There are three major pieces to this support: scalar operator<=>,
synthesis of comparison operators, and rewritten/reversed overload
resolution (e.g. a < b becomes 0 > b <=> a).

Unlike other defaulted functions, where we use synthesized_method_walk to
semi-simulate what the definition of the function will be like, this patch
determines the characteristics of a comparison operator by trying to define
it.

My handling of non-dependent rewritten operators in templates can still use
some work: build_min_non_dep_op_overload can't understand the rewrites and
crashes, so I'm avoiding it for now by clearing *overload.  This means we'll
do name lookup again at instantiation time, which can incorrectly mean a
different result.  I'll poke at this more in stage 3.

I'm leaving out a fourth section ("strong structural equality") even though
I've implemented it, because it seems likely to change radically tomorrow.

Thanks to Tim van Deurzen and Jakub for implementing lexing of the <=>
operator, and Jonathan for the initial <compare> header.

gcc/cp/
	* cp-tree.h (struct lang_decl_fn): Add maybe_deleted bitfield.
	(DECL_MAYBE_DELETED): New.
	(enum special_function_kind): Add sfk_comparison.
	(LOOKUP_REWRITTEN, LOOKUP_REVERSED): New.
	* call.c (struct z_candidate): Add rewritten and reversed methods.
	(add_builtin_candidate): Handle SPACESHIP_EXPR.
	(add_builtin_candidates): Likewise.
	(add_candidates): Don't add a reversed candidate if the parms are
	the same.
	(add_operator_candidates): Split out from build_new_op_1.  Handle
	rewritten and reversed candidates.
	(add_candidate): Swap conversions of reversed candidate.
	(build_new_op_1): Swap them back.  Build a second operation for
	rewritten candidates.
	(extract_call_expr): Handle rewritten calls.
	(same_fn_or_template): New.
	(joust): Handle rewritten and reversed candidates.
	* class.c (add_implicitly_declared_members): Add implicit op==.
	(classtype_has_op, classtype_has_defaulted_op): New.
	* constexpr.c (cxx_eval_binary_expression): Handle SPACESHIP_EXPR.
	(cxx_eval_constant_expression, potential_constant_expression_1):
	Likewise.
	* cp-gimplify.c (genericize_spaceship): New.
	(cp_genericize_r): Use it.
	* cp-objcp-common.c (cp_common_init_ts): Handle SPACESHIP_EXPR.
	* decl.c (finish_function): Handle deleted function.
	* decl2.c (grokfield): SET_DECL_FRIEND_CONTEXT on defaulted friend.
	(mark_used): Check DECL_MAYBE_DELETED.  Remove assumption that
	defaulted functions are non-static members.
	* error.c (dump_expr): Handle SPACESHIP_EXPR.
	* method.c (type_has_trivial_fn): False for sfk_comparison.
	(enum comp_cat_tag, struct comp_cat_info_t): New types.
	(comp_cat_cache): New array variable.
	(lookup_comparison_result, lookup_comparison_category)
	(is_cat, cat_tag_for, spaceship_comp_cat)
	(spaceship_type, genericize_spaceship)
	(common_comparison_type, early_check_defaulted_comparison)
	(comp_info, build_comparison_op): New.
	(synthesize_method): Handle sfk_comparison.  Handle deleted.
	(get_defaulted_eh_spec, maybe_explain_implicit_delete)
	(explain_implicit_non_constexpr, implicitly_declare_fn)
	(defaulted_late_check, defaultable_fn_check): Handle sfk_comparison.
	* name-lookup.c (get_std_name_hint): Add comparison categories.
	* tree.c (special_function_p): Add sfk_comparison.
	* typeck.c (cp_build_binary_op): Handle SPACESHIP_EXPR.

2019-11-05  Tim van Deurzen  <tim@kompiler.org>

	Add new tree code for the spaceship operator.
gcc/cp/
	* cp-tree.def: Add new tree code.
	* operators.def: New binary operator.
	* parser.c: Add new token and tree code.
libcpp/
	* cpplib.h: Add spaceship operator for C++.
	* lex.c: Implement conditional lexing of spaceship operator for C++20.

