[clang] [OpenMP] Basic BumpAllocator for (AMD)GPUs (PR #69806)

Johannes Doerfert via cfe-commits cfe-commits at lists.llvm.org
Fri Oct 20 19:44:20 PDT 2023


https://github.com/jdoerfert updated https://github.com/llvm/llvm-project/pull/69806

>From 70619108a402b01c5f1f9d307a8cf21289849d74 Mon Sep 17 00:00:00 2001
From: Johannes Doerfert <johannes at jdoerfert.de>
Date: Sat, 30 Sep 2023 23:37:28 -0700
Subject: [PATCH] [OpenMP] Basic BumpAllocator for (AMD)GPUs

The patch contains a basic BumpAllocator for (AMD)GPUs to allow us to
run more tests. The allocator implements `malloc`, both internally and
externally, while we continue to default to the NVIDIA `malloc` when we
target NVIDIA GPUs. Once we have smarter or customizable allocators we
should consider this choice, for now, this allocator is better than
none. It traps if it is out of memory, making it easy to debug. Heap
size is configured via `LIBOMPTARGET_HEAP_SIZE` and defaults to 512MB.
It allows to track allocation statistics via
`LIBOMPTARGET_DEVICE_RTL_DEBUG=8` (together with
`-fopenmp-target-debug=8`). Two tests were added, and one was enabled.

This is the next step towards fixing
 https://github.com/llvm/llvm-project/issues/66708
---
 .../__clang_openmp_device_functions.h         | 22 ++++-
 openmp/docs/design/Runtimes.rst               |  1 +
 openmp/libomptarget/DeviceRTL/CMakeLists.txt  |  2 +
 .../DeviceRTL/include/Allocator.h             | 44 ++++++++++
 .../libomptarget/DeviceRTL/src/Allocator.cpp  | 80 +++++++++++++++++
 openmp/libomptarget/DeviceRTL/src/Kernel.cpp  |  2 +
 openmp/libomptarget/DeviceRTL/src/State.cpp   | 45 +++++-----
 openmp/libomptarget/DeviceRTL/src/exports     |  1 +
 openmp/libomptarget/include/Environment.h     | 21 +++++
 .../plugins-nextgen/amdgpu/src/rtl.cpp        | 13 ++-
 .../PluginInterface/PluginInterface.cpp       | 87 ++++++++++++++++++-
 .../common/PluginInterface/PluginInterface.h  | 11 +++
 .../plugins-nextgen/cuda/src/rtl.cpp          |  5 ++
 .../generic-elf-64bit/src/rtl.cpp             |  3 +-
 .../test/mapping/lambda_mapping.cpp           |  8 +-
 openmp/libomptarget/test/offloading/malloc.c  | 37 ++++++++
 .../test/offloading/malloc_parallel.c         | 42 +++++++++
 17 files changed, 385 insertions(+), 39 deletions(-)
 create mode 100644 openmp/libomptarget/DeviceRTL/include/Allocator.h
 create mode 100644 openmp/libomptarget/DeviceRTL/src/Allocator.cpp
 create mode 100644 openmp/libomptarget/test/offloading/malloc.c
 create mode 100644 openmp/libomptarget/test/offloading/malloc_parallel.c

diff --git a/clang/lib/Headers/openmp_wrappers/__clang_openmp_device_functions.h b/clang/lib/Headers/openmp_wrappers/__clang_openmp_device_functions.h
index d5b6846b0348859..d1da5c278572178 100644
--- a/clang/lib/Headers/openmp_wrappers/__clang_openmp_device_functions.h
+++ b/clang/lib/Headers/openmp_wrappers/__clang_openmp_device_functions.h
@@ -15,9 +15,19 @@
 #endif
 
 #ifdef __cplusplus
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
 extern "C" {
+#else
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
 #endif
 
+void *llvm_device_malloc(uint64_t Size);
+void llvm_device_free(void *Ptr);
+
 #pragma omp begin declare variant match(                                       \
     device = {arch(nvptx, nvptx64)}, implementation = {extension(match_any)})
 
@@ -36,6 +46,15 @@ extern "C" {
 #pragma omp end declare variant
 
 #ifdef __AMDGCN__
+#pragma omp begin declare variant match(                                       \
+        device = {arch(amdgcn)},                                               \
+            implementation = {extension(disable_implicit_base)})
+
+void *malloc(size_t Size) { return llvm_device_malloc(Size); }
+void free(void *Ptr) { llvm_device_free(Ptr); }
+
+#pragma omp end declare variant
+
 #pragma omp begin declare variant match(device = {arch(amdgcn)})
 
