This predicate is now used by aarch64 targets.

2020-04-29  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* calls.h (cxx17_empty_base_field_p): Turn into a function declaration.
	* calls.c (cxx17_empty_base_field_p): New function.  Check
	DECL_ARTIFICIAL and RECORD_OR_UNION_TYPE_P in addition to the
	previous checks.

Allow -fcf-protection with external thunk since the external thunk can be
made compatible with -fcf-protection.

gcc/

	PR target/93654
	* config/i386/i386-options.c (ix86_set_indirect_branch_type):
	Allow -fcf-protection with -mindirect-branch=thunk-extern and
	-mfunction-return=thunk-extern.
	* doc/invoke.texi: Update notes for -fcf-protection=branch with
	-mindirect-branch=thunk-extern and -mindirect-return=thunk-extern.

gcc/testsuite/

	PR target/93654
	* gcc.target/i386/pr93654.c: New test.

2020-04-29  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* doc/sourcebuild.texi: Add missing arm_arch_v8a_hard_ok anchor.

Essentially the same fix as for x86.

2020-04-29  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/arm/arm-builtins.c (arm_atomic_assign_expand_fenv): Use
	TARGET_EXPR instead of MODIFY_EXPR for the first assignments to
	fenv_var and new_fenv_var.

This patch makes the ABI code ignore zero-sized [[no_unique_address]]
fields when deciding whether something is a HFA or HVA.

For the tests, I wanted an -march setting that was stable enough
to use check-function-bodies and also wanted to force -mfloat-abi=hard.
I couldn't see any existing way of doing both together, since most
arm-related effective-target keywords are agnostic about the choice
between -mfloat-abi=softfp and -mfloat-abi=hard.  I therefore added
a new effective-target keyword for this combination.

I used the arm_arch_* framework for the effective-target rather than
writing a new set of custom Tcl routines.  This has the nice property
of separating the "compile and assemble" cases from the "link and run"
cases.  I only need compilation to work for the new tests, so requiring
linking to work would be an unnecessary restriction.

However, including an ABI requirement is arguably stretching what the
list was originally intended to handle.  The name arm_arch_v8a_hard
doesn't fit very naturally with some of the NEON-based tests.
On the other hand, the naming convention isn't entirely consistent,
so any choice would be inconsistent with something.

2020-04-29  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* doc/sourcebuild.texi (arm_arch_v8a_hard_ok): Document new
	effective-target keyword.
	(arm_arch_v8a_hard_multilib): Likewise.
	(arm_arch_v8a_hard): Document new dg-add-options keyword.
	* config/arm/arm.c (arm_return_in_memory): Note that the APCS
	code is deprecated and has not been updated to handle
	DECL_FIELD_ABI_IGNORED.
	(WARN_PSABI_EMPTY_CXX17_BASE): New constant.
	(WARN_PSABI_NO_UNIQUE_ADDRESS): Likewise.
	(aapcs_vfp_sub_candidate): Replace the boolean pointer parameter
	avoid_cxx17_empty_base with a pointer to a bitmask.  Ignore fields
	whose DECL_FIELD_ABI_IGNORED bit is set when determining whether
	something actually is a HFA or HVA.  Record whether we see a
	[[no_unique_address]] field that previous GCCs would not have
	ignored in this way.
	(aapcs_vfp_is_call_or_return_candidate): Update the calls to
	aapcs_vfp_sub_candidate and report a -Wpsabi warning for the
	[[no_unique_address]] case.  Use TYPE_MAIN_VARIANT in the
	diagnostic messages.
	(arm_needs_doubleword_align): Add a comment explaining why we
	consider even zero-sized fields.

gcc/testsuite/
	* lib/target-supports.exp: Add v8a_hard to the list of arm_arch_*
	targets.
	* g++.target/arm/no_unique_address_1.C: New test.
	* g++.target/arm/no_unique_address_2.C: Likewise.

This ICE appears because gcc will stream it to the function_body section
when processing the variable with the initial value of the constructor
type, and the error_mark_node to the decls section.
When recompiling, the value obtained with DECL_INITIAL will be error_mark.

2020-04-29  Richard Biener  <rguenther@suse.de>
	    Li Zekun  <lizekun1@huawei.com>

	PR lto/94822
	* tree.c (component_ref_size): Guard against error_mark_node
	DECL_INITIAL as it happens with LTO.

	* gcc.dg/lto/pr94822_0.c: New testcase.
	* gcc.dg/lto/pr94822_1.c: Alternate file.
	* gcc.dg/lto/pr94822.h: Likewise.

This patch makes the ABI code ignore zero-sized [[no_unique_address]]
fields when deciding whether something is a HFA or HVA.

As things stood, we'd get two sets of -Wpsabi warnings, one when
trying to decide whether something was an SVE function, and another
when actually processing the function definition or function call.
The patch therefore makes aapcs_vfp_sub_candidate honour the
CUMULATIVE_ARGS "silent_p" flag where applicable.