2019-11-05  Jonathan Wakely  <jwakely@redhat.com>

libstdc++-v3/
	* libsupc++/compare: New header.
	* libsupc++/Makefile.am (std_HEADERS): Add compare.
	* include/std/version: Define __cpp_lib_three_way_comparison.
	* include/std/functional: #include <compare>.

From-SVN: r277865

While working on C++20 operator<=>, I noticed that build_new_op_1 was doing
too much conversion when a built-in candidate was selected; the standard
says it should only perform user-defined conversions, and then leave the
normal operator semantics to handle any standard conversions.  This is
important for operator<=> because a comparison of two different unscoped
enums is ill-formed; if we promote the enums to int here, cp_build_binary_op
never gets to see the original operand types, so we can't give the error.

I'm also disabling -Wmaybe-uninitialized for expmed.c to avoid the bootstrap
failure from the last time I applied this patch.

	* call.c (build_new_op_1): Don't apply any standard conversions to
	the operands of a built-in operator.  Don't suppress conversions in
	cp_build_unary_op.
	* typeck.c (cp_build_unary_op): Do integral promotions for enums.

	PR tree-optimization/91825
	* expmed.c: Reduce -Wmaybe-uninitialized to warning.

From-SVN: r277864

My operator<=> patch wants to split up build_new_op_1, which makes using a
tree array as well as the vec inconvenient.  build_new_op_1 already has a
vec, and build_conditional_expr_1 can release its vec right away, so this
doesn't increase garbage at all.

	* call.c (build_builtin_candidate): Take args in a vec.
	(add_builtin_candidate, add_builtin_candidates): Likewise.
	(build_conditional_expr_1, build_new_op_1): Adjust.

From-SVN: r277863

Wrappers for lookup_qualified_name and build_x_binary_op to make calling
them more convenient in places, and a function named contextual_conv_bool
for places that want contextual conversion to bool.

I noticed that we weren't showing the declaration location when we complain
about a call to a non-constexpr function where a constant expression is
required.

If maybe_instantiate_noexcept doesn't actually instantiate, there's no
reason for it to mess with clones.

	* constexpr.c (explain_invalid_constexpr_fn): Show location of fn.

	* pt.c (maybe_instantiate_noexcept): Only update clones if we
	instantiated.

	* typeck.c (contextual_conv_bool): New.

	* name-lookup.c (lookup_qualified_name): Add wrapper overload taking
	C string rather than identifier.
	* parser.c (cp_parser_userdef_numeric_literal): Use it.
	* rtti.c (emit_support_tinfos): Use it.
	* cp-tree.h (ovl_op_identifier): Change to inline functions.
	(build_x_binary_op): Add wrapper with fewer parms.

From-SVN: r277862

The RISC-V backend wants to use a libcall when optimizing for size if
more than 6 instructions are needed.  Emit_move_complex asks for no
libcalls.  This case requires 8 insns for rv64 and 16 insns for rv32,
so we get fallback code that emits a loop.  Commit_one_edge_insertion
doesn't allow code inserted for a phi node on an edge to end with a
branch, and so this triggers an assertion.  This problem goes away if
we allow libcalls when optimizing for size, which gives the code the
RISC-V backend wants, and avoids triggering the assert.

	gcc/
	PR middle-end/92263
	* expr.c (emit_move_complex): Only use BLOCK_OP_NO_LIBCALL when
	optimize_insn_for_speed_p is true.

	gcc/testsuite/
	PR middle-end/92263
	* gcc.dg/pr92263.c: New.

From-SVN: r277861

While looking at CA378 I noticed that we weren't properly diagnosing two of
the three erroneous lines in the example.

	* decl2.c (mark_used): Diagnose use of a function with unsatisfied
	constraints here.
	* typeck.c (cp_build_function_call_vec): Not here.

From-SVN: r277860

	* c-opts.c (c_common_post_options): -fconcepts-ts implies
	-fconcepts.

