[llvm] [OFFLOAD] Add plugin with support for Intel oneAPI Level Zero (PR #158900)

[Kevin Sala Penades via llvm-commits]

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@@ -0,0 +1,657 @@
+//===--- Level Zero Target RTL Implementation -----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// GenericKernel implementation for SPIR-V/Xe machine
+//
+//===----------------------------------------------------------------------===//
+
+#include "L0Kernel.h"
+#include "L0Device.h"
+#include "L0Plugin.h"
+#include "L0Program.h"
+
+namespace llvm::omp::target::plugin {
+
+Error L0KernelTy::launchImpl(GenericDeviceTy &GenericDevice,
+                             uint32_t NumThreads[3], uint32_t NumBlocks[3],
+                             KernelArgsTy &KernelArgs,
+                             KernelLaunchParamsTy LaunchParams,
+                             AsyncInfoWrapperTy &AsyncInfoWrapper) const {
+
+  auto &l0Device = L0DeviceTy::makeL0Device(GenericDevice);
+  int32_t RC = runTargetTeamRegion(l0Device, KernelArgs,
+                                   std::move(LaunchParams), AsyncInfoWrapper);
+  if (RC == OFFLOAD_SUCCESS)
+    return Plugin::success();
+  return Plugin::error(error::ErrorCode::UNKNOWN,
+                       "Error in launch Kernel %s: %d", getName(), RC);
+}
+
+Error L0KernelTy::buildKernel(L0ProgramTy &Program) {
+  const auto *KernelName = getName();
+
+  auto Module = Program.findModuleFromKernelName(KernelName);
+  ze_kernel_desc_t KernelDesc = {ZE_STRUCTURE_TYPE_KERNEL_DESC, nullptr, 0,
+                                 KernelName};
+  CALL_ZE_RET_ERROR(zeKernelCreate, Module, &KernelDesc, &zeKernel);
+  return Plugin::success();
+}
+
+Error L0KernelTy::initImpl(GenericDeviceTy &GenericDevice,
+                           DeviceImageTy &Image) {
+  auto &Program = L0ProgramTy::makeL0Program(Image);
+
+  Error Err = buildKernel(Program);
+  if (Err)
+    return Err;
+  Program.addKernel(this);
+
+  return Plugin::success();
+}
+
+/// Read global thread limit and max teams from the host runtime. These values
+/// are subject to change at any program point, so every kernel execution
+/// needs to read the most recent values.
+static std::tuple<int32_t, int32_t> readTeamsThreadLimit() {
+  int ThrLimit;
+  ThrLimit = omp_get_teams_thread_limit();
+  DP("omp_get_teams_thread_limit() returned %" PRId32 "\n", ThrLimit);
+  // omp_get_thread_limit() would return INT_MAX by default.
+  // NOTE: Windows.h defines max() macro, so we have to guard
+  //       the call with parentheses.
+  int32_t ThreadLimit =
+      (ThrLimit > 0 && ThrLimit != (std::numeric_limits<int32_t>::max)())
+          ? ThrLimit
+          : 0;
+
+  int NTeams = omp_get_max_teams();
----------------
kevinsala wrote:

I don't think the parts with OpenMP calls and OpenMP wrappers should be merged. It should be addressed in a preceding PR, or avoid these code parts in the current PR.

Why does the Intel plugin need these values and the rest of plugins don't?

https://github.com/llvm/llvm-project/pull/158900