This doesn't stop all duplicate warnings for parameters, and I suspect
we'll get duplicate warnings for return values too, but it should be
better than nothing.

2020-04-29  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/aarch64/aarch64.c (aarch64_function_arg_alignment): Add a
	comment explaining why we consider even zero-sized fields.
	(WARN_PSABI_EMPTY_CXX17_BASE): New constant.
	(WARN_PSABI_NO_UNIQUE_ADDRESS): Likewise.
	(aapcs_vfp_sub_candidate): Replace the boolean pointer parameter
	avoid_cxx17_empty_base with a pointer to a bitmask.  Ignore fields
	whose DECL_FIELD_ABI_IGNORED bit is set when determining whether
	something actually is a HFA or HVA.  Record whether we see a
	[[no_unique_address]] field that previous GCCs would not have
	ignored in this way.
	(aarch64_vfp_is_call_or_return_candidate): Add a parameter to say
	whether diagnostics should be suppressed.  Update the calls to
	aapcs_vfp_sub_candidate and report a -Wpsabi warning for the
	[[no_unique_address]] case.
	(aarch64_return_in_msb): Update call accordingly, never silencing
	diagnostics.
	(aarch64_function_value): Likewise.
	(aarch64_return_in_memory_1): Likewise.
	(aarch64_init_cumulative_args): Likewise.
	(aarch64_gimplify_va_arg_expr): Likewise.
	(aarch64_pass_by_reference_1): Take a CUMULATIVE_ARGS pointer and
	use it to decide whether arch64_vfp_is_call_or_return_candidate
	should be silent.
	(aarch64_pass_by_reference): Update calls accordingly.
	(aarch64_vfp_is_call_candidate): Use the CUMULATIVE_ARGS argument
	to decide whether arch64_vfp_is_call_or_return_candidate should be
	silent.

gcc/testsuite/
	* g++.target/aarch64/no_unique_address_1.C: New test.
	* g++.target/aarch64/no_unique_address_2.C: Likewise.

mve.exp changed the default dg-do action to "assemble", but then
left it like that for later exp files.  This meant that in a
two-multilib test run, the first arm.exp run would have a default
of "dg-do compile" and the second would have a default of
"dg-do assemble".

2020-04-29  Richard Sandiford  <richard.sandiford@arm.com>

gcc/testsuite/
	* g++.target/arm/mve.exp: Restore the original dg-do-what-default
	before finishing.

A typo in the macro call meant that the #error always triggered.

libphobos/ChangeLog:

	* testsuite/lib/libphobos.exp (check_effective_target_linux_pre_2639):
	Fix KERNEL_VERSION condition.

Adds classKind information to the front-end AST, which in turn allows us
to fix code generation of type names for extern(C) and extern(C++)
structs and classes.  Inspecting such types inside a debugger now just
works without the need to 'cast(module_name.cxx_type)'.

gcc/d/ChangeLog:

	* d-codegen.cc (d_decl_context): Don't include module in the name of
	class and struct types that aren't extern(D).

This is a simple fix for pr94820.
The PR was only fixed on i386, the same error was also reported on aarch64.
This function, because it is sometimes called even outside of function bodies, uses create_tmp_var_raw rather than create_tmp_var.
But in order for that to work, when first referenced, the VAR_DECLs need to appear in a TARGET_EXPR so that during gimplification
the var gets the right DECL_CONTEXT and is added to local decls. Without that, e.g. tree-nested.c ICEs on those.

2020-04-29  Haijian Zhang  <z.zhanghaijian@huawei.com>

	PR target/94820
	* config/aarch64/aarch64-builtins.c
	(aarch64_atomic_assign_expand_fenv): Use TARGET_EXPR instead of
	MODIFY_EXPR for first assignment to fenv_cr, fenv_sr and
	new_fenv_var.

There's no point in using value '-3', and even though not directly related,
value '-1' does match 'GOMP_DEVICE_ICV'.

	libgomp/
	* config/accel/openacc.f90 (acc_device_current): Set to '-1'.
	* openacc.f90 (acc_device_current): Likewise.
	* openacc.h (acc_device_current): Likewise.
	* openacc_lib.h (acc_device_current): Likewise.

Fix-up for commit d228ee80 "re PR
bootstrap/92314 (missing omp-device-properties', needed by
's-omp-device-properties-h')".

	gcc/
	* configure.ac <$enable_offload_targets>: Do parsing as done
	elsewhere.
	* configure: Regenerate.

Fix-up for commit 955cd057 "Add
gcc/config/gcn/t-omp-device for OpenMP declare variant kind/arch/isa".