From-SVN: r277859

PR middle-end/92333 - missing variable name referencing VLA in warnings
PR middle-end/82608 - missing -Warray-bounds on an out-of-bounds VLA index

gcc/testsuite/ChangeLog:

	PR middle-end/92333
	PR middle-end/82608
	* gcc.dg/Warray-bounds-51.c: New test.

gcc/ChangeLog:

	PR middle-end/92333
	PR middle-end/82608
	* tree-vrp.c (vrp_prop::check_array_ref): Handle VLAs with constant
	size.
	* tree-ssa-ccp.c (fold_builtin_alloca_with_align): Use a meaninful
	name and location for a temporary variable.

From-SVN: r277854

https://gcc.gnu.org/ml/gcc-patches/2019-11/msg00323.html
	cp/
	PR c++/92370
	* parser.c (cp_parser_error_1): Check EOF and UNKNOWN_LOCATION
	when skipping over version control marker.

	testsuite/
	PR c++/92370
	* g++.dg/pr92370.C: New.

From-SVN: r277853

From-SVN: r277852

PR middle-end/92341 - missing -Warray-bounds indexing past the end of a compound literal
PR middle-end/82612 - missing -Warray-bounds on a non-zero offset from the address of a non-array object

gcc/testsuite/ChangeLog:

	PR middle-end/92341
	PR middle-end/82612
	* g++.dg/warn/Warray-bounds-4.C: Adjust text of expected warning.
	* gcc.dg/Warray-bounds-53.c: New test.
	* gcc.dg/Warray-bounds-54.c: New test.

gcc/ChangeLog:

	PR middle-end/92341
	PR middle-end/82612
	* tree-sra.c (get_access_for_expr): Fail for out-of-bounds offsets.
	* tree-vrp.c (vrp_prop::check_array_ref): Correct index and text
	of message printed in a warning for empty arrays.
	(vrp_prop::check_mem_ref): Also handle function parameters and
	empty arrays.

From-SVN: r277851

2019-11-05  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/92371
	* tree-vect-loop.c (vectorizable_reduction): Set STMT_VINFO_REDUC_DEF
	on the original stmt of live stmts in the chain.
	(vectorizable_live_operation): Look at the original stmt when
	checking STMT_VINFO_REDUC_DEF.

	* gcc.dg/torture/pr92371.c: New testcase.

From-SVN: r277850

	* include/std/version [!_GLIBCXX_HOSTED]: Do not define feature test
	macros for features that are only present in hosted builds.

From-SVN: r277849

The negative concept is required for subsumption to work, it's not a
bug.

	* include/bits/iterator_concepts.h (__iter_without_nested_types):
	Remove incorrect comment.

From-SVN: r277848

The base class for ranges is currently value_range_base, which is
rather long and cumbersome.  It also occurs more often than the derived
class of value_range.  To avoid confusion, and save typing, this
patch does a global rename from value_range to value_range_equiv,
and from value_range_base to value_range.

This way, the base class is simply value_range, and the derived
class is value_range_equiv which explicitly states what it does.

From-SVN: r277847

`build_personality_function` generates a declaration for a personality
function.  The type it declares for these functions doesn't match the
type of the actual personality functions that are defined by the C++
unwinding ABI.

This doesn't cause any crashes since the compiler never generates a call
to these decl's, and hence the type of the function is never used.
Nonetheless, for the sake of consistency and readability we update the
type of this declaration.

gcc/ChangeLog:

2019-11-05  Matthew Malcomson  <matthew.malcomson@arm.com>

	* expr.c (build_personality_function): Fix generated type to
	match actual personality functions.

From-SVN: r277846

-fsanitize=hwaddress found a one-byte overwrite when running the
testsuite here.  aarch64_handle_attr_branch_protection allocates
`strlen(str)` bytes for an error string, which is populated by
`strcpy(..., str)` in the case where the branch protection string is
completely invalid.

