Use TARGET_COMPUTE_MULTILIB to search the multi-lib reuse for riscv*-*-elf*,
according following rules:

 1. Check ABI is same.
 2. Check both has atomic extension or both don't have atomic extension.
    - Because mix soft and hard atomic operation doesn't make sense and
      won't work as expect.
 3. Check current arch is superset of the target multi-lib arch.
    - It might result slower performance or larger code size, but it
      safe to run.
 4. Pick most match multi-lib set if more than one multi-lib are pass
    the above checking.

Example for how to select multi-lib:
  We build code with -march=rv32imaf and -mabi=ilp32, and we have
  following 5 multi-lib set:

    1. rv32ia/ilp32
    2. rv32ima/ilp32
    3. rv32imf/ilp32
    4. rv32imaf/ilp32f
    5. rv32imafd/ilp32

  The first and second multi-lib is safe to like, 3rd multi-lib can't
  re-use becasue it don't have atomic extension, which is mismatch according
  rule 2, and the 4th multi-lib can't re-use too due to the ABI mismatch,
  the last multi-lib can't use since current arch is not superset of the
  arch of multi-lib.

And emit error if not found suitable multi-lib set, the error message
only emit when link with standard libraries.

Example for when error will be emitted:

  $ riscv64-unknown-elf-gcc -print-multi-lib
  .;
  rv32i/ilp32;@march=rv32i@mabi=ilp32
  rv32im/ilp32;@march=rv32im@mabi=ilp32
  rv32iac/ilp32;@march=rv32iac@mabi=ilp32
  rv32imac/ilp32;@march=rv32imac@mabi=ilp32
  rv32imafc/ilp32f;@march=rv32imafc@mabi=ilp32f
  rv64imac/lp64;@march=rv64imac@mabi=lp64

  // No actual linking, so no error emitted.
  $ riscv64-unknown-elf-gcc -print-multi-directory -march=rv32ia -mabi=ilp32
  .

  // Link to default libc and libgcc, so check the multi-lib, and emit
  // error because not found suitable multilib.
  $ riscv64-unknown-elf-gcc -march=rv32ia -mabi=ilp32 ~/hello.c
  riscv64-unknown-elf-gcc: fatal error: can't found suitable multilib set for '-march=rv32ia'/'-mabi=ilp32'
  compilation terminated.

  // No error emitted, because not link to stdlib.
  $ riscv64-unknown-elf-gcc -march=rv32ia -mabi=ilp32 ~/hello.c -nostdlib

  // No error emitted, because compile only.
  $ riscv64-unknown-elf-gcc -march=rv32ia -mabi=ilp32 ~/hello.c -c

gcc/ChangeLog:

	* common/config/riscv/riscv-common.cc: Include <vector>.
	(struct riscv_multi_lib_info_t): New.
	(riscv_subset_list::match_score): Ditto.
	(find_last_appear_switch): Ditto.
	(prefixed_with): Ditto.
	(struct multi_lib_info_t): Ditto.
	(riscv_current_arch_str): Ditto.
	(riscv_current_abi_str): Ditto.
	(riscv_multi_lib_info_t::parse): Ditto.
	(riscv_check_cond): Ditto.
	(riscv_check_conds): Ditto.
	(riscv_compute_multilib): Ditto.
	(TARGET_COMPUTE_MULTILIB): Defined.
	* config/riscv/elf.h (LIB_SPEC): Call riscv_multi_lib_check if
	doing link.
	(RISCV_USE_CUSTOMISED_MULTI_LIB): New.
	* config/riscv/riscv.h (riscv_multi_lib_check): New.
	(EXTRA_SPEC_FUNCTIONS): Add riscv_multi_lib_check.
	* config/riscv/riscv-subset.h (riscv_subset_list::match_score): New.

Create a new hook to let target could override the multi-lib result,
the motivation is RISC-V might have very complicated multi-lib re-use
rule*, which is hard to maintain and use current multi-lib scripts,
we even hit the "argument list too long" error when we tried to add more
multi-lib reuse rule.

So I think it would be great to have a target specific way to determine
the multi-lib re-use rule, then we could write those rule in C, instead
of expand every possible case in MULTILIB_REUSE.

* Here is an example for RISC-V multi-lib rules:
https://gist.github.com/kito-cheng/0289cd42d9a756382e5afeb77b42b73b

gcc/ChangeLog:

	* common/common-target.def (compute_multilib): New.
	* common/common-targhooks.h (default_compute_multilib): New.
	* common/common-targhooks.cc (default_compute_multilib): New.
	* doc/tm.texi.in (TARGET_COMPUTE_MULTILIB): New.
	* doc/tm.texi: Regen.
	* gcc.cc: Include common/common-target.h.
	(set_multilib_dir) Call targetm_common.compute_multilib.
	(SWITCH_LIVE): Move to opts.h.
	(SWITCH_FALSE): Ditto.
	(SWITCH_IGNORE): Ditto.
	(SWITCH_IGNORE_PERMANENTLY): Ditto.
	(SWITCH_KEEP_FOR_GCC): Ditto.
	(struct switchstr): Ditto.
	* opts.h (SWITCH_LIVE): Move from gcc.c.
	(SWITCH_FALSE): Ditto.
	(SWITCH_IGNORE): Ditto.
	(SWITCH_IGNORE_PERMANENTLY): Ditto.
	(SWITCH_KEEP_FOR_GCC): Ditto.
	(struct switchstr): Ditto.

