From 8597c14e9b32259cc7cfd752d95fd71e7aaba0ec Mon Sep 17 00:00:00 2001 From: Cameron Zwarich Date: Mon, 11 Feb 2013 09:24:47 +0000 Subject: Add support for updating LiveIntervals to MachineBasicBlock::SplitCriticalEdge(). This is currently a bit hairier than it needs to be, since depending on where the split block resides the end ListEntry of the split block may be the end ListEntry of the original block or a new entry. Some changes to the SlotIndexes updating should make it possible to eliminate the two cases here. This also isn't as optimized as it could be. In the future Liveinterval should probably get a flag that indicates whether the LiveInterval is within a single basic block. We could ignore all such intervals when splitting an edge. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174870 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/MachineBasicBlock.cpp | 68 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) (limited to 'lib/CodeGen/MachineBasicBlock.cpp') diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp index 7457cd5201..7351302cc3 100644 --- a/lib/CodeGen/MachineBasicBlock.cpp +++ b/lib/CodeGen/MachineBasicBlock.cpp @@ -15,10 +15,12 @@ #include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/SmallString.h" #include "llvm/Assembly/Writer.h" +#include "llvm/CodeGen/LiveIntervalAnalysis.h" #include "llvm/CodeGen/LiveVariables.h" #include "llvm/CodeGen/MachineDominators.h" #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineLoopInfo.h" +#include "llvm/CodeGen/MachineRegisterInfo.h" #include "llvm/CodeGen/SlotIndexes.h" #include "llvm/IR/BasicBlock.h" #include "llvm/IR/DataLayout.h" @@ -769,6 +771,72 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) { LV->addNewBlock(NMBB, this, Succ); } + if (LiveIntervals *LIS = P->getAnalysisIfAvailable()) { + // After splitting the edge and updating SlotIndexes, live intervals may be + // in one of two situations, depending on whether this block was the last in + // the function. If the original block was the last in the function, all live + // intervals will end prior to the beginning of the new split block. If the + // original block was not at the end of the function, all live intervals will + // extend to the end of the new split block. + + bool isLastMBB = + llvm::next(MachineFunction::iterator(NMBB)) == getParent()->end(); + + SlotIndex StartIndex = Indexes->getMBBEndIdx(this); + SlotIndex PrevIndex = StartIndex.getPrevSlot(); + SlotIndex EndIndex = Indexes->getMBBEndIdx(NMBB); + + // Find the registers used from NMBB in PHIs in Succ. + SmallSet PHISrcRegs; + for (MachineBasicBlock::instr_iterator + I = Succ->instr_begin(), E = Succ->instr_end(); + I != E && I->isPHI(); ++I) { + for (unsigned ni = 1, ne = I->getNumOperands(); ni != ne; ni += 2) { + if (I->getOperand(ni+1).getMBB() == NMBB) { + MachineOperand &MO = I->getOperand(ni); + unsigned Reg = MO.getReg(); + PHISrcRegs.insert(Reg); + if (MO.isUndef() || !isLastMBB) + break; + + LiveInterval &LI = LIS->getInterval(Reg); + VNInfo *VNI = LI.getVNInfoAt(PrevIndex); + assert(VNI && "PHI sources should be live out of their predecessors."); + LI.addRange(LiveRange(StartIndex, EndIndex, VNI)); + } + } + } + + MachineRegisterInfo *MRI = &getParent()->getRegInfo(); + for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) { + unsigned Reg = TargetRegisterInfo::index2VirtReg(i); + if (PHISrcRegs.count(Reg) || !LIS->hasInterval(Reg)) + continue; + + LiveInterval &LI = LIS->getInterval(Reg); + if (!LI.liveAt(PrevIndex)) + continue; + + bool isLiveOut = false; + for (MachineBasicBlock::succ_iterator SI = succ_begin(), + SE = succ_end(); SI != SE; ++SI) { + MachineBasicBlock *SuccMBB = *SI == NMBB ? Succ : *SI; + if (LI.liveAt(LIS->getMBBStartIdx(SuccMBB))) { + isLiveOut = true; + break; + } + } + + if (isLiveOut && isLastMBB) { + VNInfo *VNI = LI.getVNInfoAt(PrevIndex); + assert(VNI && "LiveInterval should have VNInfo where it is live."); + LI.addRange(LiveRange(StartIndex, EndIndex, VNI)); + } else if (!isLiveOut && !isLastMBB) { + LI.removeRange(StartIndex, EndIndex); + } + } + } + if (MachineDominatorTree *MDT = P->getAnalysisIfAvailable()) { // Update dominator information. -- cgit v1.2.3