C++20 coroutines introduces a new operator with a mangling of 'aw'.
This patch adds that to libiberty's demangler.

libiberty/ChangeLog:

2020-01-18  Iain Sandoe  <iain@sandoe.co.uk>

	* cp-demangle.c (cplus_demangle_operators): Add the co_await
	operator.
	* testsuite/demangle-expected: Test co_await operator mangling.

This is the squashed version of the first 6 patches that were split to
facilitate review.

The changes to libiberty (7th patch) to support demangling the co_await
operator stand alone and are applied separately.

The patch series is an initial implementation of a coroutine feature,
expected to be standardised in C++20.

Standardisation status (and potential impact on this implementation)
--------------------------------------------------------------------

The facility was accepted into the working draft for C++20 by WG21 in
February 2019.  During following WG21 meetings, design and national body
comments have been reviewed, with no significant change resulting.

The current GCC implementation is against n4835 [1].

At this stage, the remaining potential for change comes from:

* Areas of national body comments that were not resolved in the version we
  have worked to:
  (a) handling of the situation where aligned allocation is available.
  (b) handling of the situation where a user wants coroutines, but does not
      want exceptions (e.g. a GPU).

* Agreed changes that have not yet been worded in a draft standard that we
  have worked to.

It is not expected that the resolution to these can produce any major
change at this phase of the standardisation process.  Such changes should be
limited to the coroutine-specific code.

ABI
---

The various compiler developers 'vendors' have discussed a minimal ABI to
allow one implementation to call coroutines compiled by another.

This amounts to:

1. The layout of a public portion of the coroutine frame.

 Coroutines need to preserve state across suspension points, the storage for
 this is called a "coroutine frame".

 The ABI mandates that pointers into the coroutine frame point to an area
 begining with two function pointers (to the resume and destroy functions
 described below); these are immediately followed by the "promise object"
 described in the standard.

 This is sufficient that the builtins can take a coroutine frame pointer and
 determine the address of the promise (or call the resume/destroy functions).

2. A number of compiler builtins that the standard library might use.

  These are implemented by this patch series.

3. This introduces a new operator 'co_await' the mangling for which is also
agreed between vendors (and has an issue filed for that against the upstream
c++abi).  Demangling for this is added to libiberty in a separate patch.

The ABI has currently no target-specific content (a given psABI might elect
to mandate alignment, but the common ABI does not do this).

Standard Library impact
-----------------------

The current implementations require addition of only a single header to
the standard library (no change to the runtime).  This header is part of
the patch.

GCC Implementation outline
--------------------------

The standard's design for coroutines does not decorate the definition of
a coroutine in any way, so that a function is only known to be a coroutine
when one of the keywords (co_await, co_yield, co_return) is encountered.

This means that we cannot special-case such functions from the outset, but
must process them differently when they are finalised - which we do from
"finish_function ()".

At a high level, this design of coroutine produces four pieces from the
original user's function:

  1. A coroutine state frame (taking the logical place of the activation
     record for a regular function).  One item stored in that state is the
     index of the current suspend point.
  2. A "ramp" function
     This is what the user calls to construct the coroutine frame and start
     the coroutine execution.  This will return some object representing the
     coroutine's eventual return value (or means to continue it when it it
     suspended).
  3. A "resume" function.
     This is what gets called when a the coroutine is resumed when suspended.
  4. A "destroy" function.
     This is what gets called when the coroutine state should be destroyed
     and its memory released.

The standard's coroutines involve cooperation of the user's authored function
with a provided "promise" class, which includes mandatory methods for
handling the state transitions and providing output values.  Most realistic
coroutines will also have one or more 'awaiter' classes that implement the
user's actions for each suspend point.  As we parse (or during template
expansion) the types of the promise and awaiter classes become known, and can
then be verified against the signatures expected by the standard.

Once the function is parsed (and templates expanded) we are able to make the
transformation into the four pieces noted above.

The implementation here takes the approach of a series of AST transforms.
The state machine suspend points are encoded in three internal functions
(one of which represents an exit from scope without cleanups).  These three
IFNs are lowered early in the middle end, such that the majority of GCC's
optimisers can be run on the resulting output.

As a design choice, we have carried out the outlining of the user's function
in the front end, and taken advantage of the existing middle end's abilities
to inline and DCE where that is profitable.

Since the state machine is actually common to both resumer and destroyer
functions, we make only a single function "actor" that contains both the
resume and destroy paths.  The destroy function is represented by a small
stub that sets a value to signal the use of the destroy path and calls the
actor.  The idea is that optimisation of the state machine need only be done
once - and then the resume and destroy paths can be identified allowing the
middle end's inline and DCE machinery to optimise as profitable as noted
above.

The middle end components for this implementation are:

A pass that:
 1. Lowers the coroutine builtins that allow the standard library header to
    interact with the coroutine frame (these fairly simple logical or
    numerical substitution of values, given a coroutine frame pointer).
 2. Lowers the IFN that represents the exit from state without cleanup.
    Essentially, this becomes a gimple goto.
 3. Sets the final size of the coroutine frame at this stage.

A second pass (that requires the revised CFG that results from the lowering
of the scope exit IFNs in the first).

 1. Lower the IFNs that represent the state machine paths for the resume and
    destroy cases.

Patches squashed into this commit:

[C++ coroutines 1] Common code and base definitions.

This part of the patch series provides the gating flag, the keywords,
cpp defines etc.

[C++ coroutines 2] Define builtins and internal functions.

This part of the patch series provides the builtin functions
used by the standard library code and the internal functions
used to implement lowering of the coroutine state machine.

[C++ coroutines 3] Front end parsing and transforms.

There are two parts to this.

1. Parsing, template instantiation and diagnostics for the standard-
   mandated class entries.

  The user authors a function that becomes a coroutine (lazily) by
  making use of any of the co_await, co_yield or co_return keywords.

  Unlike a regular function, where the activation record is placed on the
  stack, and is destroyed on function exit, a coroutine has some state that
  persists between calls - the 'coroutine frame' (thus analogous to a stack
  frame).

  We transform the user's function into three pieces:
  1. A so-called ramp function, that establishes the coroutine frame and
     begins execution of the coroutine.
  2. An actor function that contains the state machine corresponding to the
     user's suspend/resume structure.
  3. A stub function that calls the actor function in 'destroy' mode.

