[all-commits] [llvm/llvm-project] 70eab1: [AArch64][MachinePipeliner] Add pipeliner support ...

[Yuta Mukai via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 70eab122bceb94b15218c86db7045ff2448ea979
      https://github.com/llvm/llvm-project/commit/70eab122bceb94b15218c86db7045ff2448ea979
  Author: Yuta Mukai <mukai.yuta at fujitsu.com>
  Date:   2024-02-02 (Fri, 02 Feb 2024)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
    M llvm/lib/Target/AArch64/AArch64InstrInfo.h
    M llvm/lib/Target/AArch64/AArch64Subtarget.cpp
    M llvm/lib/Target/AArch64/AArch64Subtarget.h
    M llvm/lib/Target/AArch64/AArch64TargetMachine.cpp
    A llvm/test/CodeGen/AArch64/sms-acceptable-loop1.mir
    A llvm/test/CodeGen/AArch64/sms-acceptable-loop2.mir
    A llvm/test/CodeGen/AArch64/sms-acceptable-loop3.mir
    A llvm/test/CodeGen/AArch64/sms-acceptable-loop4.mir
    A llvm/test/CodeGen/AArch64/sms-unacceptable-loop1.mir
    A llvm/test/CodeGen/AArch64/sms-unacceptable-loop2.mir
    A llvm/test/CodeGen/AArch64/sms-unpipeline-insts1.mir
    A llvm/test/CodeGen/AArch64/sms-unpipeline-insts2.mir

  Log Message:
  -----------
  [AArch64][MachinePipeliner] Add pipeliner support for AArch64 (#79589)

Add AArch64 implementations for the interfaces of MachinePipeliner pass.
The pass is disabled by default for AArch64. It is enabled by specifying
--aarch64-enable-pipeliner.

5 tests in llvm-test-suites show performance improvement by more than 5%
on a Neoverse V1 processor.

| test | improvement |
| ---------------------------------------------------------------- |
-----------:|
| MultiSource/Benchmarks/TSVC/Recurrences-dbl/Recurrences-dbl.test | 16%
|
| MultiSource/Benchmarks/TSVC/Recurrences-dbl/Recurrences-flt.test | 16%
|
| SingleSource/Benchmarks/Adobe-C++/loop_unroll.test | 14% |
| SingleSource/Benchmarks/Misc/flops-5.test | 13% |
| SingleSource/Benchmarks/BenchmarkGame/spectral-norm.test | 6% |

(base flags: -mcpu=neoverse-v1 -O3 -mrecip, flags for pipelining: -mllvm
-aarch64-enable-pipeliner -mllvm
-pipeliner-max-stages=100 -mllvm -pipeliner-max-mii=100 -mllvm
-pipeliner-enable-copytophi=0)

On the other hand, there are cases of significant performance
degradation. Algorithm improvements and adding the option/pragma will be
needed in the future.