Not tested -- I don't want to re-build and it seems obvious.

gcc/ChangeLog:

2019-11-05  Matthew Malcomson  <matthew.malcomson@arm.com>

	* config/aarch64/aarch64.c (aarch64_handle_attr_cpu): Allocate
	enough bytes for the NULL character.

From-SVN: r277845

From-SVN: r277839

2019-11-05  Martin Liska  <mliska@suse.cz>

	* c-c++-common/ubsan/ptr-overflow-2.c: Update based on changed
	run-time reporting format.

From-SVN: r277838

2019-11-05  Martin Liska  <mliska@suse.cz>

	* ubsan/ubsan_flags.cpp (InitializeFlags): Trunk decided to print
	summary for all sanitizers, but we want to have UBSAN without it.

From-SVN: r277837

2019-11-05  Martin Liska  <mliska@suse.cz>

	* asan/asan_globals.cpp (CheckODRViolationViaIndicator): Reapply from
	LOCAL_PATCHES.
	(CheckODRViolationViaPoisoning): Likewise.
	(RegisterGlobal): Likewise.
	* asan/asan_interceptors.h (ASAN_INTERCEPT___CXA_RETHROW_PRIMARY_EXCEPTION): Likewise.
	(defined): Likewise.
	* asan/asan_mapping.h: Likewise.
	* sanitizer_common/sanitizer_linux_libcdep.cpp (defined): Likewise.
	* sanitizer_common/sanitizer_mac.cpp (defined): Likewise.
	* sanitizer_common/sanitizer_platform_limits_linux.cpp (defined): Likewise.
	* sanitizer_common/sanitizer_platform_limits_posix.h: Likewise.
	* sanitizer_common/sanitizer_stacktrace.cpp (GetCanonicFrame): Likewise.
	* tsan/tsan_rtl_ppc64.S: Likewise.
	* ubsan/ubsan_handlers.cpp (__ubsan::__ubsan_handle_cfi_bad_icall): Likewise.
	(__ubsan::__ubsan_handle_cfi_bad_icall_abort): Likewise.
	* ubsan/ubsan_handlers.h (struct CFIBadIcallData): Likewise.
	(struct CFICheckFailData): Likewise.
	(RECOVERABLE): Likewise.
	* ubsan/ubsan_platform.h: Likewise.

From-SVN: r277836

2019-11-05  Martin Liska  <mliska@suse.cz>

	* tsan/Makefile.am: Rename tsan_interceptors.cpp to
	tsan_interceptors_posix.
	* tsan/Makefile.in: Regenerate.

From-SVN: r277835

2019-11-05  Martin Liska  <mliska@suse.cz>

	* all source files: Merge from upstream r375507.

From-SVN: r277834

These tests check if loop peeling has been applied to avoid
having to vectorize unaligned loops.  On Z we do not have any
alignment requirements for vectorization so we also don't need want
the loop peeling here.

2019-11-05  Andreas Krebbel  <krebbel@linux.ibm.com>

	* gcc.dg/tree-ssa/gen-vect-26.c: Disable loop peeling check for
	IBM Z.
	* gcc.dg/tree-ssa/gen-vect-28.c: Likewise.

From-SVN: r277833

2019-11-05  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/92280
	* match.pd (BIT_FIELD_REF of CTOR): Unless the original CTOR
	had a single use do not create a new CTOR.
	* tree-ssa-forwprop.c (simplify_bitfield_ref): Do not re-fold
	BIT_FIELD_REF of a CTOR via GENERIC.

From-SVN: r277832

In the Z backend we still set min-vect-loop-bound to 2 to work around
corner cases where awkward epilogue code gets generated in the
vectorizer.  This has a particular bad impact when vectorizing loops
with a low iteration count.  Due to this we do not vectorize the loop
in gen-vect-11/32 - what actually is a pity.

The patch sets min-vect-loop-bound back to the default value of 0 in
order to enable vectorization.

2019-11-05  Andreas Krebbel  <krebbel@linux.ibm.com>

	* gcc.dg/tree-ssa/gen-vect-11.c: Add --param min-vect-loop-bound=0
	for IBM Z.
	* gcc.dg/tree-ssa/gen-vect-23.c: Likewise.

