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ada: Tune hash function for cross-reference entries

Tune the hash function that combines entity identifiers with source
locations of where those entities are referenced. Previously the source
location was multiplied by 2 ** 7 (i.e. shifted left by 7 bits), then
added to the entity identifier, and finally divided modulo 2 ** 16 (i.e.
masked to only use the lowest 16 bits). This hash routine caused
collisions that could make some tests up to twice slower.

With a large entity number the source location was only contributing few
bits to the hash value. This large entity number might correspond to
entity like Ada.Characters.Latin_1.NUL that occurs thousands of times in
generated code.

gcc/ada/

* lib-xref.adb (Hash): Tune hash function.

ada: Fix performance regression related to references in Refined_State

Recently added call to In_Pragma_Expression caused a performance
regression. It might require climbing syntax trees of arbitrarily deep
expressions, while previously references within pragmas were detected in
bounded time.

This patch restores the previous efficiency. However, while the original
code only detected references directly within pragma argument
associations, now we also detect references inside aggregates, e.g.
like those in pragma Refined_State.

gcc/ada/

* sem_prag.adb (Non_Significant_Pragma_Reference): Detect
references with aggregates; only assign local variables Id and C
when necessary.

ada: Use named notation in calls to Expand_Composite_Equality

Use named notation in calls to Expand_Composite_Equality.

gcc/ada/

* exp_ch4.adb
(Component_Equality, Expand_Array_Equality)
(Expand_Record_Equality): Use named notation.

ada: New warning about noncomposing user-defined "="

Print warning for a user-defined "=" that does not compose
as might be expected (i.e. is ignored for predefined "=" of
a containing record or array type). This warning is enabled by
-gnatw_q; we don't enable it by default because it generates
too many false positives. We also don't enable it via -gnatwa.

gcc/ada/

* exp_ch4.adb
(Expand_Array_Equality): Do not test Ltyp = Rtyp here, because
that is necessarily true. Move assertion thereof to more general
place.
(Expand_Composite_Equality): Pass in Outer_Type, for use in
warnings. Rename Typ to be Comp_Type, to more clearly distinguish
it from Outer_Type. Print warning when appropriate.
* exp_ch4.ads: Minor comment fix.
* errout.ads: There is no such pragma as Warning_As_Pragma --
Warning_As_Error must have been intended. Improve comment for ?x?.
* exp_ch3.adb
(Build_Untagged_Equality): Update comment to be accurate for more
recent versions of Ada.
* sem_case.adb
(Choice_Analysis): Declare user-defined "=" functions as abstract.
* sem_util.ads
(Is_Bounded_String): Give RM reference in comment.
* warnsw.ads, warnsw.adb
(Warn_On_Ignored_Equality): Implement new warning switch -gnatw_q.
* doc/gnat_ugn/building_executable_programs_with_gnat.rst:
Document new warning switch.
* gnat_ugn.texi: Regenerate.

ada: Inline composite node kind AST queries

Queries that ultimately examine the same field of an AST
node (e.g. Nkind) are visibly more efficient when inlined.

In particular, routines Is_Body_Or_Package_Declaration and Is_Body can
apparently be inlined into a single Nkind membership test.

This patch fixes some of the performance lost with the recent changes,
which increased the number of calls to Is_Body_Or_Package_Declaration
(as it is typically used to prevent AST search from climbing too far).
However, it should be generally beneficial to inline routines like this.

gcc/ada/

* sem_aux.ads (Is_Body): Annotate with Inline.
* sem_util.ads (Is_Body_Or_Package_Declaration): Likewise.

ada: Fix inherited postconditions in inlined subprograms

Protect the building of postcondition pragmas in case the
postcondition is not present due to inlining.

gcc/ada/

* freeze.adb
(Build_Inherited_Condition_Pragmas): Do nothing if A_Post is
empty.

ada: Fixed elaboration of CUDA programs.

The names of imported / exported symbols were not consistent
between the device and the host when compiling for CUDA.

Remove the function Device_Ada_Final_Link_Name as it is no
longer referenced.

gcc/ada/

* bindgen.adb: fixed the way the device init and final symbols are
computed, re-using the normal way these symbols would be computed
with a __device_ prefix. Also fixed the "is null;" procedure on
the host side which are not Ada 95, replaced with a procedure
raising an exception as it should never be called. Remove the
unused function Device_Ada_Final_Link_Name.