  The actor function is executed:
   * from "resume point 0" by the ramp.
   * from resume point N ( > 0 ) for handle.resume() calls.
   * from the destroy stub for destroy point N for handle.destroy() calls.

  The C++ coroutine design described in the standard makes use of some helper
  methods that are authored in a so-called "promise" class provided by the
  user.

  At parse time (or post substitution) the type of the coroutine promise
  will be determined.  At that point, we can look up the required promise
  class methods and issue diagnostics if they are missing or incorrect.  To
  avoid repeating these actions at code-gen time, we make use of temporary
  'proxy' variables for the coroutine handle and the promise - which will
  eventually be instantiated in the coroutine frame.

  Each of the keywords will expand to a code sequence (although co_yield is
  just syntactic sugar for a co_await).

  We defer the analysis and transformatin until template expansion is
  complete so that we have complete types at that time.

2. AST analysis and transformation which performs the code-gen for the
   outlined state machine.

   The entry point here is morph_fn_to_coro () which is called from
   finish_function () when we have completed any template expansion.

   This is preceded by helper functions that implement the phases below.

   The process proceeds in four phases.

   A Initial framing.
     The user's function body is wrapped in the initial and final suspend
     points and we begin building the coroutine frame.
     We build empty decls for the actor and destroyer functions at this
     time too.
     When exceptions are enabled, the user's function body will also be
     wrapped in a try-catch block with the catch invoking the promise
     class 'unhandled_exception' method.

   B Analysis.
     The user's function body is analysed to determine the suspend points,
     if any, and to capture local variables that might persist across such
     suspensions.  In most cases, it is not necessary to capture compiler
     temporaries, since the tree-lowering nests the suspensions correctly.
     However, in the case of a captured reference, there is a lifetime
     extension to the end of the full expression - which can mean across a
     suspend point in which case it must be promoted to a frame variable.

     At the conclusion of analysis, we have a conservative frame layout and
     maps of the local variables to their frame entry points.

   C Build the ramp function.
     Carry out the allocation for the coroutine frame (NOTE; the actual size
     computation is deferred until late in the middle end to allow for future
     optimisations that will be allowed to elide unused frame entries).
     We build the return object.

   D Build and expand the actor and destroyer function bodies.
     The destroyer is a trivial shim that sets a bit to indicate that the
     destroy dispatcher should be used and then calls into the actor.

     The actor function is the implementation of the user's state machine.
     The current suspend point is noted in an index.
     Each suspend point is encoded as a pair of internal functions, one in
     the relevant dispatcher, and one representing the suspend point.

     During this process, the user's local variables and the proxies for the
     self-handle and the promise class instanceare re-written to their
     coroutine frame equivalents.

     The complete bodies for the ramp, actor and destroy function are passed
     back to finish_function for folding and gimplification.

[C++ coroutines 4] Middle end expanders and transforms.

The first part of this is a pass that provides:
 * expansion of the library support builtins, these are simple boolean
   or numerical substitutions.

 * The functionality of implementing an exit from scope without cleanup
   is performed here by lowering an IFN to a gimple goto.

This pass has to run for non-coroutine functions, since functions calling
the builtins are not necessarily coroutines (i.e. they are implementing the
library interfaces which may be called from anywhere).

The second part is the expansion of the coroutine IFNs that describe the
state machine connections to the dispatchers.  This only has to be run
for functions that are coroutine components.  The work done by this pass
is:

   In the front end we construct a single actor function that contains
   the coroutine state machine.

   The actor function has three entry conditions:
    1. from the ramp, resume point 0 - to initial-suspend.
    2. when resume () is executed (resume point N).
    3. from the destroy () shim when that is executed.

   The actor function begins with two dispatchers; one for resume and
   one for destroy (where the initial entry from the ramp is a special-
   case of resume point 0).

   Each suspend point and each dispatch entry is marked with an IFN such
   that we can connect the relevant dispatchers to their target labels.

   So, if we have:

   CO_YIELD (NUM, FINAL, RES_LAB, DEST_LAB, FRAME_PTR)

   This is await point NUM, and is the final await if FINAL is non-zero.
   The resume point is RES_LAB, and the destroy point is DEST_LAB.

   We expect to find a CO_ACTOR (NUM) in the resume dispatcher and a
   CO_ACTOR (NUM+1) in the destroy dispatcher.

   Initially, the intent of keeping the resume and destroy paths together
   is that the conditionals controlling them are identical, and thus there
   would be duplication of any optimisation of those paths if the split
   were earlier.

   Subsequent inlining of the actor (and DCE) is then able to extract the
   resume and destroy paths as separate functions if that is found
   profitable by the optimisers.

   Once we have remade the connections to their correct postions, we elide
   the labels that the front end inserted.

[C++ coroutines 5] Standard library header.

This provides the interfaces mandated by the standard and implements
the interaction with the coroutine frame by means of inline use of
builtins expanded at compile-time.  There should be a 1:1 correspondence
with the standard sections which are cross-referenced.

There is no runtime content.

At this stage, we have the content in an inline namespace "__n4835" for
the CD we worked to.

[C++ coroutines 6] Testsuite.

There are two categories of test:

1. Checks for correctly formed source code and the error reporting.
2. Checks for transformation and code-gen.

The second set are run as 'torture' tests for the standard options
set, including LTO.  These are also intentionally run with no options
provided (from the coroutines.exp script).

gcc/ChangeLog:

2020-01-18  Iain Sandoe  <iain@sandoe.co.uk>

	* Makefile.in: Add coroutine-passes.o.
	* builtin-types.def (BT_CONST_SIZE): New.
	(BT_FN_BOOL_PTR): New.
	(BT_FN_PTR_PTR_CONST_SIZE_BOOL): New.
	* builtins.def (DEF_COROUTINE_BUILTIN): New.
	* coroutine-builtins.def: New file.
	* coroutine-passes.cc: New file.
	* function.h (struct GTY function): Add a bit to indicate that the
	function is a coroutine component.
	* internal-fn.c (expand_CO_FRAME): New.
	(expand_CO_YIELD): New.
	(expand_CO_SUSPN): New.
	(expand_CO_ACTOR): New.
	* internal-fn.def (CO_ACTOR): New.
	(CO_YIELD): New.
	(CO_SUSPN): New.
	(CO_FRAME): New.
	* passes.def: Add pass_coroutine_lower_builtins,
	pass_coroutine_early_expand_ifns.
	* tree-pass.h (make_pass_coroutine_lower_builtins): New.
	(make_pass_coroutine_early_expand_ifns): New.
	* doc/invoke.texi: Document the fcoroutines command line
	switch.

