Switch spill weights from a basic loop depth estimation to BlockFrequencyInfo.

The main advantages here are way better heuristics, taking into account not
just loop depth but also __builtin_expect and other static heuristics and will
eventually learn how to use profile info. Most of the work in this patch is
pushing the MachineBlockFrequencyInfo analysis into the right places.

This is good for a 5% speedup on zlib's deflate (x86_64), there were some very
unfortunate spilling decisions in its hottest loop in longest_match(). Other
benchmarks I tried were mostly neutral.

This changes register allocation in subtle ways, update the tests for it.
2012-02-20-MachineCPBug.ll was deleted as it's very fragile and the instruction
it looked for was gone already (but the FileCheck pattern picked up unrelated
stuff).

llvm-svn: 184105

1 files changed, 7 insertions, 7 deletions

diff --git a/llvm/lib/CodeGen/StackSlotColoring.cpp b/llvm/lib/CodeGen/StackSlotColoring.cpp
index f9515610d7e..3c35b8374d8 100644
--- a/llvm/lib/CodeGen/StackSlotColoring.cpp
+++ b/llvm/lib/CodeGen/StackSlotColoring.cpp
@@ -19,9 +19,9 @@
 #include "llvm/ADT/Statistic.h"
 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
 #include "llvm/CodeGen/LiveStackAnalysis.h"
+#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
-#include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/CodeGen/MachineMemOperand.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/PseudoSourceValue.h"
@@ -48,7 +48,7 @@ namespace {
     LiveStacks* LS;
     MachineFrameInfo *MFI;
     const TargetInstrInfo  *TII;
-    const MachineLoopInfo *loopInfo;
+    const MachineBlockFrequencyInfo *MBFI;
 
     // SSIntervals - Spill slot intervals.
     std::vector<LiveInterval*> SSIntervals;
@@ -89,8 +89,8 @@ namespace {
       AU.addRequired<SlotIndexes>();
       AU.addPreserved<SlotIndexes>();
       AU.addRequired<LiveStacks>();
-      AU.addRequired<MachineLoopInfo>();
-      AU.addPreserved<MachineLoopInfo>();
+      AU.addRequired<MachineBlockFrequencyInfo>();
+      AU.addPreserved<MachineBlockFrequencyInfo>();
       AU.addPreservedID(MachineDominatorsID);
       MachineFunctionPass::getAnalysisUsage(AU);
     }
@@ -139,7 +139,7 @@ void StackSlotColoring::ScanForSpillSlotRefs(MachineFunction &MF) {
   for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
        MBBI != E; ++MBBI) {
     MachineBasicBlock *MBB = &*MBBI;
-    unsigned loopDepth = loopInfo->getLoopDepth(MBB);
+    BlockFrequency Freq = MBFI->getBlockFreq(MBB);
     for (MachineBasicBlock::iterator MII = MBB->begin(), EE = MBB->end();
          MII != EE; ++MII) {
       MachineInstr *MI = &*MII;
@@ -154,7 +154,7 @@ void StackSlotColoring::ScanForSpillSlotRefs(MachineFunction &MF) {
           continue;
         LiveInterval &li = LS->getInterval(FI);
         if (!MI->isDebugValue())
-          li.weight += LiveIntervals::getSpillWeight(false, true, loopDepth);
+          li.weight += LiveIntervals::getSpillWeight(false, true, Freq);
         SSRefs[FI].push_back(MI);
       }
     }
@@ -396,7 +396,7 @@ bool StackSlotColoring::runOnMachineFunction(MachineFunction &MF) {
   MFI = MF.getFrameInfo();
   TII = MF.getTarget().getInstrInfo();
   LS = &getAnalysis<LiveStacks>();
-  loopInfo = &getAnalysis<MachineLoopInfo>();
+  MBFI = &getAnalysis<MachineBlockFrequencyInfo>();
 
   bool Changed = false;