[clang] [llvm] [RISCV] Relax march string order constraint (PR #78120)

[Craig Topper via cfe-commits]

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@@ -715,6 +815,8 @@ RISCVISAInfo::parseArchString(StringRef Arch, bool EnableExperimentalExtension,
 
   unsigned XLen = HasRV64 ? 64 : 32;
   std::unique_ptr<RISCVISAInfo> ISAInfo(new RISCVISAInfo(XLen));
+  SmallVector<std::string, 8> SeenExts;
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topperc wrote:

Maybe SeenExts should be a SetVector to make it more efficient to check for duplicates?

Or maybe a MapVector storing the version as the value so we don't need ExtsVersion?

https://github.com/llvm/llvm-project/pull/78120