[llvm] [RISCV] Gate CSR defined by experimental and vendor extensions (PR #104424)

[Jessica Clarke via llvm-commits]

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@@ -351,7 +364,10 @@ def SysRegVLENB: SysReg<"vlenb", 0xC22>;
 //===----------------------------------------------------------------------===//
 // Shadow Stack CSR
 //===----------------------------------------------------------------------===//
-def : SysReg<"ssp", 0x011>;
+
+let FeaturesRequired = [{ {RISCV::FeatureStdExtZicfiss} }] in {
+  def : SysReg<"ssp", 0x011>;
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jrtc27 wrote:

My initial instincts are to say that when it comes to CSRs experimental should be reserved solely for ones that don't have ratified encodings

https://github.com/llvm/llvm-project/pull/104424