SchedMachineModel: compress the CPU's WriteLatencyTable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164199 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/CodeGenSchedule.cpp b/utils/TableGen/CodeGenSchedule.cpp
index 0babda3..7946b42 100644
--- a/utils/TableGen/CodeGenSchedule.cpp
+++ b/utils/TableGen/CodeGenSchedule.cpp
@@ -270,6 +270,21 @@
   return 0;
 }
 
+bool CodeGenSchedModels::hasReadOfWrite(Record *WriteDef) const {
+  for (unsigned i = 0, e = SchedReads.size(); i < e; ++i) {
+    Record *ReadDef = SchedReads[i].TheDef;
+    if (!ReadDef || !ReadDef->isSubClassOf("ProcReadAdvance"))
+      continue;
+
+    RecVec ValidWrites = ReadDef->getValueAsListOfDefs("ValidWrites");
+    if (std::find(ValidWrites.begin(), ValidWrites.end(), WriteDef)
+        != ValidWrites.end()) {
+      return true;
+    }
+  }
+  return false;
+}
+
 namespace llvm {
 void splitSchedReadWrites(const RecVec &RWDefs,
                           RecVec &WriteDefs, RecVec &ReadDefs) {