mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-28 06:29:45 +00:00
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151031 91177308-0d34-0410-b5e6-96231b3b80d8
443 lines
14 KiB
C++
443 lines
14 KiB
C++
//===-- StackSlotColoring.cpp - Stack slot coloring pass. -----------------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file implements the stack slot coloring pass.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "stackcoloring"
|
|
#include "llvm/Function.h"
|
|
#include "llvm/Module.h"
|
|
#include "llvm/CodeGen/Passes.h"
|
|
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
|
|
#include "llvm/CodeGen/LiveStackAnalysis.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"
|
|
#include "llvm/Support/CommandLine.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/Target/TargetInstrInfo.h"
|
|
#include "llvm/Target/TargetMachine.h"
|
|
#include "llvm/ADT/BitVector.h"
|
|
#include "llvm/ADT/SmallSet.h"
|
|
#include "llvm/ADT/SmallVector.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include <vector>
|
|
using namespace llvm;
|
|
|
|
static cl::opt<bool>
|
|
DisableSharing("no-stack-slot-sharing",
|
|
cl::init(false), cl::Hidden,
|
|
cl::desc("Suppress slot sharing during stack coloring"));
|
|
|
|
static cl::opt<int> DCELimit("ssc-dce-limit", cl::init(-1), cl::Hidden);
|
|
|
|
STATISTIC(NumEliminated, "Number of stack slots eliminated due to coloring");
|
|
STATISTIC(NumDead, "Number of trivially dead stack accesses eliminated");
|
|
|
|
namespace {
|
|
class StackSlotColoring : public MachineFunctionPass {
|
|
bool ColorWithRegs;
|
|
LiveStacks* LS;
|
|
MachineFrameInfo *MFI;
|
|
const TargetInstrInfo *TII;
|
|
const MachineLoopInfo *loopInfo;
|
|
|
|
// SSIntervals - Spill slot intervals.
|
|
std::vector<LiveInterval*> SSIntervals;
|
|
|
|
// SSRefs - Keep a list of frame index references for each spill slot.
|
|
SmallVector<SmallVector<MachineInstr*, 8>, 16> SSRefs;
|
|
|
|
// OrigAlignments - Alignments of stack objects before coloring.
|
|
SmallVector<unsigned, 16> OrigAlignments;
|
|
|
|
// OrigSizes - Sizess of stack objects before coloring.
|
|
SmallVector<unsigned, 16> OrigSizes;
|
|
|
|
// AllColors - If index is set, it's a spill slot, i.e. color.
|
|
// FIXME: This assumes PEI locate spill slot with smaller indices
|
|
// closest to stack pointer / frame pointer. Therefore, smaller
|
|
// index == better color.
|
|
BitVector AllColors;
|
|
|
|
// NextColor - Next "color" that's not yet used.
|
|
int NextColor;
|
|
|
|
// UsedColors - "Colors" that have been assigned.
|
|
BitVector UsedColors;
|
|
|
|
// Assignments - Color to intervals mapping.
|
|
SmallVector<SmallVector<LiveInterval*,4>, 16> Assignments;
|
|
|
|
public:
|
|
static char ID; // Pass identification
|
|
StackSlotColoring() :
|
|
MachineFunctionPass(ID), ColorWithRegs(false), NextColor(-1) {
|
|
initializeStackSlotColoringPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.setPreservesCFG();
|
|
AU.addRequired<SlotIndexes>();
|
|
AU.addPreserved<SlotIndexes>();
|
|
AU.addRequired<LiveStacks>();
|
|
AU.addRequired<MachineLoopInfo>();
|
|
AU.addPreserved<MachineLoopInfo>();
|
|
AU.addPreservedID(MachineDominatorsID);
|
|
MachineFunctionPass::getAnalysisUsage(AU);
|
|
}
|
|
|
|
virtual bool runOnMachineFunction(MachineFunction &MF);
|
|
|
|
private:
|
|
void InitializeSlots();
|
|
void ScanForSpillSlotRefs(MachineFunction &MF);
|
|
bool OverlapWithAssignments(LiveInterval *li, int Color) const;
|
|
int ColorSlot(LiveInterval *li);
|
|
bool ColorSlots(MachineFunction &MF);
|
|
void RewriteInstruction(MachineInstr *MI, int OldFI, int NewFI,
|
|
MachineFunction &MF);
|
|
bool RemoveDeadStores(MachineBasicBlock* MBB);
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
char StackSlotColoring::ID = 0;
|
|
char &llvm::StackSlotColoringID = StackSlotColoring::ID;
|
|
|
|
INITIALIZE_PASS_BEGIN(StackSlotColoring, "stack-slot-coloring",
|
|
"Stack Slot Coloring", false, false)
|
|
INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
|
|
INITIALIZE_PASS_DEPENDENCY(LiveStacks)
|
|
INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
|
|
INITIALIZE_PASS_END(StackSlotColoring, "stack-slot-coloring",
|
|
"Stack Slot Coloring", false, false)
|
|
|
|
namespace {
|
|
// IntervalSorter - Comparison predicate that sort live intervals by
|
|
// their weight.
