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- More pre-split fixes: spill slot live interval computation bug; restore point bug.

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- If a def is spilt, remember its spill index to allow its reuse.

llvm-svn: 58375
This commit is contained in:
Evan Cheng 2008-10-29 08:39:34 +00:00
parent 3faee6737e
commit 6125b9e097
5 changed files with 148 additions and 40 deletions
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2
include/llvm/CodeGen/LiveInterval.h
View File

@ -156,6 +156,8 @@ namespace llvm {
return reg & ~(1U << (sizeof(unsigned)*8-1));
}
bool hasAtLeastOneValue() const { return !valnos.empty(); }
bool containsOneValue() const { return valnos.size() == 1; }
unsigned getNumValNums() const { return (unsigned)valnos.size(); }

131
lib/CodeGen/PreAllocSplitting.cpp
View File

@ -30,6 +30,7 @@
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
@ -69,8 +70,8 @@ namespace {
// IntervalSSMap - A map from live interval to spill slots.
DenseMap<unsigned, int> IntervalSSMap;
// RestoreMIs - All the restores inserted due to live interval splitting.
SmallPtrSet<MachineInstr*, 8> RestoreMIs;
// Def2SpillMap - A map from a def instruction index to spill index.
DenseMap<unsigned, unsigned> Def2SpillMap;
public:
static char ID;
@ -93,7 +94,7 @@ namespace {
virtual void releaseMemory() {
IntervalSSMap.clear();
RestoreMIs.clear();
Def2SpillMap.clear();
}
virtual const char *getPassName() const {
@ -124,7 +125,8 @@ namespace {
int CreateSpillStackSlot(unsigned, const TargetRegisterClass *);
bool IsAvailableInStack(unsigned, unsigned, int&) const;
bool IsAvailableInStack(MachineBasicBlock*, unsigned, unsigned, unsigned,
unsigned&, int&) const;
void UpdateSpillSlotInterval(VNInfo*, unsigned, unsigned);
@ -221,6 +223,8 @@ PreAllocSplitting::findRestorePoint(MachineBasicBlock *MBB, MachineInstr *MI,
unsigned LastIdx,
SmallPtrSet<MachineInstr*, 4> &RefsInMBB,
unsigned &RestoreIndex) {
// FIXME: Allow spill to be inserted to the beginning of the mbb. Update mbb
// begin index accordingly.
MachineBasicBlock::iterator Pt = MBB->end();
unsigned EndIdx = LIs->getMBBEndIdx(MBB);
@ -229,8 +233,8 @@ PreAllocSplitting::findRestorePoint(MachineBasicBlock *MBB, MachineInstr *MI,
if (RefsInMBB.empty() && LastIdx >= EndIdx) {
MachineBasicBlock::iterator MII = MBB->end();
MachineBasicBlock::iterator EndPt = MI;
--MII;
do {
--MII;
unsigned Index = LIs->getInstructionIndex(MII);
unsigned Gap = LIs->findGapBeforeInstr(Index);
if (Gap) {
@ -238,6 +242,7 @@ PreAllocSplitting::findRestorePoint(MachineBasicBlock *MBB, MachineInstr *MI,
RestoreIndex = Gap;
break;
}
--MII;
} while (MII != EndPt);
} else {
MachineBasicBlock::iterator MII = MI;
@ -278,7 +283,7 @@ int PreAllocSplitting::CreateSpillStackSlot(unsigned Reg,
// Create live interval for stack slot.
CurrSLI = &LSs->getOrCreateInterval(SS);
if (CurrSLI->getNumValNums())
if (CurrSLI->hasAtLeastOneValue())
CurrSValNo = CurrSLI->getValNumInfo(0);
else
CurrSValNo = CurrSLI->getNextValue(~0U, 0, LSs->getVNInfoAllocator());
@ -288,15 +293,30 @@ int PreAllocSplitting::CreateSpillStackSlot(unsigned Reg,
/// IsAvailableInStack - Return true if register is available in a split stack
/// slot at the specified index.
bool
PreAllocSplitting::IsAvailableInStack(unsigned Reg, unsigned Index, int &SS) const {
PreAllocSplitting::IsAvailableInStack(MachineBasicBlock *DefMBB,
unsigned Reg, unsigned DefIndex,
unsigned RestoreIndex, unsigned &SpillIndex,
int& SS) const {
if (!DefMBB)
return false;
DenseMap<unsigned, int>::iterator I = IntervalSSMap.find(Reg);
if (I == IntervalSSMap.end())
return false;