Co-authored-by: Steve Baird <baird@adacore.com>

ada: Rework CUDA host-side invocation of device-side elaboration code

When the binder is invoked with a "-d_c" switch, add an argument to that
switch which is the library name on the device side; so "-d_c" becomes
"-d_c=some_library_name". This does not effect the case where "-d_c" is
specified as a switch for compilation (as opposed to binding). Use this
new piece of information in the code generated by the binder to invoke
elaboration code on the device side from the host side.

gcc/ada/

* opt.ads: Declare new string pointer variable, CUDA_Device_Library_Name.
Modify comments for existing Boolean variable Enable_CUDA_Device_Expansion.
* switch-b.adb: When "-d_c" switch is encountered, check that the next
character is an "'='; use the remaining characters to initialize
Opt.CUDA_Device_Library_Name.
* bindgen.adb: Remove (for now) most support for host-side invocation of
device-side finalization. Make use of the new CUDA_Device_Library_Name
in determining the string used to refer (on the host side) to the
device-side initialization procedure. Declare the placeholder routine
that is named in the CUDA_Execute pragma (and the CUDA_Register_Function
call) as an exported null procedure, rather than as an imported procedure.
It is not clear whether it is really necessary to specify the link-name
for this should-never-be-called subprogram on the host side, but for now it
shouldn't hurt to do so.

ada: Fix detection of external calls to protected objects in instances

Detection of external-vs-internal calls to protected objects relied on
the scope stack. This didn't work when the call appeared in an instance
of generic unit, because instances are analyzed in different context to
where they appear.

gcc/ada/

* exp_ch6.adb (Expand_Protected_Subprogram_Call): Examine scope
tree and not the scope stack.

ada: Clean up unnecessary nesting in code for DLL libraries

Code cleanup; issue spotted while examining routines with No_ prefix.

gcc/ada/

* mdll.ads (Build_Import_Library): Fix grammar in comment.
* mdll.adb (Build_Import_Library): Directly execute code of a
nested routine; rename No_Lib_Prefix to Strip_Lib_Prefix.

ada: Suppress warnings on derived True/False

GNAT normally warns on "return ...;" if the "..." is known to be True or
False, but not when it is a Boolean literal True or False. This patch
also suppresses the warning when the type is derived from Boolean, and
has convention C or Fortran (and therefore True is represented as
"nonzero").

Without this fix, GNAT would give warnings like "False is always False".

gcc/ada/

* sem_warn.adb
(Check_For_Warnings): Remove unnecessary exception handler.
(Warn_On_Known_Condition): Suppress warning when we detect a True
or False that has been turned into a more complex expression
because True is represented as "nonzero". (Note that the complex
expression will subsequently be constant-folded to a Boolean True
or False). Also simplify to always print "condition is always ..."
instead of special-casing object names. The special case was
unhelpful, and indeed wrong when the expression is a literal.

ada: Deconstruct Safe_To_Capture_In_Parameter_Value

Recently routine Safe_To_Capture_Value was adapted, so that various data
properties like validity/nullness/values are tracked also for
in-parameters. Now a similar routine Safe_To_Capture_In_Parameter_Value,
which was only used to track data nullness, is redundant, so this patch
deconstructs it.

Also the removed routine had at least few problems and limitations, for
example:

1) it only worked for functions and procedures, but not for protected
entries and task types (whose discriminants work very much like
in-parameters)

2) it only worked for subprogram bodies with no spec, because of this
dubious check (here simplified):

if Nkind (Parent (Parent (Current_Scope))) /= N_Subprogram_Body then
return False;

3) it only recognized references within short-circuit operators as
certainly evaluated if they were directly their left hand expression,
e.g.:

X.all and then ...

but not when they were certainly evaluated as part of a bigger
expression on the left hand side, e.g.:

(X.all > 0) and then ...

4) it categorizes parameters with 'Unrestricted_Access attribute as safe
to capture, which is not necessarily wrong, but risky (because the
object becomes aliased).

Routine Safe_To_Capture_Value, which is kept by this patch, seems to
behave better in all those situations, though it has its own problems as
well and ideally should be further scrutinized.

gcc/ada/

* checks.adb (Safe_To_Capture_In_Parameter_Value): Remove.
* sem_util.adb (Safe_To_Capture_Value): Stop search at the current
body.

ada: Flip warning suppression routine to positive meaning

Subprogram names starting with No_ seem unnecessarily confusing.

