[PATCH v2] aarch64: Add support for AdvSIMD faminmax

[saurabh.jha@arm.com]

The AArch64 FEAT_FAMINMAX extension is optional from Armv9.2-a and
mandatory from Armv9.5-a. It introduces instructions for computing the
floating point absolute maximum and minimum of the two vectors element-wise.

This patch does three things:
1. Introduces AdvSIMD faminmax intrinsics.
2. Adds code generation support for famax and famin in terms of the
   existing operators.
3. Move report_missing_extension and reported_missing_extension_p to
   make it more usable.

The intrinsics of this extension are implemented as the following
builtin functions:
* vamax_f16
* vamaxq_f16
* vamax_f32
* vamaxq_f32
* vamaxq_f64
* vamin_f16
* vaminq_f16
* vamin_f32
* vaminq_f32
* vaminq_f64

For code generation, famax/famin is equivalent to first taking fabs of
the operands and then taking fmax/fmin of the results of fabs.
	famax/famin (a, b) = fmax/fmin (fabs (a), fabs (b))
This is correct because NaN/Inf handling of famax/famin and fmax/fmin
are same. We cannot use fmaxnm/fminnm here as Nan/Inf are handled
differently in them.

We moved the definition of `report_missing_extension` from
gcc/config/aarch64/aarch64-sve-builtins.cc to
gcc/config/aarch64/aarch64-builtins.cc and its declaration to
gcc/config/aarch64/aarch64-builtins.h. We also moved the declaration
of `reported_missing_extension_p` from
gcc/config/aarch64/aarch64-sve-builtins.cc
to gcc/config/aarch64/aarch64-builtins.cc, closer to the definition of
`report_missing_extension`. In the exsiting code structure, this leads
to `report_missing_extension` being usable from both normal builtins
and sve builtins.

gcc/ChangeLog:

	* config/aarch64/aarch64-builtins.cc
	(enum aarch64_builtins): New enum values for faminmax builtins.
	(aarch64_init_faminmax_builtins): New function to declare new builtins.
	(handle_arm_neon_h): Modify to call aarch64_init_faminmax_builtins.
	(aarch64_general_check_builtin_call): Modify to check whether +faminmax flag is being used and printing error message if not being used.
	(aarch64_expand_builtin_faminmax): New function to emit instructions of this extension.
	(aarch64_general_expand_builtin): Modify to call aarch64_expand_builtin_faminmax.
	(report_missing_extension): Move from config/aarch64/aarch64-sve-builtins.cc.
	* config/aarch64/aarch64-builtins.h
	(report_missing_extension): Declaration for this function so
that it can be used wherever this header is included.
	(reported_missing_extension_p): Move from
config/aarch64/aarch64-sve-builtins.cc
        * config/aarch64/aarch64-option-extensions.def
	(AARCH64_OPT_EXTENSION): Introduce new flag for this extension.
        * config/aarch64/aarch64-simd.md
	(aarch64_<faminmax><mode>): Introduce instruction pattern for this extension.
	* config/aarch64/aarch64-sve-builtins.cc
	(reported_missing_extension_p): Move to config/aarch64/aarch64-builtins.cc
	(report_missing_extension): Move to
config/aarch64/aarch64-builtins.cc.
        * config/aarch64/aarch64.h
	(TARGET_FAMINMAX): Introduce new flag for this extension.
        * config/aarch64/iterators.md: Introduce new iterators for this extension.
        * config/arm/types.md: Introduce neon_fp_aminmax<q> attributes.
        * doc/invoke.texi: Document extension in AArch64 Options.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/simd/faminmax-builtins-no-flag.c: New test.
	* gcc.target/aarch64/simd/faminmax-builtins.c: New test.
	* gcc.target/aarch64/simd/faminmax-codegen-no-flag.c: New test.
	* gcc.target/aarch64/simd/faminmax-codegen.c: New test.

---
Hi,

Regression tested for aarch64-none-linux-gnu and found no regressions.

This is a respin of
https://gcc.gnu.org/pipermail/gcc-patches/2024-August/658968.html
as the previous version failed patchwork CI due to not being able to
apply.

Ok for master? I don't have commit access so can someone please commit
on my behalf?

Regards,
Saurabh
---
 gcc/config/aarch64/aarch64-builtins.cc        | 173 +++++++++++++++++-
 gcc/config/aarch64/aarch64-builtins.h         |   5 +-
 .../aarch64/aarch64-option-extensions.def     |   2 +
 gcc/config/aarch64/aarch64-simd.md            |  12 ++
 gcc/config/aarch64/aarch64-sve-builtins.cc    |  22 ---
 gcc/config/aarch64/aarch64.h                  |   4 +
 gcc/config/aarch64/iterators.md               |   8 +
 gcc/config/arm/types.md                       |   6 +
 gcc/doc/invoke.texi                           |   2 +
 .../aarch64/simd/faminmax-builtins-no-flag.c  |  10 +
 .../aarch64/simd/faminmax-builtins.c          |  75 ++++++++
 .../aarch64/simd/faminmax-codegen-no-flag.c   |  54 ++++++
 .../aarch64/simd/faminmax-codegen.c           | 104 +++++++++++
 13 files changed, 445 insertions(+), 32 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/aarch64/simd/faminmax-builtins-no-flag.c
 create mode 100644 gcc/testsuite/gcc.target/aarch64/simd/faminmax-builtins.c
 create mode 100644 gcc/testsuite/gcc.target/aarch64/simd/faminmax-codegen-no-flag.c
 create mode 100644 gcc/testsuite/gcc.target/aarch64/simd/faminmax-codegen.c

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