[llvm] [AMDGPU] Add type-generic llvm.amdgcn.readfirstlane2 intrinsic (PR #87334)

[Matt Arsenault via llvm-commits]

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@@ -2206,11 +2206,18 @@ class AMDGPUWaveReduce<LLVMType data_ty = llvm_anyint_ty> : Intrinsic<
 def int_amdgcn_wave_reduce_umin : AMDGPUWaveReduce;
 def int_amdgcn_wave_reduce_umax : AMDGPUWaveReduce;
 
+// i32 llvm.amdgcn.readfirstlane(i32)
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arsenm wrote:

I think we should just upgrade the intrinsic instead of introducing a new copy 

https://github.com/llvm/llvm-project/pull/87334