An aggregate may have been rewritten before being seen by the procedure.

gcc/ada/

	* exp_util.adb (Expand_Subtype_From_Expr): Be prepared for
	rewritten aggregates as expressions.

The compiler wrongly reports an error about the expected type not
matching the same-named found type in a return statement for a function
whose result type has unknown discriminants when the full type is tagged
and has an undefaulted discriminant, and the return expression is an object
initialized by a function call. The processing for return statements that
creates an actual subtype based on the return expression type's underlying
type when that type has discriminants, and converts the expression to
the actual subtype, should only be done when the underlying discriminated
type is mutable (i.e., has defaulted discriminants). Otherwise the
unchecked conversion to the actual subtype (of the underlying full type)
can lead to a resolution problem later within Expand_Simple_Function_Return
in the expansion of tag assignments (because the target type of the
conversion is a full view and does not match the partial view of
the function's result type).

gcc/ada/

	* exp_ch6.adb (Expand_Simple_Function_Return) Bypass creation of an actual
	subtype and unchecked conversion to that subtype when the underlying type
	of the expression has discriminants without defaults.

The semantic analyzer was setting the Is_Constr_Subt_For_UN_Aliased flag on
the actual subtype of the object, which is incorrect because the nominal
subtype is constrained.  This also adjusts a recent related change.

gcc/ada/

	* exp_util.adb (Expand_Subtype_From_Expr): Check for the presence
	of the Is_Constr_Subt_For_U_Nominal flag instead of the absence
	of the Is_Constr_Subt_For_UN_Aliased flag on the subtype of the
	expression of an object declaration before reusing this subtype.
	* sem_ch3.adb (Analyze_Object_Declaration): Do not incorrectly
	set the Is_Constr_Subt_For_UN_Aliased flag on the actual subtype
	of an array with definite nominal subtype.  Remove useless test.

gcc/ada/

	* doc/gnat_rm/standard_and_implementation_defined_restrictions.rst
	(No_Dependence): Cite implicit dependences on the runtime library.
	* gnat_rm.texi, gnat_ugn.texi: Regenerate.

Add loop variants to verify that loops terminate in string handling.

gcc/ada/

	* libgnat/a-strmap.adb: Add variants to simple and while loops.
	* libgnat/a-strsea.adb: Idem.

Regain the proof of System.Exp_Mod after changes in provers and Why3.

gcc/ada/

	* libgnat/s-expmod.adb (Lemma_Add_Mod): Add new lemma to factor
	out a complex sub-proof.
	(Exp_Modular): Add assertion to help proof.

Regain the proof of System.Wid_* after changes in provers and Why3.

gcc/ada/

	* libgnat/s-widthu.adb (Lemma_Euclidean): Lemma to prove the
	relation between the quotient/remainder of a division.

Proof of Scaled_Divide was impacted by changes in provers and Why3.
Recover it partially, leaving some unproved basic inferences to be
further investigated.

gcc/ada/

	* libgnat/s-aridou.adb: Add or rework ghost code.
	* libgnat/s-aridou.ads: Add Big_Positive subtype.

This documents the limitation of addr2line with Position-Independent Code,
introduces the replacement tool gnatsymbolize and adjusts obsolete stuff.

gcc/ada/

	* doc/gnat_ugn/gnat_and_program_execution.rst
	(Non-Symbolic Traceback): Update section.
	* gnat_rm.texi, gnat_ugn.texi, gnat-style.texi: Regenerate.

Refactor specification of the Value* and Image* units and fix proofs.