With AMD GCN offloading configured, I'm seeing occasional GCC build hangs.
I've now captured and analyzed one of them:

    $ ps -f
    UID        PID  PPID  C STIME TTY          TIME CMD
    [...]
    tschwing  5113  4508  0 20:24 pts/5    00:00:00 /bin/sh -c rm -f tmp-omp-device-properties.h; \ for kind in kind arch isa; do \   echo 'const char omp_offload_device_'${kind}'[] = ' \     >> tmp-omp-device-properties.h; \   for prop in no
    tschwing  5126  5113  0 20:24 pts/5    00:00:00 sed -n s/^kind: //p
    tschwing  5127  5113  0 20:24 pts/5    00:00:00 sed s/[[:blank:]]/ /g;s/  */ /g;s/^ //;s/ $//;s/ /\\0/g;s/^/"/;s/$/\\0\\0"/
    [...]
    $ pstree -p $$
    [...]---sh(5113)-+-sed(5126)
                     `-sed(5127)
    $ ls -lrt build-gcc/gcc/*omp-device*
    -rw-r--r-- 1 tschwing eeg  39 Apr 23 20:24 build-gcc/gcc/omp-device-properties-nvptx
    -rw-r--r-- 1 tschwing eeg 634 Apr 23 20:24 build-gcc/gcc/omp-device-properties-i386
    -rw-r--r-- 1 tschwing eeg  58 Apr 23 20:24 build-gcc/gcc/tmp-omp-device-properties.h

Notably missing is the 'omp-device-properties-gcn' file...

    $ grep ^ build-gcc/gcc/*omp-device*
    build-gcc/gcc/omp-device-properties-i386:kind: cpu
    build-gcc/gcc/omp-device-properties-i386:arch: x86 x86_64 i386 i486 i586 i686 ia32
    build-gcc/gcc/omp-device-properties-i386:isa: sse4 cx16 [...]
    build-gcc/gcc/omp-device-properties-nvptx:kind: gpu
    build-gcc/gcc/omp-device-properties-nvptx:arch: nvptx
    build-gcc/gcc/omp-device-properties-nvptx:isa: sm_30 sm_35
    build-gcc/gcc/tmp-omp-device-properties.h:const char omp_offload_device_kind[] =
    build-gcc/gcc/tmp-omp-device-properties.h:"amdgcn-amdhsa\0"

..., which we here seem to be intending to fill into
'tmp-omp-device-properties.h'.

    $ grep ^omp_device_properties\ = build-gcc/gcc/Makefile
    omp_device_properties =  amdgcn-amdhsa= nvptx-none=omp-device-properties-nvptx x86_64-intelmicemul-linux-gnu=omp-device-properties-i386

Given the 's-omp-device-properties-h' Makefile rule, indeed there is an
unescaped '$${props}', which is meant to be the filename following the equals
sign -- but there is none for 'amdgcn-amdhsa=', so this tries to read from
'stdin'!

The real problem of course is elsewhere.

	gcc/
	* configure.ac <$enable_offload_targets>: 'amdgcn' is 'gcn'.
	* configure: Regenerate.

... given that the GCN target did away with the constant 'vec_select'
restriction.

	gcc/
	PR target/94279
	* rtlanal.c (set_noop_p): Handle non-constant selectors.

In libgomp offloading testing, this resolves all the 'ld: error: undefined
symbol: __gxx_personality_v0' FAILs.

	gcc/
	PR target/94282
	* common/config/gcn/gcn-common.c (gcn_except_unwind_info): New
	function.
	(TARGET_EXCEPT_UNWIND_INFO): Define.
	libgomp/
	PR target/94282
	* testsuite/libgomp.c-c++-common/function-not-offloaded.c: Remove
	'dg-allow-blank-lines-in-output'.

Building (for offloading) a '--target=amdgcn-amdhsa' GCC with
'--enable-checking=yes,extra,rtl' fails:

    during RTL pass: split2
    [...]/source-gcc/libgcc/libgcc2.c: In function '__absvdi2':
    [...]/source-gcc/libgcc/libgcc2.c:271:1: internal compiler error: RTL check: expected code 'reg', have 'const_int' in rhs_regno, at rtl.h:1923
      271 | }
	  | ^
    0x565847 ???
	    [...]/source-gcc/gcc/rtl.c:881
    0x59a8a4 ???
	    [...]/source-gcc/gcc/rtl.h:1923
    0x12e3a5c ???
	    [...]/source-gcc/gcc/config/gcn/gcn.md:631
    [...]
    Makefile:501: recipe for target '_absvdi2.o' failed
    make[4]: *** [_absvdi2.o] Error 1
    make[4]: Leaving directory '[...]/build-gcc-offload-amdgcn-amdhsa/amdgcn-amdhsa/gfx900/libgcc'

	gcc/
	PR target/94248
	* config/gcn/gcn.md (*mov<mode>_insn): Use
	'reg_overlap_mentioned_p' to check for overlap.