Cleanup related to improved detection of references to uninitialized
objects; semantics is unaffected.

gcc/ada/

* sem_warn.adb (Warn_On_In_Out): Remove No_ prefix; flip return
values between True and False; adapt caller.

ada: Cleanup detection of code within generic instances

To check if a node is located in a generic instance we can either look
at Instantiation_Location or at the Instantiation_Depth, but just
looking at the location is simpler and more efficient.

Cleanup related to improved detection of references to uninitialized
objects; semantics is unaffected.

gcc/ada/

* sem_ch13.adb (Add_Call): Just look at Instantiation_Depth.
* sem_ch3.adb (Derive_Subprograms): Likewise.
* sem_warn.adb (Check_References): Remove redundant filtering with
Instantiation_Depth that follows filtering with
Instantiation_Location.
* sinput.adb (Instantiation_Depth): Reuse Instantiation_Location.

ada: Remove redundant suppression for non-modified IN OUT parameters

Non-modified IN OUT parameters are first collected and then filtered by
examining uses of their enclosing subprograms. In this filtering we
don't need to look again at properties of the formal parameters
themselves.

Cleanup related to improved detection of references to uninitialized
objects; semantics is unaffected.

gcc/ada/

* sem_warn.adb
(No_Warn_On_In_Out): For subprograms we can simply call
Warnings_Off.
(Output_Non_Modified_In_Out_Warnings): Remove repeated
suppression.

ada: Reject boxes in delta array aggregates

Implement Ada 2022 4.3.4(11/5), which rejects box compound delimiter <>
in delta record aggregates, just like another rule rejects it in delta
array aggregates.

gcc/ada/

* sem_aggr.adb (Resolve_Delta_Array_Aggregate): Reject boxes in
delta array aggregates.

ada: Allow reuse of Enclosing_Declaration_Or_Statement by GNATprove

Move routine Enclosing_Declaration_Or_Statement from body of Sem_Res to spec
of Sem_Util, so it can be reused. In particular, GNATprove needs this
functionality to climb from an arbitrary subexpression with target_name (@)
to the enclosing assignment statement. Behaviour of the compiler is
unaffected.

gcc/ada/

* sem_res.adb (Enclosing_Declaration_Or_Statement): Moved to
Sem_Util.
* sem_util.ads (Enclosing_Declaration_Or_Statement): Moved from
Sem_Res.
* sem_util.adb (Enclosing_Declaration_Or_Statement): Likewise.

ada: Clean up unnecesary call in resolution of overloaded expressions

When experimentally enabling frontend inlining by default, the
unnecessary call to Comes_From_Predefined_Lib_Unit in Resolve appears to
be a performance bottleneck (most likely this call is expensive because
it involves a loop over the currently inlined subprograms).

Code cleanup; semantics is unaffected.

gcc/ada/

* sem_res.adb (Resolve): Only call Comes_From_Predefined_Lib_Unit
when its result might be needed.

ada: Clean up code for visibility of generic actuals

Code cleanup related to fixing visibility of actual parameters in
inlining-for-proof in GNATprove mode; semantics is unaffected.

gcc/ada/

* sem_ch12.adb (Check_Generic_Actuals): Remove redundant parens;
refactor an excessive if-statement; remove repeated call to Node.

ada: Cleanup comment about mapping parameters when inlining

Improve location of the comment about a special case for GNATprove mode.

gcc/ada/

* inline.adb (Establish_Actual_Mapping_For_Inlined_Call): Move
comment next to a condition that it describes.

ada: Put_Image aspect spec incorrectly not inherited

In some cases, a Put_Image aspect specification for a scalar type was not
correctly inherited by a descendant of that type.

gcc/ada/

* exp_put_image.adb
(Image_Should_Call_Put_Image): Correctly handle the case of an
inherited Put_Image aspect specification for a scalar type.

ada: Tune layout after switching to Ada 2022 aggregate syntax

Whitespace cleanup only.

gcc/ada/

* libgnarl/s-interr.adb: Tune whitespace.

ada: Cleanup WITH clauses after switching from obsolescent Ada 83 unit

Cleanup after replacing Unchecked_Conversion with
Ada.Unchecked_Conversion.

gcc/ada/

* libgnarl/s-interr.adb: Reorder context items and pragmas.

ada: Create operator nodes in functional style

A recent patch removed two rewritings, where we kept the operator node
but replaced its operands. This patch removes explicit setting of the
operands; instead, the operator is already created together with its
operands, which seems a bit safer and more consistent with how we
typically create operator nodes.

