diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp index b68f36b6646..c958143d666 100644 --- a/lib/CodeGen/VirtRegMap.cpp +++ b/lib/CodeGen/VirtRegMap.cpp @@ -466,36 +466,61 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) { << I->second.second); unsigned VirtReg = I->second.first; VirtRegMap::ModRef MR = I->second.second; - if (VRM.hasStackSlot(VirtReg)) { - int SS = VRM.getStackSlot(VirtReg); - DEBUG(std::cerr << " - StackSlot: " << SS << "\n"); - - // If this reference is not a use, any previous store is now dead. - // Otherwise, the store to this stack slot is not dead anymore. - std::map::iterator MDSI = MaybeDeadStores.find(SS); - if (MDSI != MaybeDeadStores.end()) { - if (MR & VirtRegMap::isRef) // Previous store is not dead. - MaybeDeadStores.erase(MDSI); - else { - // If we get here, the store is dead, nuke it now. - assert(MR == VirtRegMap::isMod && "Can't be modref!"); - MBB.erase(MDSI->second); - MaybeDeadStores.erase(MDSI); - ++NumDSE; - } - } - - // If the spill slot value is available, and this is a new definition of - // the value, the value is not available anymore. - if (MR & VirtRegMap::isMod) { - std::map::iterator It = SpillSlotsAvailable.find(SS); - if (It != SpillSlotsAvailable.end()) { - PhysRegsAvailable.erase(It->second); - SpillSlotsAvailable.erase(It); - } - } - } else { + if (!VRM.hasStackSlot(VirtReg)) { DEBUG(std::cerr << ": No stack slot!\n"); + continue; + } + int SS = VRM.getStackSlot(VirtReg); + DEBUG(std::cerr << " - StackSlot: " << SS << "\n"); + + // If this folded instruction is just a use, check to see if it's a + // straight load from the virt reg slot. + if ((MR & VirtRegMap::isRef) && !(MR & VirtRegMap::isMod)) { + int FrameIdx; + if (unsigned DestReg = MRI->isLoadFromStackSlot(&MI, FrameIdx)) { + // If this spill slot is available, insert a copy for it! + std::map::iterator It = SpillSlotsAvailable.find(SS); + if (FrameIdx == SS && It != SpillSlotsAvailable.end()) { + DEBUG(std::cerr << "Promoted Load To Copy: " << MI); + MachineFunction &MF = *MBB.getParent(); + if (DestReg != It->second) { + MRI->copyRegToReg(MBB, &MI, DestReg, It->second, + MF.getSSARegMap()->getRegClass(VirtReg)); + // Revisit the copy if the destination is a vreg. + if (MRegisterInfo::isVirtualRegister(DestReg)) { + NextMII = &MI; + --NextMII; // backtrack to the copy. + } + } + MBB.erase(&MI); + goto ProcessNextInst; + } + } + } + + // If this reference is not a use, any previous store is now dead. + // Otherwise, the store to this stack slot is not dead anymore. + std::map::iterator MDSI = MaybeDeadStores.find(SS); + if (MDSI != MaybeDeadStores.end()) { + if (MR & VirtRegMap::isRef) // Previous store is not dead. + MaybeDeadStores.erase(MDSI); + else { + // If we get here, the store is dead, nuke it now. + assert(MR == VirtRegMap::isMod && "Can't be modref!"); + MBB.erase(MDSI->second); + MaybeDeadStores.erase(MDSI); + ++NumDSE; + } + } + + // If the spill slot value is available, and this is a new definition of + // the value, the value is not available anymore. + if (MR & VirtRegMap::isMod) { + std::map::iterator It = SpillSlotsAvailable.find(SS); + if (It != SpillSlotsAvailable.end()) { + PhysRegsAvailable.erase(It->second); + SpillSlotsAvailable.erase(It); + } } } @@ -575,6 +600,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) { } } } + ProcessNextInst: MII = NextMII; } }