X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FPrologEpilogInserter.cpp;h=f169f485af3a83fa7554aceb3ef36aac4959d9a5;hb=848219ca612e5488982f23c37c7459aeedff77e3;hp=61407faaf327270580a0ef7fa6c22077a9fb6e5b;hpb=acd5f13c889cc39e72bee7b0426f8ef3426a09c3;p=oota-llvm.git diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp index 61407faaf32..f169f485af3 100644 --- a/lib/CodeGen/PrologEpilogInserter.cpp +++ b/lib/CodeGen/PrologEpilogInserter.cpp @@ -16,7 +16,6 @@ // //===----------------------------------------------------------------------===// -#include "PrologEpilogInserter.h" #include "llvm/ADT/IndexedMap.h" #include "llvm/ADT/STLExtras.h" #include "llvm/ADT/SetVector.h" @@ -28,8 +27,10 @@ #include "llvm/CodeGen/MachineLoopInfo.h" #include "llvm/CodeGen/MachineModuleInfo.h" #include "llvm/CodeGen/MachineRegisterInfo.h" +#include "llvm/CodeGen/Passes.h" #include "llvm/CodeGen/RegisterScavenging.h" #include "llvm/CodeGen/StackProtector.h" +#include "llvm/CodeGen/WinEHFuncInfo.h" #include "llvm/IR/DiagnosticInfo.h" #include "llvm/IR/InlineAsm.h" #include "llvm/IR/LLVMContext.h" @@ -48,6 +49,55 @@ using namespace llvm; #define DEBUG_TYPE "pei" +namespace { +class PEI : public MachineFunctionPass { +public: + static char ID; + PEI() : MachineFunctionPass(ID) { + initializePEIPass(*PassRegistry::getPassRegistry()); + } + + void getAnalysisUsage(AnalysisUsage &AU) const override; + + /// runOnMachineFunction - Insert prolog/epilog code and replace abstract + /// frame indexes with appropriate references. + /// + bool runOnMachineFunction(MachineFunction &Fn) override; + +private: + RegScavenger *RS; + + // MinCSFrameIndex, MaxCSFrameIndex - Keeps the range of callee saved + // stack frame indexes. + unsigned MinCSFrameIndex, MaxCSFrameIndex; + + // Save and Restore blocks of the current function. Typically there is a + // single save block, unless Windows EH funclets are involved. + SmallVector SaveBlocks; + SmallVector RestoreBlocks; + + // Flag to control whether to use the register scavenger to resolve + // frame index materialization registers. Set according to + // TRI->requiresFrameIndexScavenging() for the current function. + bool FrameIndexVirtualScavenging; + + void calculateSets(MachineFunction &Fn); + void calculateCallsInformation(MachineFunction &Fn); + void assignCalleeSavedSpillSlots(MachineFunction &Fn, + const BitVector &SavedRegs); + void insertCSRSpillsAndRestores(MachineFunction &Fn); + void calculateFrameObjectOffsets(MachineFunction &Fn); + void replaceFrameIndices(MachineFunction &Fn); + void replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &Fn, + int &SPAdj); + void scavengeFrameVirtualRegs(MachineFunction &Fn); + void insertPrologEpilogCode(MachineFunction &Fn); + + // Convenience for recognizing return blocks. + bool isReturnBlock(const MachineBasicBlock *MBB) const; +}; +} // namespace + char PEI::ID = 0; char &llvm::PrologEpilogCodeInserterID = PEI::ID; @@ -79,28 +129,39 @@ void PEI::getAnalysisUsage(AnalysisUsage &AU) const { MachineFunctionPass::getAnalysisUsage(AU); } -bool PEI::isReturnBlock(MachineBasicBlock* MBB) { +bool PEI::isReturnBlock(const MachineBasicBlock* MBB) const { return (MBB && !MBB->empty() && MBB->back().isReturn()); } /// Compute the set of return blocks void PEI::calculateSets(MachineFunction &Fn) { - // Sets used to compute spill, restore placement sets. - const std::vector &CSI = - Fn.getFrameInfo()->getCalleeSavedInfo(); - - // If no CSRs used, we are done. - if (CSI.empty()) + const MachineFrameInfo *MFI = Fn.getFrameInfo(); + + // Even when we do not change any CSR, we still want to insert the + // prologue and epilogue of the function. + // So set the save points