 // Import types which will be used by __clang_hip_libdevice_declares.h
@@ -64,9 +83,6 @@ extern "C" {
 // need to `include <new>` in C++ mode.
 #ifdef __cplusplus
 
-// We require malloc/free.
-#include <cstdlib>
-
 #pragma push_macro("OPENMP_NOEXCEPT")
 #if __cplusplus >= 201103L
 #define OPENMP_NOEXCEPT noexcept
diff --git a/openmp/docs/design/Runtimes.rst b/openmp/docs/design/Runtimes.rst
index 4c848ca76fb8d57..62ed75797955e28 100644
--- a/openmp/docs/design/Runtimes.rst
+++ b/openmp/docs/design/Runtimes.rst
@@ -1465,3 +1465,4 @@ debugging features are supported.
 
     * Enable debugging assertions in the device. ``0x01``
     * Enable diagnosing common problems during offloading . ``0x4``
+    * Enable device malloc statistics (amdgpu only). ``0x8``
diff --git a/openmp/libomptarget/DeviceRTL/CMakeLists.txt b/openmp/libomptarget/DeviceRTL/CMakeLists.txt
index fee2414b456a14c..f71bdeae3d7f091 100644
--- a/openmp/libomptarget/DeviceRTL/CMakeLists.txt
+++ b/openmp/libomptarget/DeviceRTL/CMakeLists.txt
@@ -83,6 +83,7 @@ endif()
 list(REMOVE_DUPLICATES LIBOMPTARGET_DEVICE_ARCHITECTURES)
 
 set(include_files
+  ${include_directory}/Allocator.h
   ${include_directory}/Configuration.h
   ${include_directory}/Debug.h
   ${include_directory}/Interface.h
@@ -95,6 +96,7 @@ set(include_files
 )
 
