[NVPTX] Implement `TLI.isTruncateFree(EVT, EVT)` and `TLI.isZExtFree()`

[justinfargnoli]

NVPTX currently does not override TLI.isTruncateFree(EVT, EVT) and TLI.isZExtFree(), and it probably should.

zext/truncate between i32/i64 can probably be considered free, as the values already live in separate 32-bit registers in hardware.

Originally posted by @Artem-B in #98666 (comment)

[llvmbot]

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[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Justin Fargnoli (justinfargnoli)

NVPTX currently does not override `TLI.isTruncateFree` and `TLI.isZExtFree`, and it probably should.

zext/truncate between i32/i64 can probably be considered free, as the values already live in separate 32-bit registers in hardware.

Originally posted by @Artem-B in #98666 (comment)

[SergeantCooper]

i want to work on this issue

[justinfargnoli]

@Quark-69, that's fantastic to hear! Please let me know if I should expand on what the ask is or if I can help in any way :)

[Artem-B]

@Quark-69 Go for it. Patches are welcome.

[SergeantCooper]

@justinfargnoli there were 2 virtual functions for isZextfree and 1 for istruncatefree that weren't implemented in the nvptx library. So I have to implement all these?
Also can you elaborate a little for the issue and give me some testing strategies.