Add a new optimization pass: Stack Coloring, that merges disjoint static allocations (allocas). Allocas are known to be
disjoint if they are marked by disjoint lifetime markers (@llvm.lifetime.XXX intrinsics).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163299 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CMakeLists.txt b/lib/CodeGen/CMakeLists.txt
index 2e189ad..386509b 100644
--- a/lib/CodeGen/CMakeLists.txt
+++ b/lib/CodeGen/CMakeLists.txt
@@ -95,6 +95,7 @@
SplitKit.cpp
StackProtector.cpp
StackSlotColoring.cpp
+ StackColoring.cpp
StrongPHIElimination.cpp
TailDuplication.cpp
TargetFrameLoweringImpl.cpp
diff --git a/lib/CodeGen/CodeGen.cpp b/lib/CodeGen/CodeGen.cpp
index fb2c2e8..65f0941 100644
--- a/lib/CodeGen/CodeGen.cpp
+++ b/lib/CodeGen/CodeGen.cpp
@@ -56,6 +56,7 @@
initializeRegisterCoalescerPass(Registry);
initializeSlotIndexesPass(Registry);
initializeStackProtectorPass(Registry);
+ initializeStackColoringPass(Registry);
initializeStackSlotColoringPass(Registry);
initializeStrongPHIEliminationPass(Registry);
initializeTailDuplicatePassPass(Registry);
diff --git a/lib/CodeGen/MachineFunction.cpp b/lib/CodeGen/MachineFunction.cpp
index 8d6452f..70d1bb3 100644
--- a/lib/CodeGen/MachineFunction.cpp
+++ b/lib/CodeGen/MachineFunction.cpp
@@ -458,7 +458,9 @@
unsigned StackAlign = TFI.getStackAlignment();
unsigned Align = MinAlign(SPOffset, StackAlign);
Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset, Immutable,
- /*isSS*/false, false));
+ /*isSS*/ false,
+ /*NeedSP*/ false,
+ /*Alloca*/ 0));
return -++NumFixedObjects;
}
diff --git a/lib/CodeGen/Passes.cpp b/lib/CodeGen/Passes.cpp
index 9564b5d..a6dd5de 100644
--- a/lib/CodeGen/Passes.cpp
+++ b/lib/CodeGen/Passes.cpp
@@ -529,6 +529,10 @@
// instructions dead.
addPass(&OptimizePHIsID);
+ // This pass merges large allocas. StackSlotColoring is a different pass
+ // which merges spill slots.
+ addPass(&StackColoringID);
+
// If the target requests it, assign local variables to stack slots relative
// to one another and simplify frame index references where possible.
addPass(&LocalStackSlotAllocationID);
diff --git a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index 3e18ea7..b2a2a5c 100644
--- a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -97,7 +97,7 @@
cast<ArrayType>(Ty)->getElementType()->isIntegerTy(8)));
StaticAllocaMap[AI] =
MF->getFrameInfo()->CreateStackObject(TySize, Align, false,
- MayNeedSP);
+ MayNeedSP, AI);
}
for (; BB != EB; ++BB)
diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index 46ddab0..6d2cdea 100644
--- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -873,6 +873,17 @@
break;
}
+ case ISD::LIFETIME_START:
+ case ISD::LIFETIME_END: {
+ unsigned TarOp = (Node->getOpcode() == ISD::LIFETIME_START) ?