|
|
struct IntervalSorter {
|
|
bool operator()(LiveInterval* LHS, LiveInterval* RHS) const {
|
|
return LHS->weight > RHS->weight;
|
|
}
|
|
};
|
|
}
|
|
|
|
/// ScanForSpillSlotRefs - Scan all the machine instructions for spill slot
|
|
/// references and update spill slot weights.
|
|
void StackSlotColoring::ScanForSpillSlotRefs(MachineFunction &MF) {
|
|
SSRefs.resize(MFI->getObjectIndexEnd());
|
|
|
|
// FIXME: Need the equivalent of MachineRegisterInfo for frameindex operands.
|
|
for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
|
|
MBBI != E; ++MBBI) {
|
|
MachineBasicBlock *MBB = &*MBBI;
|
|
unsigned loopDepth = loopInfo->getLoopDepth(MBB);
|
|
for (MachineBasicBlock::iterator MII = MBB->begin(), EE = MBB->end();
|
|
MII != EE; ++MII) {
|
|
MachineInstr *MI = &*MII;
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isFI())
|
|
continue;
|
|
int FI = MO.getIndex();
|
|
if (FI < 0)
|
|
continue;
|
|
if (!LS->hasInterval(FI))
|
|
continue;
|
|
LiveInterval &li = LS->getInterval(FI);
|
|
if (!MI->isDebugValue())
|
|
li.weight += LiveIntervals::getSpillWeight(false, true, loopDepth);
|
|
SSRefs[FI].push_back(MI);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// InitializeSlots - Process all spill stack slot liveintervals and add them
|
|
/// to a sorted (by weight) list.
|
|
void StackSlotColoring::InitializeSlots() {
|
|
int LastFI = MFI->getObjectIndexEnd();
|
|
OrigAlignments.resize(LastFI);
|
|
OrigSizes.resize(LastFI);
|
|
AllColors.resize(LastFI);
|
|
UsedColors.resize(LastFI);
|
|
Assignments.resize(LastFI);
|
|
|
|
// Gather all spill slots into a list.
|
|
DEBUG(dbgs() << "Spill slot intervals:\n");
|
|
for (LiveStacks::iterator i = LS->begin(), e = LS->end(); i != e; ++i) {
|
|
LiveInterval &li = i->second;
|
|
DEBUG(li.dump());
|
|
int FI = TargetRegisterInfo::stackSlot2Index(li.reg);
|
|
if (MFI->isDeadObjectIndex(FI))
|
|
continue;
|
|
SSIntervals.push_back(&li);
|
|
OrigAlignments[FI] = MFI->getObjectAlignment(FI);
|
|
OrigSizes[FI] = MFI->getObjectSize(FI);
|
|
AllColors.set(FI);
|
|
}
|
|
DEBUG(dbgs() << '\n');
|
|
|
|
// Sort them by weight.
|
|
std::stable_sort(SSIntervals.begin(), SSIntervals.end(), IntervalSorter());
|
|
|
|
// Get first "color".
|
|
NextColor = AllColors.find_first();
|
|
}
|
|
|
|
/// OverlapWithAssignments - Return true if LiveInterval overlaps with any
|
|
/// LiveIntervals that have already been assigned to the specified color.
|
|
bool
|
|
StackSlotColoring::OverlapWithAssignments(LiveInterval *li, int Color) const {
|
|
const SmallVector<LiveInterval*,4> &OtherLIs = Assignments[Color];
|
|
for (unsigned i = 0, e = OtherLIs.size(); i != e; ++i) {
|
|
LiveInterval *OtherLI = OtherLIs[i];
|
|
if (OtherLI->overlaps(*li))
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// ColorSlot - Assign a "color" (stack slot) to the specified stack slot.
|
|
///
|
|
int StackSlotColoring::ColorSlot(LiveInterval *li) {
|
|
int Color = -1;
|
|
bool Share = false;
|
|
if (!DisableSharing) {
|
|
// Check if it's possible to reuse any of the used colors.
|
|
Color = UsedColors.find_first();
|
|
while (Color != -1) {
|
|
if (!OverlapWithAssignments(li, Color)) {
|
|
Share = true;
|
|
++NumEliminated;
|
|
break;
|
|
}
|
|
Color = UsedColors.find_next(Color);
|
|
}
|
|
}
|
|
|
|
// Assign it to the first available color (assumed to be the best) if it's
|
|
// not possible to share a used color with other objects.
