[llvm] [Offload] Re-allocate overlapping memory (PR #159567)

[Ross Brunton via llvm-commits]

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@@ -615,18 +621,58 @@ TargetAllocTy convertOlToPluginAllocTy(ol_alloc_type_t Type) {
 
 Error olMemAlloc_impl(ol_device_handle_t Device, ol_alloc_type_t Type,
                       size_t Size, void **AllocationOut) {
-  auto Alloc =
-      Device->Device->dataAlloc(Size, nullptr, convertOlToPluginAllocTy(Type));
-  if (!Alloc)
-    return Alloc.takeError();
+  void *OldAlloc = nullptr;
+
+  // Repeat the allocation up to a certain amount of times. If it happens to
+  // already be allocated (e.g. by a device from another vendor) throw it away
+  // and try again.
+  for (size_t Count = 0; Count < 10; Count++) {
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RossBrunton wrote:

I chose 10 fairly arbitrarily, what do you mean by a stack?

https://github.com/llvm/llvm-project/pull/159567