if (LSs->getInterval(I->second).liveAt(Index)) {
SS = I->second;
return true;
}
return false;
DenseMap<unsigned, unsigned>::iterator II = Def2SpillMap.find(DefIndex);
if (II == Def2SpillMap.end())
return false;
// If last spill of def is in the same mbb as barrier mbb (where restore will
// be), make sure it's not below the intended restore index.
// FIXME: Undo the previous spill?
assert(LIs->getMBBFromIndex(II->second) == DefMBB);
if (DefMBB == BarrierMBB && II->second >= RestoreIndex)
return false;
SS = I->second;
SpillIndex = II->second;
return true;
}
/// UpdateSpillSlotInterval - Given the specified val# of the register live
@ -305,48 +325,58 @@ PreAllocSplitting::IsAvailableInStack(unsigned Reg, unsigned Index, int &SS) con
void
PreAllocSplitting::UpdateSpillSlotInterval(VNInfo *ValNo, unsigned SpillIndex,
unsigned RestoreIndex) {
const LiveRange *LR = CurrLI->getLiveRangeContaining(SpillIndex);
if (LR->contains(RestoreIndex)) {
assert(LIs->getMBBFromIndex(RestoreIndex) == BarrierMBB &&
"Expect restore in the barrier mbb");
MachineBasicBlock *MBB = LIs->getMBBFromIndex(SpillIndex);
if (MBB == BarrierMBB) {
// Intra-block spill + restore. We are done.
LiveRange SLR(SpillIndex, RestoreIndex, CurrSValNo);
CurrSLI->addRange(SLR);
return;
}
SmallPtrSet<const LiveRange*, 4> Processed;
LiveRange SLR(SpillIndex, LR->end, CurrSValNo);
SmallPtrSet<MachineBasicBlock*, 4> Processed;
unsigned EndIdx = LIs->getMBBEndIdx(MBB);
LiveRange SLR(SpillIndex, EndIdx+1, CurrSValNo);
CurrSLI->addRange(SLR);
Processed.insert(LR);
Processed.insert(MBB);
// Start from the spill mbb, figure out the extend of the spill slot's
// live interval.
SmallVector<MachineBasicBlock*, 4> WorkList;
MachineBasicBlock *MBB = LIs->getMBBFromIndex(SpillIndex);
if (LR->end > LIs->getMBBEndIdx(MBB))
const LiveRange *LR = CurrLI->getLiveRangeContaining(SpillIndex);
if (LR->end > EndIdx)
// If live range extend beyond end of mbb, add successors to work list.
for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
SE = MBB->succ_end(); SI != SE; ++SI)
WorkList.push_back(*SI);
// Live range may cross multiple basic blocks, add all reachable mbbs to
// the work list.
LIs->findReachableMBBs(LR->start, LR->end, WorkList);
while (!WorkList.empty()) {
MachineBasicBlock *MBB = WorkList.back();
WorkList.pop_back();
if (Processed.count(MBB))
continue;
unsigned Idx = LIs->getMBBStartIdx(MBB);
LR = CurrLI->getLiveRangeContaining(Idx);
if (LR && LR->valno == ValNo && !Processed.count(LR)) {
if (LR->contains(RestoreIndex)) {
if (LR && LR->valno == ValNo) {
EndIdx = LIs->getMBBEndIdx(MBB);
if (Idx <= RestoreIndex && RestoreIndex < EndIdx) {
// Spill slot live interval stops at the restore.
LiveRange SLR(LR->start, RestoreIndex, CurrSValNo);
LiveRange SLR(Idx, RestoreIndex, CurrSValNo);
CurrSLI->addRange(SLR);
LIs->findReachableMBBs(LR->start, RestoreIndex, WorkList);
} else if (LR->end > EndIdx) {
// Live range extends beyond end of mbb, process successors.
LiveRange SLR(Idx, EndIdx+1, CurrSValNo);
CurrSLI->addRange(SLR);
for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
SE = MBB->succ_end(); SI != SE; ++SI)
WorkList.push_back(*SI);
} else {
LiveRange SLR(LR->start, LR->end, CurrSValNo);
LiveRange SLR(Idx, LR->end, CurrSValNo);
CurrSLI->addRange(SLR);
LIs->findReachableMBBs(LR->start, LR->end, WorkList);
}
Processed.insert(LR);
Processed.insert(MBB);
}
}
}
@ -357,6 +387,9 @@ PreAllocSplitting::UpdateSpillSlotInterval(VNInfo *ValNo, unsigned SpillIndex,
void
PreAllocSplitting::UpdateRegisterInterval(VNInfo *ValNo, unsigned SpillIndex,
unsigned RestoreIndex) {
assert(LIs->getMBBFromIndex(RestoreIndex) == BarrierMBB &&
"Expect restore in the barrier mbb");