Tested-by: Thomas Schwinge <thomas@codesourcery.com>

... which hasn't been ported/fails to build when using newlib (with GCC commit
b73f6902 sources, and newlib commit
6d79e0a58866548f435527798fbd4a6849d05bc7, tag: newlib-3.3.0 sources):

    In file included from [...]/build-gcc-offload-amdgcn-amdhsa/amdgcn-amdhsa/libstdc++-v3/include/csetjmp:42,
                     from [...]/source-gcc/libstdc++-v3/include/precompiled/stdc++.h:42:
    [...]/source-gcc/newlib/libc/include/setjmp.h:15:6: error: variable or field 'longjmp' declared void
       15 | void longjmp (jmp_buf __jmpb, int __retval)
          |      ^~~~~~~
    [...]
    Makefile:1824: recipe for target 'amdgcn-amdhsa/bits/stdc++.h.gch/O2ggnu++0x.gch' failed
    make[3]: *** [amdgcn-amdhsa/bits/stdc++.h.gch/O2ggnu++0x.gch] Error 1

	PR target/92713
	* configure.ac ["${ENABLE_LIBSTDCXX}" = "default" && amdgcn*-*-*]
	(noconfigdirs): Add 'target-libstdc++-v3'.
	* configure: Regenerate.

..., per OpenACC 3.0, A.1.2. "AMD GPU Targets".

This complements commit 6687d13a "Rename
acc_device_gcn to acc_device_radeon".

	libgomp/
	* oacc-init.c (get_openacc_name): Handle 'gcn'.
	* testsuite/lib/libgomp.exp
	(offload_target_to_openacc_device_type) [amdgcn*]: Return
	'radeon'.  Adjust all users.
	(check_effective_target_openacc_amdgcn_accel_present): Rename
	to...
	(check_effective_target_openacc_radeon_accel_present): ... this.
	Adjust all users.
	(check_effective_target_openacc_amdgcn_accel_selected): Rename to...
	(check_effective_target_openacc_radeon_accel_selected): ... this.
	Adjust all users.

Fix-up for commit a2c26c50 (r278046) "Fortran]
Support absent optional args with use_device_{ptr,addr}".

	libgomp/
	* testsuite/libgomp.fortran/use_device_ptr-optional-2.f90: Add
	'dg-do run'.

2020-04-29  Jakub Jelinek  <jakub@redhat.com>

	PR target/94706
	* config/ia64/ia64.c (hfa_element_mode): Use DECL_FIELD_ABI_IGNORED
	instead of cxx17_empty_base_field_p.

c++, middle-end, rs6000: Fix C++17 ABI incompatibilities during class layout and [[no_unique_address]] handling [PR94707]

As reported by Iain and David, powerpc-darwin and powerpc-aix* have C++14
vs. C++17 ABI incompatibilities which are not fixed by mere adding of
cxx17_empty_base_field_p calls.  Unlike the issues that were seen on other
targets where the artificial empty base field affected function argument
passing or returning of values, on these two targets the difference is
during class layout, not afterwards (e.g.
struct empty_base {};
struct S : public empty_base { unsigned long long l[2]; };
will have different __alignof__ (S) between C++14 and C++17 (or possibly
with double instead of unsigned long long too)).

I've tried:
struct X { };
struct Y { int : 0; };
struct Z { int : 0; Y y; };
struct U : public X { X q; };
struct A { float a, b, c, d; };
struct B : public X { float a, b, c, d; };
struct C : public Y { float a, b, c, d; };
struct D : public Z { float a, b, c, d; };
struct E : public U { float a, b, c, d; };
struct F { [[no_unique_address]] X x; float a, b, c, d; };
struct G { [[no_unique_address]] Y y; float a, b, c, d; };
struct H { [[no_unique_address]] Z z; float a, b, c, d; };
struct I { [[no_unique_address]] U u; float a, b, c, d; };
struct J { float a, b; [[no_unique_address]] X x; float c, d; };
struct K { float a, b; [[no_unique_address]] Y y; float c, d; };
struct L { float a, b; [[no_unique_address]] Z z; float c, d; };
struct M { float a, b; [[no_unique_address]] U u; float c, d; };
 #define T(S, s) extern S s; extern void foo##s (S); int bar##s () { foo##s (s); return 0; }
T (A, a)
T (B, b)
T (C, c)
T (D, d)
T (E, e)
T (F, f)
T (G, g)
T (H, h)
T (I, i)
T (J, j)
T (K, k)
T (L, l)
T (M, m)
testcase on powerpc64-linux.  Results:
G++ 9 -std=c++14                A, B, C passed in fprs, the rest in gprs
G++ 9 -std=c++17                A passed in fprs, the rest in gprs
current trunk -std=c++14 & 17   A, B, C passed in fprs, the rest in gprs
patched trunk -std=c++14 & 17   A, B, C, F, G, J, K passed in fprs, the rest in gprs
clang++ [*] -std=c++14 & 17     A, B, C, F, G, J, K passed in fprs, the rest in gprs
[*] clang version 11.0.0 (git@github.com:llvm/llvm-project.git 5c352e69e76a26e4eda075e20aa6a9bb7686042c)

Is that what we want?  I think it matches the stated intent of P0840R2 or
what Jason/Jonathan said, and doing something different like e.g. not
treating C, G and K as homogenous because of the int : 0 in empty bases
or in zero sized [[no_unique_address] fields would be quite hard to
implement (because for C++14 the FIELD_DECL just isn't there).