+ TargetOpcode::LIFETIME_START : TargetOpcode::LIFETIME_END;
+
+ FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Node->getOperand(1));
+ BuildMI(*MBB, InsertPos, Node->getDebugLoc(), TII->get(TarOp))
+ .addFrameIndex(FI->getIndex());
+ break;
+ }
+
case ISD::INLINEASM: {
unsigned NumOps = Node->getNumOperands();
if (Node->getOperand(NumOps-1).getValueType() == MVT::Glue)
diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
index bf0a437..a8f6f0d 100644
--- a/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
@@ -656,6 +656,8 @@
break;
case ISD::MERGE_VALUES:
case ISD::TokenFactor:
+ case ISD::LIFETIME_START:
+ case ISD::LIFETIME_END:
case ISD::CopyToReg:
case ISD::CopyFromReg:
case ISD::EH_LABEL:
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 74500d5..928385a 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -4161,6 +4161,8 @@
assert((Opcode == ISD::INTRINSIC_VOID ||
Opcode == ISD::INTRINSIC_W_CHAIN ||
Opcode == ISD::PREFETCH ||
+ Opcode == ISD::LIFETIME_START ||
+ Opcode == ISD::LIFETIME_END ||
(Opcode <= INT_MAX &&
(int)Opcode >= ISD::FIRST_TARGET_MEMORY_OPCODE)) &&
"Opcode is not a memory-accessing opcode!");
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 31d633c..b587884 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -19,6 +19,7 @@
#include "llvm/ADT/SmallSet.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Constants.h"
#include "llvm/CallingConv.h"
#include "llvm/DebugInfo.h"
@@ -5215,14 +5216,30 @@
rw==1)); /* write */
return 0;
}
-
- case Intrinsic::invariant_start:
case Intrinsic::lifetime_start:
+ case Intrinsic::lifetime_end: {
+ SDValue Ops[2];
+ AllocaInst *LifetimeObject =dyn_cast_or_null<AllocaInst>(
+ GetUnderlyingObject(I.getArgOperand(1), TD));
+ // Could not find an Alloca.
+ if (!LifetimeObject)
+ return 0;
+
+ int FI = FuncInfo.StaticAllocaMap[LifetimeObject];
+ Ops[0] = getRoot();
+ Ops[1] = DAG.getFrameIndex(FI, TLI.getPointerTy(), true);
+ bool IsStart = (Intrinsic == Intrinsic::lifetime_start);
+ unsigned Opcode = (IsStart ? ISD::LIFETIME_START : ISD::LIFETIME_END);
+
+ Res = DAG.getNode(Opcode, dl, MVT::Other, Ops, 2);
+ DAG.setRoot(Res);
+ return 0;
+ }
+ case Intrinsic::invariant_start:
// Discard region information.
setValue(&I, DAG.getUNDEF(TLI.getPointerTy()));
return 0;
case Intrinsic::invariant_end:
- case Intrinsic::lifetime_end:
// Discard region information.
return 0;
case Intrinsic::donothing:
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
index 2f41e64..75989ad 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -267,6 +267,8 @@
case ISD::STACKRESTORE: return "stackrestore";
case ISD::TRAP: return "trap";
case ISD::DEBUGTRAP: return "debugtrap";
+ case ISD::LIFETIME_START: return "lifetime.start";
+ case ISD::LIFETIME_END: return "lifetime.end";
// Bit manipulation
case ISD::BSWAP: return "bswap";
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 1f5f825..7542941 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -1801,10 +1801,13 @@
User->getOpcode() == ISD::HANDLENODE) // Root of the graph.
continue;
- if (User->getOpcode() == ISD::CopyToReg ||
- User->getOpcode() == ISD::CopyFromReg ||
- User->getOpcode() == ISD::INLINEASM ||
- User->getOpcode() == ISD::EH_LABEL) {
+ unsigned UserOpcode = User->getOpcode();
+ if (UserOpcode == ISD::CopyToReg ||
+ UserOpcode == ISD::CopyFromReg ||
+ UserOpcode == ISD::INLINEASM ||
+ UserOpcode == ISD::EH_LABEL ||
+ UserOpcode == ISD::LIFETIME_START ||
+ UserOpcode == ISD::LIFETIME_END) {
// If their node ID got reset to -1 then they've already been selected.
// Treat them like a MachineOpcode.
if (User->getNodeId() == -1)
@@ -2220,6 +2223,8 @@
case ISD::CopyFromReg:
case ISD::CopyToReg:
case ISD::EH_LABEL:
+ case ISD::LIFETIME_START:
+ case ISD::LIFETIME_END:
NodeToMatch->setNodeId(-1); // Mark selected.
return 0;
case ISD::AssertSext:
diff --git a/lib/CodeGen/StackColoring.cpp b/lib/CodeGen/StackColoring.cpp
new file mode 100644
index 0000000..f1818f6
--- /dev/null
+++ b/lib/CodeGen/StackColoring.cpp
@@ -0,0 +1,657 @@
+//===-- StackColoring.cpp -------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass implements the stack-coloring optimization that looks for
+// lifetime markers machine instructions (LIFESTART_BEGIN and LIFESTART_END),
+// which represent the possible lifetime of stack slots. It attempts to
+// merge disjoint stack slots and reduce the used stack space.
