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

[Craig Topper via cfe-commits]

================
@@ -695,6 +696,106 @@ RISCVISAInfo::parseNormalizedArchString(StringRef Arch) {
   return std::move(ISAInfo);
 }
 
+static Error splitExtsByUnderscore(StringRef Exts,
+                                   std::vector<std::string> &SplitExts) {
+  SmallVector<StringRef, 8> Split;
+  if (Exts.empty())
+    return Error::success();
+
+  Exts.split(Split, "_");
+
+  for (auto Ext : Split) {
+    if (Ext.empty())
+      return createStringError(errc::invalid_argument,
+                               "extension name missing after separator '_'");
+
+    SplitExts.push_back(Ext.str());
+  }
+  return Error::success();
+}
+
+static Error processMultiLetterExtension(
+    StringRef RawExt,
+    MapVector<std::string, RISCVISAInfo::ExtensionVersion,
+              std::map<std::string, unsigned>> &SeenExtMap,
+    bool IgnoreUnknown, bool EnableExperimentalExtension,
+    bool ExperimentalExtensionVersionCheck) {
+  StringRef Type = getExtensionType(RawExt);
+  StringRef Desc = getExtensionTypeDesc(RawExt);
+  auto Pos = findLastNonVersionCharacter(RawExt) + 1;
+  StringRef Name(RawExt.substr(0, Pos));
+  StringRef Vers(RawExt.substr(Pos));
+
+  if (Type.empty()) {
+    if (IgnoreUnknown)
+      return Error::success();
+    return createStringError(errc::invalid_argument,
+                             "invalid extension prefix '" + RawExt + "'");
+  }
+
+  if (!IgnoreUnknown && Name.size() == Type.size())
+    return createStringError(errc::invalid_argument,
+                             "%s name missing after '%s'", Desc.str().c_str(),
+                             Type.str().c_str());
+
+  unsigned Major, Minor, ConsumeLength;
+  if (auto E = getExtensionVersion(Name, Vers, Major, Minor, ConsumeLength,
+                                   EnableExperimentalExtension,
+                                   ExperimentalExtensionVersionCheck)) {
+    if (IgnoreUnknown) {
+      consumeError(std::move(E));
+      return Error::success();
+    }
+    return E;
+  }
+
+  // Check if duplicated extension.
+  if (!IgnoreUnknown && (SeenExtMap.find(Name.str()) != SeenExtMap.end()))
----------------
topperc wrote:

`SeenExtMap.contains(Name.str())`

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