2020-04-29  Jakub Jelinek  <jakub@redhat.com>

	PR target/94707
	* tree-core.h (tree_decl_common): Note decl_flag_0 used for
	DECL_FIELD_ABI_IGNORED.
	* tree.h (DECL_FIELD_ABI_IGNORED): Define.
	* calls.h (cxx17_empty_base_field_p): Change into a temporary
	macro, check DECL_FIELD_ABI_IGNORED flag with no "no_unique_address"
	attribute.
	* calls.c (cxx17_empty_base_field_p): Remove.
	* tree-streamer-out.c (pack_ts_decl_common_value_fields): Handle
	DECL_FIELD_ABI_IGNORED.
	* tree-streamer-in.c (unpack_ts_decl_common_value_fields): Likewise.
	* lto-streamer-out.c (hash_tree): Likewise.
	* config/rs6000/rs6000-call.c (rs6000_aggregate_candidate): Rename
	cxx17_empty_base_seen to empty_base_seen, change type to int *,
	adjust recursive calls, use DECL_FIELD_ABI_IGNORED instead of
	cxx17_empty_base_field_p, if "no_unique_address" attribute is
	present, propagate that to the caller too.
	(rs6000_discover_homogeneous_aggregate): Adjust
	rs6000_aggregate_candidate caller, emit different diagnostics
	when c++17 empty base fields are present and when empty
	[[no_unique_address]] fields are present.
	* config/rs6000/rs6000.c (rs6000_special_round_type_align,
	darwin_rs6000_special_round_type_align): Skip DECL_FIELD_ABI_IGNORED
	fields.

	* class.c (build_base_field): Set DECL_FIELD_ABI_IGNORED on C++17 empty
	base artificial FIELD_DECLs.
	(layout_class_type): Set DECL_FIELD_ABI_IGNORED on empty class
	field_poverlapping_p FIELD_DECLs.

	* lto-common.c (compare_tree_sccs_1): Handle DECL_FIELD_ABI_IGNORED.

	* g++.target/powerpc/pr94707-1.C: New test.
	* g++.target/powerpc/pr94707-2.C: New test.
	* g++.target/powerpc/pr94707-3.C: New test.
	* g++.target/powerpc/pr94707-4.C: New test.
	* g++.target/powerpc/pr94707-5.C: New test.
	* g++.target/powerpc/pr94707-4.C: New test.

This fixes a regression when canonicalizing refs for LIM PR84362.
This possibly unshares and rewrites the refs in the internal data
and thus pointer equality no longer works in ref_always_accessed
computation.

2020-04-29  Richard Biener  <rguenther@suse.de>

	* tree-ssa-loop-im.c (ref_always_accessed::operator ()):
	Just check whether the stmt stores.

As observed in PR94719, an inherited constructor for an instantiation of
a constructor template confusingly has as its DECL_INHERITED_CTOR the
TEMPLATE_DECL of the constructor template rather than the particular
instantiation of the template.

This means two inherited constructors for two different instantiations
of the same constructor template have the same DECL_INHERITED_CTOR.  And
since in satisfy_declaration_constraints our decl satisfaction cache is
keyed off of the result of strip_inheriting_ctors, we may end up
conflating the satisfaction values of the two inherited constructors'
constraints.

This patch fixes this issue by using the original tree, not the result
of strip_inheriting_ctors, as the key to the decl satisfaction cache.

gcc/cp/ChangeLog:

	PR c++/94819
	* constraint.cc (satisfy_declaration_constraints): Use saved_t
	instead of t as the key to decl_satisfied_cache.

gcc/testsuite/ChangeLog:

	PR c++/94819
	* g++.dg/cpp2a/concepts-inherit-ctor10.C: New test.
	* g++.dg/cpp2a/concepts-inherit-ctor11.C: New test.

When printing the substituted parameter list of a requires-expression as
part of the "in requirements with ..." context line during concepts
diagnostics, we weren't considering that substitution into a parameter
pack can yield zero or multiple parameters.

This patch changes the way we print the parameter list of a
requires-expression in print_requires_expression_info.  We now print the
dependent form of the parameter list (along with its template parameter
mapping) instead of printing its substituted form.  Besides being an
improvement in its own, this also sidesteps the substitution issue in the
PR altogether.

gcc/cp/ChangeLog:

	PR c++/94808
	* error.c (print_requires_expression_info): Print the dependent
	form of the parameter list with its template parameter mapping,
	rather than printing the substituted form.

gcc/testsuite/ChangeLog:

	PR c++/94808
	* g++.dg/concepts/diagnostic12.C: New test.
	* g++.dg/concepts/diagnostic5.C: Adjust dg-message.

