[all-commits] [llvm/llvm-project] dd4d09: [ARM] Add initial support for Custom Datapath Exte...

[Mikhail Maltsev via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: dd4d09376209cdc5615097a5be92105f55d06f5d
      https://github.com/llvm/llvm-project/commit/dd4d09376209cdc5615097a5be92105f55d06f5d
  Author: Mikhail Maltsev <mikhail.maltsev at arm.com>
  Date:   2020-02-17 (Mon, 17 Feb 2020)

  Changed paths:
    A clang/test/Driver/arm-cde.c
    M llvm/include/llvm/Support/ARMTargetParser.def
    M llvm/include/llvm/Support/ARMTargetParser.h
    M llvm/lib/Target/ARM/ARM.td
    A llvm/lib/Target/ARM/ARMInstrCDE.td
    M llvm/lib/Target/ARM/ARMInstrInfo.td
    M llvm/lib/Target/ARM/ARMPredicates.td
    M llvm/lib/Target/ARM/ARMRegisterInfo.td
    M llvm/lib/Target/ARM/ARMSubtarget.h
    M llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
    M llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
    M llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp
    M llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h
    A llvm/test/MC/ARM/cde-fp-vec.s
    A llvm/test/MC/ARM/cde-integer.s
    A llvm/test/MC/ARM/cde-vec-pred.s
    A llvm/test/MC/Disassembler/ARM/cde-fp-vec.txt
    A llvm/test/MC/Disassembler/ARM/cde-integer.txt
    A llvm/test/MC/Disassembler/ARM/cde-vec-pred.txt

  Log Message:
  -----------
  [ARM] Add initial support for Custom Datapath Extension (CDE)

Summary:
This patch adds assembly-level support for a new Arm M-profile
architecture extension, Custom Datapath Extension (CDE).

A brief description of the extension is available at
https://developer.arm.com/architectures/instruction-sets/custom-instructions

The latest specification for CDE is currently a beta release and is
available at
https://static.docs.arm.com/ddi0607/aa/DDI0607A_a_armv8m_arm_supplement_cde.pdf

CDE allows chip vendors to add custom CPU instructions.  The CDE
instructions re-use the same encoding space as existing coprocessor
instructions (such as MRC, MCR, CDP etc.). Each coprocessor in range
cp0-cp7 can be configured as either general purpose (GCP) or custom
datapath (CDEv1).  This configuration is defined by the CPU vendor and
is provided to LLVM using 8 subtarget features: cdecp0 ... cdecp7.

The semantics of CDE instructions are implementation-defined, but the
instructions are guaranteed to be pure (that is, they are stateless,
they do not access memory or any registers except their explicit
inputs/outputs).

CDE requires the CPU to support at least Armv8.0-M mainline
architecture. CDE includes 3 sets of instructions:
* Instructions that operate on general purpose registers and NZCV
  flags
* Instructions that operate on the S or D register file (require
  either FP or MVE extension)
* Instructions that operate on the Q register file, require MVE

The user-facing names that can be specified on the command line are
the same as the 8 subtarget feature names. For example:

    $ clang -target arm-none-none-eabi -march=armv8m.main+cdecp0+cdecp3

tells the compiler that the coprocessors 0 and 3 are configured as
CDEv1 and the remaining coprocessors are configured as GCP (which is
the default).

Reviewers: simon_tatham, ostannard, dmgreen, eli.friedman

Reviewed By: simon_tatham

Subscribers: kristof.beyls, hiraditya, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D74044