|
|
if (!Share) {
|
|
assert(NextColor != -1 && "No more spill slots?");
|
|
Color = NextColor;
|
|
UsedColors.set(Color);
|
|
NextColor = AllColors.find_next(NextColor);
|
|
}
|
|
|
|
// Record the assignment.
|
|
Assignments[Color].push_back(li);
|
|
int FI = TargetRegisterInfo::stackSlot2Index(li->reg);
|
|
DEBUG(dbgs() << "Assigning fi#" << FI << " to fi#" << Color << "\n");
|
|
|
|
// Change size and alignment of the allocated slot. If there are multiple
|
|
// objects sharing the same slot, then make sure the size and alignment
|
|
// are large enough for all.
|
|
unsigned Align = OrigAlignments[FI];
|
|
if (!Share || Align > MFI->getObjectAlignment(Color))
|
|
MFI->setObjectAlignment(Color, Align);
|
|
int64_t Size = OrigSizes[FI];
|
|
if (!Share || Size > MFI->getObjectSize(Color))
|
|
MFI->setObjectSize(Color, Size);
|
|
return Color;
|
|
}
|
|
|
|
/// Colorslots - Color all spill stack slots and rewrite all frameindex machine
|
|
/// operands in the function.
|
|
bool StackSlotColoring::ColorSlots(MachineFunction &MF) {
|
|
unsigned NumObjs = MFI->getObjectIndexEnd();
|
|
SmallVector<int, 16> SlotMapping(NumObjs, -1);
|
|
SmallVector<float, 16> SlotWeights(NumObjs, 0.0);
|
|
SmallVector<SmallVector<int, 4>, 16> RevMap(NumObjs);
|
|
BitVector UsedColors(NumObjs);
|
|
|
|
DEBUG(dbgs() << "Color spill slot intervals:\n");
|
|
bool Changed = false;
|
|
for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i) {
|
|
LiveInterval *li = SSIntervals[i];
|
|
int SS = TargetRegisterInfo::stackSlot2Index(li->reg);
|
|
int NewSS = ColorSlot(li);
|
|
assert(NewSS >= 0 && "Stack coloring failed?");
|
|
SlotMapping[SS] = NewSS;
|
|
RevMap[NewSS].push_back(SS);
|
|
SlotWeights[NewSS] += li->weight;
|
|
UsedColors.set(NewSS);
|
|
Changed |= (SS != NewSS);
|
|
}
|
|
|
|
DEBUG(dbgs() << "\nSpill slots after coloring:\n");
|
|
for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i) {
|
|
LiveInterval *li = SSIntervals[i];
|
|
int SS = TargetRegisterInfo::stackSlot2Index(li->reg);
|
|
li->weight = SlotWeights[SS];
|
|
}
|
|
// Sort them by new weight.
|
|
std::stable_sort(SSIntervals.begin(), SSIntervals.end(), IntervalSorter());
|
|
|
|
#ifndef NDEBUG
|
|
for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i)
|
|
DEBUG(SSIntervals[i]->dump());
|
|
DEBUG(dbgs() << '\n');
|
|
#endif
|
|
|
|
if (!Changed)
|
|
return false;
|
|
|
|
// Rewrite all MO_FrameIndex operands.
|
|
SmallVector<SmallSet<unsigned, 4>, 4> NewDefs(MF.getNumBlockIDs());
|
|
for (unsigned SS = 0, SE = SSRefs.size(); SS != SE; ++SS) {
|
|
int NewFI = SlotMapping[SS];
|
|
if (NewFI == -1 || (NewFI == (int)SS))
|
|
continue;
|
|
|
|
SmallVector<MachineInstr*, 8> &RefMIs = SSRefs[SS];
|
|
for (unsigned i = 0, e = RefMIs.size(); i != e; ++i)
|
|
RewriteInstruction(RefMIs[i], SS, NewFI, MF);
|
|
}
|
|
|
|
// Delete unused stack slots.
|
|
while (NextColor != -1) {
|
|
DEBUG(dbgs() << "Removing unused stack object fi#" << NextColor << "\n");
|
|
MFI->RemoveStackObject(NextColor);
|
|
NextColor = AllColors.find_next(NextColor);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// RewriteInstruction - Rewrite specified instruction by replacing references
|
|
/// to old frame index with new one.
|
|
void StackSlotColoring::RewriteInstruction(MachineInstr *MI, int OldFI,
|
|
int NewFI, MachineFunction &MF) {
|
|
// Update the operands.
|
|
for (unsigned i = 0, ee = MI->getNumOperands(); i != ee; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isFI())
|
|
continue;
|
|
int FI = MO.getIndex();
|
|
if (FI != OldFI)
|
|
continue;
|
|
MO.setIndex(NewFI);
|
|
}
|
|
|
|
// Update the memory references. This changes the MachineMemOperands
|
|
// directly. They may be in use by multiple instructions, however all
|
|
// instructions using OldFI are being rewritten to use NewFI.