Remove the non-standard __cpp_lib_allocator_is_always_equal macro and
add the missing macros for P1032R1.

	PR libstdc++/91480
	* include/bits/allocator.h (__cpp_lib_allocator_is_always_equal):
	Remove non-standard macro.
	* include/bits/stl_iterator.h (__cpp_lib_constexpr_iterator): Define
	to indicate P1032R1 support.
	* include/bits/stl_pair.h (__cpp_lib_constexpr_utility): Likewise.
	* include/std/string_view (__cpp_lib_constexpr_string_view): Likewise.
	* include/std/tuple (__cpp_lib_constexpr_tuple): Likewise.
	* include/std/version (__cpp_lib_allocator_is_always_equal): Remove.
	(__cpp_lib_constexpr_iterator, __cpp_lib_constexpr_string_view)
	(__cpp_lib_constexpr_tuple, __cpp_lib_constexpr_utility): Define.
	* testsuite/20_util/function_objects/constexpr_searcher.cc: Check
	feature test macro.
	* testsuite/20_util/tuple/cons/constexpr_allocator_arg_t.cc: Likewise.
	* testsuite/21_strings/basic_string_view/operations/copy/char/
	constexpr.cc: Likewise.
	* testsuite/24_iterators/insert_iterator/constexpr.cc: Likewise.

By trying to reuse the existing std::_Construct function as a wrapper
for std::construct_at I introduced regressions, because changing
std::_Construct to return non-void made it ill-formed for array types.

The solution is to revert _Construct to its former state, and change
allocator_traits::construct to explicitly call construct_at instead.
This decouples all the existing callers of _Construct from the new
construct_at requirements.

	PR libstdc++/94831
	* include/bits/alloc_traits.h (_S_construct): Restore placement
	new-expression for C++11/14/17 and call std::construct_at directly
	for C++20.
	* include/bits/stl_construct.h (_Construct): Revert to non-constexpr
	function returning void.
	* testsuite/20_util/specialized_algorithms/
	uninitialized_value_construct/94831.cc: New test.
	* testsuite/23_containers/vector/cons/94831.cc: New test.

The emulation of mffsl with mffs, used when !TARGET_P9_MISC, is going
through the motions, but not storing the result in the given
operands[0]; it rather modifies operands[0] without effect.  It also
creates a DImode pseudo that it doesn't use, overwriting subregs
instead.

The patch below fixes all of these, the indentation and a typo.


I'm concerned about several issues in the mffsl testcase.  First, I
don't see that comparing the values as doubles rather than as long
longs is desirable.  These are FPSCR bitfields, not FP numbers.  I
understand mffs et al use double because they output to FP registers,
and the bit patterns are subnormal FP numbers, so it works, but given
the need for bit masking of at least one side, I'm changing the
compare to long longs.

Another issue with the test is that, if the compare fails, it calls
mffsl again to print the value, as if it would yield the same result.
But part of the FPSCR that mffsl (emulated with mffs or not) copies to
the output FP register is the FPCC, so the fcmpu used to compare the
result of the first mffsl will modify FPSCR and thus the result of the
second mffsl call.  After changing the compare, this is no longer the
case, but I still think it's better to make absolutely sure what we
print is what we compared.

Yet another issue is that the test assumed the mffs bits that are not
to be extracted by mffsl to be already zero, instead of masking them
out explicitly.  This is not about the mffs emulation in the mffsl
implementation, but about the mffs use in the test proper.  The bits
appear to be zero indeed, as the bits left out are for sticky
exceptions, but there are reserved parts of FPSCR that might turn out
to be set in the future, so we're better off masking them out
explicitly, otherwise those bits could cause the compare to fail.

If some future mffsl is changed so that it copies additional nonzero
bits, the test will fail, and then we'll have a chance to adjust it
and the emulation.


for  gcc/ChangeLog

	PR target/94812
	* gcc/config/rs6000/rs6000.md (rs6000_mffsl): Copy result to
	output operand in emulation.  Don't overwrite pseudos.

for  gcc/testsuite/ChangeLog

	PR target/94812
	* gcc.target/powerpc/test_mffsl.c: Call mffsl only once.
	Reinterpret the doubles as long longs for compares.  Mask out
	mffs bits that are not expected from mffsl.

This implements the proposed resolution of LWG 3433, which fixes
subrange::advance when called with a negative argument.

libstdc++-v3/ChangeLog:

	LWG 3433 subrange::advance(n) has UB when n < 0
	* include/std/ranges (subrange::prev): Fix typo.
	(subrange::advance): Handle a negative argument as per the proposed
	resolution of LWG 3433.
	* testsuite/std/ranges/subrange/lwg3433.cc: New test.