gcc/ada/

	* libgnat/a-nbnbig.ads: Add Always_Return annotation.
	* libgnat/s-vaispe.ads: New ghost unit for the specification of
	System.Value_I. Restore proofs.
	* libgnat/s-vauspe.ads: New ghost unit for the specification of
	System.Value_U. Restore proofs.
	* libgnat/s-valuei.adb: The specification only subprograms are
	moved to System.Value_I_Spec. Restore proofs.
	* libgnat/s-valueu.adb: The specification only subprograms are
	moved to System.Value_U_Spec. Restore proofs.
	* libgnat/s-valuti.ads
	(Uns_Params): Generic unit used to bundle together the
	specification functions of System.Value_U_Spec.
	(Int_Params): Generic unit used to bundle together the
	specification functions of System.Value_I_Spec.
	* libgnat/s-imagef.adb: It is now possible to instantiate the
	appropriate specification units instead of creating imported ghost
	subprograms.
	* libgnat/s-imagei.adb: Update to refactoring of specifications
	and fix proofs.
	* libgnat/s-imageu.adb: Likewise.
	* libgnat/s-imgint.ads: Ghost parameters are grouped together in a
	package now.
	* libgnat/s-imglli.ads: Likewise.
	* libgnat/s-imgllu.ads: Likewise.
	* libgnat/s-imgllli.ads: Likewise.
	* libgnat/s-imglllu.ads: Likewise.
	* libgnat/s-imguns.ads: Likewise.
	* libgnat/s-vallli.ads: Likewise.
	* libgnat/s-valllli.ads: Likewise.
	* libgnat/s-imagei.ads: Likewise.
	* libgnat/s-imageu.ads: Likewise.
	* libgnat/s-vaispe.adb: Likewise.
	* libgnat/s-valint.ads: Likewise.
	* libgnat/s-valuei.ads: Likewise.
	* libgnat/s-valueu.ads: Likewise.
	* libgnat/s-vauspe.adb: Likewise.

gcc/ChangeLog:

	* config/pdp11/pdp11.h (PREFERRED_DEBUGGING_TYPE): Disable
	debugging format.

gcc/ChangeLog:

	* Makefile.in: Remove -gstabs option support, DBX-related
	  macros and DBX debugging info support.
	* collect2.cc (scan_prog_file): Likewise.
	* common.opt: Likewise.
	* config.gcc: Likewise.
	* config.in: Likewise.
	* config/aarch64/aarch64-elf.h (DBX_DEBUGGING_INFO): Likewise.
	* config/alpha/alpha.cc: Likewise.
	* config/alpha/elf.h (ASM_SPEC): Likewise.
	* config/arc/arc.h (DBX_DEBUGGING_INFO): Likewise.
	(DBX_CONTIN_LENGTH): Likewise.
	* config/arm/aout.h (DBX_DEBUGGING_INFO): Likewise.
	(DBX_CONTIN_LENGTH): Likewise.
	* config/arm/netbsd-elf.h (DBX_CONTIN_LENGTH): Likewise.
	* config/darwin.h (DSYMUTIL_SPEC): Likewise.
	(ASM_DEBUG_SPEC): Likewise.
	(DBX_DEBUGGING_INFO): Likewise.
	(DBX_USE_BINCL): Likewise.
	(DBX_CONTIN_LENGTH): Likewise.
	(DBX_OUTPUT_NULL_N_SO_AT_MAIN_SOURCE_FILE_END): Likewise.
	* config/epiphany/epiphany.h (DBX_DEBUGGING_INFO): Likewise.
	(DBX_CONTIN_LENGTH): Likewise.
	* config/i386/bsd.h (DBX_NO_XREFS): Likewise.
	(DBX_CONTIN_LENGTH): Likewise.
	* config/i386/gas.h (DBX_NO_XREFS): Likewise.
	(DBX_CONTIN_LENGTH): Likewise.
	* config/ia64/ia64.h: Likewise.
	* config/ia64/sysv4.h (DBX_DEBUGGING_INFO): Likewise.
	* config/m68k/linux.h (DBX_CONTIN_LENGTH): Likewise.
	* config/m68k/openbsd.h (DBX_DEBUGGING_INFO): Likewise.
	(DBX_CONTIN_LENGTH): Likewise.
	(DBX_CONTIN_CHAR): Likewise.
	* config/mips/mips.cc (mips_output_filename): Likewise.
	(mips_option_override): Likewise.
	* config/mips/mips.h (SUBTARGET_ASM_DEBUGGING_SPEC): Likewise.
	(DBX_DEBUGGING_INFO): Likewise.
	(DBX_CONTIN_LENGTH): Likewise.
	(DBX_REGISTER_NUMBER): Likewise.
	(GP_DBX_FIRST): Likewise.
	(FP_DBX_FIRST): Likewise.
	(MD_DBX_FIRST): Likewise.
	* config/nvptx/nvptx.cc: Likewise.
	* config/openbsd.h (DBX_NO_XREFS): Likewise.
	* config/pa/pa-64.h (DBX_DEBUGGING_INFO): Likewise.
	* config/pa/pa.h (ASSEMBLER_DIALECT): Likewise.
	(DBX_CONTIN_LENGTH): Likewise.
	* config/pa/som.h (PREFERRED_DEBUGGING_TYPE): Likewise.
	(DBX_USE_BINCL): Likewise.
	(DBX_LINES_FUNCTION_RELATIVE): Likewise.
	(DBX_OUTPUT_NULL_N_SO_AT_MAIN_SOURCE_FILE_END): Likewise.
	* config/pdp11/pdp11.cc: Likewise.
	* config/pdp11/pdp11.h (DBX_DEBUGGING_INFO): Likewise.
	(PREFERRED_DEBUGGING_TYPE): Likewise.
	(DBX_CONTIN_LENGTH): Likewise.
	* config/rs6000/rs6000-builtin.cc: Likewise.
	* config/rs6000/rs6000-call.cc: Likewise.
	* config/rs6000/rs6000-logue.cc (defined): Likewise.
	* config/rs6000/rs6000.cc (rs6000_option_override_internal): Likewise.
	(HAVE_XCOFF_DWARF_EXTRAS): Likewise.
	(rs6000_xcoff_declare_function_name): Likewise.
	* config/rs6000/sysv4.h (DBX_DEBUGGING_INFO): Likewise.
	(DBX_FUNCTION_FIRST): Likewise.
	* config/rs6000/xcoff.h (XCOFF_DEBUGGING_INFO): Likewise.
	* config/rx/rx.h (DBX_DEBUGGING_INFO): Likewise.
	* config/sh/elf.h (DBX_LINES_FUNCTION_RELATIVE): Likewise.
	(DBX_OUTPUT_NULL_N_SO_AT_MAIN_SOURCE_FILE_END): Likewise.
	* config/sol2.h (NO_DBX_BNSYM_ENSYM): Likewise.
	* config/sparc/freebsd.h (DBX_CONTIN_CHAR): Likewise.
	* config/sparc/netbsd-elf.h (DBX_CONTIN_CHAR): Likewise.
	* config/sparc/sparc.h (DBX_CONTIN_LENGTH): Likewise.
	* config/vax/vax.cc (vax_file_start): Likewise.
	* config/vax/vax.h (DBX_DEBUGGING_INFO): Likewise.
	(DBX_CONTIN_LENGTH): Likewise.
	(DBX_CONTIN_CHAR): Likewise.
	(DBX_NO_XREFS): Likewise.
	(DBX_STATIC_STAB_DATA_SECTION): Likewise.
	* config/vx-common.h (DBX_DEBUGGING_INFO): Likewise.
	(XCOFF_DEBUGGING_INFO): Likewise.
	* configure: Regenerate. Likewise.
	* configure.ac: Likewise.
	* debug.h: Likewise.
	* doc/install.texi: Likewise.
	* doc/invoke.texi: Likewise.
	* doc/passes.texi: Likewise.
	* doc/tm.texi: Likewise.
	* doc/tm.texi.in: Likewise.
	* dwarf2asm.cc (XCOFF_DEBUGGING_INFO): Likewise.
	(dw2_asm_output_nstring): Likewise.
	(USE_LINKONCE_INDIRECT): Likewise.
	* dwarf2out.cc (XCOFF_DEBUGGING_INFO): Likewise.
	(HAVE_XCOFF_DWARF_EXTRAS): Likewise.
	(output_fde): Likewise.
	(output_call_frame_info): Likewise.
	(have_macinfo): Likewise.
	(add_AT_loc_list): Likewise.
	(add_AT_view_list): Likewise.
	(output_compilation_unit_header): Likewise.
	(output_pubnames): Likewise.
	(output_aranges): Likewise.
	(output_line_info): Likewise.
	(output_macinfo): Likewise.
	(dwarf2out_finish): Likewise.
	(dwarf2out_early_finish): Likewise.
	* final.cc (final_scan_insn_1): Likewise.
	(rest_of_handle_final): Likewise.
	* flag-types.h (enum debug_info_type): Likewise.
	(DBX_DEBUG): Likewise.
	(XCOFF_DEBUG): Likewise.
	* function.cc (defined): Likewise.
	* gcc.cc (defined): Likewise.
	(ASM_DEBUG_SPEC): Likewise.
	(ASM_DEBUG_OPTION_SPEC): Likewise.
	* opts.cc (common_handle_option): Likewise.
	(set_debug_level): Likewise.
	* system.h (fancy_abort): Likewise.
	* target-def.h (TARGET_ASM_CONSTRUCTOR): Likewise.
	(TARGET_ASM_DESTRUCTOR): Likewise.
	* toplev.cc (defined): Likewise.
	* varasm.cc: Likewise.
	* config/dbxcoff.h: Removed.
	* config/dbxelf.h: Removed.
	* dbxout.cc: Removed.
	* dbxout.h: Removed.
	* gstab.h: Removed.
	* stab.def: Removed.
	* xcoffout.cc: Removed.
	* xcoffout.h: Removed.

gcc/go/ChangeLog:

	* go-lang.cc (go_langhook_pushdecl): Remove -gstabs option support, DBX-related
	  macros and DBX debugging info support.
	* gospec.cc (lang_specific_driver): Likewise.

gcc/testsuite/ChangeLog:

	* lib/gcc-dg.exp: Remove -gstabs option support, DBX-related
	  macros and DBX debugging info support.
	* lib/gfortran-dg.exp: Likewise.
	* lib/target-supports.exp: Likewise.
	* g++.dg/cpp0x/alias-decl-debug-0.C: Removed.
	* g++.dg/other/PR23205.C: Removed.
	* g++.dg/other/pr23205-2.C: Removed.
	* gcc.dg/20040813-1.c: Removed.
	* gcc.dg/darwin-20040809-2.c: Removed.
	* gcc.dg/debug/pr35154.c: Removed.
	* gcc.dg/pr69471-2.c: Removed.
	* gcc.target/powerpc/stabs-attrib-vect-darwin.c: Removed.
	* gcc.target/s390/20041216-1.c: Removed.
	* gfortran.dg/debug/pr35154-stabs.f: Removed.
	* objc.dg/stabs-1.m: Removed.