SmallVector<std::pair<unsigned,unsigned>, 4> Before;
SmallVector<std::pair<unsigned,unsigned>, 4> After;
SmallVector<unsigned, 4> BeforeKills;
@ -380,7 +413,7 @@ PreAllocSplitting::UpdateRegisterInterval(VNInfo *ValNo, unsigned SpillIndex,
// Start from the restore mbb, figure out what part of the live interval
// are defined by the restore.
SmallVector<MachineBasicBlock*, 4> WorkList;
MachineBasicBlock *MBB = LIs->getMBBFromIndex(RestoreIndex);
MachineBasicBlock *MBB = BarrierMBB;
for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
SE = MBB->succ_end(); SI != SE; ++SI)
WorkList.push_back(*SI);
@ -547,7 +580,6 @@ PreAllocSplitting::ShrinkWrapLiveInterval(VNInfo *ValNo, MachineBasicBlock *MBB,
} else if (MBB == DefMBB) {
// There are no uses after the def.
MachineInstr *DefMI = LIs->getInstructionFromIndex(ValNo->def);
assert(RestoreMIs.count(DefMI) && "Not defined by a join?");
if (UseMBBs.empty()) {
// The only use must be below barrier in the barrier block. It's safe to
// remove the def.
@ -641,7 +673,8 @@ bool PreAllocSplitting::SplitRegLiveInterval(LiveInterval *LI) {
TII->storeRegToStackSlot(*BarrierMBB, SpillPt, CurrLI->reg, true, SS, RC);
SpillMI = prior(SpillPt);
LIs->InsertMachineInstrInMaps(SpillMI, SpillIndex);
} else if (!IsAvailableInStack(CurrLI->reg, RestoreIndex, SS)) {
} else if (!IsAvailableInStack(DefMBB, CurrLI->reg, ValNo->def,
RestoreIndex, SpillIndex, SS)) {
// If it's already split, just restore the value. There is no need to spill
// the def again.
if (!DefMI)
@ -667,11 +700,14 @@ bool PreAllocSplitting::SplitRegLiveInterval(LiveInterval *LI) {
LIs->InsertMachineInstrInMaps(SpillMI, SpillIndex);
}
// Remember def instruction index to spill index mapping.
if (DefMI && SpillMI)
Def2SpillMap[ValNo->def] = SpillIndex;
// Add restore.
TII->loadRegFromStackSlot(*BarrierMBB, RestorePt, CurrLI->reg, SS, RC);
MachineInstr *LoadMI = prior(RestorePt);
LIs->InsertMachineInstrInMaps(LoadMI, RestoreIndex);
RestoreMIs.insert(LoadMI);
// If live interval is spilled in the same block as the barrier, just
// create a hole in the interval.
@ -689,11 +725,8 @@ bool PreAllocSplitting::SplitRegLiveInterval(LiveInterval *LI) {
}
// Update spill stack slot live interval.
if (SpillIndex)
// If value is already in stack at the restore point, there is
// no need to update the live interval.
UpdateSpillSlotInterval(ValNo, LIs->getUseIndex(SpillIndex)+1,
LIs->getDefIndex(RestoreIndex));
UpdateSpillSlotInterval(ValNo, LIs->getUseIndex(SpillIndex)+1,
LIs->getDefIndex(RestoreIndex));
// Shrink wrap the live interval by walking up the CFG and find the
// new kills.
@ -795,6 +828,27 @@ bool PreAllocSplitting::runOnMachineFunction(MachineFunction &MF) {
// Make sure blocks are numbered in order.
MF.RenumberBlocks();
#if 0
// FIXME: Go top down.
MachineBasicBlock *Entry = MF.begin();
SmallPtrSet<MachineBasicBlock*,16> Visited;
for (df_ext_iterator<MachineBasicBlock*, SmallPtrSet<MachineBasicBlock*,16> >
DFI = df_ext_begin(Entry, Visited), E = df_ext_end(Entry, Visited);
DFI != E; ++DFI) {
BarrierMBB = *DFI;
for (MachineBasicBlock::iterator I = BarrierMBB->begin(),
E = BarrierMBB->end(); I != E; ++I) {
Barrier = &*I;
const TargetRegisterClass **BarrierRCs =
Barrier->getDesc().getRegClassBarriers();
if (!BarrierRCs)
continue;
BarrierIdx = LIs->getInstructionIndex(Barrier);
MadeChange |= SplitRegLiveIntervals(BarrierRCs);
}
}
#else
for (MachineFunction::reverse_iterator I = MF.rbegin(), E = MF.rend();
I != E; ++I) {
BarrierMBB = &*I;
@ -809,6 +863,7 @@ bool PreAllocSplitting::runOnMachineFunction(MachineFunction &MF) {
MadeChange |= SplitRegLiveIntervals(BarrierRCs);
}
}
#endif
return MadeChange;
}

