Mangling, currently only used on AArch64 for return address signing,
is an internal representation that should not be exposed via

  __builtin_return_address return value,
  __builtin_eh_return handler argument,
  _Unwind_DebugHook handler argument.

Note that a mangled address might not even fit into a void *, e.g.
with AArch64 ilp32 ABI the return address is stored as 64bit, so
the mangled return address cannot be accessed via _Unwind_GetPtr.

This patch changes the unwinder hooks as follows:

MD_POST_EXTRACT_ROOT_ADDR is removed: root address comes from
__builtin_return_address which is not mangled.

MD_POST_EXTRACT_FRAME_ADDR is renamed to MD_DEMANGLE_RETURN_ADDR,
it now operates on _Unwind_Word instead of void *, so the hook
should work when return address signing is enabled on AArch64 ilp32.
(But for that __builtin_aarch64_autia1716 should be fixed to operate
on 64bit input instead of a void *.)

MD_POST_FROB_EH_HANDLER_ADDR is removed: it is the responsibility of
__builtin_eh_return to do the mangling if necessary.

2020-07-13  Szabolcs Nagy  <szabolcs.nagy@arm.com>

libgcc/ChangeLog:

	PR target/94891
	* config/aarch64/aarch64-unwind.h (MD_POST_EXTRACT_ROOT_ADDR): Remove.
	(MD_POST_FROB_EH_HANDLER_ADDR): Remove.
	(MD_POST_EXTRACT_FRAME_ADDR): Rename to ...
	(MD_DEMANGLE_RETURN_ADDR): This.
	(aarch64_post_extract_frame_addr): Rename to ...
	(aarch64_demangle_return_addr): This.
	(aarch64_post_frob_eh_handler_addr): Remove.
	* unwind-dw2.c (uw_update_context): Demangle return address.
	(uw_frob_return_addr): Remove.

(cherry picked from commit b097c7a27fb0796b2653a1d003cbf6b7a69d8961)

Currently __builtin_eh_return takes a signed return address, which can
cause ABI and API issues: 1) pointer representation problems if the
address is passed around before eh return, 2) the source code needs
pac-ret specific changes and needs to know if pac-ret is used in the
current frame, 3) signed address may not be representible as void *
(with ilp32 abi).

Using address signing to protect eh return is ineffective because the
instruction sequence in the unwinder that starts from the address
signing and ends with a ret can be used as a return to anywhere gadget.
Using indirect branch istead of ret with bti j landing pads at the
target can reduce the potential of such gadget, which also implies
that __builtin_eh_return should not take a signed address.

This is a big hammer fix to the ABI and API issues: it turns pac-ret
off for the caller completely (not just on the eh return path).  To
harden the caller against ROP attacks, it should use indirect branch
instead of ret, this is not attempted so the patch remains small and
backportable.

2020-07-13  Szabolcs Nagy  <szabolcs.nagy@arm.com>

gcc/ChangeLog:

	PR target/94891
	* config/aarch64/aarch64.c (aarch64_return_address_signing_enabled):
	Disable return address signing if __builtin_eh_return is used.

gcc/testsuite/ChangeLog:

	PR target/94891
	* gcc.target/aarch64/return_address_sign_1.c: Update test.
	* gcc.target/aarch64/return_address_sign_b_1.c: Likewise.

(cherry picked from commit 2bc95be3bb8c8138e2e87c1c11c84bfede989d61)

This is a big hammer fix for __builtin_return_address (PR target/94891)
returning signed addresses (sometimes, depending on wether lr happens
to be signed or not at the time of call which depends on optimizations),
and similarly -pg may pass signed return address to _mcount
(PR target/94791).

At the time of return address expansion we don't know if it's signed or
not so it is done unconditionally.

2020-07-13  Szabolcs Nagy  <szabolcs.nagy@arm.com>

gcc/ChangeLog:

	PR target/94891
	PR target/94791
	* config/aarch64/aarch64-protos.h (aarch64_return_addr_rtx): Declare.
	* config/aarch64/aarch64.c (aarch64_return_addr_rtx): New.
	(aarch64_return_addr): Use aarch64_return_addr_rtx.
	* config/aarch64/aarch64.h (PROFILE_HOOK): Likewise.