Any multi-versioned function was implicitly declared as noexcept, which
leads to an abort if an exception is thrown inside the function.
The reason for this is that the function declaration is replaced by a
newly created dispatcher declaration, which has TREE_NOTHROW always set
to 1. Instead we need to set TREE_NOTHROW to the value of the original
declaration.

	PR ipa/106627

gcc/ChangeLog:

	* config/i386/i386-features.cc (ix86_get_function_versions_dispatcher):
	Set TREE_NOTHROW correctly for dispatcher declaration.
	* config/rs6000/rs6000.cc (rs6000_get_function_versions_dispatcher):
	Likewise.

gcc/testsuite/ChangeLog:

	* g++.target/i386/pr106627.C: New test.

Replace long with long long for 64-bit integer since long may be 32
bits.

	PR target/106707
	* gcc.target/i386/pr106707.c (foo): Replace long with long long.

This fixes the bootstrap failure on AArch64 following -Werror=format by
correcting the print format modifiers in the backend.

gcc/ChangeLog:

	PR other/106782
	* config/aarch64/aarch64.cc
	(aarch64_vector_costs::prefer_unrolled_loop): Replace %u with
	HOST_WIDE_INT_PRINT_UNSIGNED.

This declaration was added in r260905 but the function was never
defined.

gcc/cp/ChangeLog:

	* cp-tree.h (maybe_strip_ref_conversion): Remove.

Clang doesn't yet implement the C++20 change that makes 'typename'
optional here.

libstdc++-v3/ChangeLog:

	* include/std/ranges (adjacent_transform_view::_Iterator): Add
	typename keyword before dependent qualified-id.

We only use the __is_referenceable helper in three places now:
add_pointer, add_lvalue_reference, and add_rvalue_reference. But lots of
other traits depend on add_[lr]value_reference, and decay depends on
add_pointer, so removing the instantiation of __is_referenceable helps
compile all those other traits slightly faster.

We can just use void_t<T&> to check for a referenceable type in the
add_[lr]value_reference traits.

Then we can specialize add_pointer for reference types, so that we don't
need to use remove_reference, and then use void_t<T*> for all
non-reference types to detect when we can form a pointer to the type.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (__is_referenceable): Remove.
	(__add_lvalue_reference_helper, __add_rvalue_reference_helper):
	Use __void_t instead of __is_referenceable.
	(__add_pointer_helper): Likewise.
	(add_pointer): Add partial specializations for reference types.

We can replace some class template helpers with alias templates, which
are cheaper to instantiate.

For example, replace the __is_copy_constructible_impl class template
with an alias template that uses just evaluates the __is_constructible
built-in, using add_lvalue_reference<const T> to get the argument type
in a way that works for non-referenceable types. For a given
specialization of is_copy_constructible this results in the same number
of class templates being instantiated (for the common case of non-void,
non-function types), but the add_lvalue_reference instantiations are not
specific to the is_copy_constructible specialization and so can be
reused by other traits. Previously __is_copy_constructible_impl was a
distinct class template and its specializations were never used for
anything except is_copy_constructible.

With the new definitions of these traits that don't depend on helper
classes, it becomes more practical to optimize the
is_xxx_constructible_v variable templates to avoid instantiations.
Previously doing so would have meant two entirely separate
implementation strategies for these traits.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (__is_constructible_impl): Replace
	class template with alias template.
	(is_default_constructible, is_nothrow_constructible)
	(is_nothrow_constructible): Simplify base-specifier.
	(__is_copy_constructible_impl, __is_move_constructible_impl)
	(__is_nothrow_copy_constructible_impl)
	(__is_nothrow_move_constructible_impl): Remove class templates.
	(is_copy_constructible, is_move_constructible)
	(is_nothrow_constructible, is_nothrow_default_constructible)
	(is_nothrow_copy_constructible, is_nothrow_move_constructible):
	Adjust base-specifiers to use __is_constructible_impl.
	(__is_copy_assignable_impl, __is_move_assignable_impl)
	(__is_nt_copy_assignable_impl, __is_nt_move_assignable_impl):
	Remove class templates.
	(__is_assignable_impl): New alias template.
	(is_assignable, is_copy_assignable, is_move_assignable):
	Adjust base-specifiers to use new alias template.
	(is_nothrow_copy_assignable, is_nothrow_move_assignable):
	Adjust base-specifiers to use existing alias template.
	(__is_trivially_constructible_impl): New alias template.
	(is_trivially_constructible, is_trivially_default_constructible)
	(is_trivially_copy_constructible)
	(is_trivially_move_constructible): Adjust base-specifiers to use
	new alias template.
	(__is_trivially_assignable_impl): New alias template.
	(is_trivially_assignable, is_trivially_copy_assignable)
	(is_trivially_move_assignable): Adjust base-specifier to use
	new alias template.
	(__add_lval_ref_t, __add_rval_ref_t): New alias templates.
	(add_lvalue_reference, add_rvalue_reference): Use new alias
	templates.