Fix some testsuite failures for H8/SX multilibs where short branches where used when long branches were necessary.

	* config/h8300/h8300.md (H8/SX mult patterns): All H8/SX specific
	multiply patterns are 4 bytes long.

Multilibs should not have been split up as two logically different CPU,
so at configure time, powerpc64 was being detected, but none of the
32-bit support files were being compiled in.

libphobos/ChangeLog:

	PR d/94825
	* configure: Regenerate.
	* libdruntime/Makefile.am (DRUNTIME_SOURCES_CONFIGURED): Add both
	switchcontext.S and callwithstack.S if DRUNTIME_CPU_POWERPC.
	* libdruntime/Makefile.in: Regenerate.
	* libdruntime/config/powerpc/switchcontext.S: Add !__PPC64__ guards.
	* libdruntime/config/powerpc64/callwithstack.S: Add __PPC64__ guards.
	* m4/druntime/cpu.m4 (DRUNTIME_CPU_SOURCES): Define DRUNTIME_CPU_POWER
	for all powerpc biarchs.  Remove DRUNTIME_CPU_POWER64 conditional.

My last patch rejected a namespace-scope declaration of the
implicitly-declared friend operator== before the class, but redeclaring it
after the class should be OK.

gcc/cp/ChangeLog
2020-04-28  Jason Merrill  <jason@redhat.com>

	PR c++/94583
	* decl.c (use_eh_spec_block): Check nothrow type after
	DECL_DEFAULTED_FN.
	* pt.c (maybe_instantiate_noexcept): Call synthesize_method for
	DECL_MAYBE_DELETED fns here.
	* decl2.c (mark_used): Not here.
	* method.c (get_defaulted_eh_spec): Reject DECL_MAYBE_DELETED here.

PR analyzer/94816 reports an ICE when attempting to copy a struct
containing a field for which add_region_for_type for fails (on
an OFFSET_TYPE): the region for the src field comes from
make_region_for_unexpected_tree_code which gives it a NULL type, and
then the copy calls add_region_for_type which unconditionally
dereferences the NULL type.

This patch fixes the ICE by checking for NULL types in
add_region_for_type.

gcc/analyzer/ChangeLog:
	PR analyzer/94816
	* engine.cc (impl_region_model_context::on_unexpected_tree_code):
	Handle NULL tree.
	* region-model.cc (region_model::add_region_for_type): Handle
	NULL type.
	* region-model.h
	(test_region_model_context::on_unexpected_tree_code): Handle NULL
	tree.

gcc/testsuite/ChangeLog:
	PR analyzer/94816
	* g++.dg/analyzer/pr94816.C: New test.

Turns out for consistency with LLVM the +nofp option shouldn't remove ALL of FP and MVE, just the FP part of MVE.
This requires more surgery with feature bits so for GCC 10 I'd rather just not support +nofp for -mcpu=cortex-m55
and implement it properly for GCC 11.

2020-04-28  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

	* config/arm/arm-cpus.in (cortex-m55): Remove +nofp option.
	* doc/invoke.texi (Arm Options): Remove -mcpu=cortex-m55 from +nofp option.

In C++14, an empty class deriving from an empty base is not an
aggregate, while in C++17 it is.  In order to implement this, GCC adds
an artificial field to such classes.

This artificial field has no mapping to Fundamental Data Types in the
Arm PCS ABI and hence should not count towards determining whether an
object can be passed using the vector registers as per section
"7.1.2 Procedure Calling" in the arm PCS
https://developer.arm.com/docs/ihi0042/latest?_ga=2.60211309.1506853196.1533541889-405231439.1528186050

This patch avoids counting this artificial field in
aapcs_vfp_sub_candidate, and hence calculates whether such objects
should be passed in vector registers in the same manner as C++14 (where
the artificial field does not exist).

Before this change, the test below would pass the arguments to `f` in
general registers.  After this change, the test passes the arguments to
`f` using the vector registers.

The new behaviour matches the behaviour of `armclang`, and also matches
the GCC behaviour when run with `-std=gnu++14`.

> gcc -std=gnu++17 -march=armv8-a+simd -mfloat-abi=hard test.cpp

``` test.cpp
struct base {};

struct pair : base
{
  float first;
  float second;
  pair (float f, float s) : first(f), second(s) {}
};

void f (pair);
int main()
{
  f({3.14, 666});
  return 1;
}
```

We add a `-Wpsabi` warning to catch cases where this fix has changed the ABI for
some functions.  Unfortunately this warning is not emitted twice for multiple
calls to the same function, but I feel this is not much of a problem and can be
fixed later if needs be.

(i.e. if `main` called `f` twice in a row we only emit a diagnostic for the
first).

