[block-freq] Refactor LiveInterals::getSpillWeight to use the new MachineBlockFrequencyInfo methods.

This is slightly more interesting than the previous batch of changes.
Specifically:

1. We refactor getSpillWeight to take a MachineBlockFrequencyInfo (MBFI)
object. This enables us to completely encapsulate the actual manner we
use the MachineBlockFrequencyInfo to get our spill weights. This yields
cleaner code since one does not need to fetch the actual block frequency
before getting the spill weight if all one wants it the spill weight. It
also gives us access to entry frequency which we need for our
computation.

2. Instead of having getSpillWeight take a MachineBasicBlock (as one
might think) to look up the block frequency via the MBFI object, we
instead take in a MachineInstr object. The reason for this is that the
method is supposed to return the spill weight for an instruction
according to the comments around the function.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197296 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/LiveIntervalAnalysis.h

@@ -45,6 +45,7 @@ namespace llvm {
   class TargetInstrInfo;
   class TargetRegisterClass;
   class VirtRegMap;
+  class MachineBlockFrequencyInfo;
 
   class LiveIntervals : public MachineFunctionPass {
     MachineFunction* MF;
@@ -100,7 +101,9 @@ namespace llvm {
     virtual ~LiveIntervals();
 
     // Calculate the spill weight to assign to a single instruction.
-    static float getSpillWeight(bool isDef, bool isUse, BlockFrequency freq);
+    static float getSpillWeight(bool isDef, bool isUse,
+                                const MachineBlockFrequencyInfo *MBFI,
+                                const MachineInstr *Instr);
 
     LiveInterval &getInterval(unsigned Reg) {
       if (hasInterval(Reg))

lib/CodeGen/CalcSpillWeights.cpp

@@ -132,7 +132,7 @@ VirtRegAuxInfo::calculateSpillWeightAndHint(LiveInterval &li) {
       bool reads, writes;
       tie(reads, writes) = mi->readsWritesVirtualRegister(li.reg);
       weight = LiveIntervals::getSpillWeight(
-          writes, reads, MBFI.getBlockFreq(mi->getParent()));
+        writes, reads, &MBFI, mi);
 
       // Give extra weight to what looks like a loop induction variable update.
       if (writes && isExiting && LIS.isLiveOutOfMBB(li, mbb))

lib/CodeGen/LiveIntervalAnalysis.cpp

@@ -22,6 +22,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/CodeGen/LiveVariables.h"
+#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
 #include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
@@ -620,9 +621,12 @@ LiveIntervals::hasPHIKill(const LiveInterval &LI, const VNInfo *VNI) const {
 }
 
 float
-LiveIntervals::getSpillWeight(bool isDef, bool isUse, BlockFrequency freq) {
-  const float Scale = 1.0f / BlockFrequency::getEntryFrequency();
-  return (isDef + isUse) * (freq.getFrequency() * Scale);
+LiveIntervals::getSpillWeight(bool isDef, bool isUse,
+                              const MachineBlockFrequencyInfo *MBFI,
+                              const MachineInstr *MI) {
+  BlockFrequency Freq = MBFI->getBlockFreq(MI->getParent());
+  const float Scale = 1.0f / MBFI->getEntryFrequency();
+  return (isDef + isUse) * (Freq.getFrequency() * Scale);
 }
 
 LiveRange::Segment

lib/CodeGen/RegAllocPBQP.cpp

@@ -348,8 +348,7 @@ PBQPRAProblem *PBQPBuilderWithCoalescing::build(MachineFunction *mf,
       // value plucked randomly out of the air.
 
       PBQP::PBQPNum cBenefit =
-        copyFactor * LiveIntervals::getSpillWeight(false, true,
-                                                   mbfi->getBlockFreq(mbb));
+        copyFactor * LiveIntervals::getSpillWeight(false, true, mbfi, mi);
 
       if (cp.isPhys()) {
         if (!mf->getRegInfo().isAllocatable(dst)) {

lib/CodeGen/StackSlotColoring.cpp

@@ -142,7 +142,6 @@ void StackSlotColoring::ScanForSpillSlotRefs(MachineFunction &MF) {
   for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
        MBBI != E; ++MBBI) {
     MachineBasicBlock *MBB = &*MBBI;
-    BlockFrequency Freq = MBFI->getBlockFreq(MBB);
     for (MachineBasicBlock::iterator MII = MBB->begin(), EE = MBB->end();
          MII != EE; ++MII) {
       MachineInstr *MI = &*MII;
@@ -157,7 +156,7 @@ void StackSlotColoring::ScanForSpillSlotRefs(MachineFunction &MF) {
           continue;
         LiveInterval &li = LS->getInterval(FI);
         if (!MI->isDebugValue())
-          li.weight += LiveIntervals::getSpillWeight(false, true, Freq);
+          li.weight += LiveIntervals::getSpillWeight(false, true, MBFI, MI);
       }
       for (MachineInstr::mmo_iterator MMOI = MI->memoperands_begin(),
            EE = MI->memoperands_end(); MMOI != EE; ++MMOI) {