It is a cleanup only; semantics is unaffected.

gcc/ada/

* exp_ch4.adb
(Expand_Modular_Addition): Rewrite using Make_XXX calls.
(Expand_Modular_Op): Likewise.
(Expand_Modular_Subtraction): Likewise.
* exp_imgv.adb
(Expand_User_Defined_Enumeration_Image): Likewise.

ada: Don't reuse operator nodes in expansion

This patch removes handling of references to unset objects that relied
on Original_Node. This handling was only needed because of rewriting
that reused operator nodes, for example, when an array inequality like:

A < B

was rewritten into:

System.Compare_Array_Unsigned_8.Compare_Array_U8
(A'Address, B'Address, A'Length, B'Length) < 0

by keeping the node for operator "<" and only substituting its operands.
It seems safer to simply create an new operator node when rewriting and
not rely on Original_Node afterwards.

Cleanup related to improved detection uninitialized objects.

gcc/ada/

* checks.adb (Apply_Arithmetic_Overflow_Strict): Rewrite using a
newly created operator node.
* exp_ch4.adb (Expand_Array_Comparison): Likewise.
* exp_ch6.adb (Add_Call_By_Copy_Code): Rewriting actual parameter
using its own location and not the location of the subprogram
call.
* sem_warn.adb (Check_References): Looping with Original_Node is
no longer needed.

ada: Simplify detection of pragmas in the context items

Code cleanup; semantics is unaffected.

gcc/ada/

* sem_prag.adb (Is_In_Context_Clause): Rewrite without negations
and inequalities.

ada: Reject misplaced pragma Obsolescent

Pragma Obsolescent appearing before declaration was putting the
Obsolescent flag on the Standard package, which is certainly wrong. The
problem was that we relied on the Find_Lib_Unit_Name routine without
sanitizing the pragma placement with Check_Valid_Library_Unit_Pragma.

Part of cleaning up the warnings machinery to better handle references
to unset objects.

gcc/ada/

* sem_prag.adb (Analyze_Pragma [Pragma_Obsolescent]): Reject
misplaced pragma.

ada: Fix missing tag for with of an obsolescent function

Fix minor inconsistency in tags of warnings about obsolescent entities.

Part of cleaning up the warnings machinery to better handle references
to unset objects.

gcc/ada/

* sem_warn.adb (Output_Obsolescent_Entity_Warnings): Tag warnings
about obsolescent functions just like we tag similar warnings for
packages and procedures.

ada: Remove useless validity suppression for attribute Input

Attributes 'Input and 'Read are similar, but only the 'Read denotes a
subprogram with parameter of mode OUT where operand validity checks need
to be suppressed.

Cleanup related to fix for attributes 'Has_Same_Storage and
'Overlaps_Storage.

gcc/ada/

* exp_attr.adb (Expand_N_Attribute_Reference): Remove useless
skipping for attribute Input.

vect: Fold LEN_{LOAD,STORE} if it's for the whole vector [PR107412]

As the test case in PR107412 shows, we can fold IFN .LEN_{LOAD,
STORE} into normal vector load/store if the given length is known
to be equal to the length of the whole vector. It would help to
improve overall cycles as normally the latency of vector access
with length in bytes is bigger than normal vector access, and it
also saves the preparation for length if constant length can not
be encoded into instruction (such as on power).

PR tree-optimization/107412

gcc/ChangeLog:

* gimple-fold.cc (gimple_fold_mask_load_store_mem_ref): Rename to ...
(gimple_fold_partial_load_store_mem_ref): ... this, add one parameter
mask_p indicating it's for mask or length, and add some handlings for
IFN LEN_{LOAD,STORE}.
(gimple_fold_mask_load): Rename to ...
(gimple_fold_partial_load): ... this, add one parameter mask_p.
(gimple_fold_mask_store): Rename to ...
(gimple_fold_partial_store): ... this, add one parameter mask_p.
(gimple_fold_call): Add the handlings for IFN LEN_{LOAD,STORE},
and adjust calls on gimple_fold_mask_load_store_mem_ref to
gimple_fold_partial_load_store_mem_ref.

gcc/testsuite/ChangeLog:

* gcc.target/powerpc/pr107412.c: New test.
* gcc.target/powerpc/p9-vec-length-epil-8.c: Adjust scan times for
folded LEN_LOAD.