 set(src_files
+  ${source_directory}/Allocator.cpp
   ${source_directory}/Configuration.cpp
   ${source_directory}/Debug.cpp
   ${source_directory}/Kernel.cpp
diff --git a/openmp/libomptarget/DeviceRTL/include/Allocator.h b/openmp/libomptarget/DeviceRTL/include/Allocator.h
new file mode 100644
index 000000000000000..a28eb0fb2977eaa
--- /dev/null
+++ b/openmp/libomptarget/DeviceRTL/include/Allocator.h
@@ -0,0 +1,44 @@
+//===-------- Allocator.h - OpenMP memory allocator interface ---- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef OMPTARGET_ALLOCATOR_H
+#define OMPTARGET_ALLOCATOR_H
+
+#include "Types.h"
+
+// Forward declaration.
+struct KernelEnvironmentTy;
+
+#pragma omp begin declare target device_type(nohost)
+
+namespace ompx {
+
+namespace allocator {
+
+static uint64_t constexpr ALIGNMENT = 16;
+
+/// Initialize the allocator according to \p KernelEnvironment
+void init(bool IsSPMD, KernelEnvironmentTy &KernelEnvironment);
+
+/// Allocate \p Size bytes.
+[[gnu::alloc_size(1), gnu::assume_aligned(ALIGNMENT), gnu::malloc]] void *
+alloc(uint64_t Size);
+
+/// Free the allocation pointed to by \p Ptr.
+void free(void *Ptr);
+
+} // namespace allocator
+
+} // namespace ompx
+
+#pragma omp end declare target
+
+#endif
diff --git a/openmp/libomptarget/DeviceRTL/src/Allocator.cpp b/openmp/libomptarget/DeviceRTL/src/Allocator.cpp
new file mode 100644
index 000000000000000..7a4cbfe60dd026c
--- /dev/null
+++ b/openmp/libomptarget/DeviceRTL/src/Allocator.cpp
@@ -0,0 +1,80 @@
+//===------ State.cpp - OpenMP State & ICV interface ------------- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+//===----------------------------------------------------------------------===//
+
+#include "Allocator.h"
+#include "Configuration.h"
+#include "Environment.h"
+#include "Mapping.h"
+#include "Synchronization.h"
+#include "Types.h"
+#include "Utils.h"
+
+using namespace ompx;
+
+#pragma omp begin declare target device_type(nohost)
+
+[[gnu::used, gnu::retain, gnu::weak,
+  gnu::visibility(
+      "protected")]] DeviceMemoryPoolTy __omp_rtl_device_memory_pool;
+[[gnu::used, gnu::retain, gnu::weak,
+  gnu::visibility("protected")]] DeviceMemoryPoolTrackingTy
+    __omp_rtl_device_memory_pool_tracker;
+
+/// Stateless bump allocator that uses the __omp_rtl_device_memory_pool
+/// directly.
+struct BumpAllocatorTy final {
+
+  void *alloc(uint64_t Size) {
+    Size = utils::roundUp(Size, uint64_t(allocator::ALIGNMENT));
+
+    if (config::isDebugMode(DeviceDebugKind::AllocationTracker)) {
+      atomic::add(&__omp_rtl_device_memory_pool_tracker.NumAllocations, 1,
+                  atomic::seq_cst);
+      atomic::add(&__omp_rtl_device_memory_pool_tracker.AllocationTotal, Size,
+                  atomic::seq_cst);
+      atomic::min(&__omp_rtl_device_memory_pool_tracker.AllocationMin, Size,
+                  atomic::seq_cst);
+      atomic::max(&__omp_rtl_device_memory_pool_tracker.AllocationMax, Size,
+                  atomic::seq_cst);
+    }
+
+    uint64_t *Data =
+        reinterpret_cast<uint64_t *>(&__omp_rtl_device_memory_pool.Ptr);
+    uint64_t End =
+        reinterpret_cast<uint64_t>(Data) + __omp_rtl_device_memory_pool.Size;
+
+    uint64_t OldData = atomic::add(Data, Size, atomic::seq_cst);
+    if (OldData + Size > End)
+      __builtin_trap();
+
+    return reinterpret_cast<void *>(OldData);
+  }
+
+  void free(void *) {}
+};
+
+BumpAllocatorTy BumpAllocator;
+
+/// allocator namespace implementation
+///
+///{
+
+void allocator::init(bool IsSPMD, KernelEnvironmentTy &KernelEnvironment) {
+  // TODO: Check KernelEnvironment for an allocator choice as soon as we have
+  // more than one.
+}
+
+void *allocator::alloc(uint64_t Size) { return BumpAllocator.alloc(Size); }
+
+void allocator::free(void *Ptr) { BumpAllocator.free(Ptr); }
+
+///}
+
+#pragma omp end declare target
diff --git a/openmp/libomptarget/DeviceRTL/src/Kernel.cpp b/openmp/libomptarget/DeviceRTL/src/Kernel.cpp
index 222983577164c66..91e8a00bdef9dfd 100644
--- a/openmp/libomptarget/DeviceRTL/src/Kernel.cpp
+++ b/openmp/libomptarget/DeviceRTL/src/Kernel.cpp
@@ -10,6 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "Allocator.h"
 #include "Debug.h"
 #include "Environment.h"
 #include "Interface.h"
@@ -30,6 +31,7 @@ static void inititializeRuntime(bool IsSPMD,
   synchronize::init(IsSPMD);
   mapping::init(IsSPMD);
   state::init(IsSPMD, KernelEnvironment);
+  allocator::init(IsSPMD, KernelEnvironment);
 }
 
 /// Simple generic state machine for worker threads.
diff --git a/openmp/libomptarget/DeviceRTL/src/State.cpp b/openmp/libomptarget/DeviceRTL/src/State.cpp
index 68fe0b383548e53..ef1c1fb409c7469 100644
--- a/openmp/libomptarget/DeviceRTL/src/State.cpp
+++ b/openmp/libomptarget/DeviceRTL/src/State.cpp
@@ -9,6 +9,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "State.h"
+#include "Allocator.h"
+#include "Configuration.h"
 #include "Debug.h"
 #include "Environment.h"
 #include "Interface.h"
@@ -25,18 +27,16 @@ using namespace ompx;
 ///
 ///{
 
-/// Add worst-case padding so that future allocations are properly aligned.
-/// FIXME: The stack shouldn't require worst-case padding. Alignment needs to be
-/// passed in as an argument and the stack rewritten to support it.
-constexpr const uint32_t Alignment = 16;
-
 /// External symbol to access dynamic shared memory.
-[[gnu::aligned(Alignment)]] extern unsigned char DynamicSharedBuffer[];
+[[gnu::aligned(
+    allocator::ALIGNMENT)]] extern unsigned char DynamicSharedBuffer[];
 #pragma omp allocate(DynamicSharedBuffer) allocator(omp_pteam_mem_alloc)
 