for those. + + // Use the points found by shrink-wrapping, if any. + if (MFI->getSavePoint()) { + SaveBlocks.push_back(MFI->getSavePoint()); + assert(MFI->getRestorePoint() && "Both restore and save must be set"); + MachineBasicBlock *RestoreBlock = MFI->getRestorePoint(); + // If RestoreBlock does not have any successor and is not a return block + // then the end point is unreachable and we do not need to insert any + // epilogue. + if (!RestoreBlock->succ_empty() || isReturnBlock(RestoreBlock)) + RestoreBlocks.push_back(RestoreBlock); return; + } // Save refs to entry and return blocks. - EntryBlock = Fn.begin(); - for (MachineFunction::iterator MBB = Fn.begin(), E = Fn.end(); - MBB != E; ++MBB) - if (isReturnBlock(MBB)) - ReturnBlocks.push_back(MBB); - - return; + SaveBlocks.push_back(Fn.begin()); + for (MachineBasicBlock &MBB : Fn) { + if (MBB.isEHFuncletEntry()) + SaveBlocks.push_back(&MBB); + if (isReturnBlock(&MBB)) + RestoreBlocks.push_back(&MBB); + } } /// StackObjSet - A set of stack object indexes @@ -124,13 +185,12 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) { // instructions. calculateCallsInformation(Fn); - // Allow the target machine to make some adjustments to the function - // e.g. UsedPhysRegs before calculateCalleeSavedRegisters. - TFI->processFunctionBeforeCalleeSavedScan(Fn, RS); + // Determine which of the registers in the callee save list should be saved. + BitVector SavedRegs; + TFI->determineCalleeSaves(Fn, SavedRegs, RS); - // Scan the function for modified callee saved registers and insert spill code - // for any callee saved registers that are modified. - calculateCalleeSavedRegisters(Fn); + // Insert spill code for any callee saved registers that are modified. + assignCalleeSavedSpillSlots(Fn, SavedRegs); // Determine placement of CSR spill/restore code: // place all spills in the entry block, all restores in return blocks. @@ -178,7 +238,8 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) { } delete RS; - ReturnBlocks.clear(); + SaveBlocks.clear(); + RestoreBlocks.clear(); return true; } @@ -194,12 +255,12 @@ void PEI::calculateCallsInformation(MachineFunction &Fn) { bool AdjustsStack = MFI->adjustsStack(); // Get the function call frame set-up and tear-down instruction opcode - int FrameSetupOpcode = TII.getCallFrameSetupOpcode(); - int FrameDestroyOpcode = TII.getCallFrameDestroyOpcode(); + unsigned FrameSetupOpcode = TII.getCallFrameSetupOpcode(); + unsigned FrameDestroyOpcode = TII.getCallFrameDestroyOpcode(); // Early exit for targets which have no call frame setup/destroy pseudo // instructions. - if (FrameSetupOpcode == -1 && FrameDestroyOpcode == -1) + if (FrameSetupOpcode == ~0u && FrameDestroyOpcode == ~0u) return; std::vector FrameSDOps; @@ -236,39 +297,27 @@ void PEI::calculateCallsInformation(MachineFunction &Fn) { } } - -/// calculateCalleeSavedRegisters - Scan the function for modified callee saved -/// registers. -void PEI::calculateCalleeSavedRegisters(MachineFunction &F) { - const TargetRegisterInfo *RegInfo = F.getSubtarget().getRegisterInfo(); - const TargetFrameLowering *TFI = F.getSubtarget().getFrameLowering(); - MachineFrameInfo *MFI = F.getFrameInfo(); - - // Get the callee saved register list... - const MCPhysReg *CSRegs = RegInfo->getCalleeSavedRegs(&F); - +void PEI::assignCalleeSavedSpillSlots(MachineFunction &F, + const BitVector &SavedRegs) { // These are used to keep track the callee-save area. Initialize them. MinCSFrameIndex = INT_MAX; MaxCSFrameIndex = 0; - // Early exit for targets which have no callee saved registers. - if (!CSRegs || CSRegs[0] == 0) + if (SavedRegs.empty()) return; - // In Naked functions we aren't going to save any registers. - if (F.getFunction()->hasFnAttribute(Attribute::Naked)) - return; + const TargetRegisterInfo *RegInfo = F.getSubtarget().getRegisterInfo(); + const MCPhysReg *CSRegs = RegInfo->getCalleeSavedRegs(&F); std::vector CSI; for (unsigned i = 0; CSRegs[i]; ++i) { unsigned Reg = CSRegs[i]; - // Functions which call __builtin_unwind_init get all their registers saved. - if (F.getRegInfo().isPhysRegUsed(Reg) || F.getMMI().callsUnwindInit()) { - // If the reg is modified, save it! + if (SavedRegs.test(Reg)) CSI.push_back(CalleeSavedInfo(Reg)); - } } + const TargetFrameLowering *TFI = F.getSubtarget().getFrameLowering(); + MachineFrameInfo *MFI = F.getFrameInfo(); if (!TFI->assignCalleeSavedSpillSlots(F, RegInfo, CSI)) { // If target doesn't implement this, use generic code. @@ -324,6 +373,61 @@ void PEI::calculateCalleeSavedRegisters(MachineFunction &F) { MFI->setCalleeSavedInfo(CSI); } +/// Helper function to update the liveness information for the callee-saved +/// registers. +static void updateLiveness(MachineFunction &MF) { + MachineFrameInfo *MFI = MF.getFrameInfo(); + // Visited will contain all the basic blocks that are in the region + // where the callee saved registers are alive: + // - Anything that is not Save or Restore -> LiveThrough. + // - Save -> LiveIn. + // - Restore -> LiveOut. + // The live-out is not attached to the block, so no need to keep + // Restore in this set. + SmallPtrSet Visited; + SmallVector WorkList; + MachineBasicBlock *Entry = &MF.front(); + MachineBasicBlock *Save = MFI->getSavePoint(); + + if (!Save) + Save = Entry; + + if (Entry != Save) { + WorkList.push_back(Entry); + Visited.insert(Entry); + } + Visited.insert(Save); + + MachineBasicBlock *Restore = MFI->getRestorePoint(); + if (Restore) + // By construction Restore cannot be visited, otherwise it + // means there exists a path to Restore that does not go + // through Save. + WorkList.push_back(Restore); + + while (!WorkList.empty()) { + const MachineBasicBlock *CurBB = WorkList.pop_back_val(); + // By construction, the region that is after the save point is + // dominated by the Save and post-dominated by the Restore. + if (CurBB == Save) + continue; + // Enqueue all the successors not already visited. + // Those are by construction either before Save or after Restore. + for (MachineBasicBlock *SuccBB : CurBB->successors()) + if (Visited.insert(SuccBB).second) + WorkList.push_back(SuccBB); + } + + const std::vector &CSI = MFI->getCalleeSavedInfo(); + + for (unsigned i = 0, e = CSI.size(); i != e; ++i) { + for (MachineBasicBlock *MBB : Visited) + // Add the callee-saved register as live-in. + // It's killed at the spill. + MBB->addLiveIn(CSI[i].getReg()); + } +} + /// insertCSRSpillsAndRestores - Insert spill and restore code for /// callee saved registers used in the function. /// @@ -344,26 +448,24 @@ void PEI::insertCSRSpillsAndRestores(MachineFunction &Fn) { MachineBasicBlock::iterator I; // Spill using target interface. - I = EntryBlock->begin(); - if (!TFI->spillCalleeSavedRegisters(*EntryBlock, I, CSI, TRI)) { - for (unsigned i = 0, e = CSI.size(); i != e; ++i) { - // Add the callee-saved register as live-in. - // It's killed at the spill. - EntryBlock->addLiveIn(CSI[i].getReg()); - - // Insert the spill to the stack frame. - unsigned Reg = CSI[i].getReg(); - const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg); - TII.storeRegToStackSlot(*EntryBlock, I, Reg, true, CSI[i].getFrameIdx(), - RC, TRI); + for (MachineBasicBlock *SaveBlock : SaveBlocks) { + I = SaveBlock->begin(); + if (!TFI->spillCalleeSavedRegisters(*SaveBlock, I, CSI, TRI)) { + for (unsigned i = 0, e = CSI.size(); i != e; ++i) { + // Insert the spill to the stack frame. + unsigned