RE: [PATCH 00/22] arm: New framework for MVE intrinsics

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

Hi Christophe,

> -----Original Message-----
> From: Christophe Lyon <christophe.lyon@arm.com>
> Sent: Tuesday, April 18, 2023 2:46 PM
> To: gcc-patches@gcc.gnu.org; Kyrylo Tkachov <Kyrylo.Tkachov@arm.com>;
> Richard Earnshaw <Richard.Earnshaw@arm.com>; Richard Sandiford
> <Richard.Sandiford@arm.com>
> Cc: Christophe Lyon <Christophe.Lyon@arm.com>
> Subject: [PATCH 00/22] arm: New framework for MVE intrinsics
> 
> Hi,
> 
> This is the beginning of a long patch series to change the way Arm MVE
> intrinsics are implemented. The goal is to get rid of arm_mve.h, which
> takes a long time to parse and compile.
> 

Thanks for doing this. It is a significant improvement to the MVE intrinsics and should address some of the biggest maintainability and scalability issues we have in that area.
I'll be going through the patches one-by-one (I've looked at these offline already before), but the approach looks good to me at a high level.

My hope is that we'll move all the intrinsics, including the Neon ones to use this framework in the future, but getting the framework in place first is a good major first step in that direction.

Thanks,
Kyrill

> Roughly speaking, it's about using a framework very similar to what is
> implemented for AArch64/SVE intrinsics. I haven't converted all the
> intrinsics yet, but I think it would be good to start the conversion
> when stage-1 reopens.
> 
> * Factorizing names
> One of the main implementation differences I noticed between SVE and
> MVE is that mve.md provides only full builtin names at the moment, and
> makes almost no use of "parameterized names"
> (https://gcc.gnu.org/onlinedocs/gccint/Parameterized-
> Names.html#Parameterized-Names).
> 
> Without this, we'd need the builtin expander to use a large
> switch/case of the form:
> 
> switch (code)
> case VADDQ_S: insn_code = code_for_mve_vaddq_s (...)
> case VADDQ_U: insn_code = code_for_mve_vaddq_u (...)
> case VSUBQ_S: insn_code = code_for_mve_vsubq_s (...)
> case VSUBQ_U: insn_code = code_for_mve_vsubq_u (...)
> ....
> 
> so part of the work (which I called "factorize" in the commit
> messages) is about replacing
> 
> (define_insn "mve_vaddq_n_<supf><mode>"
> with
> (define_insn "@mve_<mve_insn>q_n_<supf><mode>"
> with the help of a new iterator (mve_insn).
> 
> Doing so makes it more obvious that some patterns are identical,
> except for the instruction name. I took this opportunity to merge
> them, so for instance I have a patch which merges add, sub and mul
> patterns.  Although not strictly necessary for the MVE intrinsics
> restructuring work, this is a good opportunity to reduce such code
> duplication (I did notice a few bugs during that process, which led me
> to post a few small patches in the past months).  Note that identical
> patterns will probably remain after the series, they can be merged
> later if we want.
> 
> This factorization also implies the introduction of new iterators, but
> also means that several existing ones become useless. These patches do
> not remove them because it's a bit painful to reorder patches which
> remove lines at some "random" places, leading to merge conflicts. It's
> much simpler to write a big cleanup patch at the end of the serie to
> remove all such useless iterators at once.
> 
> * Intrinsic re-implementation
> After intrinsic names have been factorized, the actual
> re-implementation patch is small:
> - add 1 line in each of arm-mve-builtins-base.{cc,def,h} describing
>   the intrinsic shape/signature, types and predicates involved,
>   RTX/unspec codes
> - remove the intrinsic definitions from arm_mve.h
> 
> The full series of ~140 patches is organized like this:
> - patches 1 and 2 introduce the new framework
> - new implementation of vreinterpretq
> - new implementation of vuninitialized
> - patch groups of varying size, consisting in:
>   - add a new "shape" if needed (e.g. unary, binary, ternary, ....)
>   - add framework support functions if needed
>   - factorize a set of intrinsics (at minimum, just make use of
>     parameterized-names)
