[RFC PATCH v1 00/10] RISC-V: Support the Zicond (conditional-operations) extension

[Philipp Tomsich <philipp.tomsich@vrull.eu>]

The (proposed, but about to be frozen) Zicond extension adds 2
unconditional R-type instructions that can be used to build branchless
sequences that have conditional-arithmetic/bitwise/select semantics
and integrate will with the RISC-V architecture.

See the Zicond specification for details:
  https://github.com/riscv/riscv-zicond/releases/download/v1.0-draft-20230207/riscv-zicond_1.0-draft-20230207.pdf

The Zicond extension defines a conditional-zero(-or-value)
instruction, which is similar to the following C construct:
  rd = rc ? rs : 0

This functionality can be tied back into if-convertsion and also
matches some typical programming idioms.  This series includes backend
support for Zicond both to handle conditional-zero constructions and
if-conversion.  We also change the previously submitted
XVentanaCondops support to use the Zicond infrastructure.

Tested against SPEC CPU 2017.



Philipp Tomsich (10):
  docs: Document a canonical RTL for a conditional-zero insns
  RISC-V: Recognize Zicond (conditional operations) extension
  RISC-V: Generate czero.eqz/nez on noce_try_store_flag_mask
    if-conversion
  RISC-V: Support immediates in Zicond
  RISC-V: Support noce_try_store_flag_mask as czero.eqz/czero.nez
  RISC-V: Recognize sign-extract + and cases for czero.eqz/nez
  RISC-V: Recognize bexti in negated if-conversion
  ifcvt: add if-conversion to conditional-zero instructions
  RISC-V: Recognize xventanacondops extension
  RISC-V: Support XVentanaCondOps extension

 gcc/common/config/riscv/riscv-common.cc       |   5 +
 gcc/config/riscv/predicates.md                |  12 +
 gcc/config/riscv/riscv-opts.h                 |   5 +
 gcc/config/riscv/riscv.cc                     |  15 ++
 gcc/config/riscv/riscv.md                     |  28 +++
 gcc/config/riscv/riscv.opt                    |   3 +
 gcc/config/riscv/xventanacondops.md           |  29 +++
 gcc/config/riscv/zicond.md                    | 156 +++++++++++++
 gcc/doc/md.texi                               |  17 ++
 gcc/ifcvt.cc                                  | 216 ++++++++++++++++++
 .../gcc.target/riscv/xventanacondops-and-01.c |  16 ++
 .../gcc.target/riscv/xventanacondops-and-02.c |  15 ++
 .../gcc.target/riscv/xventanacondops-eq-01.c  |  11 +
 .../gcc.target/riscv/xventanacondops-eq-02.c  |  14 ++
 .../riscv/xventanacondops-ifconv-imm.c        |  19 ++
 .../gcc.target/riscv/xventanacondops-le-01.c  |  16 ++
 .../gcc.target/riscv/xventanacondops-le-02.c  |  11 +
 .../gcc.target/riscv/xventanacondops-lt-01.c  |  16 ++
 .../gcc.target/riscv/xventanacondops-lt-03.c  |  16 ++
 .../gcc.target/riscv/xventanacondops-ne-01.c  |  10 +
 .../gcc.target/riscv/xventanacondops-ne-03.c  |  13 ++
 .../gcc.target/riscv/xventanacondops-ne-04.c  |  13 ++
 .../gcc.target/riscv/xventanacondops-xor-01.c |  14 ++
 .../gcc.target/riscv/zicond-and-01.c          |  16 ++
 .../gcc.target/riscv/zicond-and-02.c          |  15 ++
 gcc/testsuite/gcc.target/riscv/zicond-eq-01.c |  11 +
 gcc/testsuite/gcc.target/riscv/zicond-eq-02.c |  14 ++
 .../gcc.target/riscv/zicond-ifconv-imm.c      |  19 ++
 gcc/testsuite/gcc.target/riscv/zicond-le-01.c |  16 ++
 gcc/testsuite/gcc.target/riscv/zicond-le-02.c |  11 +
 gcc/testsuite/gcc.target/riscv/zicond-lt-01.c |  16 ++
 gcc/testsuite/gcc.target/riscv/zicond-lt-03.c |  16 ++
 gcc/testsuite/gcc.target/riscv/zicond-ne-01.c |  10 +
 gcc/testsuite/gcc.target/riscv/zicond-ne-03.c |  13 ++
 gcc/testsuite/gcc.target/riscv/zicond-ne-04.c |  13 ++
 .../gcc.target/riscv/zicond-xor-01.c          |  14 ++
 36 files changed, 854 insertions(+)
 create mode 100644 gcc/config/riscv/xventanacondops.md
 create mode 100644 gcc/config/riscv/zicond.md
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-and-01.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-and-02.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-eq-01.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-eq-02.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-ifconv-imm.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-le-01.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-le-02.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-lt-01.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-lt-03.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-ne-01.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-ne-03.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-ne-04.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/xventanacondops-xor-01.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-and-01.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-and-02.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-eq-01.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-eq-02.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-ifconv-imm.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-le-01.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-le-02.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-lt-01.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-lt-03.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-ne-01.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-ne-03.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-ne-04.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-xor-01.c

-- 
2.34.1