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

[Craig Topper via cfe-commits]

================
@@ -793,153 +887,69 @@ RISCVISAInfo::parseArchString(StringRef Arch, bool EnableExperimentalExtension,
       Minor = Version->Minor;
     }
 
-    ISAInfo->addExtension(StringRef(&Baseline, 1), {Major, Minor});
+    // Postpone AddExtension until end of this function
+    SeenExtMap[StringRef(&Baseline, 1).str()] = {Major, Minor};
   }
 
   // Consume the base ISA version number and any '_' between rvxxx and the
   // first extension
   Exts = Exts.drop_front(ConsumeLength);
   Exts.consume_front("_");
 
-  auto StdExtsItr = StdExts.begin();
-  auto StdExtsEnd = StdExts.end();
-  auto GoToNextExt = [](StringRef::iterator &I, unsigned ConsumeLength,
-                        StringRef::iterator E) {
-    I += 1 + ConsumeLength;
-    if (I != E && *I == '_')
-      ++I;
-  };
-  for (auto I = Exts.begin(), E = Exts.end(); I != E;) {
-    char C = *I;
-
-    // Check ISA extensions are specified in the canonical order.
-    while (StdExtsItr != StdExtsEnd && *StdExtsItr != C)
-      ++StdExtsItr;
-
-    if (StdExtsItr == StdExtsEnd) {
-      // Either c contains a valid extension but it was not given in
-      // canonical order or it is an invalid extension.
-      if (StdExts.contains(C)) {
-        return createStringError(
-            errc::invalid_argument,
-            "standard user-level extension not given in canonical order '%c'",
-            C);
-      }
-
-      return createStringError(errc::invalid_argument,
-                               "invalid standard user-level extension '%c'", C);
-    }
-
-    // Move to next char to prevent repeated letter.
-    ++StdExtsItr;
-
-    StringRef Next;
-    unsigned Major, Minor, ConsumeLength;
-    if (std::next(I) != E)
-      Next = StringRef(std::next(I), E - std::next(I));
-    if (auto E = getExtensionVersion(StringRef(&C, 1), Next, Major, Minor,
-                                     ConsumeLength, EnableExperimentalExtension,
-                                     ExperimentalExtensionVersionCheck)) {
-      if (IgnoreUnknown) {
-        consumeError(std::move(E));
-        GoToNextExt(I, ConsumeLength, Exts.end());
-        continue;
-      }
-      return std::move(E);
-    }
-
-    // The order is OK, then push it into features.
-    // Currently LLVM supports only "mafdcvh".
-    if (!isSupportedExtension(StringRef(&C, 1))) {
-      if (IgnoreUnknown) {
-        GoToNextExt(I, ConsumeLength, Exts.end());
-        continue;
+  std::vector<std::string> SplitedExts;
+  if (auto E = splitExtsByUnderscore(Exts, SplitedExts))
+    return std::move(E);
+
+  for (auto Ext : SplitedExts) {
----------------
topperc wrote:

`auto &Ext`

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