[PATCH v2 0/3] RISC-V: Support ZC* extensions.

[Jiawei <jiawei@iscas.ac.cn>]

RISC-V Code Size Reduction(ZC*) extensions is a group of extensions 
which define subsets of the existing C extension (Zca, Zcd, Zcf) and new
extensions(Zcb, Zcmp, Zcmt) which only contain 16-bit encodings.[1]

The implementation of the RISC-V Code Size Reduction extension in GCC is
an important step towards making the RISC-V architecture more efficient.

The cooperation with OpenHW group has played a crucial role in this effort,
with facilitating the implementation, testing and validation. Currently
works can also find in OpenHW group's github repo.[2]

Thanks to Tariq Kurd, Ibrahim Abu Kharmeh for help with explain the 
specification, and Jeremy Bennett's patient guidance throughout the whole 
development process.a

V2 changes:
Fix Kito's comments in first version, Eswin assisted in optimizing the implementation of Zcmp extension:
https://gcc.gnu.org/pipermail/gcc-patches/2023-May/617440.html
https://gcc.gnu.org/pipermail/gcc-patches/2023-May/617442.html

https://gcc.gnu.org/pipermail/gcc-patches/2023-June/620869.html


[1] github.com/riscv/riscv-code-size-reduction/tree/main/Zc-specification

[2] github.com/openhwgroup/corev-gcc

Co-Authored by: Charlie Keaney <charlie.keaney@embecosm.com>
Co-Authored by: Mary Bennett <mary.bennett@embecosm.com>
Co-Authored by: Nandni Jamnadas <nandni.jamnadas@embecosm.com>
Co-Authored by: Sinan Lin <sinan.lin@linux.alibaba.com>
Co-Authored by:	Simon Cook <simon.cook@embecosm.com>
Co-Authored by: Shihua Liao <shihua@iscas.ac.cn>
Co-Authored by: Yulong Shi <yulong@iscas.ac.cn>

  RISC-V: Minimal support for ZC extensions.
  RISC-V: Enable compressible features when use ZC* extensions.
  RISC-V: Add ZC* test for march args being passed.


Jiawei (3):
  RISC-V: Minimal support for ZC* extensions.
  RISC-V: Enable compressible features when use ZC* extensions.
  RISC-V: Add ZC* test for failed march args being passed.

 gcc/common/config/riscv/riscv-common.cc   | 38 +++++++++++++++++++++++
 gcc/config/riscv/riscv-c.cc               |  2 +-
 gcc/config/riscv/riscv-opts.h             | 16 ++++++++++
 gcc/config/riscv/riscv-shorten-memrefs.cc |  3 +-
 gcc/config/riscv/riscv.cc                 | 11 ++++---
 gcc/config/riscv/riscv.h                  |  2 +-
 gcc/config/riscv/riscv.opt                |  3 ++
 gcc/testsuite/gcc.target/riscv/arch-22.c  |  5 +++
 gcc/testsuite/gcc.target/riscv/arch-23.c  |  5 +++
 9 files changed, 78 insertions(+), 7 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/riscv/arch-22.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/arch-23.c

-- 
2.25.1