[clang] [compiler-rt] [llvm] Reland "[X86][AVX10.2] Support AVX10.2 option and VMPSADBW/VADDP[D,H,S] new instructions (#101452)" (PR #101616)

[Shengchen Kan via llvm-commits]

================
@@ -223,6 +227,10 @@ InstructionContext RecognizableInstr::insnContext() const {
           insnContext = EVEX_KB_U(IC_EVEX_XD);
         else if (OpPrefix == X86Local::PS)
           insnContext = EVEX_KB_U(IC_EVEX);
+        else {
+          errs() << "Instruction does not use a prefix: " << Name << "\n";
+          llvm_unreachable("Invalid prefix");
----------------
KanRobert wrote:

The default op prefix for `EVEX` is `PS` in compiler. 6e20df1a3b0f7654b2821fe182c7ae9bd52672e6

Should we use the message like

```
llvm_unreachable(("Invalid prefix for" + Name).c_str())
```


https://github.com/llvm/llvm-project/pull/101616