 /// The kernel environment passed to the init method by the compiler.
 static KernelEnvironmentTy *SHARED(KernelEnvironmentPtr);
 
+///}
+
 namespace {
 
 /// Fallback implementations are missing to trigger a link time error.
@@ -44,29 +44,20 @@ namespace {
 /// dedicated begin/end declare variant.
 ///
 ///{
-
 extern "C" {
 [[gnu::weak, gnu::leaf]] void *malloc(uint64_t Size);
 [[gnu::weak, gnu::leaf]] void free(void *Ptr);
-}
 
-///}
+void *llvm_device_malloc(uint64_t Size) { return allocator::alloc(Size); }
+void llvm_device_free(void *Ptr) { allocator::free(Ptr); }
 
-/// AMDGCN implementations of the shuffle sync idiom.
-///
-///{
 #pragma omp begin declare variant match(device = {arch(amdgcn)})
 
-extern "C" {
-void *malloc(uint64_t Size) {
-  // TODO: Use some preallocated space for dynamic malloc.
-  return nullptr;
-}
-
-void free(void *Ptr) {}
-}
+[[gnu::weak]] void *malloc(uint64_t Size) { return llvm_device_malloc(Size); }
+[[gnu::weak]] void free(void *Ptr) { llvm_device_free(Ptr); }
 
 #pragma omp end declare variant
+}
 ///}
 
 /// A "smart" stack in shared memory.
@@ -95,7 +86,7 @@ struct SharedMemorySmartStackTy {
   uint32_t computeThreadStorageTotal() {
     uint32_t NumLanesInBlock = mapping::getNumberOfThreadsInBlock();
     return utils::align_down((state::SharedScratchpadSize / NumLanesInBlock),
-                             Alignment);
+                             allocator::ALIGNMENT);
   }
 
   /// Return the top address of the warp data stack, that is the first address
@@ -105,8 +96,10 @@ struct SharedMemorySmartStackTy {
   }
 
   /// The actual storage, shared among all warps.
-  [[gnu::aligned(Alignment)]] unsigned char Data[state::SharedScratchpadSize];
-  [[gnu::aligned(Alignment)]] unsigned char Usage[mapping::MaxThreadsPerTeam];
+  [[gnu::aligned(
+      allocator::ALIGNMENT)]] unsigned char Data[state::SharedScratchpadSize];
+  [[gnu::aligned(
+      allocator::ALIGNMENT)]] unsigned char Usage[mapping::MaxThreadsPerTeam];
 };
 
 static_assert(state::SharedScratchpadSize / mapping::MaxThreadsPerTeam <= 256,
@@ -121,7 +114,9 @@ void SharedMemorySmartStackTy::init(bool IsSPMD) {
 
 void *SharedMemorySmartStackTy::push(uint64_t Bytes) {
   // First align the number of requested bytes.
-  uint64_t AlignedBytes = utils::align_up(Bytes, Alignment);
+  /// FIXME: The stack shouldn't require worst-case padding. Alignment needs to
+  /// be passed in as an argument and the stack rewritten to support it.
+  uint64_t AlignedBytes = utils::align_up(Bytes, allocator::ALIGNMENT);
 
   uint32_t StorageTotal = computeThreadStorageTotal();
 
@@ -149,7 +144,7 @@ void *SharedMemorySmartStackTy::push(uint64_t Bytes) {
 }
 
 void SharedMemorySmartStackTy::pop(void *Ptr, uint32_t Bytes) {
-  uint64_t AlignedBytes = utils::align_up(Bytes, Alignment);
+  uint64_t AlignedBytes = utils::align_up(Bytes, allocator::ALIGNMENT);
   if (utils::isSharedMemPtr(Ptr)) {
     int TId = mapping::getThreadIdInBlock();
     Usage[TId] -= AlignedBytes;
diff --git a/openmp/libomptarget/DeviceRTL/src/exports b/openmp/libomptarget/DeviceRTL/src/exports
index 288ddf90b4a9f2d..5567257f6b3cc75 100644
--- a/openmp/libomptarget/DeviceRTL/src/exports
+++ b/openmp/libomptarget/DeviceRTL/src/exports
@@ -16,3 +16,4 @@ free
 memcmp
 printf
 __assert_fail
+malloc
diff --git a/openmp/libomptarget/include/Environment.h b/openmp/libomptarget/include/Environment.h
index 48a0fa933bdd8c0..8194736ae4e0a9d 100644
--- a/openmp/libomptarget/include/Environment.h
+++ b/openmp/libomptarget/include/Environment.h
@@ -43,6 +43,27 @@ struct DeviceEnvironmentTy {
   uint64_t HardwareParallelism;
 };
 