(cherry picked from commit 463a54e5d4956143f81c1f23b91cbd2d93855741)

sjlj.S did not have the GNU property note markup and the BTI c
instructions that are necessary when it is built with branch
protection.

The notes are only added when libitm is built with branch
protection, because old linkers mishandle the note (merge
them incorrectly or emit warnings), the BTI instructions
are added unconditionally.

2020-07-09  Szabolcs Nagy  <szabolcs.nagy@arm.com>

libitm/ChangeLog:

	* config/aarch64/sjlj.S: Add BTI marking and related definitions,
	and add BTI c to function entries.

(cherry picked from commit 319078dad62eba942d33c8975bdcbb09d1c68ba6)

lse.S did not have the GNU property note markup and the BTI c
instructions that are necessary when it is built with branch
protection.

The notes are only added when libgcc is built with branch
protection, because old linkers mishandle the note (merge
them incorrectly or emit warnings), the BTI instructions
are added unconditionally.

Note: BTI c is only necessary at function entry if the function
may be called indirectly, currently lse functions are not called
indirectly, but BTI is added for ABI reasons e.g. to allow
linkers later to emit stub code with indirect jump.

2020-07-09  Szabolcs Nagy  <szabolcs.nagy@arm.com>

libgcc/ChangeLog:

	PR target/96001
	* config/aarch64/lse.S: Add BTI marking and related definitions,
	and add BTI c to function entries.

(cherry picked from commit f0f62fa0320762119446893c67cb52934bc5a05e)

lse.S did not have GNU stack note, this may cause missing
PT_GNU_STACK in binaries on Linux and FreeBSD.

2020-07-09  Szabolcs Nagy  <szabolcs.nagy@arm.com>

libgcc/ChangeLog:

	* config/aarch64/lse.S: Add stack note.

(cherry picked from commit e73ec755489afc9fcc75dfac6f06ac73e243e72a)

sjlj.S only had the note on Linux, but it is supposed
to have it on FreeBSD too.

2020-07-09  Szabolcs Nagy  <szabolcs.nagy@arm.com>

libitm/ChangeLog:

	* config/aarch64/sjlj.S: Add stack note if __FreeBSD__ is defined.

(cherry picked from commit 463ba375f7b857995068403a4c63690d03162c00)

Define the __ARM_FEATURE_BTI_DEFAULT feature test
macro when BTI branch protection is enabled.

2020-07-09  Szabolcs Nagy  <szabolcs.nagy@arm.com>

gcc/ChangeLog:

	* config/aarch64/aarch64-c.c (aarch64_update_cpp_builtins): Add
	__ARM_FEATURE_BTI_DEFAULT support.

(cherry picked from commit 63b6808e69699ba576492efa29d92b626cc26eba)

OpenACC 2.6 specifies that the array descriptor (when present) must be
copied to the target before attaching pointers in Fortran. This patch
reverses the stripping of GOMP_MAP_TO_PSET and GOMP_MAP_POINTER that
was introduced by the "OpenACC reference count overhaul" patch.

2020-07-10  Julian Brown  <julian@codesourcery.com>
	    Thomas Schwinge  <thomas@codesourcery.com>

gcc/
	* gimplify.c (gimplify_scan_omp_clauses): Do not strip
	GOMP_MAP_TO_PSET/GOMP_MAP_POINTER for OpenACC enter/exit data
	directives (see also PR92929).

gcc/testsuite/
	* gfortran.dg/goacc/finalize-1.f: Update expected dump output.

libgomp/
	* testsuite/libgomp.oacc-fortran/dynamic-pointer-1.f90: New test.

Co-Authored-By: Thomas Schwinge <thomas@codesourcery.com>
(cherry picked from commit b20097c65d2e74b1901fba1c55c77f0407e542d2)

This patch adjusts how dynamic reference counts work so that they match
the semantics of the source program more closely, instead of representing
"excess" reference counts beyond those that represent pointers in the
internal libgomp splay-tree data structure. This allows some corner
cases to be handled more gracefully.

