[OpenMP][OMPIRBuilder] Fix LLVM IR codegen for collapsed device loop

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

@@ -2876,9 +2876,10 @@ OpenMPIRBuilder::applyWorkshareLoopTarget(DebugLoc DL, CanonicalLoopInfo *CLI,
   // We need to model loop body region as the function f(cnt, loop_arg).
   // That's why we replace loop induction variable by the new counter
   // which will be one of loop body function argument
-  for (auto Use = CLI->getIndVar()->user_begin();
-       Use != CLI->getIndVar()->user_end(); ++Use) {
-    if (Instruction *Inst = dyn_cast<Instruction>(*Use)) {
+  SmallVector<User *> Users(CLI->getIndVar()->user_begin(),
+                            CLI->getIndVar()->user_end());
+  for (auto Use : Users) {
+    if (Instruction *Inst = dyn_cast<Instruction>(Use)) {
       if (ParallelRegionBlockSet.count(Inst->getParent())) {
         Inst->replaceUsesOfWith(CLI->getIndVar(), NewLoopCntLoad);
       }

mlir/test/Target/LLVMIR/omptarget-wsloop-collapsed.mlir

@@ -0,0 +1,39 @@
+// RUN: mlir-translate -mlir-to-llvmir %s | FileCheck %s
+
+// The aim of the test is to check the GPU LLVM IR codegen
+// for nested omp do loop with collapse clause inside omp target region
+
+module attributes {dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<"dlti.alloca_memory_space", 5 : ui32>>, llvm.data_layout = "e-p:64:64-p1:64:64-p2:32:32-p3:32:32-p4:64:64-p5:32:32-p6:32:32-p7:160:256:256:32-p8:128:128-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64-S32-A5-G1-ni:7:8", llvm.target_triple = "amdgcn-amd-amdhsa", omp.is_gpu = true, omp.is_target_device = true } {
+  llvm.func @target_collapsed_wsloop(%arg0: !llvm.ptr) {
+    %loop_ub = llvm.mlir.constant(99 : i32) : i32
+    %loop_lb = llvm.mlir.constant(0 : i32) : i32
+    %loop_step = llvm.mlir.constant(1 : index) : i32
+    omp.wsloop for  (%arg1, %arg2) : i32 = (%loop_lb, %loop_lb) to (%loop_ub, %loop_ub) inclusive step (%loop_step, %loop_step) {
+      %1 = llvm.add %arg1, %arg2  : i32
+      %2 = llvm.mul %arg2, %loop_ub overflow<nsw>  : i32
+      %3 = llvm.add %arg1, %2 :i32
+      %4 = llvm.getelementptr %arg0[%3] : (!llvm.ptr, i32) -> !llvm.ptr, i32
+      llvm.store %1, %4 : i32, !llvm.ptr
+      omp.yield
+    }
+    llvm.return
+  }
+}
+
+// CHECK: define void @[[FUNC_COLLAPSED_WSLOOP:.*]](ptr %[[ARG0:.*]])
+// CHECK:   call void @__kmpc_for_static_loop_4u(ptr addrspacecast (ptr addrspace(1) @[[GLOB2:[0-9]+]] to ptr),
+// CHECK-SAME: ptr @[[COLLAPSED_WSLOOP_BODY_FN:.*]], ptr %[[STRUCT_ARG:.*]], i32 10000,
+// CHECK-SAME: i32 %[[NUM_THREADS:.*]], i32 0)
+
+// CHECK: define internal void @[[COLLAPSED_WSLOOP_BODY_FN]](i32 %[[LOOP_CNT:.*]], ptr %[[LOOP_BODY_ARG:.*]])
+// CHECK:   %[[TMP0:.*]] = urem i32 %[[LOOP_CNT]], 100
+// CHECK:   %[[TMP1:.*]] = udiv i32 %[[LOOP_CNT]], 100
+// CHECK:   %[[TMP2:.*]] = mul i32 %[[TMP1]], 1
+// CHECK:   %[[TMP3:.*]] = add i32 %[[TMP2]], 0
+// CHECK:   %[[TMP4:.*]] = mul i32 %[[TMP0]], 1
+// CHECK:   %[[TMP5:.*]] = add i32 %[[TMP4]], 0
+// CHECK:   %[[TMP6:.*]] = add i32 %[[TMP3]], %[[TMP5]]
+// CHECK:   %[[TMP7:.*]] = mul nsw i32 %[[TMP5]], 99
+// CHECK:   %[[TMP8:.*]] = add i32 %[[TMP3]], %[[TMP7]]
+// CHECK:   %[[TMP9:.*]] = getelementptr i32, ptr %[[ARRAY:.*]], i32 %[[TMP8]]
+// CHECK:   store i32 %[[TMP6]], ptr %[[TMP9]], align 4

openmp/libomptarget/test/offloading/fortran/target-parallel-do-collapse.f90

@@ -0,0 +1,44 @@
+! Basic offloading test with a target region
+! REQUIRES: flang
+! UNSUPPORTED: nvptx64-nvidia-cuda-LTO
+! UNSUPPORTED: aarch64-unknown-linux-gnu
+! UNSUPPORTED: aarch64-unknown-linux-gnu-LTO
+! UNSUPPORTED: x86_64-pc-linux-gnu
+! UNSUPPORTED: x86_64-pc-linux-gnu-LTO
+
+! RUN: %libomptarget-compile-fortran-generic
+! RUN: env LIBOMPTARGET_INFO=16 %libomptarget-run-generic 2>&1 | %fcheck-generic
+program main
+   use omp_lib
+   implicit none
+   integer :: i,j
+   integer :: array(10,10), errors = 0
+   do i = 1, 10
+      do j = 1, 10
+         array(j, i) = 0
+      end do
+   end do
+
+   !$omp target parallel do map(from:array) collapse(2)
+   do i = 1, 10
+      do j = 1, 10
+         array( j, i) = i + j
+      end do
+    end do
+    !$omp end target parallel do
+
+    do i = 1, 10
+       do j = 1, 10
+          if ( array( j, i) .ne. (i + j) ) then
+             errors = errors + 1
+          end if
+       end do
+   end do
+
+   print *,"number of errors: ", errors
+
+end program main
+
+! CHECK:  "PluginInterface" device {{[0-9]+}} info: Launching kernel {{.*}}
+! CHECK:  number of errors: 0
+