[clang] [flang] [llvm] [openmp] [OpenMP][Offload] Add offload runtime support for dyn_groupprivate clause (PR #152831)

[Johannes Doerfert via cfe-commits]

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@@ -508,14 +517,82 @@ Error GenericKernelTy::printLaunchInfoDetails(GenericDeviceTy &GenericDevice,
   return Plugin::success();
 }
 
+Expected<DynBlockMemConfTy>
+GenericKernelTy::prepareBlockMemory(GenericDeviceTy &GenericDevice,
+                                    KernelArgsTy &KernelArgs,
+                                    uint32_t NumBlocks) const {
+  uint32_t MaxBlockMemSize = GenericDevice.getMaxBlockSharedMemSize();
+  uint32_t DynBlockMemSize = KernelArgs.DynCGroupMem;
+  uint32_t TotalBlockMemSize = StaticBlockMemSize + DynBlockMemSize;
+  uint32_t DynNativeBlockMemSize = DynBlockMemSize;
+  void *DynFallbackPtr = nullptr;
+
+  // No enough block memory to cover the static one. Cannot run the kernel.
+  if (StaticBlockMemSize > MaxBlockMemSize)
+    return Plugin::error(ErrorCode::INVALID_ARGUMENT,
+                         "Static block memory size exceeds maximum");
+  // No enough block memory to cover dynamic one, and the fallback is aborting.
+  else if (static_cast<DynCGroupMemFallbackType>(
+               KernelArgs.Flags.DynCGroupMemFallback) ==
+               DynCGroupMemFallbackType::Abort &&
+           TotalBlockMemSize > MaxBlockMemSize)
+    return Plugin::error(
+        ErrorCode::INVALID_ARGUMENT,
+        "Static and dynamic block memory size exceeds maximum");
+
+  DynCGroupMemFallbackType DynFallback = DynCGroupMemFallbackType::None;
+  if (DynBlockMemSize && (!GenericDevice.hasNativeBlockSharedMem() ||
+                          TotalBlockMemSize > MaxBlockMemSize)) {
+    // Launch without native dynamic block memory.
+    DynNativeBlockMemSize = 0;
+    DynFallback = static_cast<DynCGroupMemFallbackType>(
+        KernelArgs.Flags.DynCGroupMemFallback);
+    if (DynFallback == DynCGroupMemFallbackType::DefaultMem) {
+      // Get global memory as fallback.
+      auto AllocOrErr = GenericDevice.dataAlloc(
+          NumBlocks * DynBlockMemSize,
+          /*HostPtr=*/nullptr, TargetAllocTy::TARGET_ALLOC_DEVICE);
+      if (!AllocOrErr)
+        return AllocOrErr.takeError();
+      DynFallbackPtr = *AllocOrErr;
+    } else {
+      // Do not provide any memory as fallback.
+      DynBlockMemSize = 0;
+    }
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jdoerfert wrote:

Style: short case fist.

https://github.com/llvm/llvm-project/pull/152831