<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/126949>126949</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [OMPIRBuilder] - Empty target task proxy function generated by OMPIRBuilder (`emitTargetTaskProxyFunction`)
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            openmp,
            mlir,
            llvm:openmpirbuilder
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          bhandarkar-pranav
      </td>
    </tr>
</table>

<pre>
    Reproducer: 

```
$> mlir-translate -mlir-to-llvmir ${LLVM_PROJECT_DIR}/mlir/test/Target/LLVMIR/omptarget-depend-host-only
$> cat ${LLVM_PROJECT_DIR}/mlir/test/Target/LLVMIR/omptarget-depend-host-only.mlir
// RUN: mlir-translate -mlir-to-llvmir %s | FileCheck %s

module attributes {omp.is_target_device = false} {
  llvm.func @omp_target_depend_() {
    %0 = llvm.mlir.constant(39 : index) : i64
    %1 = llvm.mlir.constant(1 : index) : i64
    %2 = llvm.mlir.constant(40 : index) : i64
    %3 = omp.map.bounds lower_bound(%1 : i64) upper_bound(%0 : i64) extent(%2 : i64) stride(%1 : i64) start_idx(%1 : i64)
    %4 = llvm.mlir.addressof @_QFEa : !llvm.ptr
    %5 = omp.map.info var_ptr(%4 : !llvm.ptr, !llvm.array<40 x i32>) map_clauses(from) capture(ByRef) bounds(%3) -> !llvm.ptr {name = "a"}
    omp.target depend(taskdependin -> %4 : !llvm.ptr) map_entries(%5 -> %arg0 : !llvm.ptr) {
      %6 = llvm.mlir.constant(100 : index) : i32
 llvm.store %6, %arg0 : i32, !llvm.ptr
      omp.terminator
    }
 llvm.return
  }

  llvm.mlir.global internal @_QFEa() {addr_space = 0 : i32} : !llvm.array<40 x i32> {
    %0 = llvm.mlir.zero : !llvm.array<40 x i32>
    llvm.return %0 : !llvm.array<40 x i32>
  }
}

// CHECK: define void @omp_target_depend_()
// CHECK-NOT: define {{.*}} @
// CHECK-NOT: call i32 @__tgt_target_kernel({{.*}})
// CHECK: call void @__omp_offloading_[[DEV:.*]]_[[FIL:.*]]_omp_target_depend__l[[LINE:.*]](ptr {{.*}})
// CHECK-NEXT: ret void

// CHECK: define internal void @__omp_offloading_[[DEV]]_[[FIL]]_omp_target_depend__l[[LINE]](ptr %[[ADDR_A:.*]])
// CHECK: store i32 100, ptr %[[ADDR_A]], align 4
```
Two problems in the output

1. Empty target task proxy function `@.omp_target_task_proxy_func`
```
define internal void @.omp_target_task_proxy_func(i32 %thread.id, ptr %task) {
entry:
  ret void
}

```
2. After 1 is fixed, we'll end up with dual execution of the kernel because we hit a corner case (single basic block task bodies) in `OpenMPIRBuilder::OutlineInfo::collectBlocks` such that the entire task body is not outlined in the target task.
```
codeRepl: ; preds = %entry
  %omp_global_thread_num = call i32 @__kmpc_global_thread_num(ptr @2)
  %5 = call ptr @__kmpc_omp_task_alloc(ptr @2, i32 %omp_global_thread_num, i32 0, i64 40, i64 0, ptr @.omp_target_task_proxy_func)
  call void @__kmpc_omp_wait_deps(ptr @2, i32 %omp_global_thread_num, i32 1, ptr %.dep.arr.addr, i32 0, ptr null)
  call void @__kmpc_omp_task_begin_if0(ptr @2, i32 %omp_global_thread_num, ptr %5)
 call void @.omp_target_task_proxy_func(i32 %omp_global_thread_num, ptr %5) ;;;  first execution of the kernel once problem 1 is fixed.
  call void @__kmpc_omp_task_complete_if0(ptr @2, i32 %omp_global_thread_num, ptr %5)
 br label %target.task.body

target.task.body: ; preds = %codeRepl
  call void @__omp_offloading_10307_a581555_omp_target_depend__l11(ptr @_QFEa) ;;;; Second execution of the kernel when problem 1 is fixed
  ret void
}