2020-07-10  Julian Brown  <julian@codesourcery.com>
	    Thomas Schwinge  <thomas@codesourcery.com>

	libgomp/
	* libgomp.h (struct splay_tree_key_s): Change virtual_refcount to
	dynamic_refcount.
	(struct gomp_device_descr): Remove GOMP_MAP_VARS_OPENACC_ENTER_DATA.
	* oacc-mem.c (acc_map_data): Substitute virtual_refcount for
	dynamic_refcount.
	(acc_unmap_data): Update comment.
	(goacc_map_var_existing, goacc_enter_datum): Adjust for
	dynamic_refcount semantics.
	(goacc_exit_datum_1, goacc_exit_datum): Re-add some error checking.
	Adjust for dynamic_refcount semantics.
	(goacc_enter_data_internal): Implement "present" case of dynamic
	memory-map handling here.  Update "non-present" case for
	dynamic_refcount semantics.
	(goacc_exit_data_internal): Use goacc_exit_datum_1.
	* target.c (gomp_map_vars_internal): Remove
	GOMP_MAP_VARS_OPENACC_ENTER_DATA handling.  Update for dynamic_refcount
	handling.
	(gomp_unmap_vars_internal): Remove virtual_refcount handling.
	(gomp_load_image_to_device): Substitute dynamic_refcount for
	virtual_refcount.
	* testsuite/libgomp.oacc-c-c++-common/pr92843-1.c: Remove XFAILs.
	* testsuite/libgomp.oacc-c-c++-common/refcounting-1.c: New test.
	* testsuite/libgomp.oacc-c-c++-common/refcounting-2.c: New test.
	* testsuite/libgomp.oacc-c-c++-common/struct-3-1-1.c: New test.
	* testsuite/libgomp.oacc-fortran/deep-copy-6.f90: Remove XFAILs and
	trace output.
	* testsuite/libgomp.oacc-fortran/deep-copy-6-no_finalize.F90: Remove
	trace output.
	* testsuite/libgomp.oacc-fortran/dynamic-incr-structural-1.f90: New
	test.
	* testsuite/libgomp.oacc-c-c++-common/structured-dynamic-lifetimes-4.c:
	Remove stale comment.
	* testsuite/libgomp.oacc-fortran/mdc-refcount-1-1-1.f90: Remove XFAILs.
	* testsuite/libgomp.oacc-fortran/mdc-refcount-1-1-2.F90: Likewise.
	* testsuite/libgomp.oacc-fortran/mdc-refcount-1-2-1.f90: Likewise.
	* testsuite/libgomp.oacc-fortran/mdc-refcount-1-2-2.f90: Likewise.
	* testsuite/libgomp.oacc-fortran/mdc-refcount-1-3-1.f90: Likewise.
	* testsuite/libgomp.oacc-fortran/mdc-refcount-1-4-1.f90: Adjust XFAIL.

Co-Authored-By: Thomas Schwinge <thomas@codesourcery.com>
(cherry picked from commit 6f5b4b64d25a36f085ab90efc3d54c025a7fff49)

This patch factors out the parts of goacc_enter_datum and
goacc_exit_datum that can be shared with goacc_enter_data_internal
and goacc_exit_data_internal respectively (in the next patch),
without overloading function return values or complicating code paths
unnecessarily.

2020-07-10  Julian Brown  <julian@codesourcery.com>
	    Thomas Schwinge  <thomas@codesourcery.com>

libgomp/
	* oacc-mem.c (goacc_map_var_existing): New function.
	(goacc_enter_datum): Use above function.
	(goacc_exit_datum_1): New function.
	(goacc_exit_datum): Use above function.

Co-Authored-By: Thomas Schwinge <thomas@codesourcery.com>
(cherry picked from commit cb7effde6f36b43d50c8cd7f86eaa05937da7205)

This is a fix for the pointer (or array) size inadvertently being used
for the bias with attach and detach mapping kinds, for both C and C++.