Define partial specializations of std::decay and its __decay_selector
helper so that remove_reference, is_array and is_function are not
instantiated for every type, and remove_extent is not instantiated for
arrays.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (__decay_selector): Add partial
	specializations for array types. Only check for function types
	when not dealing with an array.
	(decay): Add partial specializations for reference types.

This avoids having to instantiate a class template when we can detect
the true cases easily with a partial specialization.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (is_lvalue_reference_v)
	(is_rvalue_reference_v, is_reference_v, is_const_v)
	(is_volatile_v): Define using partial specializations instead
	of instantiating class templates.

This avoids having to instantiate a class template that just uses the
same built-in anyway.

None of the corresponding class templates have any type-completeness
static assertions, so we're not losing any diagnostics by using the
built-ins directly.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (is_enum_v, is_class_v, is_union_v)
	(is_empty_v, is_polymoprhic_v, is_abstract_v, is_final_v)
	(is_base_of_v, is_aggregate_v): Use built-in directly instead of
	instantiating class template.

C2x has completely removed unprototyped functions, so that () now
means the same as (void) in both function declarations and
definitions, where previously that change had been made for
definitions only.  Implement this accordingly.

This is a change where GNU/Linux distribution builders might wish to
try builds with a -std=gnu2x default to start early on getting old
code fixed that still has () declarations for functions taking
arguments, in advance of GCC moving to -std=gnu2x as default maybe in
GCC 14 or 15; I don't know how much such code is likely to be in
current use.

Bootstrapped with no regressions for x86_64-pc-linux-gnu.

gcc/c/
	* c-decl.cc (grokparms): Handle () in a function declaration the
	same as (void) for C2X.

gcc/testsuite/
	* gcc.dg/c11-unproto-3.c, gcc.dg/c2x-unproto-3.c,
	gcc.dg/c2x-unproto-4.c: New tests.
	* gcc.dg/c2x-old-style-definition-6.c, gcc.dg/c2x-unproto-1.c,
	gcc.dg/c2x-unproto-2.c: Update for removal of unprototyped
	functions.

This patch extends the SLP layout optimisation pass so that it
tries to remove layout changes that are brought about by permutes
of existing vectors.  This fixes the bb-slp-pr54400.c regression on
x86_64 and also means that we can remove the permutes in cases like:

typedef float v4sf __attribute__((vector_size(sizeof(float)*4)));

float __attribute__((noipa))
f(v4sf v0, v4sf v1)
{
  return v0[0]*v1[0]+v0[1]*v1[1]+v0[2]*v1[2]+v0[3]*v1[3];
}

The new test is a simple adaption of bb-slp-pr54400.c, with the
same style of markup.

gcc/
	* tree-vect-slp.cc (vect_build_slp_tree_2): When building a
	VEC_PERM_EXPR of an existing vector, set the SLP_TREE_LANES
	to the number of vector elements, if that's a known constant.
	(vect_optimize_slp_pass::is_compatible_layout): Remove associated
	comment about zero SLP_TREE_LANES.
	(vect_optimize_slp_pass::start_choosing_layouts): Iterate over
	all partition members when looking for potential layouts.
	Handle existing permutes of fixed-length vectors.

gcc/testsuite/
	* gcc.dg/vect/bb-slp-pr54400.c: Extend to aarch64.
	* gcc.dg/vect/bb-slp-layout-18.c: New test.

The conversion of a move pattern where both operands are AX_REG
should be prevented.

2022-09-01  Uroš Bizjak  <ubizjak@gmail.com>

gcc/ChangeLog:

	PR target/106707
	* config/i386/i386.md (moves to/from AX_REG into xchg peephole2):
	Do not convert a move pattern where both operands are AX_REG.

gcc/testsuite/ChangeLog:

	PR target/106707
	* gcc.target/i386/pr106707.c: New test.

gcc/ChangeLog:

	* range-op-float.cc (build_le): Convert to dconst*inf.
	(build_ge): Same.
	* value-range.cc (frange::set_signbit): Same.
	(frange::normalize_kind): Same.
	(range_tests_floats): Same.
	* value-range.h (vrp_val_max): Same.
	(vrp_val_min): Same.
	(frange::set_varying): Same.