```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJy0V01v67oR_TX0hrAhUZI_Fl74E017382rmz50J1DSyGZDkQJJJXF_fTGUbMuOE9-2KGAgETln5szhzFDi1oq9ApiTZEmS9YA37qDNPDtwVXDzys2wNlzxt0Gmi-N8B7XRRZODIdGCkmCBv3HQ_YIFYTGJNrSSwgyd4cpK7oAO22c9lPKtEoai1WT548cfv6W_757_vFm9pOunHZmsCduiKWFbB9YRtn3hZg_4Dxo_7Qjb6qp2fnFYQA2qGB60dUOt5PESPufu_xRj5KEYaEvYlu7-_hN1eJhuYimZrOhWSFgdIH_1S616lS4aCZQ7Z0TWOEDLpa7qkbBpSyIt4E3kQEm0piWXFshkjUYkWFCKIUZlo3JK4kBX9QWDxFPCpoTNztYUAwfekwci0VGulXVcOcKm0YxiPkIV8OFx-DCOL9jwa2z4AMq-hsbBA2zksahKxetRphtVWCr1O5jUP_g0k_AMZDPa1PX1btDfhQ8HPnRH7LxhnREF3PFnHTcuFcXH570Lz_gmR14UBqzVJZ5O-tfthnsYYaG3qZ25YJOrHIUqNX3jJkUbHzH-BGWr8yM3hh9JtIoD-kFFxEi0QdIVr9Nc8saCJWxaGl3has5r1xhMcnncQYlLraRtoAgXhthHvWBYQopXbRUSxjhhDJuppY-s28KjbeERNnXcvrYPQp3c3UuiZQnKGQEdg-Rsz80-uAe5FLTXbvxNWQb3iitiCPcA67QB76QV9BITrXoaX06rSxhMJRR3-nyIrR7e2IBrjPIb7fKlWz3DvdQZl1QoB0Zxea6PS8Ni7aS25l3nXyhh9_cUuXP03_f7v8DoRx46dC8Vem6hR7Au31PW3ahc_Wmz-gvCCyiFAvqmRfHdzLpBDn8-v_TQmOBkOSLMx0FF4uALRM6lRHpe4tTt3SncKxgFEqPdOPsc_eznxDpNkbcuS6l5IdQ-9bfncr35g0QL7ylZk2TdLW-fflwvf046la3pj6efmytbwqZd-z3gOPy5-YdP2IDzPL-V_1x4v5DRbSq_lMMVeZa0O4v1epcubvK7J3bblHhqYRBgE95z0-FXlEuxVzS-eRd5ede0NjqTUFkqFHUHoLpxdeNaZcIR3VS1O9JucuHAQsDHkeKF6oRWFD3FwaiXK1ql3ipFq-61pxf2K4G_c8KmvkBZ4g4GeDESRS9nNL7MPByURxK186R_1Od-63FhI7ooHRgaUmFpKT7AO34HwiZSUlAFbWr6LtyBFg2XFD4gb3ziuvR6tT1CM8jxEqHvQA_CUU5zbRQYmnOLo3NqhdpLoBm3IqeZ1Plrq2amCz_UZ6g_GQfPNajffn_aLRshC_8OSaLFc-OkUPCkSt0u5FpKyN0S_VgyDqht8gN1B-48J1BOGDgHOGJqSjs8W_RTnM66d6yjG11yXcAOaunHWbSktYHCdldb0irsJxlL8NDaWZ22Z5OqpvKW13Pltarzz4an-o8DdnpPON_0Ht_tdvi2QuxryqXU-RV4RbsKuUvotO9bRYxjGp__u3TPgxJs6d1MuTOtdy58n9v_glXYK-ZRATXeHP7V6Io2GqhGykdMPPEM9kKlogz-Qzodi6QLchXjlxr0VzxjSbU_SkthrPuyr7TK4TSjej06eixArqtagoP_XYPMUMkzkO2owexHvmWwtdqJ8mn1XtecW-oO9ZubJQyiYJLyZBomSXL3HgnDS07da1FPVYz9N8i1Kr4U9v0A6o6wj4fmoJhHxSya8QHMw0k0i6ZsMp0NDvNyOg7GcRBDNJtmBSuChEfTYAxBOA2m0xgGYs4ClgQsZOEkiYLZiGVlGTIe8zJMZhkLSRxAxYUc-bcnbfYDYW0D85CNZ_Fs4A_B-s9wxnQNqqrxHZutCGPtB2v3gHASLVoTYbJuljKGn-9mjtvDrNlbEgdSWGcv8Zxw0n_oP_eHcLKmw8c34R4UGO6goNmR9vE4_8k4gEq49kv6hdvX3xG87bCoLJsNGiPnB-dqi1Pe3_d74Q5NNsrxs2Tr02r_DGuj_wk5fpN7iSxh206ltzn7dwAAAP__tDQLxg">