+// NOTE: This pass is not StackSlotColoring, which optimizes spill slots.
+//
+// TODO: In the future we plan to improve stack coloring in the following ways:
+// 1. Allow merging multiple small slots into a single larger slot at different
+// offsets.
+// 2. Merge this pass with StackSlotColoring and allow merging of allocas with
+// spill slots.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "stackcoloring"
+#include "MachineTraceMetrics.h"
+#include "llvm/Function.h"
+#include "llvm/Module.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SparseSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/LiveInterval.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
+#include "llvm/CodeGen/MachineDominators.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineMemOperand.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/SlotIndexes.h"
+#include "llvm/DebugInfo.h"
+#include "llvm/MC/MCInstrItineraries.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+static cl::opt<bool>
+DisableColoring("no-stack-coloring",
+ cl::init(false), cl::Hidden,
+ cl::desc("Suppress stack coloring"));
+
+STATISTIC(NumMarkerSeen, "Number of life markers found.");
+STATISTIC(StackSpaceSaved, "Number of bytes saved due to merging slots.");
+STATISTIC(StackSlotMerged, "Number of stack slot merged.");
+
+//===----------------------------------------------------------------------===//
+// StackColoring Pass
+//===----------------------------------------------------------------------===//
+
+namespace {
+/// StackColoring - A machine pass for merging disjoint stack allocations,
+/// marked by the LIFETIME_START and LIFETIME_END pseudo instructions.
+class StackColoring : public MachineFunctionPass {
+ MachineFrameInfo *MFI;
+ MachineFunction *MF;
+
+ /// A class representing liveness information for a single basic block.
+ /// Each bit in the BitVector represents the liveness property
+ /// for a different stack slot.
+ struct BlockLifetimeInfo {
+ /// Which slots BEGINs in each basic block.
+ BitVector Begin;
+ /// Which slots ENDs in each basic block.
+ BitVector End;
+ /// Which slots are marked as LIVE_IN, coming into each basic block.
+ BitVector LiveIn;
+ /// Which slots are marked as LIVE_OUT, coming out of each basic block.
+ BitVector LiveOut;
+ };
+
+ /// Maps active slots (per bit) for each basic block.
+ DenseMap<MachineBasicBlock*, BlockLifetimeInfo> BlockLiveness;
+
+ /// Maps serial numbers to basic blocks.
+ DenseMap<MachineBasicBlock*, int> BasicBlocks;
+ /// Maps basic blocks to a serial number.
+ SmallVector<MachineBasicBlock*, 8> BasicBlockNumbering;
+
+ /// Maps liveness intervals for each slot.
+ SmallVector<LiveInterval*, 16> Intervals;
+ /// VNInfo is used for the construction of LiveIntervals.
+ VNInfo::Allocator VNInfoAllocator;
+ /// SlotIndex analysis object.
+ SlotIndexes* Indexes;
+
+ /// The list of lifetime markers found. These markers are to be removed
+ /// once the coloring is done.
+ SmallVector<MachineInstr*, 8> Markers;
+
+ /// SlotSizeSorter - A Sort utility for arranging stack slots according
+ /// to their size.
+ struct SlotSizeSorter {
+ MachineFrameInfo *MFI;
+ SlotSizeSorter(MachineFrameInfo *mfi) : MFI(mfi) { }
+ bool operator()(int LHS, int RHS) {
+ // We use -1 to denote a uninteresting slot. Place these slots at the end.
+ if (LHS == -1) return false;
+ if (RHS == -1) return true;
+ // Sort according to size.
+ return MFI->getObjectSize(LHS) > MFI->getObjectSize(RHS);
+ }
+};
+
+public:
+ static char ID;
+ StackColoring() : MachineFunctionPass(ID) {
+ initializeStackColoringPass(*PassRegistry::getPassRegistry());
+ }
+ void getAnalysisUsage(AnalysisUsage &AU) const;
+ bool runOnMachineFunction(MachineFunction &MF);
+
+private:
+ /// Debug.
+ void dump();
+
+ /// Removes all of the lifetime marker instructions from the function.
+ /// \returns true if any markers were removed.
+ bool removeAllMarkers();
+
+ /// Scan the machine function and find all of the lifetime markers.
+ /// Record the findings in the BEGIN and END vectors.
+ /// \returns the number of markers found.
