[all-commits] [llvm/llvm-project] 30b27e: [AMDGPU] Use new opcode for indexed vgpr reads

[Jay Foad via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 30b27ecfc2516c019209d2ea4b05903548635647
      https://github.com/llvm/llvm-project/commit/30b27ecfc2516c019209d2ea4b05903548635647
  Author: Jay Foad <jay.foad at amd.com>
  Date:   2021-11-19 (Fri, 19 Nov 2021)

  Changed paths:
    M llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
    M llvm/lib/Target/AMDGPU/SIPreEmitPeephole.cpp
    M llvm/lib/Target/AMDGPU/VOP1Instructions.td
    M llvm/test/CodeGen/AMDGPU/amdgpu-codegenprepare-idiv.ll
    M llvm/test/CodeGen/AMDGPU/bypass-div.ll
    M llvm/test/CodeGen/AMDGPU/llvm.mulo.ll
    M llvm/test/CodeGen/AMDGPU/mul_uint24-amdgcn.ll
    M llvm/test/CodeGen/AMDGPU/sdiv64.ll
    M llvm/test/CodeGen/AMDGPU/set-gpr-idx-peephole.mir
    M llvm/test/CodeGen/AMDGPU/srem64.ll
    M llvm/test/CodeGen/AMDGPU/udiv.ll
    M llvm/test/CodeGen/AMDGPU/udiv64.ll
    M llvm/test/CodeGen/AMDGPU/urem64.ll

  Log Message:
  -----------
  [AMDGPU] Use new opcode for indexed vgpr reads

Introduce V_MOV_B32_indirect_read for indexed vgpr reads
(and rename the old V_MOV_B32_indirect to
V_MOV_B32_indirect_write) so they can be unambiguously
distinguished from regular V_MOV_B32_e32. Previously they
were distinguished by looking for extra implicit operands
but this is fragile because regular moves sometimes have
extra implicit operands too:
- either by accident, when instructions end up with
  duplicate implicit operands (see e.g. D100939)
- or by design, when SIInstrInfo::copyPhysReg breaks a
  multi-dword copy into individual subreg mov instructions
  and adds implicit operands for the super-register.

The effect of this is that SIInstrInfo::isFoldableCopy can
be simplified and identifies more foldable copies. The test
diffs show that more immediate 0 values have been folded as
inline operands.

SIInstrInfo::isReallyTriviallyReMaterializable could
probably be simplified too but that is not part of this
patch.

Differential Revision: https://reviews.llvm.org/D114230