From-SVN: r277831

This fixes various issues with the useable_hw check in s390.exp.  The
check is supposed to verify whether a testcase can be run on the
current hardware.

- the test never returned true for -m31 because vzero is not available
  in ESA mode and -m31 defaults to -mesa
- the missing v0 clobber on the vzero instruction made the check fail
  if the stack pointer got saved in f0
- the lcbb instruction used for checking whether we are on a z13
  also requires vx.  Replace it with an instruction from the generic
  instruction set extensions.
- no support for z14 and z15 so far

gcc/testsuite/ChangeLog:

2019-11-05  Andreas Krebbel  <krebbel@linux.ibm.com>

	* gcc.target/s390/s390.exp
	(check_effective_target_s390_useable_hw): Add inline asm for z14
	and z15. Replace instruction for z13 with lochiz. Add register
	clobbers. Check also for __zarch__ when doing the __VX__ test.

From-SVN: r277830

This fixes an ICE in gcc.dg/attr-vector_size.c testcase.

gcc/ChangeLog:

2019-11-05  Andreas Krebbel  <krebbel@linux.ibm.com>

	* config/s390/s390.c (s390_vector_alignment): Check if the value
	fits into uhwi before using it.

From-SVN: r277829

All these tests fail when using -mpure-code:
* some force A or R profile
* some use Neon
* some use -fpic/-fPIC
all of which are not supported by this option.

2019-11-05  Christophe Lyon  <christophe.lyon@linaro.org>

	* gcc.target/arm/attr-crypto.c: Skip if -mpure-code is used.
	* gcc.target/arm/attr-neon-fp16.c: Likewise.
	* gcc.target/arm/combine-cmp-shift.c: Likewise.
	* gcc.target/arm/data-rel-1.c: Likewise.
	* gcc.target/arm/data-rel-2.c: Likewise.
	* gcc.target/arm/data-rel-3.c: Likewise.
	* gcc.target/arm/ftest-armv7a-arm.c: Likewise.
	* gcc.target/arm/ftest-armv7a-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv7r-arm.c: Likewise.
	* gcc.target/arm/ftest-armv7r-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv7ve-arm.c: Likewise.
	* gcc.target/arm/ftest-armv7ve-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv8a-arm.c: Likewise.
	* gcc.target/arm/ftest-armv8a-thumb.c: Likewise.
	* gcc.target/arm/lceil-vcvt_1.c: Likewise.
	* gcc.target/arm/lfloor-vcvt_1.c: Likewise.
	* gcc.target/arm/lround-vcvt_1.c: Likewise.
	* gcc.target/arm/memset-inline-10.c: Likewise.
	* gcc.target/arm/mod_2.c: Likewise.
	* gcc.target/arm/mod_256.c: Likewise.
	* gcc.target/arm/pr40657-1.c: Likewise.
	* gcc.target/arm/pr44788.c: Likewise.
	* gcc.target/arm/pr50305.c: Likewise.
	* gcc.target/arm/pr51835.c: Likewise.
	* gcc.target/arm/pr51915.c: Likewise.
	* gcc.target/arm/pr52006.c: Likewise.
	* gcc.target/arm/pr53187.c: Likewise.
	* gcc.target/arm/pr58784.c: Likewise.
	* gcc.target/arm/pr59575.c: Likewise.
	* gcc.target/arm/pr59923.c: Likewise.
	* gcc.target/arm/pr60650-2.c: Likewise.
	* gcc.target/arm/pr60657.c: Likewise.
	* gcc.target/arm/pr60663.c: Likewise.
	* gcc.target/arm/pr67439_1.c: Likewise.
	* gcc.target/arm/pr68620.c: Likewise.
	* gcc.target/arm/pr7676.c: Likewise.
	* gcc.target/arm/pr79239.c: Likewise.
	* gcc.target/arm/pr81863.c: Likewise.
	* gcc.target/arm/pragma_attribute.c: Likewise.
	* gcc.target/arm/pragma_cpp_fma.c: Likewise.
	* gcc.target/arm/require-pic-register-loc.c: Likewise.
	* gcc.target/arm/thumb-ltu.c: Likewise.
	* gcc.target/arm/thumb1-pic-high-reg.c: Likewise.
	* gcc.target/arm/thumb1-pic-single-base.c: Likewise.
	* gcc.target/arm/tlscall.c: Likewise.
	* gcc.target/arm/unsigned-float.c: Likewise.
	* gcc.target/arm/vrinta-ce.c: Likewise.

