[llvm] [AMDGPU][Offload] Enable memory manager use for up to ~3GB allocation size in omp_target_alloc (PR #151882)

[via llvm-commits]

hidekisaito wrote:

> > > I'm wondering if it wouldn't be better to just expose the device's memory size and have the MemoryManager use that internally when configuring this.
> > 
> > 
> > What threshold to set at what memory capacity, by default, is inherently device dependent.
> 
> I thought the memory manager already took the device into account.

No, it does not. Currently, all device under plugin-nextgen gets Memory Manager enabled by default at threshold of "1 << 13"
--- via GenericDeviceTy::init(), override through ENV var. 

https://github.com/llvm/llvm-project/pull/151882