|
|
const Value *OldSV = PseudoSourceValue::getFixedStack(OldFI);
|
|
const Value *NewSV = PseudoSourceValue::getFixedStack(NewFI);
|
|
for (MachineInstr::mmo_iterator I = MI->memoperands_begin(),
|
|
E = MI->memoperands_end(); I != E; ++I)
|
|
if ((*I)->getValue() == OldSV)
|
|
(*I)->setValue(NewSV);
|
|
}
|
|
|
|
|
|
/// RemoveDeadStores - Scan through a basic block and look for loads followed
|
|
/// by stores. If they're both using the same stack slot, then the store is
|
|
/// definitely dead. This could obviously be much more aggressive (consider
|
|
/// pairs with instructions between them), but such extensions might have a
|
|
/// considerable compile time impact.
|
|
bool StackSlotColoring::RemoveDeadStores(MachineBasicBlock* MBB) {
|
|
// FIXME: This could be much more aggressive, but we need to investigate
|
|
// the compile time impact of doing so.
|
|
bool changed = false;
|
|
|
|
SmallVector<MachineInstr*, 4> toErase;
|
|
|
|
for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
|
|
I != E; ++I) {
|
|
if (DCELimit != -1 && (int)NumDead >= DCELimit)
|
|
break;
|
|
|
|
MachineBasicBlock::iterator NextMI = llvm::next(I);
|
|
if (NextMI == MBB->end()) continue;
|
|
|
|
int FirstSS, SecondSS;
|
|
unsigned LoadReg = 0;
|
|
unsigned StoreReg = 0;
|
|
if (!(LoadReg = TII->isLoadFromStackSlot(I, FirstSS))) continue;
|
|
if (!(StoreReg = TII->isStoreToStackSlot(NextMI, SecondSS))) continue;
|
|
if (FirstSS != SecondSS || LoadReg != StoreReg || FirstSS == -1) continue;
|
|
|
|
++NumDead;
|
|
changed = true;
|
|
|
|
if (NextMI->findRegisterUseOperandIdx(LoadReg, true, 0) != -1) {
|
|
++NumDead;
|
|
toErase.push_back(I);
|
|
}
|
|
|
|
toErase.push_back(NextMI);
|
|
++I;
|
|
}
|
|
|
|
for (SmallVector<MachineInstr*, 4>::iterator I = toErase.begin(),
|
|
E = toErase.end(); I != E; ++I)
|
|
(*I)->eraseFromParent();
|
|
|
|
return changed;
|
|
}
|
|
|
|
|
|
bool StackSlotColoring::runOnMachineFunction(MachineFunction &MF) {
|
|
DEBUG({
|
|
dbgs() << "********** Stack Slot Coloring **********\n"
|
|
<< "********** Function: "
|
|
<< MF.getFunction()->getName() << '\n';
|
|
});
|
|
|
|
MFI = MF.getFrameInfo();
|
|
TII = MF.getTarget().getInstrInfo();
|
|
LS = &getAnalysis<LiveStacks>();
|
|
loopInfo = &getAnalysis<MachineLoopInfo>();
|
|
|
|
bool Changed = false;
|
|
|
|
unsigned NumSlots = LS->getNumIntervals();
|
|
if (NumSlots == 0)
|
|
// Nothing to do!
|
|
return false;
|
|
|
|
// If there are calls to setjmp or sigsetjmp, don't perform stack slot
|
|
// coloring. The stack could be modified before the longjmp is executed,
|
|
// resulting in the wrong value being used afterwards. (See
|
|
// <rdar://problem/8007500>.)
|
|
if (MF.exposesReturnsTwice())
|
|
return false;
|
|
|
|
// Gather spill slot references
|
|
ScanForSpillSlotRefs(MF);
|
|
InitializeSlots();
|
|
Changed = ColorSlots(MF);
|
|
|
|
NextColor = -1;
|
|
SSIntervals.clear();
|
|
for (unsigned i = 0, e = SSRefs.size(); i != e; ++i)
|
|
SSRefs[i].clear();
|
|
SSRefs.clear();
|
|
OrigAlignments.clear();
|
|
OrigSizes.clear();
|
|
AllColors.clear();
|
|
UsedColors.clear();
|
|
for (unsigned i = 0, e = Assignments.size(); i != e; ++i)
|
|
Assignments[i].clear();
|
|
Assignments.clear();
|
|
|
|
if (Changed) {
|
|
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
|
|
Changed |= RemoveDeadStores(I);
|
|
}
|
|
|
|
return Changed;
|
|
}
|