gcc/c-family/ChangeLog:

2020-01-18  Iain Sandoe  <iain@sandoe.co.uk>

	* c-common.c (co_await, co_yield, co_return): New.
	* c-common.h (RID_CO_AWAIT, RID_CO_YIELD,
	RID_CO_RETURN): New enumeration values.
	(D_CXX_COROUTINES): Bit to identify coroutines are active.
	(D_CXX_COROUTINES_FLAGS): Guard for coroutine keywords.
	* c-cppbuiltin.c (__cpp_coroutines): New cpp define.
	* c.opt (fcoroutines): New command-line switch.

gcc/cp/ChangeLog:

2020-01-18  Iain Sandoe  <iain@sandoe.co.uk>

	* Make-lang.in: Add coroutines.o.
	* cp-tree.h (lang_decl-fn): coroutine_p, new bit.
	(DECL_COROUTINE_P): New.
	* lex.c (init_reswords): Enable keywords when the coroutine flag
	is set,
	* operators.def (co_await): New operator.
	* call.c (add_builtin_candidates): Handle CO_AWAIT_EXPR.
	(op_error): Likewise.
	(build_new_op_1): Likewise.
	(build_new_function_call): Validate coroutine builtin arguments.
	* constexpr.c (potential_constant_expression_1): Handle
	CO_AWAIT_EXPR, CO_YIELD_EXPR, CO_RETURN_EXPR.
	* coroutines.cc: New file.
	* cp-objcp-common.c (cp_common_init_ts): Add CO_AWAIT_EXPR,
	CO_YIELD_EXPR, CO_RETRN_EXPR as TS expressions.
	* cp-tree.def (CO_AWAIT_EXPR, CO_YIELD_EXPR, (CO_RETURN_EXPR): New.
	* cp-tree.h (coro_validate_builtin_call): New.
	* decl.c (emit_coro_helper): New.
	(finish_function): Handle the case when a function is found to
	be a coroutine, perform the outlining and emit the outlined
	functions. Set a bit to signal that this is a coroutine component.
	* parser.c (enum required_token): New enumeration RT_CO_YIELD.
	(cp_parser_unary_expression): Handle co_await.
	(cp_parser_assignment_expression): Handle co_yield.
	(cp_parser_statement): Handle RID_CO_RETURN.
	(cp_parser_jump_statement): Handle co_return.
	(cp_parser_operator): Handle co_await operator.
	(cp_parser_yield_expression): New.
	(cp_parser_required_error): Handle RT_CO_YIELD.
	* pt.c (tsubst_copy): Handle CO_AWAIT_EXPR.
	(tsubst_expr): Handle CO_AWAIT_EXPR, CO_YIELD_EXPR and
	CO_RETURN_EXPRs.
	* tree.c (cp_walk_subtrees): Likewise.

libstdc++-v3/ChangeLog:

2020-01-18  Iain Sandoe  <iain@sandoe.co.uk>

	* include/Makefile.am: Add coroutine to the std set.
	* include/Makefile.in: Regenerated.
	* include/std/coroutine: New file.

gcc/testsuite/ChangeLog:

