[llvm] [NVPTX] Add prefetch tensormap variant (PR #146203)

[Durgadoss R via llvm-commits]

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@@ -983,7 +986,10 @@ The '``@llvm.nvvm.prefetch.*``' and '``@llvm.nvvm.prefetchu.*``' intrinsic
 correspond to the '``prefetch.*``;' and '``prefetchu.*``' family of PTX instructions. 
 The '``prefetch.*``' instructions bring the cache line containing the
 specified address in global or local memory address space into the 
-specified cache level (L1 or L2). The '`prefetchu.*``' instruction brings the cache line 
+specified cache level (L1 or L2). If the '``.tensormap``' qualifier is specified then the 
+prefetch instruction brings the cache line containing the specified address in the 
+'``.const``' or '``.param memory``' state space for subsequent use by the '``cp.async.bulk.tensor``' 
+instruction.The '`prefetchu.*``' instruction brings the cache line 
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durga4github wrote:

nit: space after .

https://github.com/llvm/llvm-project/pull/146203