2020-07-09  Julian Brown  <julian@codesourcery.com>
	    Thomas Schwinge  <thomas@codesourcery.com>

gcc/c/
	PR middle-end/95270
	* c-typeck.c (c_finish_omp_clauses): Set OMP_CLAUSE_SIZE (bias) to zero
	for standalone attach/detach clauses.

gcc/cp/
	PR middle-end/95270
	* semantics.c (finish_omp_clauses): Likewise.

include/
	PR middle-end/95270
	* gomp-constants.h (gomp_map_kind): Expand comment for attach/detach
	mapping kinds.

gcc/testsuite/
	PR middle-end/95270
	* c-c++-common/goacc/mdc-1.c: Update expected dump output for zero
	bias.

libgomp/
	PR middle-end/95270
	* testsuite/libgomp.oacc-c-c++-common/pr95270-1.c: New test.
	* testsuite/libgomp.oacc-c-c++-common/pr95270-2.c: New test.

(cherry picked from commit 0d00fe404c162ad0cf922ca8455aa23a74042b63)

Arrange for GOMP_MAP_ATTACH to be grouped together with a preceding
GOMP_MAP_TO_PSET or other "to" data movement clause, except in cases
where an explicit "attach" clause is used.

2020-07-09  Julian Brown  <julian@codesourcery.com>

include/
	* gomp-constants.h (gomp_map_kind): Update comment for GOMP_MAP_TO_PSET.

libgomp/
	* oacc-mem.c (find_group_last): Group data-movement clauses
	(GOMP_MAP_TO_PSET, GOMP_MAP_TO, etc.) together with a subsequent
	GOMP_MAP_ATTACH.  Allow standalone GOMP_MAP_ATTACH also.

(cherry picked from commit 8d2e5026d22b3f30e7df7adfd4ebf4ebc1e77e2d)

Fix a bug with mapping Fortran components which themselves have derived
types in the OpenACC 2.5+ manual deep-copy support.

2020-07-09  Julian Brown  <julian@codesourcery.com>

gcc/fortran/
	* trans-openmp.c (gfc_trans_omp_clauses): Use 'inner' not 'decl' for
	derived type members which themselves have derived types.

gcc/testsuite/
	* gfortran.dg/goacc/mapping-tests-3.f90: New test.
	* gfortran.dg/goacc/mapping-tests-4.f90: New test.

(cherry picked from commit ac8996edb14eef0a15cd0ce850fde2be5e227e69)

The following testcase ICEs since r10-3199.
There is a switch with default label, where the controlling expression has
range just 0..7 and there are case labels for all those 8 values, but
nothing has yet optimized away the default.
Since r10-3199, set_switch_stmt_execution_predicate sets the switch to
default label's edge's predicate to a false predicate and then
compute_bb_predicates propagates the predicates through the cfg, but false
predicates aren't really added.  The caller of compute_bb_predicates
in one place handles NULL bb->aux as false predicate:
      if (fbi.info)
	{
	  if (bb->aux)
	    bb_predicate = *(predicate *) bb->aux;
	  else
	    bb_predicate = false;
	}
      else
	bb_predicate = true;
but then in two further spots that the patch below is changing
it assumes bb->aux must be non-NULL.  Those two spots are guarded by a
condition that is only true if fbi.info is non-NULL, so I think the right
fix is to treat NULL aux as false predicate in those spots too.

2020-07-13  Jakub Jelinek  <jakub@redhat.com>

	PR ipa/96130
	* ipa-fnsummary.c (analyze_function_body): Treat NULL bb->aux
	as false predicate.

	* gcc.dg/torture/pr96130.c: New test.

(cherry picked from commit 776e48e0931db69f158f40e5cb8e15463d879a42)

Avoid printing informational notes when -Wmismatched-tags is suppressed in system headers (PR c++/96063)

Related:
PR c++/96063 - mismatched-tags warnings in stdlib headers

gcc/cp/ChangeLog:

	PR c++/96063
	* parser.c (class_decl_loc_t::diag_mismatched_tags): Print notes only
	if warning_at returns nonzero.

gcc/testsuite/ChangeLog:

	PR c++/96063
	* g++.dg/warn/Wmismatched-tags-7.C: New test.
	* g++.dg/warn/Wmismatched-tags-8.C: New test.