+ unsigned collectMarkers(unsigned NumSlot);
+
+ /// Perform the dataflow calculation and calculate the lifetime for each of
+ /// the slots, based on the BEGIN/END vectors. Set the LifetimeLIVE_IN and
+ /// LifetimeLIVE_OUT maps that represent which stack slots are live coming
+ /// in and out blocks.
+ void calculateLocalLiveness();
+
+ /// Construct the LiveIntervals for the slots.
+ void calculateLiveIntervals(unsigned NumSlots);
+
+ /// Go over the machine function and change instructions which use stack
+ /// slots to use the joint slots.
+ void remapInstructions(DenseMap<int, int> &SlotRemap);
+
+ /// Map entries which point to other entries to their destination.
+ /// A->B->C becomes A->C.
+ void expungeSlotMap(DenseMap<int, int> &SlotRemap, unsigned NumSlots);
+};
+} // end anonymous namespace
+
+char StackColoring::ID = 0;
+char &llvm::StackColoringID = StackColoring::ID;
+
+INITIALIZE_PASS_BEGIN(StackColoring,
+ "stack-coloring", "Merge disjoint stack slots", false, false)
+INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
+INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
+INITIALIZE_PASS_END(StackColoring,
+ "stack-coloring", "Merge disjoint stack slots", false, false)
+
+void StackColoring::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<MachineDominatorTree>();
+ AU.addPreserved<MachineDominatorTree>();
+ AU.addRequired<SlotIndexes>();
+ MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+void StackColoring::dump() {
+ for (df_iterator<MachineFunction*> FI = df_begin(MF), FE = df_end(MF);
+ FI != FE; ++FI) {
+ unsigned Num = BasicBlocks[*FI];
+ DEBUG(dbgs()<<"Inspecting block #"<<Num<<" ["<<FI->getName()<<"]\n");
+ Num = 0;
+ DEBUG(dbgs()<<"BEGIN : {");
+ for (unsigned i=0; i < BlockLiveness[*FI].Begin.size(); ++i)
+ DEBUG(dbgs()<<BlockLiveness[*FI].Begin.test(i)<<" ");
+ DEBUG(dbgs()<<"}\n");
+
+ DEBUG(dbgs()<<"END : {");
+ for (unsigned i=0; i < BlockLiveness[*FI].End.size(); ++i)
+ DEBUG(dbgs()<<BlockLiveness[*FI].End.test(i)<<" ");
+
+ DEBUG(dbgs()<<"}\n");
+
+ DEBUG(dbgs()<<"LIVE_IN: {");
+ for (unsigned i=0; i < BlockLiveness[*FI].LiveIn.size(); ++i)
+ DEBUG(dbgs()<<BlockLiveness[*FI].LiveIn.test(i)<<" ");
+
+ DEBUG(dbgs()<<"}\n");
+ DEBUG(dbgs()<<"LIVEOUT: {");
+ for (unsigned i=0; i < BlockLiveness[*FI].LiveOut.size(); ++i)
+ DEBUG(dbgs()<<BlockLiveness[*FI].LiveOut.test(i)<<" ");
+ DEBUG(dbgs()<<"}\n");
+ }
+}
+
+unsigned StackColoring::collectMarkers(unsigned NumSlot) {
+ unsigned MarkersFound = 0;
+ // Scan the function to find all lifetime markers.
+ // NOTE: We use the a reverse-post-order iteration to ensure that we obtain a
+ // deterministic numbering, and because we'll need a post-order iteration
+ // later for solving the liveness dataflow problem.
+ for (df_iterator<MachineFunction*> FI = df_begin(MF), FE = df_end(MF);
+ FI != FE; ++FI) {
+
+ // Assign a serial number to this basic block.
