[llvm] [RISCV] Add QingKe "XW" compressed opcode extension (PR #97925)

[via llvm-commits]

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@@ -799,6 +800,14 @@ Error RISCVISAInfo::checkDependency() {
         errc::invalid_argument,
         "'zabha' requires 'a' or 'zaamo' extension to also be specified");
 
+  if (HasD && Exts.count("xwchc") != 0)
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ArcaneNibble wrote:

I don't believe the opcode encodings *conflict* with XLen != 32, but, as no 64-bit microcontrollers from this vendor currently exist, I will add this check.

https://github.com/llvm/llvm-project/pull/97925