2020-01-18  Iain Sandoe  <iain@sandoe.co.uk>

	* g++.dg/coroutines/co-await-syntax-00-needs-expr.C: New test.
	* g++.dg/coroutines/co-await-syntax-01-outside-fn.C: New test.
	* g++.dg/coroutines/co-await-syntax-02-outside-fn.C: New test.
	* g++.dg/coroutines/co-await-syntax-03-auto.C: New test.
	* g++.dg/coroutines/co-await-syntax-04-ctor-dtor.C: New test.
	* g++.dg/coroutines/co-await-syntax-05-constexpr.C: New test.
	* g++.dg/coroutines/co-await-syntax-06-main.C: New test.
	* g++.dg/coroutines/co-await-syntax-07-varargs.C: New test.
	* g++.dg/coroutines/co-await-syntax-08-lambda-auto.C: New test.
	* g++.dg/coroutines/co-return-syntax-01-outside-fn.C: New test.
	* g++.dg/coroutines/co-return-syntax-02-outside-fn.C: New test.
	* g++.dg/coroutines/co-return-syntax-03-auto.C: New test.
	* g++.dg/coroutines/co-return-syntax-04-ctor-dtor.C: New test.
	* g++.dg/coroutines/co-return-syntax-05-constexpr-fn.C: New test.
	* g++.dg/coroutines/co-return-syntax-06-main.C: New test.
	* g++.dg/coroutines/co-return-syntax-07-vararg.C: New test.
	* g++.dg/coroutines/co-return-syntax-08-bad-return.C: New test.
	* g++.dg/coroutines/co-return-syntax-09-lambda-auto.C: New test.
	* g++.dg/coroutines/co-yield-syntax-00-needs-expr.C: New test.
	* g++.dg/coroutines/co-yield-syntax-01-outside-fn.C: New test.
	* g++.dg/coroutines/co-yield-syntax-02-outside-fn.C: New test.
	* g++.dg/coroutines/co-yield-syntax-03-auto.C: New test.
	* g++.dg/coroutines/co-yield-syntax-04-ctor-dtor.C: New test.
	* g++.dg/coroutines/co-yield-syntax-05-constexpr.C: New test.
	* g++.dg/coroutines/co-yield-syntax-06-main.C: New test.
	* g++.dg/coroutines/co-yield-syntax-07-varargs.C: New test.
	* g++.dg/coroutines/co-yield-syntax-08-needs-expr.C: New test.
	* g++.dg/coroutines/co-yield-syntax-09-lambda-auto.C: New test.
	* g++.dg/coroutines/coro-builtins.C: New test.
	* g++.dg/coroutines/coro-missing-gro.C: New test.
	* g++.dg/coroutines/coro-missing-promise-yield.C: New test.
	* g++.dg/coroutines/coro-missing-ret-value.C: New test.
	* g++.dg/coroutines/coro-missing-ret-void.C: New test.
	* g++.dg/coroutines/coro-missing-ueh-1.C: New test.
	* g++.dg/coroutines/coro-missing-ueh-2.C: New test.
	* g++.dg/coroutines/coro-missing-ueh-3.C: New test.
	* g++.dg/coroutines/coro-missing-ueh.h: New test.
	* g++.dg/coroutines/coro-pre-proc.C: New test.
	* g++.dg/coroutines/coro.h: New file.
	* g++.dg/coroutines/coro1-ret-int-yield-int.h: New file.
	* g++.dg/coroutines/coroutines.exp: New file.
	* g++.dg/coroutines/torture/alloc-00-gro-on-alloc-fail.C: New test.
	* g++.dg/coroutines/torture/alloc-01-overload-newdel.C: New test.
	* g++.dg/coroutines/torture/call-00-co-aw-arg.C: New test.
	* g++.dg/coroutines/torture/call-01-multiple-co-aw.C: New test.
	* g++.dg/coroutines/torture/call-02-temp-co-aw.C: New test.
	* g++.dg/coroutines/torture/call-03-temp-ref-co-aw.C: New test.
	* g++.dg/coroutines/torture/class-00-co-ret.C: New test.
	* g++.dg/coroutines/torture/class-01-co-ret-parm.C: New test.
	* g++.dg/coroutines/torture/class-02-templ-parm.C: New test.
	* g++.dg/coroutines/torture/class-03-operator-templ-parm.C: New test.
	* g++.dg/coroutines/torture/class-04-lambda-1.C: New test.
	* g++.dg/coroutines/torture/class-05-lambda-capture-copy-local.C: New test.
	* g++.dg/coroutines/torture/class-06-lambda-capture-ref.C: New test.
	* g++.dg/coroutines/torture/co-await-00-trivial.C: New test.
	* g++.dg/coroutines/torture/co-await-01-with-value.C: New test.
	* g++.dg/coroutines/torture/co-await-02-xform.C: New test.
	* g++.dg/coroutines/torture/co-await-03-rhs-op.C: New test.
	* g++.dg/coroutines/torture/co-await-04-control-flow.C: New test.
	* g++.dg/coroutines/torture/co-await-05-loop.C: New test.
	* g++.dg/coroutines/torture/co-await-06-ovl.C: New test.
	* g++.dg/coroutines/torture/co-await-07-tmpl.C: New test.
	* g++.dg/coroutines/torture/co-await-08-cascade.C: New test.
	* g++.dg/coroutines/torture/co-await-09-pair.C: New test.
	* g++.dg/coroutines/torture/co-await-10-template-fn-arg.C: New test.
	* g++.dg/coroutines/torture/co-await-11-forwarding.C: New test.
	* g++.dg/coroutines/torture/co-await-12-operator-2.C: New test.
	* g++.dg/coroutines/torture/co-await-13-return-ref.C: New test.
	* g++.dg/coroutines/torture/co-ret-00-void-return-is-ready.C: New test.
	* g++.dg/coroutines/torture/co-ret-01-void-return-is-suspend.C: New test.
	* g++.dg/coroutines/torture/co-ret-03-different-GRO-type.C: New test.
	* g++.dg/coroutines/torture/co-ret-04-GRO-nontriv.C: New test.
	* g++.dg/coroutines/torture/co-ret-05-return-value.C: New test.
	* g++.dg/coroutines/torture/co-ret-06-template-promise-val-1.C: New test.
	* g++.dg/coroutines/torture/co-ret-07-void-cast-expr.C: New test.
	* g++.dg/coroutines/torture/co-ret-08-template-cast-ret.C: New test.
	* g++.dg/coroutines/torture/co-ret-09-bool-await-susp.C: New test.
	* g++.dg/coroutines/torture/co-ret-10-expression-evaluates-once.C: New test.
	* g++.dg/coroutines/torture/co-ret-11-co-ret-co-await.C: New test.
	* g++.dg/coroutines/torture/co-ret-12-co-ret-fun-co-await.C: New test.
	* g++.dg/coroutines/torture/co-ret-13-template-2.C: New test.
	* g++.dg/coroutines/torture/co-ret-14-template-3.C: New test.
	* g++.dg/coroutines/torture/co-yield-00-triv.C: New test.
	* g++.dg/coroutines/torture/co-yield-01-multi.C: New test.
	* g++.dg/coroutines/torture/co-yield-02-loop.C: New test.
	* g++.dg/coroutines/torture/co-yield-03-tmpl.C: New test.
	* g++.dg/coroutines/torture/co-yield-04-complex-local-state.C: New test.
	* g++.dg/coroutines/torture/co-yield-05-co-aw.C: New test.
	* g++.dg/coroutines/torture/co-yield-06-fun-parm.C: New test.
	* g++.dg/coroutines/torture/co-yield-07-template-fn-param.C: New test.
	* g++.dg/coroutines/torture/co-yield-08-more-refs.C: New test.
	* g++.dg/coroutines/torture/co-yield-09-more-templ-refs.C: New test.
	* g++.dg/coroutines/torture/coro-torture.exp: New file.
	* g++.dg/coroutines/torture/exceptions-test-0.C: New test.
	* g++.dg/coroutines/torture/func-params-00.C: New test.
	* g++.dg/coroutines/torture/func-params-01.C: New test.
	* g++.dg/coroutines/torture/func-params-02.C: New test.
	* g++.dg/coroutines/torture/func-params-03.C: New test.
	* g++.dg/coroutines/torture/func-params-04.C: New test.
	* g++.dg/coroutines/torture/func-params-05.C: New test.
	* g++.dg/coroutines/torture/func-params-06.C: New test.
	* g++.dg/coroutines/torture/lambda-00-co-ret.C: New test.
	* g++.dg/coroutines/torture/lambda-01-co-ret-parm.C: New test.
	* g++.dg/coroutines/torture/lambda-02-co-yield-values.C: New test.
	* g++.dg/coroutines/torture/lambda-03-auto-parm-1.C: New test.
	* g++.dg/coroutines/torture/lambda-04-templ-parm.C: New test.
	* g++.dg/coroutines/torture/lambda-05-capture-copy-local.C: New test.
	* g++.dg/coroutines/torture/lambda-06-multi-capture.C: New test.
	* g++.dg/coroutines/torture/lambda-07-multi-yield.C: New test.
	* g++.dg/coroutines/torture/lambda-08-co-ret-parm-ref.C: New test.
	* g++.dg/coroutines/torture/local-var-0.C: New test.
	* g++.dg/coroutines/torture/local-var-1.C: New test.
	* g++.dg/coroutines/torture/local-var-2.C: New test.
	* g++.dg/coroutines/torture/local-var-3.C: New test.
	* g++.dg/coroutines/torture/local-var-4.C: New test.
	* g++.dg/coroutines/torture/mid-suspend-destruction-0.C: New test.
	* g++.dg/coroutines/torture/pr92933.C: New test.