+struct DeviceMemoryPoolTy {
+  void *Ptr;
+  uint64_t Size;
+};
+
+struct DeviceMemoryPoolTrackingTy {
+  uint64_t NumAllocations;
+  uint64_t AllocationTotal;
+  uint64_t AllocationMin;
+  uint64_t AllocationMax;
+
+  void combine(DeviceMemoryPoolTrackingTy &Other) {
+    NumAllocations += Other.NumAllocations;
+    AllocationTotal += Other.AllocationTotal;
+    AllocationMin = AllocationMin > Other.AllocationMin ? Other.AllocationMin
+                                                        : AllocationMin;
+    AllocationMax = AllocationMax < Other.AllocationMax ? Other.AllocationMax
+                                                        : AllocationMax;
+  }
+};
+
 // NOTE: Please don't change the order of those members as their indices are
 // used in the middle end. Always add the new data member at the end.
 // Different from KernelEnvironmentTy below, this structure contains members
diff --git a/openmp/libomptarget/plugins-nextgen/amdgpu/src/rtl.cpp b/openmp/libomptarget/plugins-nextgen/amdgpu/src/rtl.cpp
index 148ca09654092cb..ab24856f9bc78e4 100644
--- a/openmp/libomptarget/plugins-nextgen/amdgpu/src/rtl.cpp
+++ b/openmp/libomptarget/plugins-nextgen/amdgpu/src/rtl.cpp
@@ -2529,10 +2529,16 @@ struct AMDGPUDeviceTy : public GenericDeviceTy, AMDGenericDeviceTy {
     return Plugin::success();
   }
   Error getDeviceHeapSize(uint64_t &Value) override {
-    Value = 0;
+    Value = DeviceMemoryPoolSize;
+    return Plugin::success();
+  }
+  Error setDeviceHeapSize(uint64_t Value) override {
+    for (DeviceImageTy *Image : LoadedImages)
+      if (auto Err = setupDeviceMemoryPool(Plugin::get(), *Image, Value))
+        return Err;
+    DeviceMemoryPoolSize = Value;
     return Plugin::success();
   }
-  Error setDeviceHeapSize(uint64_t Value) override { return Plugin::success(); }
 
   /// AMDGPU-specific function to get device attributes.
   template <typename Ty> Error getDeviceAttr(uint32_t Kind, Ty &Value) {
@@ -2625,6 +2631,9 @@ struct AMDGPUDeviceTy : public GenericDeviceTy, AMDGenericDeviceTy {
 
   /// Reference to the host device.
   AMDHostDeviceTy &HostDevice;
+
+  /// The current size of the global device memory pool (managed by us).
+  uint64_t DeviceMemoryPoolSize = 1L << 29L /* 512MB */;
 };
 
 Error AMDGPUDeviceImageTy::loadExecutable(const AMDGPUDeviceTy &Device) {
diff --git a/openmp/libomptarget/plugins-nextgen/common/PluginInterface/PluginInterface.cpp b/openmp/libomptarget/plugins-nextgen/common/PluginInterface/PluginInterface.cpp
index c8fb8d552f429a0..0243f0205dbf0e5 100644
--- a/openmp/libomptarget/plugins-nextgen/common/PluginInterface/PluginInterface.cpp
+++ b/openmp/libomptarget/plugins-nextgen/common/PluginInterface/PluginInterface.cpp
@@ -590,6 +590,35 @@ Error GenericDeviceTy::init(GenericPluginTy &Plugin) {
 }
 