Reg = CSI[i].getReg(); + const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg); + TII.storeRegToStackSlot(*SaveBlock, I, Reg, true, CSI[i].getFrameIdx(), + RC, TRI); + } } + // Update the live-in information of all the blocks up to the save point. + updateLiveness(Fn); } // Restore using target interface. - for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri) { - MachineBasicBlock *MBB = ReturnBlocks[ri]; + for (MachineBasicBlock *MBB : RestoreBlocks) { I = MBB->end(); - --I; // Skip over all terminator instructions, which are part of the return // sequence. @@ -495,7 +597,7 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) { unsigned Align = MFI->getObjectAlignment(i); // Adjust to alignment boundary - Offset = (Offset+Align-1)/Align*Align; + Offset = RoundUpToAlignment(Offset, Align); MFI->setObjectOffset(i, -Offset); // Set the computed offset } @@ -504,7 +606,7 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) { for (int i = MaxCSFI; i >= MinCSFI ; --i) { unsigned Align = MFI->getObjectAlignment(i); // Adjust to alignment boundary - Offset = (Offset+Align-1)/Align*Align; + Offset = RoundUpToAlignment(Offset, Align); MFI->setObjectOffset(i, Offset); Offset += MFI->getObjectSize(i); @@ -537,7 +639,7 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) { unsigned Align = MFI->getLocalFrameMaxAlign(); // Adjust to alignment boundary. - Offset = (Offset + Align - 1) / Align * Align; + Offset = RoundUpToAlignment(Offset, Align); DEBUG(dbgs() << "Local frame base offset: " << Offset << "\n"); @@ -656,8 +758,7 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) { // If the frame pointer is eliminated, all frame offsets will be relative to // SP not FP. Align to MaxAlign so this works. StackAlign = std::max(StackAlign, MaxAlign); - unsigned AlignMask = StackAlign - 1; - Offset = (Offset + AlignMask) & ~uint64_t(AlignMask); + Offset = RoundUpToAlignment(Offset, StackAlign); } // Update frame info to pretend that this is part of the stack... @@ -674,21 +775,21 @@ void PEI::insertPrologEpilogCode(MachineFunction &Fn) { const TargetFrameLowering &TFI = *Fn.getSubtarget().getFrameLowering(); // Add prologue to the function... - TFI.emitPrologue(Fn); + for (MachineBasicBlock *SaveBlock : SaveBlocks) + TFI.emitPrologue(Fn, *SaveBlock); - // Add epilogue to restore the callee-save registers in each exiting block - for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) { - // If last instruction is a return instruction, add an epilogue - if (!I->empty() && I->back().isReturn()) - TFI.emitEpilogue(Fn, *I); - } + // Add epilogue to restore the callee-save registers in each exiting block. + for (MachineBasicBlock *RestoreBlock : RestoreBlocks) + TFI.emitEpilogue(Fn, *RestoreBlock); // Emit additional code that is required to support segmented stacks, if // we've been asked for it. This, when linked with a runtime with support // for segmented stacks (libgcc is one), will result in allocating stack // space in small chunks instead of one large contiguous block. - if (Fn.shouldSplitStack()) - TFI.adjustForSegmentedStacks(Fn); + if (Fn.shouldSplitStack()) { + for (MachineBasicBlock *SaveBlock : SaveBlocks) + TFI.adjustForSegmentedStacks(Fn, *SaveBlock); + } // Emit additional code that is required to explicitly handle the stack in // HiPE native code (if needed) when loaded in the Erlang/OTP runtime. The @@ -696,7 +797,8 @@ void PEI::insertPrologEpilogCode(MachineFunction &Fn) { // different conditional check and another BIF for allocating more stack // space. if (Fn.getFunction()->getCallingConv() == CallingConv::HiPE) - TFI.adjustForHiPEPrologue(Fn); + for (MachineBasicBlock *SaveBlock : SaveBlocks) + TFI.adjustForHiPEPrologue(Fn, *SaveBlock); } /// replaceFrameIndices - Replace all MO_FrameIndex operands with physical @@ -706,6 +808,25 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) { const TargetFrameLowering &TFI = *Fn.getSubtarget().getFrameLowering(); if (!TFI.needsFrameIndexResolution(Fn)) return; + MachineModuleInfo &MMI = Fn.getMMI(); + const Function *F = Fn.getFunction(); + const Function *ParentF = MMI.getWinEHParent(F); + unsigned FrameReg; + if (F == ParentF) { + WinEHFuncInfo &FuncInfo = MMI.getWinEHFuncInfo(Fn.getFunction()); + // FIXME: This should be unconditional but we have bugs in the preparation + // pass. + if (FuncInfo.UnwindHelpFrameIdx != INT_MAX) + FuncInfo.UnwindHelpFrameOffset = TFI.getFrameIndexReferenceFromSP( + Fn, FuncInfo.UnwindHelpFrameIdx, FrameReg); + } else if (MMI.hasWinEHFuncInfo(F)) { + WinEHFuncInfo &FuncInfo = MMI.getWinEHFuncInfo(Fn.getFunction()); + auto I = FuncInfo.CatchHandlerParentFrameObjIdx.find(F); + if (I != FuncInfo.CatchHandlerParentFrameObjIdx.end()) + FuncInfo.CatchHandlerParentFrameObjOffset[F] = + TFI.getFrameIndexReferenceFromSP(Fn, I->second, FrameReg); + } + // Store SPAdj at exit of a basic block. SmallVector SPState; SPState.resize(Fn.getNumBlockIDs()); @@ -744,8 +865,8 @@ void PEI::replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &Fn, const TargetInstrInfo &TII = *Fn.getSubtarget().getInstrInfo(); const TargetRegisterInfo &TRI = *Fn.getSubtarget().getRegisterInfo(); const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering(); - int FrameSetupOpcode = TII.getCallFrameSetupOpcode(); - int FrameDestroyOpcode = TII.getCallFrameDestroyOpcode(); + unsigned FrameSetupOpcode = TII.getCallFrameSetupOpcode(); + unsigned FrameDestroyOpcode = TII.getCallFrameDestroyOpcode(); if (RS && !FrameIndexVirtualScavenging) RS->enterBasicBlock(BB); @@ -776,11 +897,11 @@ void PEI::replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &Fn, if (!MI->getOperand(i).isFI()) continue; - // Frame indicies in debug values are encoded in a target independent + // Frame indices in debug values are encoded in a target independent // way with simply the frame index and offset rather than any // target-specific addressing mode. if (MI->isDebugValue()) { - assert(i == 0 && "Frame indicies can only appear as the first " + assert(i == 0 && "Frame indices can only appear as the first " "operand of a DBG_VALUE machine instruction"); unsigned Reg; MachineOperand &Offset = MI->getOperand(1); @@ -811,17 +932,6 @@ void PEI::replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &Fn, continue; } - // Frame allocations are target independent. Simply swap the index with - // the offset. - if (MI->getOpcode() == TargetOpcode::FRAME_ALLOC) { - assert(TFI->hasFP(Fn) && "frame alloc requires FP"); - MachineOperand &FI = MI->getOperand(i); - unsigned Reg; - int FrameOffset = TFI->getFrameIndexReference(Fn, FI.getIndex(), Reg); - FI.ChangeToImmediate(FrameOffset); - continue; - } - // Some instructions (e.g. inline asm instructions) can have // multiple frame indices and/or cause eliminateFrameIndex // to insert more than one instruction. We need the register @@ -924,12 +1034,8 @@ PEI::scavengeFrameVirtualRegs(MachineFunction &Fn) { // Replace this reference to the virtual register with the // scratch register. assert (ScratchReg && "Missing scratch register!"); - MachineRegisterInfo &MRI = Fn.getRegInfo(); Fn.getRegInfo().replaceRegWith(Reg, ScratchReg); - // Make sure MRI now accounts this register as used. - MRI.setPhysRegUsed(ScratchReg); - // Because this instruction was processed by the RS before this // register was allocated, make sure that the RS now records the // register as being used.