Here's an interesting issue: in this code a ) is missing:

  enum { E = (2 } e;

but we compile the code anyway, and E is set to 0 in build_enumerator,
which is sneaky.

The problem is that cp_parser_enum_specifier parses tentatively, because
when we see the enum keyword, we don't know yet if we'll find an
enum-specifier, opaque-enum-declaration, or elaborated-enum-specifier.

In this test when we call cp_parser_enumerator_list we're still parsing
tentatively, and as a consequence, parens.require_close (parser) in
cp_parser_primary_expression doesn't report any errors.  But we only go
on to parse the enumerator-list after we've seen a {, at which point we
might as well commit -- we know we're dealing with an enum-specifier.

gcc/cp/ChangeLog:

	PR c++/96077
	* parser.c (cp_parser_enum_specifier): Commit to tentative parse
	after we've seen an opening brace.

gcc/testsuite/ChangeLog:

	PR c++/96077
	* g++.dg/parse/enum14.C: New test.

(cherry picked from commit 4fd124a23664c712f1bb1a7e91fa23fe83d72c0b)

The testcase was errorneously accessing the global variable via a
type that might require bigger alignment than provided.  Fix that
via an appropriate attribute.

2020-07-13  Richard Biener  <rguenther@suse.de>

	PR testsuite/96180
	* gcc.dg/torture/pr96133.c: Align global variable.

(cherry picked from commit 7a4770f0394751860ee54520b23007938907ac33)

The store to the whole of each volatile object was picked apart
like there had been an individual assignment to each of the
fields.  Reads were added as part of that; see PR for details.
The reads from volatile memory were a clear bug; individual
stores questionable.  A separate patch clarifies the docs.

gcc:

2020-07-09  Richard Biener  <rguenther@suse.de>

	PR middle-end/94600
	* expr.c (expand_constructor): Make a temporary also if we're
	storing to volatile memory.

gcc/testsuite:

2020-07-09  Hans-Peter Nilsson  <hp@axis.com>

	PR middle-end/94600
	* gcc.dg/pr94600-1.c, gcc.dg/pr94600-2.c, gcc.dg/pr94600-3.c,
	gcc.dg/pr94600-4.c, gcc.dg/pr94600-5.c, gcc.dg/pr94600-6.c,
	gcc.dg/pr94600-7.c, gcc.dg/pr94600-8.c: New tests.

(cherry picked from commit a4aca1edaf37d43b2b7e9111825837a7a317b1b0)

The following testcase ICEs, because during the cfg cleanup, we see:
  switch (i$e_11) <default: <L12> [33.33%], case -3: <lab2> [33.33%], case 0: <L10> [33.33%], case 2: <lab2> [33.33%]>
...
lab2:
  __builtin_unreachable ();
where lab2 is FORCED_LABEL.  The way it works, we go through the case labels
and when we reach the first one that points to gimple_seq_unreachable*
basic block, we remove the edge (if any) from the switch bb to the bb
containing the label and bbs reachable only through that edge we've just
removed.  Once we do that, we must throw away all other cases that use
the same label (or some other labels from the same bb we've removed the edge
to and the bb).  To avoid quadratic behavior, this is not done by walking
all remaining cases immediately before removing, but only when processing
them later.
For normal labels this works, fine, if the label is in a deleted bb, it will
have NULL label_to_block and we handle that case, or, if the unreachable bb
has some other edge to it, only the edge will be removed and not the bb,
and again, find_edge will not find the edge and we only remove the case.
And if a label would be to some other block, that other block wouldn't have
been removed earlier because there would be still an edge from the switch
block.
Now, FORCED_LABEL (and I think DECL_NONLOCAL too) break this, because
those labels aren't removed, but instead moved to some surrounding basic
block.  So, when we later process those, when their gimple_seq_unreachable*
basic block is removed, label_to_block will return some unrelated block
(in the testcase the switch bb), so we decide to keep the case which doesn't
seem to be unreachable, but we don't really have an edge from the switch
block to the block the label got moved to.

