[llvm] [NVPTX] Implement isTruncateFree and isZExtFree for i32/i64 Optimizations (PR #114683)

[Justin Fargnoli via llvm-commits]

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@@ -616,6 +616,10 @@ class NVPTXTargetLowering : public TargetLowering {
     return true;
   }
 
+  bool isTruncateFree(EVT FromVT, EVT ToVT) const override;
+  bool isZExtFree(EVT FromVT, EVT ToVT) const override;
+  bool isZExtFree(Type *SrcTy, Type *DstTy) const override;
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justinfargnoli wrote:

Let's move this up to where the existing implementation of [`isTruncateFree()` resides](https://github.com/llvm/llvm-project/blob/c6cce261f5f7e1bdb092374d51e44ab7bc04e769/llvm/lib/Target/NVPTX/NVPTXISelLowering.h#L501). 

https://github.com/llvm/llvm-project/pull/114683