[clang] [llvm] [RISCV][P-ext] Support Packed Element Extract (PR #221565)

[Hongyu Chen via cfe-commits]

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+// REQUIRES: riscv-registered-target
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XChy wrote:

Yep, I tried an LLVM build with only the X86 target, and it passed. Sorry for my unfamiliarity with the frontend...

https://github.com/llvm/llvm-project/pull/221565