I thought first about punting in gimple_seq_unreachable* on
FORCED_LABEL/DECL_NONLOCAL labels, but that might penalize even code that
doesn't care, so this instead just makes sure that for
FORCED_LABEL/DECL_NONLOCAL labels that are being removed (and thus moved
randomly) we remember in a hash_set the fact that those labels should be
treated as removed for the purpose of the optimization, and later on
handle those labels that way.

2020-07-02  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/95857
	* tree-cfg.c (group_case_labels_stmt): When removing an unreachable
	base_bb, remember all forced and non-local labels on it and later
	treat those as if they have NULL label_to_block.  Formatting fix.
	Fix a comment typo.

	* gcc.dg/pr95857.c: New test.

(cherry picked from commit 00f24f56732861d09a9716fa5b6b8a96c2289143)

gcc/ChangeLog:

	PR target/95581
	* config/rs6000/rs6000-call.c: Add new type v16qi_ftype_pcvoid.
	(altivec_init_builtins) Change __builtin_altivec_mask_for_load to use
	v16qi_ftype_pcvoid with correct number of parameters.

(cherry picked from commit c6b7ba5de624f2a17d799bac5ff017cd065ce035)

This patch adds execution tests that use the MMA builtins and
check for the right answer, and new tests that checks whether
__builtin_cpu_supports and __builtin_cpu_is return sane
answers for power10.

2020-06-30  Rajalakshmi Srinivasaraghavan  <rajis@linux.vnet.ibm.com>
	    Aaron Sawdey  <acsawdey@linux.ibm.com>

gcc/testsuite/
	* gcc.target/powerpc/p10-identify.c: New file.
	* gcc.target/powerpc/p10-arch31.c: New file.
	* gcc.target/powerpc/mma-single-test.c: New file.
	* gcc.target/powerpc/mma-double-test.c: New file.

(cherry picked from commit ed1d3639e42dccc9372f11c6231c3ffe0589fd1c)

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/241999

Make the costs such that they do not exaclty reflect
the actual instructions costs from the manual but make
the codegen emit the code we want it to.

gcc/ChangeLog:

	* config/aarch64/aarch64.c (thunderx2t99_regmove_cost,
	thunderx2t99_vector_cost): Likewise.

The code snippet for this test was returning 1 if power10
instructions executed correctly. It should return 0 if the
test passes.

	2020-07-07  Aaron Sawdey  <acsawdey@linux.ibm.com>

gcc/testsuite/
	* lib/target-supports.exp (check_power10_hw_available):
	Return 0 for passing test.

(cherry picked from commit 7126583af5d29235584b51b3b05eeaba2adef024)

Built-in initialization occurs only once and fairly early, when the
command line options are in force.  If the -mcpu=<CPU> is pre-power10,
then we fail to initialize the MMA built-ins, so they are not
available to call in a #pragma target/attribute target function.
The fix is to basically always (on server type cpus) initialize the MMA
built-ins so we can use them in #pragma target/attribute target functions.

2020-07-09  Peter Bergner  <bergner@linux.ibm.com>

gcc/
	PR target/96125
	* config/rs6000/rs6000-call.c (rs6000_init_builtins): Define the MMA
	specific types __vector_quad and __vector_pair, and initialize the
	MMA built-ins if TARGET_EXTRA_BUILTINS is set.
	(mma_init_builtins): Don't test for mask set in rs6000_builtin_mask.
	Remove now unneeded mask variable.
	* config/rs6000/rs6000.c (rs6000_option_override_internal): Add the
	OPTION_MASK_MMA flag for power10 if not already set.

gcc/testsuite/
	PR target/96125
	* gcc.target/powerpc/pr96125.c: New test.