 Error GenericDeviceTy::deinit(GenericPluginTy &Plugin) {
+
+  if (OMPX_DebugKind.get() & uint32_t(DeviceDebugKind::AllocationTracker)) {
+    GenericGlobalHandlerTy &GHandler = Plugin.getGlobalHandler();
+    for (auto *Image : LoadedImages) {
+      DeviceMemoryPoolTrackingTy ImageDeviceMemoryPoolTracking = {0, 0, ~0U, 0};
+      GlobalTy TrackerGlobal("__omp_rtl_device_memory_pool_tracker",
+                             sizeof(DeviceMemoryPoolTrackingTy),
+                             &ImageDeviceMemoryPoolTracking);
+      if (auto Err =
+              GHandler.readGlobalFromDevice(*this, *Image, TrackerGlobal))
+        return Err;
+      DeviceMemoryPoolTracking.combine(ImageDeviceMemoryPoolTracking);
+    }
+
+    // TODO: Write this by default into a file.
+    printf("\n\n|-----------------------\n"
+           "| Device memory tracker:\n"
+           "|-----------------------\n"
+           "| #Allocations: %lu\n"
+           "| Byes allocated: %lu\n"
+           "| Minimal allocation: %lu\n"
+           "| Maximal allocation: %lu\n"
+           "|-----------------------\n\n\n",
+           DeviceMemoryPoolTracking.NumAllocations,
+           DeviceMemoryPoolTracking.AllocationTotal,
+           DeviceMemoryPoolTracking.AllocationMin,
+           DeviceMemoryPoolTracking.AllocationMax);
+  }
+
   // Delete the memory manager before deinitializing the device. Otherwise,
   // we may delete device allocations after the device is deinitialized.
   if (MemoryManager)
@@ -648,6 +677,17 @@ GenericDeviceTy::loadBinary(GenericPluginTy &Plugin,
   if (auto Err = setupDeviceEnvironment(Plugin, *Image))
     return std::move(Err);
 
+  // Setup the global device memory pool if needed.
+  if (shouldSetupDeviceMemoryPool()) {
+    uint64_t HeapSize;
+    auto SizeOrErr = getDeviceHeapSize(HeapSize);
+    if (SizeOrErr) {
+      REPORT("No global device memory pool due to error: %s\n",
+             toString(std::move(SizeOrErr)).data());
+    } else if (auto Err = setupDeviceMemoryPool(Plugin, *Image, HeapSize))
+      return std::move(Err);
+  }
+
   // Register all offload entries of the image.
   if (auto Err = registerOffloadEntries(*Image))
     return std::move(Err);
@@ -713,6 +753,45 @@ Error GenericDeviceTy::setupDeviceEnvironment(GenericPluginTy &Plugin,
   return Plugin::success();
 }
 
+Error GenericDeviceTy::setupDeviceMemoryPool(GenericPluginTy &Plugin,
+                                             DeviceImageTy &Image,
+                                             uint64_t PoolSize) {
+  // Free the old pool, if any.
+  if (DeviceMemoryPool.Ptr) {
+    if (auto Err = dataDelete(DeviceMemoryPool.Ptr,
+                              TargetAllocTy::TARGET_ALLOC_DEVICE))
+      return Err;
+  }
+
+  DeviceMemoryPool.Size = PoolSize;
+  auto AllocOrErr = dataAlloc(PoolSize, /*HostPtr=*/nullptr,
+                              TargetAllocTy::TARGET_ALLOC_DEVICE);
+  if (AllocOrErr) {
+    DeviceMemoryPool.Ptr = *AllocOrErr;
+  } else {
+    auto Err = AllocOrErr.takeError();
+    REPORT("Failure to allocate device memory for global memory pool: %s\n",
+           toString(std::move(Err)).data());
+    DeviceMemoryPool.Ptr = nullptr;
+    DeviceMemoryPool.Size = 0;
+  }
+
+  // Create the metainfo of the device environment global.
+  GlobalTy TrackerGlobal("__omp_rtl_device_memory_pool_tracker",
+                         sizeof(DeviceMemoryPoolTrackingTy),
+                         &DeviceMemoryPoolTracking);
+  GenericGlobalHandlerTy &GHandler = Plugin.getGlobalHandler();
+  if (auto Err = GHandler.writeGlobalToDevice(*this, Image, TrackerGlobal))
+    return Err;
+
+  // Create the metainfo of the device environment global.
+  GlobalTy DevEnvGlobal("__omp_rtl_device_memory_pool",
+                        sizeof(DeviceMemoryPoolTy), &DeviceMemoryPool);
+
+  // Write device environment values to the device.
+  return GHandler.writeGlobalToDevice(*this, Image, DevEnvGlobal);
+}
+
 Error GenericDeviceTy::setupRPCServer(GenericPluginTy &Plugin,
                                       DeviceImageTy &Image) {
   // The plugin either does not need an RPC server or it is unavailible.
@@ -1327,10 +1406,6 @@ Error GenericPluginTy::init() {
 }
 