Testing:
    Bootstrapped and regression tested on arm-linux.
    This change fixes the struct-layout-1 tests Jakub added
    https://gcc.gnu.org/pipermail/gcc-patches/2020-April/544204.html
    Regression tested on arm-none-eabi.

gcc/ChangeLog:

2020-04-28  Matthew Malcomson  <matthew.malcomson@arm.com>
	    Jakub Jelinek  <jakub@redhat.com>

	PR target/94711
	* config/arm/arm.c (aapcs_vfp_sub_candidate): Account for C++17 empty
	base class artificial fields.
	(aapcs_vfp_is_call_or_return_candidate): Warn when PCS ABI
	decision is different after this fix.

From what I can tell -Wanalyzer-use-of-uninitialized-value has not
yet found a true diagnostic in real-world code, and seems to be
particularly susceptible to false positives.  These relate to bugs in
the region_model code.

For GCC 10 it seems best to remove this warning, which this patch does.
Internally it also removes POISON_KIND_UNINIT.

I'm working on a rewrite of the region_model code for GCC 11 that I
hope will fix these issues, and allow this warning to be reintroduced.

gcc/analyzer/ChangeLog:
	PR analyzer/94447
	PR analyzer/94639
	PR analyzer/94732
	PR analyzer/94754
	* analyzer.opt (Wanalyzer-use-of-uninitialized-value): Delete.
	* program-state.cc (selftest::test_program_state_dumping): Update
	expected dump result for removal of "uninit".
	* region-model.cc (poison_kind_to_str): Delete POISON_KIND_UNINIT
	case.
	(root_region::ensure_stack_region): Initialize stack with null
	svalue_id rather than with a typeless POISON_KIND_UNINIT value.
	(root_region::ensure_heap_region): Likewise for the heap.
	(region_model::dump_summary_of_rep_path_vars): Remove
	summarization of uninit values.
	(region_model::validate): Remove check that the stack has a
	POISON_KIND_UNINIT value.
	(poisoned_value_diagnostic::emit): Remove POISON_KIND_UNINIT
	case.
	(poisoned_value_diagnostic::describe_final_event): Likewise.
	(selftest::test_dump): Update expected dump result for removal of
	"uninit".
	(selftest::test_svalue_equality): Remove "uninit" and "freed".
	* region-model.h (enum poison_kind): Remove POISON_KIND_UNINIT.

gcc/ChangeLog:
	PR analyzer/94447
	PR analyzer/94639
	PR analyzer/94732
	PR analyzer/94754
	* doc/invoke.texi (Static Analyzer Options): Remove
	-Wanalyzer-use-of-uninitialized-value.
	(-Wno-analyzer-use-of-uninitialized-value): Remove item.

gcc/testsuite/ChangeLog:
	PR analyzer/94447
	PR analyzer/94639
	PR analyzer/94732
	PR analyzer/94754
	* gcc.dg/analyzer/data-model-1.c: Mark "use of uninitialized
	value" warnings as xfail for now.
	* gcc.dg/analyzer/data-model-5b.c: Remove uninitialized warning.
	* gcc.dg/analyzer/pr94099.c: Mark "uninitialized" warning as xfail
	for now.
	* gcc.dg/analyzer/pr94447.c: New test.
	* gcc.dg/analyzer/pr94639.c: New test.
	* gcc.dg/analyzer/pr94732.c: New test.
	* gcc.dg/analyzer/pr94754.c: New test.
	* gcc.dg/analyzer/zlib-6.c: Mark "uninitialized" warning as xfail
	for now.

GCC_CET_HOST_FLAGS uses -Wl,-z,ibt,-z,shstk to check if Linux/x86 host
has Intel CET enabled by introducing an Intel CET violation on purpose.
To avoid false positive, check whether -Wl,-z,ibt,-z,shstk works first.
-fcf-protection=none is added to avoid false negative when -fcf-protection
is enabled by default.

config/

	PR bootstrap/94739
	* cet.m4 (GCC_CET_HOST_FLAGS): Add -fcf-protection=none to
	-Wl,-z,ibt,-z,shstk.  Check whether -fcf-protection=none
	-Wl,-z,ibt,-z,shstk works first.

libiberty/

	PR bootstrap/94739
	* configure: Regenerated.

lto-plugin/

	PR bootstrap/94739
	* configure: Regenerated.

On the following testcase, match.pd during GENERIC folding
changes the -1U / x < y into __imag__ .MUL_OVERFLOW (x, y),
but unfortunately unlike for normal calls nothing sets TREE_SIDE_EFFECTS on
the call.  There is the process_call_operands function that non-internal
call creation calls and it is usable for internal calls too,
e.g. TREE_SIDE_EFFECTS is derived from checking whether the
call has side-effects (non-ECF_{CONST,PURE}; we have those for internal
calls) and from whether any of the arguments has TREE_SIDE_EFFECTS.

2020-04-28  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/94809
	* tree.c (build_call_expr_internal_loc_array): Call
	process_call_operands.

	* gcc.c-torture/execute/pr94809.c: New test.