CalculateSpillWeights does not need to be a pass

Based on discussions with Lang Hames and Jakob Stoklund Olesen at the hacker's lab, and in the light of upcoming work on the PBQP register allocator, it was though that CalcSpillWeights does not need to be a pass. This change will enable to customize / tune the spill weight computation depending on the allocator.

Update the documentation style while there.

No functionnal change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194269 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/CalcSpillWeights.h

@@ -21,7 +21,9 @@ namespace llvm {
   class MachineBlockFrequencyInfo;
   class MachineLoopInfo;
 
-  /// normalizeSpillWeight - The spill weight of a live interval is computed as:
+  /// \brief Normalize the spill weight of a live interval
+  ///
+  /// The spill weight of a live interval is computed as:
   ///
   ///   (sum(use freq) + sum(def freq)) / (K + size)
   ///
@@ -38,8 +40,8 @@ namespace llvm {
     return UseDefFreq / (Size + 25*SlotIndex::InstrDist);
   }
 
-  /// VirtRegAuxInfo - Calculate auxiliary information for a virtual
-  /// register such as its spill weight and allocation hint.
+  /// \brief Calculate auxiliary information for a virtual register such as its
+  /// spill weight and allocation hint.
   class VirtRegAuxInfo {
     MachineFunction &MF;
     LiveIntervals &LIS;
@@ -52,29 +54,16 @@ namespace llvm {
                    const MachineBlockFrequencyInfo &mbfi)
         : MF(mf), LIS(lis), Loops(loops), MBFI(mbfi) {}
 
-    /// CalculateWeightAndHint - (re)compute li's spill weight and allocation
-    /// hint.
+    /// \brief (re)compute li's spill weight and allocation hint.
     void CalculateWeightAndHint(LiveInterval &li);
   };
 
-  /// CalculateSpillWeights - Compute spill weights for all virtual register
+  /// \brief Compute spill weights and allocation hints for all virtual register
   /// live intervals.
-  class CalculateSpillWeights : public MachineFunctionPass {
-  public:
-    static char ID;
-
-    CalculateSpillWeights() : MachineFunctionPass(ID) {
-      initializeCalculateSpillWeightsPass(*PassRegistry::getPassRegistry());
-    }
-
-    virtual void getAnalysisUsage(AnalysisUsage &au) const;
-
-    virtual bool runOnMachineFunction(MachineFunction &fn);
-
-  private:
-    /// Returns true if the given live interval is zero length.
-    bool isZeroLengthInterval(LiveInterval *li) const;
-  };
+  void calculateSpillWeights(LiveIntervals &LIS,
+                             MachineFunction &MF,
+                             const MachineLoopInfo &MLI,
+                             const MachineBlockFrequencyInfo &MBFI);
 
 }
 

include/llvm/InitializePasses.h

@@ -89,7 +89,6 @@ void initializeCFGSimplifyPassPass(PassRegistry&);
 void initializeFlattenCFGPassPass(PassRegistry&);
 void initializeStructurizeCFGPass(PassRegistry&);
 void initializeCFGViewerPass(PassRegistry&);
-void initializeCalculateSpillWeightsPass(PassRegistry&);
 void initializeCodeGenPreparePass(PassRegistry&);
 void initializeConstantMergePass(PassRegistry&);
 void initializeConstantPropagationPass(PassRegistry&);

lib/CodeGen/CalcSpillWeights.cpp

@@ -22,38 +22,21 @@
 #include "llvm/Target/TargetRegisterInfo.h"
 using namespace llvm;
 
-char CalculateSpillWeights::ID = 0;
-INITIALIZE_PASS_BEGIN(CalculateSpillWeights, "calcspillweights",
-                "Calculate spill weights", false, false)
-INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
-INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
-INITIALIZE_PASS_END(CalculateSpillWeights, "calcspillweights",
-                "Calculate spill weights", false, false)
-
-void CalculateSpillWeights::getAnalysisUsage(AnalysisUsage &au) const {
-  au.addRequired<LiveIntervals>();
-  au.addRequired<MachineBlockFrequencyInfo>();
-  au.addRequired<MachineLoopInfo>();
-  au.setPreservesAll();
-  MachineFunctionPass::getAnalysisUsage(au);
-}
-
-bool CalculateSpillWeights::runOnMachineFunction(MachineFunction &MF) {
-
+void llvm::calculateSpillWeights(LiveIntervals &LIS,
+                           MachineFunction &MF,
+                           const MachineLoopInfo &MLI,
+                           const MachineBlockFrequencyInfo &MBFI) {
   DEBUG(dbgs() << "********** Compute Spill Weights **********\n"
                << "********** Function: " << MF.getName() << '\n');
 
-  LiveIntervals &LIS = getAnalysis<LiveIntervals>();
   MachineRegisterInfo &MRI = MF.getRegInfo();
-  VirtRegAuxInfo VRAI(MF, LIS, getAnalysis<MachineLoopInfo>(),
-                      getAnalysis<MachineBlockFrequencyInfo>());
+  VirtRegAuxInfo VRAI(MF, LIS, MLI, MBFI);
   for (unsigned i = 0, e = MRI.getNumVirtRegs(); i != e; ++i) {
     unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
     if (MRI.reg_nodbg_empty(Reg))
       continue;
     VRAI.CalculateWeightAndHint(LIS.getInterval(Reg));
   }
-  return false;
 }
 