 Error GenericPluginTy::deinit() {
-  // There is no global handler if no device is available.
-  if (GlobalHandler)
-    delete GlobalHandler;
-
   // Deinitialize all active devices.
   for (int32_t DeviceId = 0; DeviceId < NumDevices; ++DeviceId) {
     if (Devices[DeviceId]) {
@@ -1340,6 +1415,10 @@ Error GenericPluginTy::deinit() {
     assert(!Devices[DeviceId] && "Device was not deinitialized");
   }
 
+  // There is no global handler if no device is available.
+  if (GlobalHandler)
+    delete GlobalHandler;
+
   if (RPCServer)
     delete RPCServer;
 
diff --git a/openmp/libomptarget/plugins-nextgen/common/PluginInterface/PluginInterface.h b/openmp/libomptarget/plugins-nextgen/common/PluginInterface/PluginInterface.h
index 4a9c223eefbcf62..ddcf3b3cc9b9537 100644
--- a/openmp/libomptarget/plugins-nextgen/common/PluginInterface/PluginInterface.h
+++ b/openmp/libomptarget/plugins-nextgen/common/PluginInterface/PluginInterface.h
@@ -625,6 +625,10 @@ struct GenericDeviceTy : public DeviceAllocatorTy {
   /// this behavior by overriding the shouldSetupDeviceEnvironment function.
   Error setupDeviceEnvironment(GenericPluginTy &Plugin, DeviceImageTy &Image);
 
+  /// Setup the global device memory pool, if the plugin requires one.
+  Error setupDeviceMemoryPool(GenericPluginTy &Plugin, DeviceImageTy &Image,
+                              uint64_t PoolSize);
+
   // Setup the RPC server for this device if needed. This may not run on some
   // plugins like the CPU targets. By default, it will not be executed so it is
   // up to the target to override this using the shouldSetupRPCServer function.
@@ -831,6 +835,10 @@ struct GenericDeviceTy : public DeviceAllocatorTy {
   /// setupDeviceEnvironment() function.
   virtual bool shouldSetupDeviceEnvironment() const { return true; }
 
+  /// Indicate whether the device should setup the global device memory pool. If
+  /// false is return the value on the device will be uninitialized.
+  virtual bool shouldSetupDeviceMemoryPool() const { return true; }
+
   /// Indicate whether or not the device should setup the RPC server. This is
   /// only necessary for unhosted targets like the GPU.
   virtual bool shouldSetupRPCServer() const { return false; }
@@ -911,6 +919,9 @@ struct GenericDeviceTy : public DeviceAllocatorTy {
   /// Return the kernel environment object for kernel \p Name.
   Expected<KernelEnvironmentTy>
   getKernelEnvironmentForKernel(StringRef Name, DeviceImageTy &Image);
+
+  DeviceMemoryPoolTy DeviceMemoryPool = {nullptr, 0};
+  DeviceMemoryPoolTrackingTy DeviceMemoryPoolTracking = {0, 0, ~0U, 0};
 };
 
 /// Class implementing common functionalities of offload plugins. Each plugin
diff --git a/openmp/libomptarget/plugins-nextgen/cuda/src/rtl.cpp b/openmp/libomptarget/plugins-nextgen/cuda/src/rtl.cpp
index 1bb8dc1064d8637..431e34ca75cd652 100644
--- a/openmp/libomptarget/plugins-nextgen/cuda/src/rtl.cpp
+++ b/openmp/libomptarget/plugins-nextgen/cuda/src/rtl.cpp
@@ -843,6 +843,11 @@ struct CUDADeviceTy : public GenericDeviceTy {
     return Plugin::success();
   }
 
+  virtual bool shouldSetupDeviceMemoryPool() const override {
+    /// We use the CUDA malloc for now.
+    return false;
+  }
+
   /// Getters and setters for stack and heap sizes.
   Error getDeviceStackSize(uint64_t &Value) override {
     return getCtxLimit(CU_LIMIT_STACK_SIZE, Value);
diff --git a/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/src/rtl.cpp b/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/src/rtl.cpp
index 8f2022bac9d8aee..619f4dfed9b4e63 100644
--- a/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/src/rtl.cpp
+++ b/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/src/rtl.cpp
@@ -307,8 +307,9 @@ struct GenELF64DeviceTy : public GenericDeviceTy {
     return Plugin::success();
   }
 
-  /// This plugin should not setup the device environment.
+  /// This plugin should not setup the device environment or memory pool.
   virtual bool shouldSetupDeviceEnvironment() const override { return false; };
+  virtual bool shouldSetupDeviceMemoryPool() const override { return false; };
 
