[TableGen] Add a SmallPtrSet to track WriteRes that are referenced by some ReadAdvance. NFC (#124160)

Use this to remove a linear scan from CodeGenProcModel::hasReadOfWrite.

This reduces build time of RISCVGenSubtargetInfo.inc on by machine from
~6 seconds to ~3 seconds.

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/utils/TableGen/Common/CodeGenSchedule.h b/llvm/utils/TableGen/Common/CodeGenSchedule.h
index 5d5aa44d882e..0dce1fa30811 100644
--- a/llvm/utils/TableGen/Common/CodeGenSchedule.h
+++ b/llvm/utils/TableGen/Common/CodeGenSchedule.h
@@ -19,6 +19,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/TableGen/Record.h"
 #include "llvm/TableGen/SetTheory.h"
@@ -250,6 +251,9 @@ struct CodeGenProcModel {
   // Map from the ReadType field to the parent ReadAdvance record.
   DenseMap<const Record *, const Record *> ReadAdvanceMap;
 
+  // Set of WriteRes that are referenced by a ReadAdvance.
+  SmallPtrSet<const Record *, 8> ReadOfWriteSet;
+
   // Per-operand machine model resources associated with this processor.
   ConstRecVec ProcResourceDefs;