fixup! use FrameIndex as key; simplify map

Author: michaelmaitland

llvm/include/llvm/CodeGen/ReachingDefAnalysis.h

@@ -141,12 +141,12 @@ class ReachingDefAnalysis : public MachineFunctionPass {
   DenseMap<MachineInstr *, int> InstIds;
 
   MBBReachingDefsInfo MBBReachingDefs;
+
+  /// MBBFrameObjsReachingDefs[{i, j}] is a list of instruction indices
+  /// (relative to begining of MBB i) that define frame index j in MBB i. This
+  /// is used in answering reaching definition queries.
   using MBBFrameObjsReachingDefsInfo =
-      DenseMap<unsigned, DenseMap<int, SmallVector<int>>>;
-  // MBBFrameObjsReachingDefs[i][j] is a list of instruction indices (relative
-  // to begining of MBB) that define frame index (j +
-  // MF->getFrameInfo().getObjectIndexBegin()) in MBB i. This is used in
-  // answering reaching definition queries.
+      DenseMap<std::pair<unsigned, int>, SmallVector<int>>;
   MBBFrameObjsReachingDefsInfo MBBFrameObjsReachingDefs;
 
   /// Default values are 'nothing happened a long time ago'.

llvm/lib/CodeGen/ReachingDefAnalysis.cpp

@@ -147,9 +147,7 @@ void ReachingDefAnalysis::processDefs(MachineInstr *MI) {
       assert(FrameIndex >= 0 && "Can't handle negative frame indicies yet!");
       if (!isFIDef(*MI, FrameIndex, TII))
         continue;
-
-      int Key = FrameIndex - ObjectIndexBegin;
-      MBBFrameObjsReachingDefs[MBBNumber][Key].push_back(CurInstr);
+      MBBFrameObjsReachingDefs[{MBBNumber, FrameIndex}].push_back(CurInstr);
     }
     if (!isValidRegDef(MO))
       continue;
@@ -344,15 +342,10 @@ int ReachingDefAnalysis::getReachingDef(MachineInstr *MI, Register Reg) const {
     int Key = FrameIndex - ObjectIndexBegin;
 
     // Check that there was a reaching def.
-    auto Lookup1 = MBBFrameObjsReachingDefs.find(MBBNumber);
-    if (Lookup1 == MBBFrameObjsReachingDefs.end())
-      return LatestDef;
-    auto &InnerMap = Lookup1->second;
-    auto Lookup2 = InnerMap.find(Key);
-    if (Lookup2 == InnerMap.end())
+    auto Lookup = MBBFrameObjsReachingDefs.find({MBBNumber, Key});
+    if (Lookup == MBBFrameObjsReachingDefs.end())
       return LatestDef;
-    auto &Defs = Lookup2->second;
-
+    auto &Defs = Lookup->second;
     for (int Def : Defs) {
       if (Def >= InstId)
         break;