(cherry picked from commit fd263be4b523ff1b7f7dda49d856cc57221e8d21)

gcc/ChangeLog:

2020-07-08  Will Schmidt  <will_schmidt@vnet.ibm.com>

	* config/rs6000/altivec.h (vec_vmsumudm): New define.
	* config/rs6000/altivec.md (UNSPEC_VMSUMUDM): New unspec.
	  (altivec_vmsumudm): New define_insn.
	* config/rs6000/rs6000-builtin.def (altivec_vmsumudm): New BU_ALTIVEC_3
	  entry. (vmsumudm): New BU_ALTIVEC_OVERLOAD_3 entry.
	* config/rs6000/rs6000-call.c (altivec_overloaded_builtins): Add entries for
	  ALTIVEC_BUILTIN_VMSUMUDM variants of vec_msum.
	* doc/extend.texi: Add document for vmsumudm behind vmsum.

gcc/testsuite/ChangeLog:

2020-07-08  Will Schmidt  <will_schmidt@vnet.ibm.com>

	* gcc.target/powerpc/builtins-msum-runnable.c: New test.
	* gcc.target/powerpc/vsx-builtin-msum.c: New test.

(cherry picked from commit c1a57681a64150d2fc336ba8e055c5f82e3737e8)

We were wrongly checking is_empty_class on the result of strip_array_types
rather than the actual field type.  We weren't considering the alignment of
the data member.  We needed to handle unions the same way as
layout_nonempty_base_or_field.

gcc/cp/ChangeLog:

	PR c++/96105
	PR c++/96052
	PR c++/95976
	* class.c (check_field_decls): An array of empty classes is not an
	empty data member.
	(layout_empty_base_or_field): Handle explicit alignment.
	Fix union handling.

gcc/testsuite/ChangeLog:

	PR c++/96105
	PR c++/96052
	PR c++/95976
	* g++.dg/cpp2a/no_unique_address4.C: New test.
	* g++.dg/cpp2a/no_unique_address5.C: New test.
	* g++.dg/cpp2a/no_unique_address6.C: New test.

This fixes the case where we try to fold a read from an
array initalizer and happen to cross the boundary of
multiple CTORs which isn't really supported.  For the
interesting cases like the testcase we actually handle
the folding by encoding the whole initializer.

2020-07-10  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/96133
	* gimple-fold.c (fold_array_ctor_reference): Do not
	recurse to folding a CTOR that does not fully cover the
	asked for object.

	* gcc.dg/torture/pr96133.c: New testcase.

(cherry picked from commit 6e41c27bf549d957eb399d39d7d0c213f8733351)

If reduction partition's SCC is broken by runtime alias checks, force
a negative post order to it so that it will be scheduled in the last.

2020-07-09  Bin Cheng  <bin.cheng@linux.alibaba.com>

gcc/
	PR tree-optimization/95804
	* tree-loop-distribution.c (break_alias_scc_partitions): Force
	negative post order to reduction partition.

gcc/testsuite/
	PR tree-optimization/95804
	* gcc.dg/tree-ssa/pr95804.c: New test.

(cherry picked from commit dd21b03900085c4d60bf03207ad28bcbfbc86a4b)

gcc/
	PR tree-optimization/95638
	* tree-loop-distribution.c (pg_edge_callback_data): New field.
	(loop_distribution::break_alias_scc_partitions): Record and restore
	postorder information.  Fix memory leak.

gcc/testsuite/
	PR tree-optimization/95638
	* g++.dg/tree-ssa/pr95638.C: New test.

(cherry picked from commit 2c0069fafb53ccb7a45a6815025dfcbd2882a36e)

libstdc++-v3/ChangeLog:

	* include/bits/unique_ptr.h (operator<<): Define for C++20.
	* testsuite/20_util/unique_ptr/io/lwg2948.cc: New test.
	* testsuite/20_util/default_delete/48631_neg.cc: Adjust dg-error
	line number.
	* testsuite/20_util/default_delete/void_neg.cc: Likewise.