Bootstrap found yet another unused variable:
../../gcc/config/arm/vfp.md:1651:17: warning: unused variable 'regname' [-Wunused-variable]

2020-01-18  Jakub Jelinek  <jakub@redhat.com>

	* config/arm/vfp.md (*clear_vfp_multiple): Remove unused variable.

As reported in PR93312, the:
> > > > > >         * config/arm/arm.c (clear_operation_p): New function.
change broke RTL checking bootstrap.

On the testcase from the PR (which is distilled from libgcc2.c, so I think
we don't need to add it into testsuite) we ICE because SET_DEST (elt) is
not a REG, but SUBREG.  The code uses REGNO on it, which is invalid, but
only stores it into a variable, then performs REG_P (reg) check,
determines it is not a REG and bails early.

The following patch just moves the regno variable initialization after that
check, it isn't used in between.  And, as a small optimization, because
reg doesn't change, doesn't use REGNO (reg) a second time to set last_regno.

2020-01-18  Jakub Jelinek  <jakub@redhat.com>

	PR target/93312
	* config/arm/arm.c (clear_operation_p): Don't use REGNO until
	after checking the argument is a REG.  Don't use REGNO (reg)
	again to set last_regno, reuse regno variable instead.

	PR libfortran/93234
	* io/unit.c (set_internal_unit): Set round and sign flags
	correctly.

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

PR analyzer/93290 reports an ICE on calls to isnan().
The root cause is that an UNORDERED_EXPR is passed
to region_model::eval_condition_without_cm, and there's
a stray gcc_unreachable () in the case where we're comparing
an svalue against itself.

I attempted a more involved patch that properly handled NaN in general
but it seems I've baked the assumption of reflexivity too deeply into
the constraint_manager code.

For now, this patch avoids the ICE and documents the limitation.

gcc/analyzer/ChangeLog:
	PR analyzer/93290
	* region-model.cc (region_model::eval_condition_without_cm): Avoid
	gcc_unreachable for unexpected operations for the case where
	we're comparing an svalue against itself.

gcc/ChangeLog
	* doc/analyzer.texi (Limitations): Add note about NaN.

gcc/testsuite/ChangeLog:
	PR analyzer/93290
	* gcc.dg/analyzer/pr93290.c: New test.

	PR libfortran/90374
	* io/format.c (parse_format_list): Zero width not allowed with
	FMT_D.
	* io/write_float.def (build_float_string): Include range of
	higher exponent values that require wider width.

	PR c++/92542
	* g++.dg/pr92542.C: New.

	PR c++/92542
	* g++.dg/pr92542.C: New.

[GCC/ARM, 2/2] Add support for ASRL(imm), LSLL(imm) and LSRL(imm) instructions for Armv8.1-M Mainline

This patch is adding the following instructions:

ASRL (imm)
LSLL (imm)
LSRL (imm)

*** gcc/ChangeLog ***

2020-01-17  Mihail-Calin Ionescu  <mihail.ionescu@arm.com>
	    Sudakshina Das  <sudi.das@arm.com>

	* config/arm/arm.md (ashldi3): Generate thumb2_lsll for both reg
	and valid immediate.
	(ashrdi3): Generate thumb2_asrl for both reg and valid immediate.
	(lshrdi3): Generate thumb2_lsrl for valid immediates.
	* config/arm/constraints.md (Pg): New.
	* config/arm/predicates.md (long_shift_imm): New.
	(arm_reg_or_long_shift_imm): Likewise.
	* config/arm/thumb2.md (thumb2_asrl): New immediate alternative.
	(thumb2_lsll): Likewise.
	(thumb2_lsrl): New.

*** gcc/testsuite/ChangeLog ***

2020-01-17  Mihail-Calin Ionescu  <mihail.ionescu@arm.com>
	    Sudakshina Das  <sudi.das@arm.com>

	* gcc.target/arm/armv8_1m-shift-imm_1.c: New test.

This patch is adding the following instructions:

ASRL (reg)
LSLL (reg)

*** gcc/ChangeLog ***

2020-01-17  Mihail-Calin Ionescu <mihail.ionescu@arm.com>
	    Sudakshina Das  <sudi.das@arm.com>

	* config/arm/arm.md (ashldi3): Generate thumb2_lsll for TARGET_HAVE_MVE.
	(ashrdi3): Generate thumb2_asrl for TARGET_HAVE_MVE.
	* config/arm/arm.c (arm_hard_regno_mode_ok): Allocate even odd
	register pairs for doubleword quantities for ARMv8.1M-Mainline.
	* config/arm/thumb2.md (thumb2_asrl): New.
	(thumb2_lsll): Likewise.

2020-01-17  Mihail-Calin Ionescu <mihail.ionescu@arm.com>
	    Sudakshina Das  <sudi.das@arm.com>

	* gcc.target/arm/armv8_1m-shift-reg_1.c: New test.

2020-01-17  Jakub Jelinek  <jakub@redhat.com>

	* config/arm/arm.c (cmse_nonsecure_call_inline_register_clear): Remove
	unused variable.

2020-01-17  Andrew Stubbs  <ams@codesourcery.com>

	libgomp/
	* config/accel/openacc.f90 (openacc_kinds): Rename acc_device_gcn to
	acc_device_radeon.
	(openacc): Likewise.
	* openacc.f90 (openacc_kinds): Likewise.
	(openacc): Likewise.
	* openacc.h (acc_device_t): Likewise.
	* openacc_lib.h: Likewise.
	* testsuite/lib/libgomp.exp
	(check_effective_target_openacc_amdgcn_accel_present): Likewise.
	* testsuite/libgomp.oacc-c-c++-common/acc_prof-init-1.c
	(cb_compute_construct_end): Likewise.
	* testsuite/libgomp.oacc-c-c++-common/acc_prof-kernels-1.c
	(cb_enqueue_launch_start): Likewise.
	* testsuite/libgomp.oacc-c-c++-common/acc_prof-parallel-1.c
	(cb_enter_data_end): Likewise.
	(cb_exit_data_start): Likewise.
	(cb_exit_data_end): Likewise.
	(cb_compute_construct_end): Likewise.
	(cb_enqueue_launch_start): Likewise.
	(cb_enqueue_launch_end): Likewise.
	* testsuite/libgomp.oacc-c-c++-common/asyncwait-nop-1.c
	(main): Likewise.