+ BasicBlocks[*FI] = BasicBlockNumbering.size();;
+ BasicBlockNumbering.push_back(*FI);
+
+ BlockLiveness[*FI].Begin.resize(NumSlot);
+ BlockLiveness[*FI].End.resize(NumSlot);
+
+ for (MachineBasicBlock::iterator BI = (*FI)->begin(), BE = (*FI)->end();
+ BI != BE; ++BI) {
+
+ if (BI->getOpcode() != TargetOpcode::LIFETIME_START &&
+ BI->getOpcode() != TargetOpcode::LIFETIME_END)
+ continue;
+
+ Markers.push_back(BI);
+
+ bool IsStart = BI->getOpcode() == TargetOpcode::LIFETIME_START;
+ MachineOperand &MI = BI->getOperand(0);
+ unsigned Slot = MI.getIndex();
+
+ MarkersFound++;
+
+ const Value* Allocation = MFI->getObjectAllocation(Slot);
+ if (Allocation) {
+ DEBUG(dbgs()<<"Found lifetime marker for allocation: "<<
+ Allocation->getName()<<"\n");
+ }
+
+ if (IsStart) {
+ BlockLiveness[*FI].Begin.set(Slot);
+ } else {
+ if (BlockLiveness[*FI].Begin.test(Slot)) {
+ // Allocas that start and end within a single block are handled
+ // specially when computing the LiveIntervals to avoid pessimizing
+ // the liveness propagation.
+ BlockLiveness[*FI].Begin.reset(Slot);
+ } else {
+ BlockLiveness[*FI].End.set(Slot);
+ }
+ }
+ }
+ }
+
+ // Update statistics.
+ NumMarkerSeen += MarkersFound;
+ return MarkersFound;
+}
+
+void StackColoring::calculateLocalLiveness() {
+ // Perform a standard reverse dataflow computation to solve for
+ // global liveness. The BEGIN set here is equivalent to KILL in the standard
+ // formulation, and END is equivalent to GEN. The result of this computation
+ // is a map from blocks to bitvectors where the bitvectors represent which
+ // allocas are live in/out of that block.
+ SmallPtrSet<MachineBasicBlock*, 8> BBSet(BasicBlockNumbering.begin(),
+ BasicBlockNumbering.end());
+ unsigned NumSSMIters = 0;
+ bool changed = true;
+ while (changed) {
+ changed = false;
+ ++NumSSMIters;
+
+ SmallPtrSet<MachineBasicBlock*, 8> NextBBSet;
+
+ for (SmallVector<MachineBasicBlock*, 8>::iterator
+ PI = BasicBlockNumbering.begin(), PE = BasicBlockNumbering.end();
+ PI != PE; ++PI) {
+
+ MachineBasicBlock *BB = *PI;
+ if (!BBSet.count(BB)) continue;
+
+ BitVector LocalLiveIn;
+ BitVector LocalLiveOut;
+
+ // Forward propagation from begins to ends.
+ for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(),
+ PE = BB->pred_end(); PI != PE; ++PI)
+ LocalLiveIn |= BlockLiveness[*PI].LiveOut;
+ LocalLiveIn |= BlockLiveness[BB].End;
+ LocalLiveIn.reset(BlockLiveness[BB].Begin);
+
+ // Reverse propagation from ends to begins.
+ for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
+ SE = BB->succ_end(); SI != SE; ++SI)
+ LocalLiveOut |= BlockLiveness[*SI].LiveIn;
+ LocalLiveOut |= BlockLiveness[BB].Begin;
+ LocalLiveOut.reset(BlockLiveness[BB].End);
+
+ LocalLiveIn |= LocalLiveOut;
+ LocalLiveOut |= LocalLiveIn;
+
+ // After adopting the live bits, we need to turn-off the bits which
+ // are de-activated in this block.
+ LocalLiveOut.reset(BlockLiveness[BB].End);
+ LocalLiveIn.reset(BlockLiveness[BB].Begin);
+
+ if (LocalLiveIn.test(BlockLiveness[BB].LiveIn)) {
+ changed = true;
+ BlockLiveness[BB].LiveIn |= LocalLiveIn;
+
+ for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(),
+ PE = BB->pred_end(); PI != PE; ++PI)
+ NextBBSet.insert(*PI);
+ }
+
+ if (LocalLiveOut.test(BlockLiveness[BB].LiveOut)) {
+ changed = true;
+ BlockLiveness[BB].LiveOut |= LocalLiveOut;
+
+ for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
+ SE = BB->succ_end(); SI != SE; ++SI)
+ NextBBSet.insert(*SI);
+ }
+ }
+
+ BBSet = NextBBSet;
+ }// while changed.
+}
+
+void StackColoring::calculateLiveIntervals(unsigned NumSlots) {
+ SmallVector<SlotIndex, 16> Starts;
+ SmallVector<SlotIndex, 16> Finishes;
+
+ // For each block, find which slots are active within this block
+ // and update the live intervals.