 // Return the preferred allocation register for reg, given a COPY instruction.

lib/CodeGen/CodeGen.cpp

@@ -22,7 +22,6 @@ using namespace llvm;
 void llvm::initializeCodeGen(PassRegistry &Registry) {
   initializeBasicTTIPass(Registry);
   initializeBranchFolderPassPass(Registry);
-  initializeCalculateSpillWeightsPass(Registry);
   initializeDeadMachineInstructionElimPass(Registry);
   initializeEarlyIfConverterPass(Registry);
   initializeExpandPostRAPass(Registry);

lib/CodeGen/RegAllocBasic.cpp

@@ -126,7 +126,6 @@ RABasic::RABasic(): MachineFunctionPass(ID) {
   initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
   initializeRegisterCoalescerPass(*PassRegistry::getPassRegistry());
   initializeMachineSchedulerPass(*PassRegistry::getPassRegistry());
-  initializeCalculateSpillWeightsPass(*PassRegistry::getPassRegistry());
   initializeLiveStacksPass(*PassRegistry::getPassRegistry());
   initializeMachineDominatorTreePass(*PassRegistry::getPassRegistry());
   initializeMachineLoopInfoPass(*PassRegistry::getPassRegistry());
@@ -143,7 +142,6 @@ void RABasic::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addPreserved<SlotIndexes>();
   AU.addRequired<LiveDebugVariables>();
   AU.addPreserved<LiveDebugVariables>();
-  AU.addRequired<CalculateSpillWeights>();
   AU.addRequired<LiveStacks>();
   AU.addPreserved<LiveStacks>();
   AU.addRequired<MachineBlockFrequencyInfo>();

lib/CodeGen/RegAllocGreedy.cpp

@@ -315,7 +315,6 @@ RAGreedy::RAGreedy(): MachineFunctionPass(ID) {
   initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
   initializeRegisterCoalescerPass(*PassRegistry::getPassRegistry());
   initializeMachineSchedulerPass(*PassRegistry::getPassRegistry());
-  initializeCalculateSpillWeightsPass(*PassRegistry::getPassRegistry());
   initializeLiveStacksPass(*PassRegistry::getPassRegistry());
   initializeMachineDominatorTreePass(*PassRegistry::getPassRegistry());
   initializeMachineLoopInfoPass(*PassRegistry::getPassRegistry());
@@ -339,7 +338,6 @@ void RAGreedy::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addPreserved<LiveDebugVariables>();
   AU.addRequired<LiveStacks>();
   AU.addPreserved<LiveStacks>();
-  AU.addRequired<CalculateSpillWeights>();
   AU.addRequired<MachineDominatorTree>();
   AU.addPreserved<MachineDominatorTree>();
   AU.addRequired<MachineLoopInfo>();
@@ -1840,6 +1838,8 @@ bool RAGreedy::runOnMachineFunction(MachineFunction &mf) {
   SpillPlacer = &getAnalysis<SpillPlacement>();
   DebugVars = &getAnalysis<LiveDebugVariables>();
 
+  calculateSpillWeights(*LIS, mf, *Loops, *MBFI);
+
   DEBUG(LIS->dump());
 
   SA.reset(new SplitAnalysis(*VRM, *LIS, *Loops));

lib/CodeGen/RegAllocPBQP.cpp

@@ -95,7 +95,6 @@ public:
       : MachineFunctionPass(ID), builder(b.take()), customPassID(cPassID) {
     initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
     initializeLiveIntervalsPass(*PassRegistry::getPassRegistry());
-    initializeCalculateSpillWeightsPass(*PassRegistry::getPassRegistry());
     initializeLiveStacksPass(*PassRegistry::getPassRegistry());
     initializeVirtRegMapPass(*PassRegistry::getPassRegistry());
   }
@@ -432,7 +431,6 @@ void RegAllocPBQP::getAnalysisUsage(AnalysisUsage &au) const {
   //au.addRequiredID(SplitCriticalEdgesID);
   if (customPassID)
     au.addRequiredID(*customPassID);
-  au.addRequired<CalculateSpillWeights>();
   au.addRequired<LiveStacks>();
   au.addPreserved<LiveStacks>();
   au.addRequired<MachineBlockFrequencyInfo>();
@@ -551,6 +549,8 @@ bool RegAllocPBQP::runOnMachineFunction(MachineFunction &MF) {
   lss = &getAnalysis<LiveStacks>();
   mbfi = &getAnalysis<MachineBlockFrequencyInfo>();
 
+  calculateSpillWeights(*lis, MF, getAnalysis<MachineLoopInfo>(), *mbfi);
+
   vrm = &getAnalysis<VirtRegMap>();
   spiller.reset(createInlineSpiller(*this, MF, *vrm));