[all-commits] [llvm/llvm-project] 8a1255: [ARM] Improve codegen of volatile load/store of i64

[Victor Campos via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 8a12553223180246eeafaa0fa7bfa11e834d34b6
      https://github.com/llvm/llvm-project/commit/8a12553223180246eeafaa0fa7bfa11e834d34b6
  Author: Victor Campos <victor.campos at arm.com>
  Date:   2020-03-11 (Wed, 11 Mar 2020)

  Changed paths:
    M llvm/lib/Target/ARM/ARMExpandPseudoInsts.cpp
    M llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
    M llvm/lib/Target/ARM/ARMISelLowering.cpp
    M llvm/lib/Target/ARM/ARMISelLowering.h
    M llvm/lib/Target/ARM/ARMInstrInfo.td
    M llvm/lib/Target/ARM/ARMInstrThumb2.td
    A llvm/test/CodeGen/ARM/i64_volatile_load_store.ll

  Log Message:
  -----------
  [ARM] Improve codegen of volatile load/store of i64

Summary:
Instead of generating two i32 instructions for each load or store of a volatile
i64 value (two LDRs or STRs), now emit LDRD/STRD.

These improvements cover architectures implementing ARMv5TE or Thumb-2.

The code generation explicitly deviates from using the register-offset
variant of LDRD/STRD. In this variant, the register allocated to the
register-offset cannot be reused in any of the remaining operands. Such
restriction seems to be non-trivial to implement in LLVM, thus it is
left as a to-do.

Reviewers: dmgreen, efriedma, john.brawn, nickdesaulniers

Reviewed By: efriedma, nickdesaulniers

Subscribers: danielkiss, alanphipps, hans, nathanchance, nickdesaulniers, vvereschaka, kristof.beyls, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70072