   /// Getters and setters for stack size and heap size not relevant.
   Error getDeviceStackSize(uint64_t &Value) override {
diff --git a/openmp/libomptarget/test/mapping/lambda_mapping.cpp b/openmp/libomptarget/test/mapping/lambda_mapping.cpp
index acec6c82288a842..63b1719fbbc36ff 100644
--- a/openmp/libomptarget/test/mapping/lambda_mapping.cpp
+++ b/openmp/libomptarget/test/mapping/lambda_mapping.cpp
@@ -1,7 +1,7 @@
-// On AMDGPU we don't have malloc support yet. We need optimizations
-// to avoid a thread state which requires malloc.
-//
-// XUN: %libomptarget-compilexx-run-and-check-generic
+// Unonptimized, we need 24000000 bytes heap
+// RUN: %libomptarget-compilexx-generic
+// RUN: env LIBOMPTARGET_HEAP_SIZE=24000000 \
+// RUN: %libomptarget-run-generic 2>&1 | %fcheck-generic
 // RUN: %libomptarget-compileoptxx-run-and-check-generic
 
 #include <iostream>
diff --git a/openmp/libomptarget/test/offloading/malloc.c b/openmp/libomptarget/test/offloading/malloc.c
new file mode 100644
index 000000000000000..ad49ace20062560
--- /dev/null
+++ b/openmp/libomptarget/test/offloading/malloc.c
@@ -0,0 +1,37 @@
+// RUN: %libomptarget-compile-generic && %libomptarget-run-generic
+// RUN: %libomptarget-compileopt-generic && %libomptarget-run-generic
+
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+  long unsigned *DP = 0;
+  int N = 128;
+  int Threads = 128;
+  int Teams = 440;
+
+  // Allocate ~55MB on the device.
+#pragma omp target map(from : DP)
+  DP = (long unsigned *)malloc(sizeof(long unsigned) * N * Threads * Teams);
+
+#pragma omp target teams distribute parallel for num_teams(Teams)              \
+    thread_limit(Threads) is_device_ptr(DP)
+  for (int i = 0; i < Threads * Teams; ++i) {
+    for (int j = 0; j < N; ++j) {
+      DP[i * N + j] = i + j;
+    }
+  }
+
+  long unsigned s = 0;
+#pragma omp target teams distribute parallel for num_teams(Teams)              \
+    thread_limit(Threads) reduction(+ : s)
+  for (int i = 0; i < Threads * Teams; ++i) {
+    for (int j = 0; j < N; ++j) {
+      s += DP[i * N + j];
+    }
+  }
+
+  // CHECK: Sum: 203458478080
+  printf("Sum: %li\n", s);
+  return 0;
+}
diff --git a/openmp/libomptarget/test/offloading/malloc_parallel.c b/openmp/libomptarget/test/offloading/malloc_parallel.c
new file mode 100644
index 000000000000000..b8e975ca55a8fff
--- /dev/null
+++ b/openmp/libomptarget/test/offloading/malloc_parallel.c
@@ -0,0 +1,42 @@
+// RUN: %libomptarget-compile-generic && %libomptarget-run-generic
+// RUN: %libomptarget-compileopt-generic && %libomptarget-run-generic
+
+#include <omp.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+  long unsigned **DP = 0;
+  int N = 128;
+  int Threads = 128;
+  int Teams = 440;
+
+#pragma omp target map(from : DP)
+  DP = (long unsigned **)malloc(sizeof(long unsigned *) * Threads * Teams);
+
+#pragma omp target teams distribute parallel for num_teams(Teams)              \
+    thread_limit(Threads)
+  for (int i = 0; i < Threads * Teams; ++i)
+    DP[i] = (long unsigned *)malloc(sizeof(long unsigned) * N);
+
+#pragma omp target teams distribute parallel for num_teams(Teams)              \
+    thread_limit(Threads)
+  for (int i = 0; i < Threads * Teams; ++i) {
+    for (int j = 0; j < N; ++j) {
+      DP[i][j] = i + j;
+    }
+  }
+
+  long unsigned s = 0;
+#pragma omp target teams distribute parallel for num_teams(Teams)              \
+    thread_limit(Threads) reduction(+ : s)
+  for (int i = 0; i < Threads * Teams; ++i) {
+    for (int j = 0; j < N; ++j) {
+      s += DP[i][j];
+    }
+  }
+
+  // CHECK: Sum: 203458478080
+  printf("Sum: %li\n", s);
+  return 0;
+}



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