2
lib/CodeGen/RegAllocLinearScan.cpp
View File

@ -550,7 +550,7 @@ static void addStackInterval(LiveInterval *cur, LiveStacks *ls_,
SI.weight += Weight;
VNInfo *VNI;
if (SI.getNumValNums())
if (SI.hasAtLeastOneValue())
VNI = SI.getValNumInfo(0);
else
VNI = SI.getNextValue(~0U, 0, ls_->getVNInfoAllocator());

51
test/CodeGen/X86/pre-split10.ll Normal file
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@ -0,0 +1,51 @@
; RUN: llvm-as < %s | llc -march=x86 -mattr=+sse2 -pre-alloc-split
define i32 @main(i32 %argc, i8** %argv) nounwind {
entry:
br label %bb14.i
bb14.i: ; preds = %bb14.i, %entry
%i8.0.reg2mem.0.i = phi i32 [ 0, %entry ], [ %0, %bb14.i ] ; <i32> [#uses=1]
%0 = add i32 %i8.0.reg2mem.0.i, 1 ; <i32> [#uses=2]
%1 = add double 0.000000e+00, 0.000000e+00 ; <double> [#uses=1]
%2 = add double 0.000000e+00, 0.000000e+00 ; <double> [#uses=1]
%3 = add double 0.000000e+00, 0.000000e+00 ; <double> [#uses=1]
%exitcond75.i = icmp eq i32 %0, 32 ; <i1> [#uses=1]
br i1 %exitcond75.i, label %bb24.i, label %bb14.i
bb24.i: ; preds = %bb14.i
%4 = fdiv double 0.000000e+00, 0.000000e+00 ; <double> [#uses=1]
%5 = fdiv double %1, 0.000000e+00 ; <double> [#uses=1]
%6 = fdiv double %2, 0.000000e+00 ; <double> [#uses=1]
%7 = fdiv double %3, 0.000000e+00 ; <double> [#uses=1]
br label %bb31.i
bb31.i: ; preds = %bb31.i, %bb24.i
%tmp.0.reg2mem.0.i = phi i32 [ 0, %bb24.i ], [ %indvar.next64.i, %bb31.i ] ; <i32> [#uses=1]
%indvar.next64.i = add i32 %tmp.0.reg2mem.0.i, 1 ; <i32> [#uses=2]
%exitcond65.i = icmp eq i32 %indvar.next64.i, 64 ; <i1> [#uses=1]
br i1 %exitcond65.i, label %bb33.i, label %bb31.i
bb33.i: ; preds = %bb31.i
br label %bb35.preheader.i
bb5.i.i: ; preds = %bb35.preheader.i
%8 = call double @floor(double 0.000000e+00) nounwind readnone ; <double> [#uses=0]
br label %bb7.i.i
bb7.i.i: ; preds = %bb35.preheader.i, %bb5.i.i
br label %bb35.preheader.i
bb35.preheader.i: ; preds = %bb7.i.i, %bb33.i
%9 = sub double 0.000000e+00, %4 ; <double> [#uses=1]
store double %9, double* null, align 8
%10 = sub double 0.000000e+00, %5 ; <double> [#uses=1]
store double %10, double* null, align 8
%11 = sub double 0.000000e+00, %6 ; <double> [#uses=1]
store double %11, double* null, align 8
%12 = sub double 0.000000e+00, %7 ; <double> [#uses=1]
store double %12, double* null, align 8
br i1 false, label %bb7.i.i, label %bb5.i.i
}
declare double @floor(double) nounwind readnone

2
test/CodeGen/X86/pre-split3.ll
View File

@ -1,5 +1,5 @@
; RUN: llvm-as < %s | llc -march=x86 -mattr=+sse2 -pre-alloc-split -stats |& \
; RUN: grep {pre-alloc-split} | grep {Number of intervals split} | grep 2
; RUN: grep {pre-alloc-split} | grep {Number of intervals split} | grep 1
define i32 @t(i32 %arg) {
entry: