[TableGen] Only store direct superclasses in Record (#123072)

In Record only store the direct superclasses instead of all
superclasses. getSuperClasses recurses to find all superclasses when
necessary.

This gives a small reduction in memory usage. On lib/Target/X86/X86.td I
measured about 2.0% reduction in total bytes allocated (measured by
valgrind) and 1.3% reduction in peak memory usage (measured by
/usr/bin/time -v).

---------

Co-authored-by: Min-Yih Hsu <min@myhsu.dev>

1 files changed, 2 insertions, 9 deletions

diff --git a/llvm/lib/TableGen/TGParser.cpp b/llvm/lib/TableGen/TGParser.cpp
index 3d914b9..423daf6 100644
--- a/llvm/lib/TableGen/TGParser.cpp
+++ b/llvm/lib/TableGen/TGParser.cpp
@@ -332,17 +332,10 @@ bool TGParser::AddSubClass(Record *CurRec, SubClassReference &SubClass) {
 
   // Since everything went well, we can now set the "superclass" list for the
   // current record.
-  for (const auto &[SC, Loc] : SC->getSuperClasses()) {
-    if (CurRec->isSubClassOf(SC))
-      return Error(SubClass.RefRange.Start,
-                   "Already subclass of '" + SC->getName() + "'!\n");
-    CurRec->addSuperClass(SC, Loc);
-  }
-
   if (CurRec->isSubClassOf(SC))
     return Error(SubClass.RefRange.Start,
                  "Already subclass of '" + SC->getName() + "'!\n");
-  CurRec->addSuperClass(SC, SubClass.RefRange);
+  CurRec->addDirectSuperClass(SC, SubClass.RefRange);
   return false;
 }
 
@@ -4056,7 +4049,7 @@ bool TGParser::ParseClass() {
   if (CurRec) {
     // If the body was previously defined, this is an error.
     if (!CurRec->getValues().empty() ||
-        !CurRec->getSuperClasses().empty() ||
+        !CurRec->getDirectSuperClasses().empty() ||
         !CurRec->getTemplateArgs().empty())
       return TokError("Class '" + CurRec->getNameInitAsString() +
                       "' already defined");