>   - actual re-implementation of the intrinsics
> 
> I kept patches small so the incremental progress is easy to follow and
> check.  I'll submit the patches in small groups, this first one will
> make sure we agree on the implementation.
> 
> Tested on arm-eabi with -mthumb/-mfloat-abi=hard/-march=armv8.1-
> m.main+mve.
> 
> To help reviewers, I suggest to compare arm-mve-builtins.cc with
> aarch64-sve-builtins.cc.
> 
> Christophe Lyon (22):
>   arm: move builtin function codes into general numberspace
>   arm: [MVE intrinsics] Add new framework
>   arm: [MVE intrinsics] Rework vreinterpretq
>   arm: [MVE intrinsics] Rework vuninitialized
>   arm: [MVE intrinsics] add binary_opt_n shape
>   arm: [MVE intrinsics] add unspec_based_mve_function_exact_insn
>   arm: [MVE intrinsics] factorize vadd vsubq vmulq
>   arm: [MVE intrinsics] rework vaddq vmulq vsubq
>   arm: [MVE intrinsics] add binary shape
>   arm: [MVE intrinsics] factorize vandq veorq vorrq vbicq
>   arm: [MVE intrinsics] rework vandq veorq
>   arm: [MVE intrinsics] add binary_orrq shape
>   arm: [MVE intrinsics] rework vorrq
>   arm: [MVE intrinsics] add unspec_mve_function_exact_insn
>   arm: [MVE intrinsics] add create shape
>   arm: [MVE intrinsics] factorize vcreateq
>   arm: [MVE intrinsics] rework vcreateq
>   arm: [MVE intrinsics] factorize several binary_m operations
>   arm: [MVE intrinsics] factorize several binary _n operations
>   arm: [MVE intrinsics] factorize several binary _m_n operations
>   arm: [MVE intrinsics] factorize several binary operations
>   arm: [MVE intrinsics] rework vhaddq vhsubq vmulhq vqaddq vqsubq
>     vqdmulhq vrhaddq vrmulhq
> 
>  gcc/config.gcc                                |    2 +-
>  gcc/config/arm/arm-builtins.cc                |  237 +-
>  gcc/config/arm/arm-builtins.h                 |    1 +
>  gcc/config/arm/arm-c.cc                       |   42 +-
>  gcc/config/arm/arm-mve-builtins-base.cc       |  163 +
>  gcc/config/arm/arm-mve-builtins-base.def      |   50 +
>  gcc/config/arm/arm-mve-builtins-base.h        |   47 +
>  gcc/config/arm/arm-mve-builtins-functions.h   |  387 +
>  gcc/config/arm/arm-mve-builtins-shapes.cc     |  529 ++
>  gcc/config/arm/arm-mve-builtins-shapes.h      |   47 +
>  gcc/config/arm/arm-mve-builtins.cc            | 2013 ++++-
>  gcc/config/arm/arm-mve-builtins.def           |   40 +-
>  gcc/config/arm/arm-mve-builtins.h             |  672 +-
>  gcc/config/arm/arm-protos.h                   |   24 +
>  gcc/config/arm/arm.cc                         |   27 +
>  gcc/config/arm/arm_mve.h                      | 7581 +----------------
>  gcc/config/arm/arm_mve_builtins.def           |    6 -
>  gcc/config/arm/arm_mve_types.h                | 1430 ----
>  gcc/config/arm/iterators.md                   |  240 +-
>  gcc/config/arm/mve.md                         | 1747 +---
>  gcc/config/arm/predicates.md                  |    4 +
>  gcc/config/arm/t-arm                          |   32 +-
>  gcc/config/arm/unspecs.md                     |    1 +
>  gcc/config/arm/vec-common.md                  |    8 +-
>  gcc/testsuite/g++.target/arm/mve.exp          |    8 +-
>  .../arm/mve/general-c++/nomve_fp_1.c          |   15 +
>  .../arm/mve/general-c++/vreinterpretq_1.C     |   25 +
>  .../gcc.target/arm/mve/general-c/nomve_fp_1.c |   15 +
>  .../arm/mve/general-c/vreinterpretq_1.c       |   25 +
>  29 files changed, 4926 insertions(+), 10492 deletions(-)
>  create mode 100644 gcc/config/arm/arm-mve-builtins-base.cc
>  create mode 100644 gcc/config/arm/arm-mve-builtins-base.def
>  create mode 100644 gcc/config/arm/arm-mve-builtins-base.h
>  create mode 100644 gcc/config/arm/arm-mve-builtins-functions.h
>  create mode 100644 gcc/config/arm/arm-mve-builtins-shapes.cc
>  create mode 100644 gcc/config/arm/arm-mve-builtins-shapes.h
>  create mode 100644 gcc/testsuite/g++.target/arm/mve/general-
> c++/nomve_fp_1.c
>  create mode 100644 gcc/testsuite/g++.target/arm/mve/general-
> c++/vreinterpretq_1.C
>  create mode 100644 gcc/testsuite/gcc.target/arm/mve/general-
> c/nomve_fp_1.c
>  create mode 100644 gcc/testsuite/gcc.target/arm/mve/general-
> c/vreinterpretq_1.c
> 
> --
> 2.34.1