We're starting to abuse the infinity endpoints in the frange code and
the associated range operators.  Building infinities are rather cheap,
and we could even inline them, but I think it's best to just not
recalculate them all the time.

I see about 20 uses of real_inf in the source code, not including the
backends.  And I'm about to add more :).

gcc/ChangeLog:

	* emit-rtl.cc (init_emit_once): Initialize dconstinf and
	dconstninf.
	* real.h: Add dconstinf and dconstninf.

PR c++/99968 is fixed since GCC 12.1 so we can remove the workaround.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (is_scoped_enum): Remove workaround.

libstdc++-v3/ChangeLog:

	* include/std/ranges (__detail::__unarize): Define.
	(adjacent_view::_Iterator): Befriend adjacent_transform_view.
	(adjacent_transform_view): Define.
	(adjacent_transform_view::_Iterator): Define.
	(adjacent_transform_view::_Sentinel): Define.
	(views::__detail::__can_adjacent_transform_view): Define.
	(views::_AdjacentTransform): Define.
	(views::adjacent_transform): Define.
	(views::pairwise_transform): Define.
	* testsuite/std/ranges/adaptors/adjacent_transform/1.cc: New test.

Now that we have DFS_BACK_EDGE marks we can simply avoid walking
those instead of repeatedly looking for a cycle on the current chain.

	* gimple-predicate-analysis.cc (compute_control_dep_chain):
	Remove cycle detection, instead avoid walking backedges.

The following hides some internal details of compute_control_dep_chain.

	* gimple-predicate-analysis.cc (compute_control_dep_chain):
	New wrapping overload.
	(uninit_analysis::init_use_preds): Simplify.
	(uninit_analysis::init_from_phi_def): Likewise.

While looking at the DWARF handling of char8_t I wondered why we weren't
setting TREE_STRING_FLAG on it.  I hoped that setting that flag would be an
easy fix for PR102958, but it doesn't seem to be sufficicent.  But it still
seems correct.

I also tried setting the flag on char16_t and char32_t, but that broke
because braced_list_to_string assumes char-sized elements.  Since we don't
set the flag on wchar_t, I abandoned that idea.

gcc/c-family/ChangeLog:

	* c-common.cc (c_common_nodes_and_builtins): Set TREE_STRING_FLAG on
	char8_t.
	(braced_list_to_string): Check for char-sized elements.

Now that we keep track of the signbit, we can use it to fold __builtin_signbit.

I am assuming I don't have try too hard to get the actual signbit
number and 1 will do.  Especially, since we're inconsistent in trunk whether
we fold the builtin or whether we calculate it at runtime.

abulafia:~$ cat a.c
float nzero = -0.0;

main(){
    printf("0x%x\n", __builtin_signbit(-0.0));
    printf("0x%x\n", __builtin_signbit(nzero));
}
abulafia:~$ gcc a.c -w && ./a.out
0x1
0x80000000

It is amazing that we've been failing to fold something as simple as
this:

	if (x > 5.0)
	  num = __builtin_signbit (x);

It does the right thing now :-P.

gcc/ChangeLog:

	* gimple-range-fold.cc
	(fold_using_range::range_of_builtin_int_call): Add case for
	CFN_BUILT_IN_SIGNBIT.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/vrp-float-signbit-1.c: New test.

As discussed here:

	https://gcc.gnu.org/pipermail/gcc-patches/2022-August/600656.html

This adds an frange property to keep track of the sign bit.  We keep
it updated at all times, but we don't use it make any decisions when
!HONOR_SIGNED_ZEROS.

With this property we can now query the range for the appropriate sign
with frange::get_signbit ().  Possible values are yes, no, and unknown.

gcc/ChangeLog:

	* range-op-float.cc (foperator_equal::op1_range): Do not copy sign
	bit.
	(foperator_not_equal::op1_range): Same.
	* value-query.cc (range_query::get_tree_range): Set sign bit.
	* value-range-pretty-print.cc (vrange_printer::visit): Dump sign bit.
	* value-range.cc (frange::set_signbit): New.
	(frange::set): Adjust for sign bit.
	(frange::normalize_kind): Same.
	(frange::union_): Remove useless comment.
	(frange::intersect): Same.
	(frange::contains_p): Adjust for sign bit.
	(frange::singleton_p): Same.
	(frange::verify_range): Same.
	(range_tests_signbit): New tests.
	(range_tests_floats): Call range_tests_signbit.
	* value-range.h (class frange_props): Add signbit
	(class frange): Same.

Improve compile times by avoiding unnecessary class template
instantiations.