+ for (MachineFunction::iterator MBB = MF->begin(), MBBe = MF->end();
+ MBB != MBBe; ++MBB) {
+ Starts.clear();
+ Starts.resize(NumSlots);
+ Finishes.clear();
+ Finishes.resize(NumSlots);
+
+ BitVector Alive = BlockLiveness[MBB].LiveIn;
+ Alive |= BlockLiveness[MBB].LiveOut;
+
+ if (Alive.any()) {
+ for (int pos = Alive.find_first(); pos != -1;
+ pos = Alive.find_next(pos)) {
+ Starts[pos] = Indexes->getMBBStartIdx(MBB);
+ Finishes[pos] = Indexes->getMBBEndIdx(MBB);
+ }
+ }
+
+ for (SmallVector<MachineInstr*, 8>::iterator it = Markers.begin(),
+ e = Markers.end(); it != e; ++it) {
+ MachineInstr *MI = *it;
+ assert((MI->getOpcode() == TargetOpcode::LIFETIME_START ||
+ MI->getOpcode() == TargetOpcode::LIFETIME_END) &&
+ "Invalid Lifetime marker");
+
+ if (MI->getParent() == MBB) {
+ bool IsStart = MI->getOpcode() == TargetOpcode::LIFETIME_START;
+ MachineOperand &Mo = MI->getOperand(0);
+ int Slot = Mo.getIndex();
+ assert(Slot >= 0 && "Invalid slot");
+ if (IsStart) {
+ Starts[Slot] = Indexes->getInstructionIndex(MI);
+ } else {
+ Finishes[Slot] = Indexes->getInstructionIndex(MI);
+ }
+ }
+ }
+
+ for (unsigned i = 0; i < NumSlots; ++i) {
+ assert(!!Starts[i] == !!Finishes[i] && "Unmatched range");
+ if (Starts[i] == Finishes[i])
+ continue;
+
+ assert(Starts[i] && Finishes[i] && "Invalid interval");
+ VNInfo *ValNum = Intervals[i]->getValNumInfo(0);
+ SlotIndex S = Starts[i];
+ SlotIndex F = Finishes[i];
+ if (S < F) {
+ // We have a single consecutive region.
+ Intervals[i]->addRange(LiveRange(S, F, ValNum));
+ } else {
+ // We have two non consecutive regions. This happens when
+ // LIFETIME_START appears after the LIFETIME_END marker.
+ SlotIndex NewStart = Indexes->getMBBStartIdx(MBB);
+ SlotIndex NewFin = Indexes->getMBBEndIdx(MBB);
+ Intervals[i]->addRange(LiveRange(NewStart, F, ValNum));
+ Intervals[i]->addRange(LiveRange(S, NewFin, ValNum));
+ }
+ }
+ }
+}
+
+bool StackColoring::removeAllMarkers() {
+ unsigned Count = 0;
+ for (unsigned i = 0; i < Markers.size(); ++i) {
+ Markers[i]->eraseFromParent();
+ Count++;
+ }
+ Markers.clear();
+
+ DEBUG(dbgs()<<"Removed "<<Count<<" markers.\n");
+ return Count;
+}
+
+void StackColoring::remapInstructions(DenseMap<int, int> &SlotRemap) {
+ unsigned FixedInstr = 0;
+ unsigned FixedMemOp = 0;
+ unsigned FixedDbg = 0;
+ MachineModuleInfo *MMI = &MF->getMMI();
+
+ // Remap debug information that refers to stack slots.
+ MachineModuleInfo::VariableDbgInfoMapTy &VMap = MMI->getVariableDbgInfo();
+ for (MachineModuleInfo::VariableDbgInfoMapTy::iterator VI = VMap.begin(),
+ VE = VMap.end(); VI != VE; ++VI) {
+ const MDNode *Var = VI->first;
+ if (!Var) continue;
+ std::pair<unsigned, DebugLoc> &VP = VI->second;
+ if (SlotRemap.count(VP.first)) {
+ DEBUG(dbgs()<<"Remapping debug info for ["<<Var->getName()<<"].\n");
+ VP.first = SlotRemap[VP.first];
+ FixedDbg++;
+ }
+ }
+
+ // Keep a list of *allocas* which need to be remapped.
