RegPressure: Order the "pressure sets" by number of regunits per set.

This lets heuristics easily pick the most important set to follow.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187108 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 53 insertions, 8 deletions

diff --git a/utils/TableGen/CodeGenRegisters.cpp b/utils/TableGen/CodeGenRegisters.cpp
index d9f230ef1c..fcc9f3d350 100644
--- a/utils/TableGen/CodeGenRegisters.cpp
+++ b/utils/TableGen/CodeGenRegisters.cpp
@@ -956,7 +956,7 @@ CodeGenRegBank::CodeGenRegBank(RecordKeeper &Records) {
     std::sort(TupRegsCopy.begin(), TupRegsCopy.end(), LessRecordRegister());
     for (unsigned j = 0, je = TupRegsCopy.size(); j != je; ++j)
       getReg((TupRegsCopy)[j]);
-    TupRegsCopy.clear();    
+    TupRegsCopy.clear();
   }
 
   // Now all the registers are known. Build the object graph of explicit
@@ -1620,6 +1620,16 @@ void CodeGenRegBank::computeRegUnitSets() {
   }
 }
 
+struct LessUnits {
+  const CodeGenRegBank &RegBank;
+  LessUnits(const CodeGenRegBank &RB): RegBank(RB) {}
+
+  bool operator()(unsigned ID1, unsigned ID2) {
+    return RegBank.getRegPressureSet(ID1).Units.size()
+      < RegBank.getRegPressureSet(ID2).Units.size();
+  }
+};
+
 void CodeGenRegBank::computeDerivedInfo() {
   computeComposites();
   computeSubRegIndexLaneMasks();
@@ -1631,6 +1641,21 @@ void CodeGenRegBank::computeDerivedInfo() {
   // Compute a unique set of RegUnitSets. One for each RegClass and inferred
   // supersets for the union of overlapping sets.
   computeRegUnitSets();
+
+  // Get the weight of each set.
+  for (unsigned Idx = 0, EndIdx = RegUnitSets.size(); Idx != EndIdx; ++Idx)
+    RegUnitSets[Idx].Weight = getRegUnitSetWeight(RegUnitSets[Idx].Units);
+
+  // Find the order of each set.
+  RegUnitSetOrder.reserve(RegUnitSets.size());
+  for (unsigned Idx = 0, EndIdx = RegUnitSets.size(); Idx != EndIdx; ++Idx)
+    RegUnitSetOrder.push_back(Idx);
+
+  std::stable_sort(RegUnitSetOrder.begin(), RegUnitSetOrder.end(),
+                   LessUnits(*this));
+  for (unsigned Idx = 0, EndIdx = RegUnitSets.size(); Idx != EndIdx; ++Idx) {
+    RegUnitSets[RegUnitSetOrder[Idx]].Order = Idx;
+  }
 }
 
 //
diff --git a/utils/TableGen/CodeGenRegisters.h b/utils/TableGen/CodeGenRegisters.h
index 33f32b0812..37f75b4a48 100644
--- a/utils/TableGen/CodeGenRegisters.h
+++ b/utils/TableGen/CodeGenRegisters.h
@@ -433,6 +433,10 @@ namespace llvm {
 
     std::string Name;
     std::vector<unsigned> Units;
+    unsigned Weight; // Cache the sum of all unit weights.
+    unsigned Order;  // Cache the sort key.
+
+    RegUnitSet() : Weight(0), Order(0) {}
   };
 
   // Base vector for identifying TopoSigs. The contents uniquely identify a
@@ -484,6 +488,9 @@ namespace llvm {
     // already exist for a register class, we create a new entry in this vector.
     std::vector<std::vector<unsigned> > RegClassUnitSets;
 
+    // Give each register unit set an order based on sorting criteria.
+    std::vector<unsigned> RegUnitSetOrder;
+
     // Add RC to *2RC maps.
     void addToMaps(CodeGenRegisterClass*);
 
