RE: [Arm] Implement CDE predicated intrinsics for MVE registers

[Kyrylo Tkachov <Kyrylo.Tkachov@arm.com>]

Hi Matthew,

> -----Original Message-----
> From: Matthew Malcomson <Matthew.Malcomson@arm.com>
> Sent: 08 April 2020 09:32
> To: gcc-patches@gcc.gnu.org
> Cc: Kyrylo Tkachov <Kyrylo.Tkachov@arm.com>; Richard Earnshaw
> <Richard.Earnshaw@arm.com>; Ramana Radhakrishnan
> <Ramana.Radhakrishnan@arm.com>; nickc@redhat.com; nd <nd@arm.com>
> Subject: [Arm] Implement CDE predicated intrinsics for MVE registers
> 
> This is an update of the previous patch but rebased onto recent MVE patches.
> https://gcc.gnu.org/pipermail/gcc-patches/2020-April/543414.html
> 
> These intrinsics are the predicated version of the intrinsics inroduced
> in https://gcc.gnu.org/pipermail/gcc-patches/2020-April/543527.html.
> 
> These are not yet public on developer.arm.com but we have reached
> internal consensus on them.
> 
> The approach follows the same method as for the CDE intrinsics for MVE
> registers, most notably using the same arm_resolve_overloaded_builtin
> function with minor modifications.
> 
> The resolver hook has been moved from arm-builtins.c to arm-c.c so it
> can access the c-common function build_function_call_vec.  This function
> is needed to perform the same checks on arguments as a normal C or C++
> function would perform.
> It is fine to put this resolver in arm-c.c since it's only use is for
> the ACLE functions, and these are only available in C/C++.
> So that the resolver function has access to information it needs from
> the builtins, we put two query functions into arm-builtins.c and use
> them from arm-c.c.
> 
> We rely on the order that the builtins are defined in
> gcc/config/arm/arm_cde_builtins.def, knowing that the predicated
> versions come after the non-predicated versions.
> 
> The machine description patterns for these builtins are simpler than
> those for the non-predicated versions, since the accumulator versions
> *and* non-accumulator versions both need an input vector now.
> The input vector is needed for the non-accumulator version to describe
> the original values for those lanes that are not updated during the
> merge operation.
> 
> We additionally need to introduce qualifiers for these new builtins,
> which follow the same pattern as the non-predicated versions but with an
> extra argument to describe the predicate.
> 
> Error message changes:
> - We directly mention the builtin argument when complaining that an
>   argument is not in the correct range.
>   This more closely matches the C error messages.
> - We ensure the resolver complains about *all* invalid arguments to a
>   function instead of just the first one.
> - The resolver error messages index arguments from 1 instead of 0 to
>   match the arguments coming from the C/C++ frontend.
> 
> In order to allow the user to give an argument for the merging predicate
> when they don't care what data is stored in the 'false' lanes, we also
> move the __arm_vuninitializedq* intrinsics from arm_mve.h to
> arm_mve_types.h which is shared with arm_cde.h.
> 
> We only move the fully type-specified `__arm_vuninitializedq*`
> intrinsics and not the polymorphic versions, since moving the
> polymorphic versions requires moving the _Generic framework as well as
> just the intrinsics we're interested in.  This matches the approach taken
> for the `__arm_vreinterpret*` functions in this include file.
> 
> This patch also contains a slight change in spacing of an existing
> assembly instruction to be emitted.
> This is just to help writing tests -- vmsr usually has a tab and a space
> between the mnemonic and the first argument, but in one case it just has
> a tab -- making all the same helps make test regexps simpler.
> 
> Testing Done:
>     Bootstrap and full regtest on arm-none-linux-gnueabihf
>     Full regtest on arm-none-eabi

Ok once the prerequisites have gone in.
Thanks,
Kyrill

> 
> gcc/ChangeLog:
> 
> 2020-04-08  Matthew Malcomson  <matthew.malcomson@arm.com>
> 
> 	* config/arm/arm-builtins.c (CX_UNARY_UNONE_QUALIFIERS): New.
> 	(CX_BINARY_UNONE_QUALIFIERS): New.
> 	(CX_TERNARY_UNONE_QUALIFIERS): New.
> 	(arm_resolve_overloaded_builtin): Move to arm-c.c.
> 	(arm_expand_builtin_args): Update error message.
> 	(enum resolver_ident): New.
> 	(arm_describe_resolver): New.
> 	(arm_cde_end_args): New.
> 	* config/arm/arm-builtins.h: New file.
> 	* config/arm/arm-c.c (arm_resolve_overloaded_builtin): New.
> 	(arm_resolve_cde_builtin): Moved from arm-builtins.c.
> 	* config/arm/arm_cde.h (__arm_vcx1q_m, __arm_vcx1qa_m,
> 	__arm_vcx2q_m, __arm_vcx2qa_m, __arm_vcx3q_m,
> __arm_vcx3qa_m):
> 	New.
> 	* config/arm/arm_cde_builtins.def (vcx1q_p_, vcx1qa_p_,
> 	vcx2q_p_, vcx2qa_p_, vcx3q_p_, vcx3qa_p_): New builtin defs.
> 	* config/arm/iterators.md (CDE_VCX): New int iterator.
> 	(a) New int attribute.
> 	* config/arm/mve.md (arm_vcx1q<a>_p_v16qi,
> arm_vcx2q<a>_p_v16qi,
> 	arm_vcx3q<a>_p_v16qi): New patterns.
> 	* config/arm/vfp.md (thumb2_movhi_fp16): Extra space in assembly.
> 
> gcc/testsuite/ChangeLog:
> 
> 2020-04-08  Matthew Malcomson  <matthew.malcomson@arm.com>
> 
> 	* gcc.target/arm/acle/cde-errors.c: Add predicated forms.
> 	* gcc.target/arm/acle/cde-mve-error-1.c: Add predicated forms.
> 	* gcc.target/arm/acle/cde-mve-error-2.c: Add predicated forms.
> 	* gcc.target/arm/acle/cde-mve-error-3.c: Add predicated forms.
> 	* gcc.target/arm/acle/cde-mve-full-assembly.c: Add predicated
> 	forms.
> 	* gcc.target/arm/acle/cde-mve-tests.c: Add predicated forms.
> 	* gcc.target/arm/acle/cde_v_1_err.c (test_imm_range): Update for
> 	error message format change.
> 	* gcc.target/arm/mve/intrinsics/vldrwq_gather_base_wb_z_f32.c:
> 	Update scan-assembler regexp.