[clang] [llvm] [RISCV]Support Sspmp, Sspmpen and Smpmpdeleg Extensions (PR #207696)

[Liao Chunyu via cfe-commits]

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@@ -1095,6 +1095,16 @@ def FeatureStdExtSsccfg
 def FeatureStdExtSsccptr
     : RISCVExtension<1, 0, "Main memory supports page table reads">;
 
+def FeatureStdExtSspmp
+    : RISCVExtension<1, 0, "S-level Physical Memory Protection (SPMP)",
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ChunyuLiao wrote:

The code changes are minimal. Let's wait for the spec to be ratified. 

https://github.com/llvm/llvm-project/pull/207696