__is_array_known_bounds and __is_array_unknown_bounds can be defined
without instantiating extent, by providing partial specializations for
the true cases.

std::extent can avoid recursing down through a multidimensional array,
so it stops after providing the result. Previously extent<T[n][m], 0>
would instantiate extent<T[n], -1u> and extent<T, -2u> as well.

std::is_array_v can use partial specializations to avoid instantiating
std::is_array, and similarly for std::rank_v and std::extent_v.

std::is_bounded_array_v and std::is_unbounded_array_v can also use
partial specializations, and then the class templates can be defined in
terms of the variable templates. This makes sense for these traits,
because they are new in C++20 and so the variable templates are always
available, which isn't true in general for C++11 and C++14 traits.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (__is_array_known_bounds): Add partial
	specialization instead of using std::extent.
	(__is_array_unknown_bounds): Likewise.
	(extent): Add partial specializations to stop recursion after
	the result is found.
	(is_array_v): Add partial specializations instead of
	instantiating the class template.
	(rank_v, extent_v): Likewise.
	(is_bounded_array_v, is_unbounded_array_v): Likewise.
	(is_bounded_array, is_unbounded_array): Define in terms of the
	variable templates.

As discussed on IRC, the r13-2299-g68c61c2d bug only got missed
because dump_printf_loc had incorrect format attribute and therefore
almost no -Wformat=* checking was performed on it.
3, 0 are suitable for function with (whatever, whatever, const char *, va_list)
arguments, not for (whatever, whatever, const char *, ...), that one should
use 3, 4.

The following patch fixes that and adjusts all spots to fix warnings.
In many cases it is just through an ugly cast (for %G casts to gimple *
from gassign */gphi * and the like and for %p casts to void * from slp_node
etc.).
There are 3 spots where the mismatch was worse though, two using %u or %d
for unsigned HOST_WIDE_INT argument and one %T for enum argument (promoted
to int).

2022-09-01  Jakub Jelinek  <jakub@redhat.com>

	PR other/106782
	* dumpfile.h (dump_printf_loc): Use ATTRIBUTE_GCC_DUMP_PRINTF (3, 4)
	instead of ATTRIBUTE_GCC_DUMP_PRINTF (3, 0).
	* tree-parloops.cc (parloops_is_slp_reduction): Cast pointers to
	derived types of gimple to gimple * to avoid -Wformat warnings.
	* tree-vect-loop-manip.cc (vect_set_loop_condition,
	vect_update_ivs_after_vectorizer): Likewise.
	* tree-vect-stmts.cc (vectorizable_load): Likewise.
	* tree-vect-patterns.cc (vect_split_statement,
	vect_recog_mulhs_pattern, vect_recog_average_pattern,
	vect_determine_precisions_from_range,
	vect_determine_precisions_from_users): Likewise.
	* gimple-loop-versioning.cc
	(loop_versioning::analyze_term_using_scevs): Likewise.
	* tree-vect-slp.cc (vect_build_slp_tree_1): Likewise.
	(vect_build_slp_tree): Cast slp_tree to void * to avoid
	-Wformat warnings.
	(optimize_load_redistribution_1, vect_match_slp_patterns,
	vect_build_slp_instance, vect_optimize_slp_pass::materialize,
	vect_optimize_slp_pass::dump, vect_slp_convert_to_external,
	vect_slp_analyze_node_operations, vect_bb_partition_graph): Likewise.
	(vect_print_slp_tree): Likewise.  Also use
	HOST_WIDE_INT_PRINT_UNSIGNED instead of %u.
	* tree-vect-loop.cc (vect_determine_vectorization_factor,
	vect_analyze_scalar_cycles_1, vect_analyze_loop_operations,
	vectorizable_induction, vect_transform_loop): Cast pointers to derived
	types of gimple to gimple * to avoid -Wformat warnings.
	(vect_analyze_loop_2): Cast slp_tree to void * to avoid
	-Wformat warnings.
	(vect_estimate_min_profitable_iters): Use HOST_WIDE_INT_PRINT_UNSIGNED
	instead of %d.
	* tree-vect-slp-patterns.cc (vect_pattern_validate_optab): Use %G
	instead of %T and STMT_VINFO_STMT (SLP_TREE_REPRESENTATIVE (node))
	instead of SLP_TREE_DEF_TYPE (node).

The following patch introduces a new warning - -Winvalid-utf8 similarly
to what clang now has - to diagnose invalid UTF-8 byte sequences in
comments, but not just in those, but also in string/character literals
and outside of them.

The warning is on by default when explicit -finput-charset=UTF-8 is
used and C++23 compilation is requested and if -{,W}pedantic or
-pedantic-errors it is actually a pedwarn.

The reason it is on by default only for -finput-charset=UTF-8 is
that the sources often are UTF-8, but sometimes could be some ASCII
compatible single byte encoding where non-ASCII characters only
appear in comments.  So having the warning off by default
is IMO desirable.  The C++23 pedantic mode for when the source code
is UTF-8 is -std=c++23 -pedantic-errors -finput-charset=UTF-8.

2022-09-01  Jakub Jelinek  <jakub@redhat.com>

	PR c++/106655
libcpp/
	* include/cpplib.h (struct cpp_options): Implement C++23
	P2295R6 - Support for UTF-8 as a portable source ...