[llvm] [SDAG][NVPTX] Add TLI check for preferring custom FP_TO_SINT operations to FP_TO_UINT (PR #132470)

[Artem Belevich via llvm-commits]

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@@ -6179,6 +6179,33 @@ Instruction *NVPTXTargetLowering::emitTrailingFence(IRBuilderBase &Builder,
   return nullptr;
 }
 
+// Rather than default to SINT when both UINT and SINT are custom, we only
+// change the opcode when UINT is not legal and SINT is. UINT is preferred when
+// both are custom since unsigned CVT instructions can lead to slightly better
+// SASS code with fewer instructions.
+unsigned NVPTXTargetLowering::getFPToXIntOpcode(unsigned Op, EVT FromVT,
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Artem-B wrote:

I don't have a strong preference either way. The patch does improve things for NVPTX, however marginally. 

https://github.com/llvm/llvm-project/pull/132470