From-SVN: r277828

2019-11-05  Martin Liska  <mliska@suse.cz>

	* symbol-summary.h: Use ggc_delete.

From-SVN: r277827

Here is the one-liner that fixes the incorrect
vec_perm cost for thunderx2t99 chip.
With the patch applied 526.blender of CPU2017
gets ~5% improvement with no measurable changes
for other benchmarks.

2019-11-05  Anton Youdkevitch  <anton.youdkevitch@bell-sw.com>

	* config/aarch64/aarch64.c (thunderx2t99_vector_cost):
	Change vec_perm field to 10.

From-SVN: r277826

From-SVN: r277824

2019-11-05  Martin Liska  <mliska@suse.cz>

	* symbol-summary.h: Rename allocator to m_allocator and
	add comment.

From-SVN: r277823

2019-11-05  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/92324
	* tree-vect-loop.c (check_reduction_path): For MIN/MAX require
	all signed or unsigned operations.

	* gcc.dg/vect/pr92324-3.c: New testcase.

From-SVN: r277822

	* hsa-brig.c: Include alloc-pool.h
	* hsa-dump.c: Likewise.
	* hsa-gen.c: Likewise.
	* hse-regalloc.c: Likewise.
	* ipa-hsa.c: Likewise.
	* ipa-predicate.c: Likewise.
	* ipa-reference.c: Likewise.
	* ipa-sra.c: Likewise.
	* omp-expand.c: Likewise.
	* omp-general.c: Likewise.
	* omp-low.c: Likewise.
	* sumbol-summary.h (function_summary_base): Add allocator.
	(function_summary<T *>::function_summary): Update construction.
	(fast_function_summary<T *, V>::fast_function_summary): Likewise.
	(call_summary_base): Add allcator.
	(call_summary<T *>::call_summary): Update construction.
	(fast_call_summary<T *, V>::fast_call_summary): Likewise.

From-SVN: r277821

re PR tree-optimization/91945 (ICE: tree check: expected integer_cst, have var_decl in get_len, at tree.h:5837 since r274997)

	PR tree-optimization/91945
	* builtins.c (compute_objsize): For ARRAY_REF, only multiply off
	by tpsize if it is both non-NULL and INTEGER_CST, otherwise punt.
	Formatting fix.

	* gfortran.dg/pr91945.f90: New test.

From-SVN: r277820

	PR c++/92343
	* constexpr.c (potential_constant_expression_1): Return true rather
	than false for PREDICT_EXPR.

	* g++.dg/cpp2a/attr-likely6.C: New test.

From-SVN: r277819

Move vrp_set_zero_nonzero_bits from tree-vrp.c into vr-values.c, and make it use wi_set_zero_nonzero_bits.

Move vrp_set_zero_nonzero_bits from tree-vrp.c into vr-values.c, and
make it use wi_set_zero_nonzero_bits.  Remove the now redundant
wide_int_range_set_zero_nonzero_bits.

From-SVN: r277818

        gcc/
        * config/gcn/t-omp-device: New.
        Should have been part of Rev. 277797.

From-SVN: r277817

2019-11-05  Martin Liska  <mliska@suse.cz>

	PR c++/92339
	* fold-const.c (operand_compare::hash_operand): Remove
	FIELD_DECL handling.
2019-11-05  Martin Liska  <mliska@suse.cz>

	PR c++/92339
	* g++.dg/pr92339.C: New test.

From-SVN: r277816