+ DenseMap<const Value*, const Value*> Allocas;
+ for (DenseMap<int, int>::iterator it = SlotRemap.begin(),
+ e = SlotRemap.end(); it != e; ++it) {
+ const Value* From = MFI->getObjectAllocation(it->first);
+ const Value* To = MFI->getObjectAllocation(it->second);
+ assert(To && From && "Invalid allocation object");
+ Allocas[From] = To;
+ }
+
+ // Remap all instructions to the new stack slots.
+ MachineFunction::iterator BB, BBE;
+ MachineBasicBlock::iterator I, IE;
+ for (BB = MF->begin(), BBE = MF->end(); BB != BBE; ++BB)
+ for (I = BB->begin(), IE = BB->end(); I != IE; ++I) {
+
+ // Update the MachineMemOperand to use the new alloca.
+ for (MachineInstr::mmo_iterator MM = I->memoperands_begin(),
+ E = I->memoperands_end(); MM != E; ++MM) {
+ MachineMemOperand *MMO = *MM;
+
+ const Value *V = MMO->getValue();
+
+ if (!V)
+ continue;
+
+ // Climb up and find the original alloca.
+ V = GetUnderlyingObject(V);
+ // If we did not find one, or if the one that we found is not in our
+ // map, then move on.
+ if (!V || !Allocas.count(V))
+ continue;
+
+ MMO->setValue(Allocas[V]);
+ FixedMemOp++;
+ }
+
+ // Update all of the machine instruction operands.
+ for (unsigned i = 0 ; i < I->getNumOperands(); ++i) {
+ MachineOperand &MO = I->getOperand(i);
+
+ if (!MO.isFI())
+ continue;
+ int FromSlot = MO.getIndex();
+
+ // Don't touch arguments.
+ if (FromSlot<0)
+ continue;
+
+ // Only look at mapped slots.
+ if (!SlotRemap.count(FromSlot))
+ continue;
+
+ // Fix the machine instructions.
+ int ToSlot = SlotRemap[FromSlot];
+ MO.setIndex(ToSlot);
+ FixedInstr++;
+ }
+ }
+
+ DEBUG(dbgs()<<"Fixed "<<FixedMemOp<<" machine memory operands.\n");
+ DEBUG(dbgs()<<"Fixed "<<FixedDbg<<" debug locations.\n");
+ DEBUG(dbgs()<<"Fixed "<<FixedInstr<<" machine instructions.\n");
+}
+
+void StackColoring::expungeSlotMap(DenseMap<int, int> &SlotRemap,
+ unsigned NumSlots) {
+ // Expunge slot remap map.
+ for (unsigned i=0; i < NumSlots; ++i) {
+ // If we are remapping i
+ if (SlotRemap.count(i)) {
+ int Target = SlotRemap[i];
+ // As long as our target is mapped to something else, follow it.
+ while (SlotRemap.count(Target)) {
+ Target = SlotRemap[Target];
+ SlotRemap[i] = Target;
+ }
+ }
+ }
+}
+
+bool StackColoring::runOnMachineFunction(MachineFunction &Func) {
+ DEBUG(dbgs() << "********** Stack Coloring **********\n"
+ << "********** Function: "
+ << ((Value*)Func.getFunction())->getName() << '\n');
+ MF = &Func;
+ MFI = MF->getFrameInfo();
+ Indexes = &getAnalysis<SlotIndexes>();
+ BlockLiveness.clear();
+ BasicBlocks.clear();
+ BasicBlockNumbering.clear();
+ Markers.clear();
+ Intervals.clear();
+ VNInfoAllocator.Reset();
+
+ unsigned NumSlots = MFI->getObjectIndexEnd();
+
+ // If there are no stack slots then there are no markers to remove.
+ if (!NumSlots)
+ return false;
+
+ SmallVector<int, 8> SortedSlots;
+
+ SortedSlots.reserve(NumSlots);
+ Intervals.reserve(NumSlots);
+
+ unsigned NumMarkers = collectMarkers(NumSlots);
+
+ unsigned TotalSize = 0;
+ DEBUG(dbgs()<<"Found "<<NumMarkers<<" markers and "<<NumSlots<<" slots\n");
+ DEBUG(dbgs()<<"Slot structure:\n");
+
+ for (int i=0; i < MFI->getObjectIndexEnd(); ++i) {
+ DEBUG(dbgs()<<"Slot #"<<i<<" - "<<MFI->getObjectSize(i)<<" bytes.\n");
+ TotalSize += MFI->getObjectSize(i);
+ }
+
+ DEBUG(dbgs()<<"Total Stack size: "<<TotalSize<<" bytes\n\n");
+
+ // Don't continue because there are not enough lifetime markers, or the
+ // stack or too small, or we are told not to optimize the slots.
