llvm/test/CodeGen/AMDGPU/merge-load-store.mir

# RUN: llc -march=amdgcn -verify-machineinstrs -run-pass si-load-store-opt -o - %s | FileCheck %s

# Check that SILoadStoreOptimizer honors memory dependencies between moved
# instructions.
#
# The following IR snippet would usually be optimized by the peephole optimizer.
# However, an equivalent situation can occur with buffer instructions as well.

# CHECK-LABEL: name: mem_dependency
# CHECK: DS_READ2_B32 %0, 0, 1,
# CHECK: DS_WRITE_B32 %0, killed %1, 64,
# CHECK: DS_READ2_B32 %0, 16, 17,
# CHECK: DS_WRITE_B32 killed %0, %5, 0

--- |
  define amdgpu_kernel void @mem_dependency(i32 addrspace(3)* %ptr.0) nounwind {
    %ptr.4 = getelementptr i32, i32 addrspace(3)* %ptr.0, i32 1
    %ptr.64 = getelementptr i32, i32 addrspace(3)* %ptr.0, i32 16
    %1 = load i32, i32 addrspace(3)* %ptr.0
    store i32 %1, i32 addrspace(3)* %ptr.64
    %2 = load i32, i32 addrspace(3)* %ptr.64
    %3 = load i32, i32 addrspace(3)* %ptr.4
    %4 = add i32 %2, %3
    store i32 %4, i32 addrspace(3)* %ptr.0
    ret void
  }
...
---
name:            mem_dependency
alignment:       0
exposesReturnsTwice: false
legalized:       false
regBankSelected: false
selected:        false
tracksRegLiveness: true
liveins:
  - { reg: '$vgpr0', virtual-reg: '%1' }
frameInfo:
  isFrameAddressTaken: false
  isReturnAddressTaken: false
  hasStackMap:     false
  hasPatchPoint:   false
  stackSize:       0
  offsetAdjustment: 0
  maxAlignment:    0
  adjustsStack:    false
  hasCalls:        false
  maxCallFrameSize: 0
  hasOpaqueSPAdjustment: false
  hasVAStart:      false
  hasMustTailInVarArgFunc: false
body:             |
  bb.0:
    liveins: $vgpr0

    %1:vgpr_32 = COPY $vgpr0
    $m0 = S_MOV_B32 -1
    %2:vgpr_32 = DS_READ_B32 %1, 0, 0, implicit $m0, implicit $exec :: (load 4 from %ir.ptr.0)
    DS_WRITE_B32 %1, killed %2, 64, 0, implicit $m0, implicit $exec :: (store 4 into %ir.ptr.64)

    ; Make this load unmergeable, to tempt SILoadStoreOptimizer into merging the
    ; other two loads.
    %6:vreg_64 = DS_READ2_B32 %1, 16, 17, 0, implicit $m0, implicit $exec :: (load 8 from %ir.ptr.64, align 4)
    %3:vgpr_32 = COPY %6.sub0
    %4:vgpr_32 = DS_READ_B32 %1, 4, 0, implicit $m0, implicit $exec :: (load 4 from %ir.ptr.4)
    %5:vgpr_32 = V_ADD_I32_e32 killed %3, killed %4, implicit-def $vcc, implicit $exec
    DS_WRITE_B32 killed %1, %5, 0, 0, implicit killed $m0, implicit $exec :: (store 4 into %ir.ptr.0)
    S_ENDPGM

...