In a freestanding library we don't install the <pstl/pstl_config.h>
header, so don't try to include it unless it exists.

Explicitly declare aligned alloc functions for freestanding, because
<cstdlib> doesn't declare them.

	PR libstdc++/92376
	* include/bits/c++config: Only do PSTL config when the header is
	present, to fix freestanding.
	* libsupc++/new_opa.cc [!_GLIBCXX_HOSTED]: Declare allocation
	functions if they were detected by configure.

Make gdb shorthands such as 'pr' accept an argument, in addition to
implictly taking register '$' as the thing to examine.

The 'eval ...' one-liners are used to workaround GDB bug #22466.

	* gdbinit.in (help-gcc-hooks): New command.
	(pp, pr, prl, pt, pct, pgg, pgq, pgs, pge, pmz, ptc, pdn, ptn, pdd, prc,
	pi, pbm, pel, trt): Take $arg0 instead of $ if supplied. Update
	documentation.

Had mistakenly used a target macro that was not defined and not the
relevant one instead of the macro that should be used.

TARGET_ARMV8_6 is not defined, and also not the macro we want to check.
Instead check TARGET_F64MM.

gcc/ChangeLog:

2020-01-17  Matthew Malcomson  <matthew.malcomson@arm.com>

	* config/aarch64/aarch64-sve.md (@aarch64_sve_ld1ro<mode>): Use
	the correct target macro.

	PR testsuite/93227
	* g++.dg/cpp0x/std-layout1.C: Use -Wno-deprecated-declarations for
	C++20, due to std::is_pod being deprecated.

We take no action to ensure the SVE vector size is large enough.  It is
left to the user to check that before compiling this intrinsic or before
running such a program on a machine.

The main difference between ld1ro and ld1rq is in the allowed offsets,
the implementation difference is that ld1ro is implemented using integer
modes since there are no pre-existing vector modes of the relevant size.
Adding new vector modes simply for this intrinsic seems to make the code
less tidy.

Specifications can be found under the "Arm C Language Extensions for
Scalable Vector Extension" title at
https://developer.arm.com/architectures/system-architectures/software-standards/acle

gcc/ChangeLog:

2020-01-17  Matthew Malcomson  <matthew.malcomson@arm.com>

	* config/aarch64/aarch64-protos.h
	(aarch64_sve_ld1ro_operand_p): New.
	* config/aarch64/aarch64-sve-builtins-base.cc
	(class load_replicate): New.
	(class svld1ro_impl): New.
	(class svld1rq_impl): Change to inherit from load_replicate.
	(svld1ro): New sve intrinsic function base.
	* config/aarch64/aarch64-sve-builtins-base.def (svld1ro):
	New DEF_SVE_FUNCTION.
	* config/aarch64/aarch64-sve-builtins-base.h
	(svld1ro): New decl.
	* config/aarch64/aarch64-sve-builtins.cc
	(function_expander::add_mem_operand): Modify assert to allow
	OImode.
	* config/aarch64/aarch64-sve.md (@aarch64_sve_ld1ro<mode>): New
	pattern.
	* config/aarch64/aarch64.c
	(aarch64_sve_ld1rq_operand_p): Implement in terms of ...
	(aarch64_sve_ld1rq_ld1ro_operand_p): This.
	(aarch64_sve_ld1ro_operand_p): New.
	* config/aarch64/aarch64.md (UNSPEC_LD1RO): New unspec.
	* config/aarch64/constraints.md (UOb,UOh,UOw,UOd): New.
	* config/aarch64/predicates.md
	(aarch64_sve_ld1ro_operand_{b,h,w,d}): New.

gcc/testsuite/ChangeLog:

2020-01-17  Matthew Malcomson  <matthew.malcomson@arm.com>

	* gcc.target/aarch64/sve/acle/asm/ld1ro_f16.c: New test.
	* gcc.target/aarch64/sve/acle/asm/ld1ro_f32.c: New test.
	* gcc.target/aarch64/sve/acle/asm/ld1ro_f64.c: New test.
	* gcc.target/aarch64/sve/acle/asm/ld1ro_s16.c: New test.
	* gcc.target/aarch64/sve/acle/asm/ld1ro_s32.c: New test.
	* gcc.target/aarch64/sve/acle/asm/ld1ro_s64.c: New test.
	* gcc.target/aarch64/sve/acle/asm/ld1ro_s8.c: New test.
	* gcc.target/aarch64/sve/acle/asm/ld1ro_u16.c: New test.
	* gcc.target/aarch64/sve/acle/asm/ld1ro_u32.c: New test.
	* gcc.target/aarch64/sve/acle/asm/ld1ro_u64.c: New test.
	* gcc.target/aarch64/sve/acle/asm/ld1ro_u8.c: New test.

This patch is necessary for sve-ld1ro intrinsic I posted in
https://gcc.gnu.org/ml/gcc-patches/2020-01/msg00466.html .

I had mistakenly thought this option was already enabled upstream.

This provides the option +f64mm, that turns on the 64 bit floating point
matrix multiply extension.  This extension is only available for
AArch64.  Turning on this extension also turns on the SVE extension.

This extension is optional and only available at Armv8.2-A and onward.