+ if (NumMarkers < 2 || TotalSize < 16 || DisableColoring) {
+ DEBUG(dbgs()<<"Will not try to merge slots.\n");
+ return removeAllMarkers();
+ }
+
+ for (unsigned i=0; i < NumSlots; ++i) {
+ LiveInterval *LI = new LiveInterval(i, 0);
+ Intervals.push_back(LI);
+ LI->getNextValue(Indexes->getZeroIndex(), VNInfoAllocator);
+ SortedSlots.push_back(i);
+ }
+
+ // Calculate the liveness of each block.
+ calculateLocalLiveness();
+
+ // Propagate the liveness information.
+ calculateLiveIntervals(NumSlots);
+
+ // Maps old slots to new slots.
+ DenseMap<int, int> SlotRemap;
+ unsigned RemovedSlots = 0;
+ unsigned ReducedSize = 0;
+
+ // Do not bother looking at empty intervals.
+ for (unsigned I = 0; I < NumSlots; ++I) {
+ if (Intervals[SortedSlots[I]]->empty())
+ SortedSlots[I] = -1;
+ }
+
+ // This is a simple greedy algorithm for merging allocas. First, sort the
+ // slots, placing the largest slots first. Next, perform an n^2 scan and look
+ // for disjoint slots. When you find disjoint slots, merge the samller one
+ // into the bigger one and update the live interval. Remove the small alloca
+ // and continue.
+
+ // Sort the slots according to their size. Place unused slots at the end.
+ std::sort(SortedSlots.begin(), SortedSlots.end(), SlotSizeSorter(MFI));
+
+ bool Chanded = true;
+ while (Chanded) {
+ Chanded = false;
+ for (unsigned I = 0; I < NumSlots; ++I) {
+ if (SortedSlots[I] == -1)
+ continue;
+
+ for (unsigned J=0; J < NumSlots; ++J) {
+ if (SortedSlots[J] == -1)
+ continue;
+
+ int FirstSlot = SortedSlots[I];
+ int SecondSlot = SortedSlots[J];
+ LiveInterval *First = Intervals[FirstSlot];
+ LiveInterval *Second = Intervals[SecondSlot];
+ assert (!First->empty() && !Second->empty() && "Found an empty range");
+
+ // Merge disjoint slots.
+ if (!First->overlaps(*Second)) {
+ Chanded = true;
+ First->MergeRangesInAsValue(*Second, First->getValNumInfo(0));
+ SlotRemap[SecondSlot] = FirstSlot;
+ SortedSlots[J] = -1;
+ DEBUG(dbgs()<<"Merging #"<<I<<" and slots #"<<J<<" together.\n");
+ unsigned MaxAlignment = std::max(MFI->getObjectAlignment(FirstSlot),
+ MFI->getObjectAlignment(SecondSlot));
+
+ assert(MFI->getObjectSize(FirstSlot) >=
+ MFI->getObjectSize(SecondSlot) &&
+ "Merging a small object into a larger one");
+
+ RemovedSlots+=1;
+ ReducedSize += MFI->getObjectSize(SecondSlot);
+ MFI->setObjectAlignment(FirstSlot, MaxAlignment);
+ MFI->RemoveStackObject(SecondSlot);
+ }
+ }
+ }
+ }// While changed.
+
+ // Record statistics.
+ StackSpaceSaved += ReducedSize;
+ StackSlotMerged += RemovedSlots;
+ DEBUG(dbgs()<<"Merge "<<RemovedSlots<<" slots. Saved "<<
+ ReducedSize<<" bytes\n");
+
+ // Scan the entire function and update all machine operands that use frame
+ // indices to use the remapped frame index.
+ expungeSlotMap(SlotRemap, NumSlots);
+ remapInstructions(SlotRemap);
+
+ // Release the intervals.
+ for (unsigned I = 0; I < NumSlots; ++I) {
+ delete Intervals[I];
+ }
+
+ return removeAllMarkers();
+}