@@ -622,6 +629,13 @@ namespace llvm {
       return Weight;
     }
 
+    unsigned getRegSetIDAt(unsigned Order) const {
+      return RegUnitSetOrder[Order];
+    }
+    const RegUnitSet &getRegSetAt(unsigned Order) const {
+      return RegUnitSets[RegUnitSetOrder[Order]];
+    }
+
     // Increase a RegUnitWeight.
     void increaseRegUnitWeight(unsigned RUID, unsigned Inc) {
       getRegUnit(RUID).Weight += Inc;
@@ -631,7 +645,7 @@ namespace llvm {
     unsigned getNumRegPressureSets() const { return RegUnitSets.size(); }
 
     // Get a set of register unit IDs for a given dimension of pressure.
-    RegUnitSet getRegPressureSet(unsigned Idx) const {
+    const RegUnitSet &getRegPressureSet(unsigned Idx) const {
       return RegUnitSets[Idx];
     }
 
diff --git a/utils/TableGen/RegisterInfoEmitter.cpp b/utils/TableGen/RegisterInfoEmitter.cpp
index 942163e77d..4d423e484f 100644
--- a/utils/TableGen/RegisterInfoEmitter.cpp
+++ b/utils/TableGen/RegisterInfoEmitter.cpp
@@ -223,7 +223,7 @@ EmitRegUnitPressure(raw_ostream &OS, const CodeGenRegBank &RegBank,
      << "getRegPressureSetName(unsigned Idx) const {\n"
      << "  static const char *PressureNameTable[] = {\n";
   for (unsigned i = 0; i < NumSets; ++i ) {
-    OS << "    \"" << RegBank.getRegPressureSet(i).Name << "\",\n";
+    OS << "    \"" << RegBank.getRegSetAt(i).Name << "\",\n";
   }
   OS << "    0 };\n"
      << "  return PressureNameTable[Idx];\n"
@@ -235,9 +235,9 @@ EmitRegUnitPressure(raw_ostream &OS, const CodeGenRegBank &RegBank,
      << "getRegPressureSetLimit(unsigned Idx) const {\n"
      << "  static const unsigned PressureLimitTable[] = {\n";
   for (unsigned i = 0; i < NumSets; ++i ) {
-    const RegUnitSet &RegUnits = RegBank.getRegPressureSet(i);
-    OS << "    " << RegBank.getRegUnitSetWeight(RegUnits.Units)
-       << ",  \t// " << i << ": " << RegUnits.Name << "\n";
+    const RegUnitSet &RegUnits = RegBank.getRegSetAt(i);
+    OS << "    " << RegUnits.Weight << ",  \t// " << i << ": "
+       << RegUnits.Name << "\n";
   }
   OS << "    0 };\n"
      << "  return PressureLimitTable[Idx];\n"
@@ -252,9 +252,15 @@ EmitRegUnitPressure(raw_ostream &OS, const CodeGenRegBank &RegBank,
   for (unsigned i = 0, StartIdx = 0, e = NumRCUnitSets; i != e; ++i) {
     RCSetStarts[i] = StartIdx;
     ArrayRef<unsigned> PSetIDs = RegBank.getRCPressureSetIDs(i);
+    std::vector<unsigned> PSets;
+    PSets.reserve(PSetIDs.size());
     for (ArrayRef<unsigned>::iterator PSetI = PSetIDs.begin(),
            PSetE = PSetIDs.end(); PSetI != PSetE; ++PSetI) {
-      OS << *PSetI << ",  ";
+      PSets.push_back(RegBank.getRegPressureSet(*PSetI).Order);
+    }
+    std::sort(PSets.begin(), PSets.end());
+    for (unsigned i = 0, e = PSets.size(); i < e; ++i) {
+      OS << PSets[i] << ",  ";
       ++StartIdx;
     }
     OS << "-1,  \t// #" << RCSetStarts[i] << " ";
@@ -264,7 +270,7 @@ EmitRegUnitPressure(raw_ostream &OS, const CodeGenRegBank &RegBank,
       OS << "inferred";
       for (ArrayRef<unsigned>::iterator PSetI = PSetIDs.begin(),
              PSetE = PSetIDs.end(); PSetI != PSetE; ++PSetI) {
-        OS << "~" << RegBank.getRegPressureSet(*PSetI).Name;
+        OS << "~" << RegBank.getRegSetAt(*PSetI).Name;
       }
     }
     OS << "\n    ";