[PATCH] D74044: [ARM] Add initial support for Custom Datapath Extension (CDE)

[Mikhail Maltsev via Phabricator via cfe-commits]

miyuki created this revision.
miyuki added reviewers: simon_tatham, ostannard, dmgreen, eli.friedman.
Herald added subscribers: llvm-commits, cfe-commits, hiraditya, kristof.beyls.
Herald added projects: clang, LLVM.

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).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D74044

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

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