Return true for (...) functions. (gimple_canonical_types_compatible_p): Compare TYPE_NO_NAMED_ARGS_STDARG_P. * tree.h (TYPE_NO_NAMED_ARGS_STDARG_P): New. (build_function_type): Update prototype. gcc/c-family/ * c-common.cc (def_fn_type): Call build_function_type for zero-argument variable-argument function. (c_common_nodes_and_builtins): Build default_function_type with build_function_type. * c.opt (fallow-parameterless-variadic-functions): Mark as ignored option. gcc/c/ * c-decl.cc (grokdeclarator): Pass arg_info->no_named_args_stdarg_p to build_function_type. (grokparms): Check arg_info->no_named_args_stdarg_p before converting () to (void). (build_arg_info): Initialize no_named_args_stdarg_p. (get_parm_info): Set no_named_args_stdarg_p. (start_function): Pass TYPE_NO_NAMED_ARGS_STDARG_P to build_function_type. (store_parm_decls): Count (...) functions as prototyped. * c-parser.cc (c_parser_direct_declarator): Allow '...' after open parenthesis to start parameter list. (c_parser_parms_list_declarator): Always allow '...' with no arguments, call pedwarn_c11 and set no_named_args_stdarg_p. * c-tree.h (struct c_arg_info): Add field no_named_args_stdarg_p. * c-typeck.cc (composite_type): Handle TYPE_NO_NAMED_ARGS_STDARG_P. (function_types_compatible_p): Compare TYPE_NO_NAMED_ARGS_STDARG_P. gcc/fortran/ * trans-types.cc (gfc_get_function_type): Do not use build_varargs_function_type_vec for unprototyped function. gcc/lto/ * lto-common.cc (compare_tree_sccs_1): Compare TYPE_NO_NAMED_ARGS_STDARG_P. gcc/objc/ * objc-next-runtime-abi-01.cc (build_next_objc_exception_stuff): Use build_function_type to build type of objc_setjmp_decl. gcc/testsuite/ * gcc.dg/c11-stdarg-1.c, gcc.dg/c11-stdarg-2.c, gcc.dg/c11-stdarg-3.c, gcc.dg/c2x-stdarg-1.c, gcc.dg/c2x-stdarg-2.c, gcc.dg/c2x-stdarg-3.c, gcc.dg/c2x-stdarg-4.c, gcc.dg/gnu2x-stdarg-1.c, gcc.dg/torture/c2x-stdarg-split-1a.c, gcc.dg/torture/c2x-stdarg-split-1b.c: New tests. * gcc.dg/Wold-style-definition-2.c, gcc.dg/format/sentinel-1.c: Update expected diagnostics. * gcc.dg/c2x-nullptr-1.c (test5): Cast unused parameter to (void). * gcc.dg/diagnostic-token-ranges.c: Use -pedantic. Expect warning in place of error. --- gcc/config/csky/csky.cc | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'gcc/config/csky/csky.cc') diff --git a/gcc/config/csky/csky.cc b/gcc/config/csky/csky.cc index f7b2bf8e7c1..537eee6ab88 100644 --- a/gcc/config/csky/csky.cc +++ b/gcc/config/csky/csky.cc @@ -2086,7 +2086,8 @@ csky_setup_incoming_varargs (cumulative_args_t pcum_v, cfun->machine->uses_anonymous_args = 1; local_cum = *pcum; - csky_function_arg_advance (local_cum_v, arg); + if (!TYPE_NO_NAMED_ARGS_STDARG_P (TREE_TYPE (current_function_decl))) + csky_function_arg_advance (local_cum_v, arg); regs_to_push = CSKY_NPARM_REGS - local_cum.reg; if (regs_to_push) *pretend_size = regs_to_push * UNITS_PER_WORD; -- cgit v1.2.1