(cherry picked from commit 187da2ce31f13b2f75d5bb780e30ee364ead9d1d)

The bug report is that transform_view's sentinel<false> cannot be
compared to its iterator<true>.  The comparison is supposed to use
operator==(iterator<Const>, sentinel<Const>) after converting
sentinel<false> to sentinel<true>. However, the operator== is a hidden
friend so is not a candidate when comparing iterator<true> with
sentinel<false>. The required conversion would only happen if we'd found
the operator, but we can't find the operator until after the conversion
happens.

A new LWG issue has been reported, but not yet assigned a number.  The
solution suggested by Casey Carter is to make the hidden friends of the
sentinel types work with iterators of any const-ness, so that no
conversions are required.

Patrick Palka observed that join_view has a similar problem and a
similar fix is used for its sentinel.

	PR libstdc++/95322
	* include/std/ranges (transform_view::_Sentinel): Allow hidden
	friends to work with _Iterator<true> and _Iterator<false>.
	(join_view::_Sentinel): Likewise.
	* testsuite/std/ranges/adaptors/95322.cc: New test.

(cherry picked from commit 6c2582c0406250c66e2eb3651f8e8638796b7f53)

I implicitly assumed that programs using pmr::synchronized_pool_resource
would also be using multiple threads, and so the weak symbols in
gthr-posix.h would be resolved by linking to libpthread. If that isn't
true then it crashes when trying to use pthread_key_create.

This commit makes the pool resource check __gthread_active_p() before
using thread-specific data, and just use a single set of memory pools
when there's only a single thread.

	PR libstdc++/94936
	* src/c++17/memory_resource.cc (synchronized_pool_resource::_TPools):
	Add comment about single-threaded behaviour.
	(synchronized_pool_resource::_TPools::move_nonempty_chunks()): Hoist
	class member access out of loop.
	(synchronized_pool_resource::synchronized_pool_resource())
	(synchronized_pool_resource::~synchronized_pool_resource())
	(synchronized_pool_resource::release()): Check __gthread_active_p
	before creating and/or deleting the thread-specific data key.
	(synchronized_pool_resource::_M_thread_specific_pools()): Adjust
	assertions.
	(synchronized_pool_resource::do_allocate(size_t, size_t)): Add fast
	path for single-threaded case.
	(synchronized_pool_resource::do_deallocate(void*, size_t, size_t)):
	Likewise. Return if unable to find a pool that owns the allocation.
	* testsuite/20_util/synchronized_pool_resource/allocate_single.cc:
	New test.
	* testsuite/20_util/synchronized_pool_resource/cons_single.cc: New
	test.
	* testsuite/20_util/synchronized_pool_resource/release_single.cc: New
	test.

(cherry picked from commit ec40967f1323069da3a5a45286f71fa4f80926df)

It's not difficult for multiple threads to drain the entropy available
to the RDSEED instruction, at which point we throw an exception. This
change will try to use RDRAND after RDSEED fails repeatedly, and only
throw if RDRAND also fails repeatedly. This doesn't guarantee a random
value can always be read, but reduces the likelihood of failure when
using the RDSEED instruction.

	PR libstdc++/94087
	* src/c++11/random.cc (__x86_rdseed): Allow fallback function to be
	passed in.
	(__x86_rdseed_rdrand): New function that uses rdseed with rdrand
	fallback.
	(random_device::_M_init): Use __x86_rdseed_rdrand when both
	instructions are available.
	* testsuite/26_numerics/random/random_device/94087.cc: New test.

(cherry picked from commit a2d196e75cef95c2b70734ad02e94f9da0e769fe)

 - This optimization will adjust stack, but it not check/update other
   stack pointer use-site, the example is when the arguments put on
   stack, the offset become wrong after optimization.

 - However adjust stack frame usage after register allocation could be
   error prone, so we decide to turn off this optimization for such case.

 - Ye-Ting Kuo report this issue on github:
   https://github.com/riscv/riscv-gcc/pull/192

gcc/ChangeLog:

	* config/riscv/riscv-sr.c (riscv_remove_unneeded_save_restore_calls):
	Abort if any arguments on stack.

gcc/testsuite/ChangeLog

	* gcc.target/riscv/save-restore-9.c: New.

(cherry picked from commit 4c0d1322033ce979532425d336530b217f6b5fd3)