We also add the ACLE defined macro for this extension.

gcc/ChangeLog:

2020-01-17  Matthew Malcomson  <matthew.malcomson@arm.com>

	* config/aarch64/aarch64-c.c (_ARM_FEATURE_MATMUL_FLOAT64):
	Introduce this ACLE specified predefined macro.
	* config/aarch64/aarch64-option-extensions.def (f64mm): New.
	(fp): Disabling this disables f64mm.
	(simd): Disabling this disables f64mm.
	(fp16): Disabling this disables f64mm.
	(sve): Disabling this disables f64mm.
	* config/aarch64/aarch64.h (AARCH64_FL_F64MM): New.
	(AARCH64_ISA_F64MM): New.
	(TARGET_F64MM): New.
	* doc/invoke.texi (f64mm): Document new option.

gcc/testsuite/ChangeLog:

2020-01-17  Matthew Malcomson  <matthew.malcomson@arm.com>

	* gcc.target/aarch64/pragma_cpp_predefs_2.c: Check for f64mm
	predef.

Enable the most basic form of compare-branch fusion since various CPUs
support it. This has no measurable effect on cores which don't support
branch fusion, but increases fusion opportunities on cores which do.

gcc/
	* config/aarch64/aarch64.c (generic_tunings): Add branch fusion.
	(neoversen1_tunings): Likewise.

This was failing because uses_template_parms didn't recognize LAMBDA_EXPR as
a kind of expression.  Instead of trying to enumerate all the different
varieties of expression and then aborting if what's left isn't
error_mark_node, let's handle error_mark_node and then assume anything else
is an expression.

	* pt.c (uses_template_parms): Don't try to enumerate all the
	expression cases.

As the following testcase shows, when deprecated attribute is on a template,
we'd never print the message if any, because the attribute is not
present on the TEMPLATE_DECL with which warn_deprecated_use is called,
but on its DECL_TEMPLATE_RESULT or its type.

2020-01-17  Jakub Jelinek  <jakub@redhat.com>

	PR c++/93228
	* parser.c (cp_parser_template_name): Look up deprecated attribute
	in DECL_TEMPLATE_RESULT or its type's attributes.

	* g++.dg/cpp1y/attr-deprecated-3.C: New test.

the preprocessor evaluator has a skip_eval counter, but we weren't
checking it after parsing has_include(foo), but before looking for
foo.  Resulting in unnecessary io for 'FALSE_COND && has_include <foo>'

	PR preprocessor/93306
	* expr.c (parse_has_include): Refactor.  Check skip_eval before
	looking.

Various 32-bit targets show failures in gcc.dg/analyzer/data-model-1.c
with tests of the form:
  __analyzer_eval (q[-2].x == 107024); /* { dg-warning "TRUE" } */
  __analyzer_eval (q[-2].y == 107025); /* { dg-warning "TRUE" } */
where they emit UNKNOWN instead.

The root cause is that gimple has a byte-based twos-complement offset
of -16 expressed like this:
  _55 = q_92 + 4294967280;  (32-bit)
or:
  _55 = q_92 + 18446744073709551600; (64-bit)

Within region_model::convert_byte_offset_to_array_index that unsigned
offset was being divided by the element size to get an offset within
an array.

This happened to work on 64-bit target and host, but not elsewhere;
the offset needs to be converted to a signed type before the division
is meaningful.

This patch does so, fixing the failures.

gcc/analyzer/ChangeLog:
	PR analyzer/93281
	* region-model.cc
	(region_model::convert_byte_offset_to_array_index): Convert to
	ssizetype before dividing by byte_size.  Use fold_binary rather
	than fold_build2 to avoid needlessly constructing a tree for the
	non-const case.

The separate shrinkwrapping pass may insert stores in the middle
of atomics loops which can cause issues on some implementations.
Avoid this by delaying splitting atomics patterns until after
prolog/epilog generation.

gcc/
	PR target/92692
	* config/aarch64/aarch64.c (aarch64_split_compare_and_swap)
	Add assert to ensure prolog has been emitted.
	(aarch64_split_atomic_op): Likewise.
	* config/aarch64/atomics.md (aarch64_compare_and_swap<mode>)
	Use epilogue_completed rather than reload_completed.
	(aarch64_atomic_exchange<mode>): Likewise.
	(aarch64_atomic_<atomic_optab><mode>): Likewise.
	(atomic_nand<mode>): Likewise.
	(aarch64_atomic_fetch_<atomic_optab><mode>): Likewise.
	(atomic_fetch_nand<mode>): Likewise.
	(aarch64_atomic_<atomic_optab>_fetch<mode>): Likewise.
	(atomic_nand_fetch<mode>): Likewise.

AIUI, the main purpose of REVERSE_CONDITION is to take advantage of
any integer vs. FP information encoded in the CC mode, particularly
when handling LT, LE, GE and GT.  For integer comparisons we can
safely map LT->GE, LE->GT, GE->LT and GT->LE, but for float comparisons
this would usually be invalid without -ffinite-math-only.

The aarch64 definition of REVERSE_CONDITION used
reverse_condition_maybe_unordered for FP comparisons, which had the
effect of converting an unordered-signalling LT, LE, GE or GT into a
quiet UNGE, UNGT, UNLT or UNLE.  And it would do the same in reverse:
convert a quiet UN* into an unordered-signalling comparison.

This would be safe in practice (although a little misleading) if we
always used a compare:CCFP or compare:CCFPE to do the comparison and
then used (gt (reg:CCFP/CCFPE CC_REGNUM) (const_int 0)) etc. to test
the result.  In that case any signal is raised by the compare and the
choice of quiet vs. signalling relations doesn't matter when testing
the result.  The problem is that we also want to use GT directly on
float registers, where any signal is raised by the comparison operation
itself and so must follow the normal rtl rules (GT signalling,
UNLE quiet).

I think the safest fix is to make REVERSIBLE_CC_MODE return false
for FP comparisons.  We can then use the default REVERSE_CONDITION
for integer comparisons and the usual conservatively-correct
reversed_comparison_code_parts behaviour for FP comparisons.
Unfortunately reversed_comparison_code_parts doesn't yet handle
-ffinite-math-only, but that's probably GCC 11 material.

A downside is that:

    int f (float x, float y) { return !(x < y); }

now generates:

        fcmpe   s0, s1
        cset    w0, mi
        eor     w0, w0, 1
        ret

without -ffinite-math-only.  Maybe for GCC 11 we should define rtx
codes for all IEEE comparisons, so that we don't have this kind of
representational gap.

Changing REVERSE_CONDITION itself is pretty easy.  However, the macro
was also used in the ccmp handling, which relied on being able to
reverse all comparisons.  The patch adds new reversed patterns for
cases in which the original condition needs to be kept.

