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If def is in the same mbb as the barrier, spilt the value after the last use before the barrier. 

llvm-svn: 58314
This commit is contained in:
Evan Cheng 2008-10-28 05:28:21 +00:00
parent 382c1a7c7d
commit 5e88d90379
1 changed files with 18 additions and 8 deletions
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26
llvm/lib/CodeGen/PreAllocSplitting.cpp
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@ -107,7 +107,7 @@ namespace {
unsigned&);
MachineBasicBlock::iterator
findSpillPoint(MachineBasicBlock*, MachineInstr*,
findSpillPoint(MachineBasicBlock*, MachineInstr*, MachineInstr*,
SmallPtrSet<MachineInstr*, 4>&, unsigned&);
MachineBasicBlock::iterator
@ -166,12 +166,13 @@ PreAllocSplitting::findNextEmptySlot(MachineBasicBlock *MBB, MachineInstr *MI,
/// none is found.
MachineBasicBlock::iterator
PreAllocSplitting::findSpillPoint(MachineBasicBlock *MBB, MachineInstr *MI,
MachineInstr *DefMI,
SmallPtrSet<MachineInstr*, 4> &RefsInMBB,
unsigned &SpillIndex) {
MachineBasicBlock::iterator Pt = MBB->begin();
// Go top down if RefsInMBB is empty.
if (RefsInMBB.empty()) {
if (RefsInMBB.empty() && !DefMI) {
MachineBasicBlock::iterator MII = MBB->begin();
MachineBasicBlock::iterator EndPt = MI;
do {
@ -186,7 +187,9 @@ PreAllocSplitting::findSpillPoint(MachineBasicBlock *MBB, MachineInstr *MI,
} while (MII != EndPt);
} else {
MachineBasicBlock::iterator MII = MI;
while (MII != MBB->begin() && !RefsInMBB.count(MII)) {
MachineBasicBlock::iterator EndPt = DefMI
? MachineBasicBlock::iterator(DefMI) : MBB->begin();
while (MII != EndPt && !RefsInMBB.count(MII)) {
unsigned Index = LIs->getInstructionIndex(MII);
if (LIs->hasGapBeforeInstr(Index)) {
Pt = MII;
@ -561,7 +564,7 @@ bool PreAllocSplitting::SplitRegLiveInterval(LiveInterval *LI) {
if (ValNo->def == ~0U) {
// If it's defined by a phi, we must split just before the barrier.
MachineBasicBlock::iterator SpillPt =
findSpillPoint(BarrierMBB, Barrier, RefsInMBB, SpillIndex);
findSpillPoint(BarrierMBB, Barrier, NULL, RefsInMBB, SpillIndex);
if (SpillPt == BarrierMBB->begin())
return false; // No gap to insert spill.
// Add spill.
@ -578,10 +581,17 @@ bool PreAllocSplitting::SplitRegLiveInterval(LiveInterval *LI) {
// If it's already split, just restore the value. There is no need to spill
// the def again.
// Check if it's possible to insert a spill after the def MI.
MachineBasicBlock::iterator SpillPt =
findNextEmptySlot(DefMBB, DefMI, SpillIndex);
if (SpillPt == DefMBB->end())
return false; // No gap to insert spill.
MachineBasicBlock::iterator SpillPt;
if (DefMBB == BarrierMBB) {
// Add spill after the def and the last use before the barrier.
SpillPt = findSpillPoint(BarrierMBB, Barrier, DefMI, RefsInMBB, SpillIndex);
if (SpillPt == DefMBB->begin())
return false; // No gap to insert spill.
} else {
SpillPt = findNextEmptySlot(DefMBB, DefMI, SpillIndex);
if (SpillPt == DefMBB->end())
return false; // No gap to insert spill.
}
SS = MFI->CreateStackObject(RC->getSize(), RC->getAlignment());
// Add spill. The store instruction kills the register if def is before