[llvm-branch-commits] [TableGen] Slightly improve error location for a fatal error (PR #170790)

[Matt Arsenault via llvm-branch-commits]

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@@ -1316,11 +1316,18 @@ CodeGenRegBank::getOrCreateSubClass(const CodeGenRegisterClass *RC,
   return {&RegClasses.back(), true};
 }
 
-CodeGenRegisterClass *CodeGenRegBank::getRegClass(const Record *Def) const {
+CodeGenRegisterClass *CodeGenRegBank::getRegClass(const Record *Def,
+                                                  ArrayRef<SMLoc> Loc) const {
   if (CodeGenRegisterClass *RC = Def2RC.lookup(Def))
     return RC;
 
-  PrintFatalError(Def->getLoc(), "Not a known RegisterClass!");
+  ArrayRef<SMLoc> DiagLoc = Loc.empty() ? Def->getLoc() : Loc;
+  // TODO: Ideally we should update the API to allow resolving HwMode.
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arsenm wrote:

No, that would not be very ergonomic. The point is to have reusable patterns and not have to spam every possible detail through every deeply nested multi class 

https://github.com/llvm/llvm-project/pull/170790