[clang] [llvm] goldsteinn/uitofp nneg folds and analysis (PR #86154)

llvmbot wrote: @llvm/pr-subscribers-clang Author: None (goldsteinn) Changes - **[InstCombine] Add canonicalization of `sitofp` -> `uitofp nneg`** - **[CVP] Add tests for adding `nneg` flag to `uitofp` and converting `sitofp` -> `uitofp nneg`; NFC** - **[CVP] Convert `sitofp` -> `uitofp nn

[clang] [llvm] goldsteinn/uitofp nneg folds and analysis (PR #86154)

https://github.com/goldsteinn created https://github.com/llvm/llvm-project/pull/86154 - **[InstCombine] Add canonicalization of `sitofp` -> `uitofp nneg`** - **[CVP] Add tests for adding `nneg` flag to `uitofp` and converting `sitofp` -> `uitofp nneg`; NFC** - **[CVP] Convert `sitofp` -> `uitof