The test is based on gcc.dg/torture/pr91323.c.  It might well fail
on other targets that have similar bugs; please XFAIL as appropriate
if you don't want to fix the target for GCC 10.

2020-01-17  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/aarch64/aarch64.h (REVERSIBLE_CC_MODE): Return false
	for FP modes.
	(REVERSE_CONDITION): Delete.
	* config/aarch64/iterators.md (CC_ONLY): New mode iterator.
	(CCFP_CCFPE): Likewise.
	(e): New mode attribute.
	* config/aarch64/aarch64.md (ccmp<GPI:mode>): Rename to...
	(@ccmp<CC_ONLY:mode><GPI:mode>): ...this, using CC_ONLY instead of CC.
	(fccmp<GPF:mode>, fccmpe<GPF:mode>): Merge into...
	(@ccmp<CCFP_CCFPE:mode><GPF:mode>): ...this combined pattern.
	(@ccmp<CC_ONLY:mode><GPI:mode>_rev): New pattern.
	(@ccmp<CCFP_CCFPE:mode><GPF:mode>_rev): Likewise.
	* config/aarch64/aarch64.c (aarch64_gen_compare_reg): Update
	name of generator from gen_ccmpdi to gen_ccmpccdi.
	(aarch64_gen_ccmp_next): Use code_for_ccmp.  If we want to reverse
	the previous comparison but aren't able to, use the new ccmp_rev
	patterns instead.

If a TARGET_EXPR has poly-int size, the gimplifier would treat it
like a VLA and use gimplify_vla_decl.  gimplify_vla_decl in turn
would use an alloca and expect all references to be gimplified
via the DECL_VALUE_EXPR.  This caused confusion later in
gimplify_var_or_parm_decl_1 when we (correctly) had direct rather
than indirect references.

For completeness, the patch also fixes similar tests in the RETURN_EXPR
handling and OpenMP depend clauses.

2020-01-17  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* gimplify.c (gimplify_return_expr): Use poly_int_tree_p rather
	than testing directly for INTEGER_CST.
	(gimplify_target_expr, gimplify_omp_depend): Likewise.

gcc/testsuite/
	* g++.target/aarch64/sve/acle/general-c++/gimplify_1.C: New test.

The use of -fno-automatic should not affect the save attribute of a
recursive procedure. The first test case checks unsaved variables
and the second checks saved variables.

The following testcase ICEs on powerpc64le-linux.  The problem is that
get_vectype_for_scalar_type returns NULL, and while most places in
tree-vect-stmts.c handle that case, this spot doesn't and punts only
if it is non-NULL, but with different number of elts than expected.

2020-01-17  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/93292
	* tree-vect-stmts.c (vectorizable_comparison): Punt also if
	get_vectype_for_scalar_type returns NULL.

	* g++.dg/opt/pr93292.C: New test.

2020-01-17  Jakub Jelinek  <jakub@redhat.com>

	PR testsuite/93294
	* lib/c-compat.exp (compat-use-alt-compiler): Handle
	-fdiagnostics-urls=never similarly to -fdiagnostics-color=never.
	(compat_setup_dfp): Likewise.

Really old git versions (like 1.6.0) require
"git log --pretty=tformat:%p:%t:%H"
or else we see:

Updating GIT tree
Current branch master is up to date.
fatal: invalid --pretty format: %p:%t:%H
Adjusting file timestamps
Touching gcc/config.in...
Touching gcc/config/arm/arm-tune.md...

...and an empty revision in LAST_UPDATED and gcc/REVISION.
In its absence, for newer git versions, "tformat" is the default
qualifier, documented as such default for at least git-2.11.0.

Here we had been recursing in tsubst_copy_and_build if type2 was a TREE_LIST
because that function knew how to deal with pack expansions, and tsubst
didn't.  But tsubst_copy_and_build expects to be dealing with expressions,
so we crash when trying to convert_from_reference a type.

	* pt.c (tsubst) [TREE_LIST]: Handle pack expansion.
	(tsubst_copy_and_build) [TRAIT_EXPR]: Always use tsubst for type2.

	* params.opt (-param=max-predicted-iterations): Increase range from 0.
	* predict.c (estimate_loops): Add 1 to param_max_predicted_iterations.

This patch fixes ICE on invalid code, specifically files that have
conflict-marker-like signs before EOF.

	PR c/92833
gcc/c/
	* c-parser.c (c_parser_consume_token): Fix peeked token stack pop
	to support 4 available tokens.

gcc/testsuite/
	* c-c++-common/pr92833-1.c, c-c++-common/pr92833-2.c,
	c-c++-common/pr92833-3.c, c-c++-common/pr92833-4.c: New tests.

While analyzing code size regression in SPEC2k GCC binary I noticed that we
perform some inline decisions because we think that number of executions are
very high.
In particular there was inline decision inlining gen_rtx_fmt_ee to find_reloads
believing that it is called 4 billion times.  This turned out to be cummulation
of roundoff errors in propagate_freq which was bit mechanically updated from
original sreals to C++ sreals and later to new probabilities.

This led us to estimate that a loopback edge is reached with probability 2.3
which was capped to 1-1/10000 and since this happened in nested loop it quickly
escalated to large values.

Originally capping to REG_BR_PROB_BASE avoided such problems but now we have
much higher range.

This patch avoids going from probabilites to REG_BR_PROB_BASE so precision is
kept.  In addition it makes the propagation to not estimate more than
param-max-predicted-loop-iterations.  The first change makes the cap to not
be triggered on the gcc build, but it is still better to be safe than sorry.

	* ipa-fnsummary.c (estimate_calls_size_and_time): Fix formating of
	dump.
	* params.opt: (max-predicted-iterations): Set bounds.
	* predict.c (real_almost_one, real_br_prob_base,
	real_inv_br_prob_base, real_one_half, real_bb_freq_max): Remove.
	(propagate_freq): Add max_cyclic_prob parameter; cap cyclic
	probabilities; do not truncate to reg_br_prob_bases.
	(estimate_loops_at_level): Pass max_cyclic_prob.
	(estimate_loops): Compute max_cyclic_prob.
	(estimate_bb_frequencies): Do not initialize real_*; update calculation
	of back edge prob.
	* profile-count.c (profile_probability::to_sreal): New.
	* profile-count.h (class sreal): Move up in file.
	(profile_probability::to_sreal): Declare.