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Diffstat (limited to 'contrib/llvm/lib/Target/WebAssembly/WebAssemblyPEI.cpp')
| -rw-r--r-- | contrib/llvm/lib/Target/WebAssembly/WebAssemblyPEI.cpp | 1066 |
1 files changed, 0 insertions, 1066 deletions
diff --git a/contrib/llvm/lib/Target/WebAssembly/WebAssemblyPEI.cpp b/contrib/llvm/lib/Target/WebAssembly/WebAssemblyPEI.cpp deleted file mode 100644 index d570d42..0000000 --- a/contrib/llvm/lib/Target/WebAssembly/WebAssemblyPEI.cpp +++ /dev/null @@ -1,1066 +0,0 @@ -//===-- WebAssemblyPEI.cpp - Insert Prolog/Epilog code in function --===// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -// -// This pass is responsible for finalizing the functions frame layout, saving -// callee saved registers, and for emitting prolog & epilog code for the -// function. -// -// This pass must be run after register allocation. After this pass is -// executed, it is illegal to construct MO_FrameIndex operands. -// -// This is a copy of lib/CodeGen/PrologEpilogInserter.cpp except that it does -// not assert that all virtual registers are gone (because WebAssembly currently -// uses virtual rather than physical registers), and only runs -// MRI.clearVirtRegs() if scavenging happened (which it never does). It also -// uses a different class name so it can be registered via INITIALIZE_PASS. -// It is otherwise unmodified, so any changes to the target-independent PEI -// can be easily applied. -//===----------------------------------------------------------------------===// - -#include "llvm/ADT/IndexedMap.h" -#include "llvm/ADT/STLExtras.h" -#include "llvm/ADT/SetVector.h" -#include "llvm/ADT/SmallSet.h" -#include "llvm/ADT/Statistic.h" -#include "llvm/CodeGen/MachineDominators.h" -#include "llvm/CodeGen/MachineFrameInfo.h" -#include "llvm/CodeGen/MachineInstr.h" -#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" -#include "llvm/Support/CommandLine.h" -#include "llvm/Support/Compiler.h" -#include "llvm/Support/Debug.h" -#include "llvm/Support/raw_ostream.h" -#include "llvm/Target/TargetFrameLowering.h" -#include "llvm/Target/TargetInstrInfo.h" -#include "llvm/Target/TargetMachine.h" -#include "llvm/Target/TargetRegisterInfo.h" -#include "llvm/Target/TargetSubtargetInfo.h" -#include <climits> - -using namespace llvm; - -#define DEBUG_TYPE "pei" -namespace llvm { -void initializeWasmPEIPass(PassRegistry&); -} -namespace { -class WasmPEI : public MachineFunctionPass { -public: - static char ID; - WasmPEI() : MachineFunctionPass(ID) { - initializeWasmPEIPass(*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<MachineBasicBlock *, 1> SaveBlocks; - SmallVector<MachineBasicBlock *, 4> 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); -}; -} // namespace - -char WasmPEI::ID = 0; - -namespace llvm { -FunctionPass *createWebAssemblyPEI() { - return new WasmPEI(); -} -} - -static cl::opt<unsigned> -WarnStackSize("wasm-warn-stack-size", cl::Hidden, cl::init((unsigned)-1), - cl::desc("Warn for stack size bigger than the given" - " number")); - -INITIALIZE_PASS_BEGIN(WasmPEI, "wasmprologepilog", - "Wasm Prologue/Epilogue Insertion", false, false) -INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo) -INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree) -INITIALIZE_PASS_DEPENDENCY(StackProtector) -INITIALIZE_PASS_DEPENDENCY(TargetPassConfig) -INITIALIZE_PASS_END(WasmPEI, "wasmprologepilog", - "Wasm Prologue/Epilogue Insertion & Frame Finalization", - false, false) - -STATISTIC(NumScavengedRegs, "Number of frame index regs scavenged"); -STATISTIC(NumBytesStackSpace, - "Number of bytes used for stack in all functions"); - -void WasmPEI::getAnalysisUsage(AnalysisUsage &AU) const { - AU.setPreservesCFG(); - AU.addPreserved<MachineLoopInfo>(); - AU.addPreserved<MachineDominatorTree>(); - AU.addRequired<StackProtector>(); - AU.addRequired<TargetPassConfig>(); - MachineFunctionPass::getAnalysisUsage(AU); -} - -/// Compute the set of return blocks -void WasmPEI::calculateSets(MachineFunction &Fn) { - 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() || RestoreBlock->isReturnBlock()) - RestoreBlocks.push_back(RestoreBlock); - return; - } - - // Save refs to entry and return blocks. - SaveBlocks.push_back(&Fn.front()); - for (MachineBasicBlock &MBB : Fn) { - if (MBB.isEHFuncletEntry()) - SaveBlocks.push_back(&MBB); - if (MBB.isReturnBlock()) - RestoreBlocks.push_back(&MBB); - } -} - -/// StackObjSet - A set of stack object indexes -typedef SmallSetVector<int, 8> StackObjSet; - -/// runOnMachineFunction - Insert prolog/epilog code and replace abstract -/// frame indexes with appropriate references. -/// -bool WasmPEI::runOnMachineFunction(MachineFunction &Fn) { - const Function* F = Fn.getFunction(); - const TargetRegisterInfo *TRI = Fn.getSubtarget().getRegisterInfo(); - const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering(); - - // LOCALMOD: assert removed from target-independent PEI - //assert(!Fn.getRegInfo().getNumVirtRegs() && "Regalloc must assign all vregs"); - - RS = TRI->requiresRegisterScavenging(Fn) ? new RegScavenger() : nullptr; - FrameIndexVirtualScavenging = TRI->requiresFrameIndexScavenging(Fn); - - // Calculate the MaxCallFrameSize and AdjustsStack variables for the - // function's frame information. Also eliminates call frame pseudo - // instructions. - calculateCallsInformation(Fn); - - // Determine which of the registers in the callee save list should be saved. - BitVector SavedRegs; - TFI->determineCalleeSaves(Fn, SavedRegs, RS); - - // 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. - calculateSets(Fn); - - // Add the code to save and restore the callee saved registers. - if (!F->hasFnAttribute(Attribute::Naked)) - insertCSRSpillsAndRestores(Fn); - - // Allow the target machine to make final modifications to the function - // before the frame layout is finalized. - TFI->processFunctionBeforeFrameFinalized(Fn, RS); - - // Calculate actual frame offsets for all abstract stack objects... - calculateFrameObjectOffsets(Fn); - - // Add prolog and epilog code to the function. This function is required - // to align the stack frame as necessary for any stack variables or - // called functions. Because of this, calculateCalleeSavedRegisters() - // must be called before this function in order to set the AdjustsStack - // and MaxCallFrameSize variables. - if (!F->hasFnAttribute(Attribute::Naked)) - insertPrologEpilogCode(Fn); - - // Replace all MO_FrameIndex operands with physical register references - // and actual offsets. - // - replaceFrameIndices(Fn); - - // If register scavenging is needed, as we've enabled doing it as a - // post-pass, scavenge the virtual registers that frame index elimination - // inserted. - if (TRI->requiresRegisterScavenging(Fn) && FrameIndexVirtualScavenging) { - scavengeFrameVirtualRegs(Fn); - // Clear any vregs created by virtual scavenging. - // LOCALMOD: made this call conditional with scavengeFrameVirtualregs() - Fn.getRegInfo().clearVirtRegs(); - } - - // Warn on stack size when we exceeds the given limit. - MachineFrameInfo *MFI = Fn.getFrameInfo(); - uint64_t StackSize = MFI->getStackSize(); - if (WarnStackSize.getNumOccurrences() > 0 && WarnStackSize < StackSize) { - DiagnosticInfoStackSize DiagStackSize(*F, StackSize); - F->getContext().diagnose(DiagStackSize); - } - - delete RS; - SaveBlocks.clear(); - RestoreBlocks.clear(); - return true; -} - -/// calculateCallsInformation - Calculate the MaxCallFrameSize and AdjustsStack -/// variables for the function's frame information and eliminate call frame -/// pseudo instructions. -void WasmPEI::calculateCallsInformation(MachineFunction &Fn) { - const TargetInstrInfo &TII = *Fn.getSubtarget().getInstrInfo(); - const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering(); - MachineFrameInfo *MFI = Fn.getFrameInfo(); - - unsigned MaxCallFrameSize = 0; - bool AdjustsStack = MFI->adjustsStack(); - - // Get the function call frame set-up and tear-down instruction opcode - unsigned FrameSetupOpcode = TII.getCallFrameSetupOpcode(); - unsigned FrameDestroyOpcode = TII.getCallFrameDestroyOpcode(); - - // Early exit for targets which have no call frame setup/destroy pseudo - // instructions. - if (FrameSetupOpcode == ~0u && FrameDestroyOpcode == ~0u) - return; - - std::vector<MachineBasicBlock::iterator> FrameSDOps; - for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) - for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) - if (I->getOpcode() == FrameSetupOpcode || - I->getOpcode() == FrameDestroyOpcode) { - assert(I->getNumOperands() >= 1 && "Call Frame Setup/Destroy Pseudo" - " instructions should have a single immediate argument!"); - unsigned Size = I->getOperand(0).getImm(); - if (Size > MaxCallFrameSize) MaxCallFrameSize = Size; - AdjustsStack = true; - FrameSDOps.push_back(I); - } else if (I->isInlineAsm()) { - // Some inline asm's need a stack frame, as indicated by operand 1. - unsigned ExtraInfo = I->getOperand(InlineAsm::MIOp_ExtraInfo).getImm(); - if (ExtraInfo & InlineAsm::Extra_IsAlignStack) - AdjustsStack = true; - } - - MFI->setAdjustsStack(AdjustsStack); - MFI->setMaxCallFrameSize(MaxCallFrameSize); - - for (std::vector<MachineBasicBlock::iterator>::iterator - i = FrameSDOps.begin(), e = FrameSDOps.end(); i != e; ++i) { - MachineBasicBlock::iterator I = *i; - - // If call frames are not being included as part of the stack frame, and - // the target doesn't indicate otherwise, remove the call frame pseudos - // here. The sub/add sp instruction pairs are still inserted, but we don't - // need to track the SP adjustment for frame index elimination. - if (TFI->canSimplifyCallFramePseudos(Fn)) - TFI->eliminateCallFramePseudoInstr(Fn, *I->getParent(), I); - } -} - -void WasmPEI::assignCalleeSavedSpillSlots(MachineFunction &F, - const BitVector &SavedRegs) { - // These are used to keep track the callee-save area. Initialize them. - MinCSFrameIndex = INT_MAX; - MaxCSFrameIndex = 0; - - if (SavedRegs.empty()) - return; - - const TargetRegisterInfo *RegInfo = F.getSubtarget().getRegisterInfo(); - const MCPhysReg *CSRegs = RegInfo->getCalleeSavedRegs(&F); - - std::vector<CalleeSavedInfo> CSI; - for (unsigned i = 0; CSRegs[i]; ++i) { - unsigned Reg = CSRegs[i]; - 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. - - if (CSI.empty()) - return; // Early exit if no callee saved registers are modified! - - unsigned NumFixedSpillSlots; - const TargetFrameLowering::SpillSlot *FixedSpillSlots = - TFI->getCalleeSavedSpillSlots(NumFixedSpillSlots); - - // Now that we know which registers need to be saved and restored, allocate - // stack slots for them. - for (std::vector<CalleeSavedInfo>::iterator I = CSI.begin(), E = CSI.end(); - I != E; ++I) { - unsigned Reg = I->getReg(); - const TargetRegisterClass *RC = RegInfo->getMinimalPhysRegClass(Reg); - - int FrameIdx; - if (RegInfo->hasReservedSpillSlot(F, Reg, FrameIdx)) { - I->setFrameIdx(FrameIdx); - continue; - } - - // Check to see if this physreg must be spilled to a particular stack slot - // on this target. - const TargetFrameLowering::SpillSlot *FixedSlot = FixedSpillSlots; - while (FixedSlot != FixedSpillSlots + NumFixedSpillSlots && - FixedSlot->Reg != Reg) - ++FixedSlot; - - if (FixedSlot == FixedSpillSlots + NumFixedSpillSlots) { - // Nope, just spill it anywhere convenient. - unsigned Align = RC->getAlignment(); - unsigned StackAlign = TFI->getStackAlignment(); - - // We may not be able to satisfy the desired alignment specification of - // the TargetRegisterClass if the stack alignment is smaller. Use the - // min. - Align = std::min(Align, StackAlign); - FrameIdx = MFI->CreateStackObject(RC->getSize(), Align, true); - if ((unsigned)FrameIdx < MinCSFrameIndex) MinCSFrameIndex = FrameIdx; - if ((unsigned)FrameIdx > MaxCSFrameIndex) MaxCSFrameIndex = FrameIdx; - } else { - // Spill it to the stack where we must. - FrameIdx = - MFI->CreateFixedSpillStackObject(RC->getSize(), FixedSlot->Offset); - } - - I->setFrameIdx(FrameIdx); - } - } - - 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<MachineBasicBlock *, 8> Visited; - SmallVector<MachineBasicBlock *, 8> 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 && Save != Restore) - 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<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo(); - - for (unsigned i = 0, e = CSI.size(); i != e; ++i) { - for (MachineBasicBlock *MBB : Visited) { - MCPhysReg Reg = CSI[i].getReg(); - // Add the callee-saved register as live-in. - // It's killed at the spill. - if (!MBB->isLiveIn(Reg)) - MBB->addLiveIn(Reg); - } - } -} - -/// insertCSRSpillsAndRestores - Insert spill and restore code for -/// callee saved registers used in the function. -/// -void WasmPEI::insertCSRSpillsAndRestores(MachineFunction &Fn) { - // Get callee saved register information. - MachineFrameInfo *MFI = Fn.getFrameInfo(); - const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo(); - - MFI->setCalleeSavedInfoValid(true); - - // Early exit if no callee saved registers are modified! - if (CSI.empty()) - return; - - const TargetInstrInfo &TII = *Fn.getSubtarget().getInstrInfo(); - const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering(); - const TargetRegisterInfo *TRI = Fn.getSubtarget().getRegisterInfo(); - MachineBasicBlock::iterator I; - - // Spill using target interface. - 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 (MachineBasicBlock *MBB : RestoreBlocks) { - I = MBB->end(); - - // Skip over all terminator instructions, which are part of the return - // sequence. - MachineBasicBlock::iterator I2 = I; - while (I2 != MBB->begin() && (--I2)->isTerminator()) - I = I2; - - bool AtStart = I == MBB->begin(); - MachineBasicBlock::iterator BeforeI = I; - if (!AtStart) - --BeforeI; - - // Restore all registers immediately before the return and any - // terminators that precede it. - if (!TFI->restoreCalleeSavedRegisters(*MBB, I, CSI, TRI)) { - for (unsigned i = 0, e = CSI.size(); i != e; ++i) { - unsigned Reg = CSI[i].getReg(); - const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg); - TII.loadRegFromStackSlot(*MBB, I, Reg, CSI[i].getFrameIdx(), RC, TRI); - assert(I != MBB->begin() && - "loadRegFromStackSlot didn't insert any code!"); - // Insert in reverse order. loadRegFromStackSlot can insert - // multiple instructions. - if (AtStart) - I = MBB->begin(); - else { - I = BeforeI; - ++I; - } - } - } - } -} - -/// AdjustStackOffset - Helper function used to adjust the stack frame offset. -static inline void -AdjustStackOffset(MachineFrameInfo *MFI, int FrameIdx, - bool StackGrowsDown, int64_t &Offset, - unsigned &MaxAlign, unsigned Skew) { - // If the stack grows down, add the object size to find the lowest address. - if (StackGrowsDown) - Offset += MFI->getObjectSize(FrameIdx); - - unsigned Align = MFI->getObjectAlignment(FrameIdx); - - // If the alignment of this object is greater than that of the stack, then - // increase the stack alignment to match. - MaxAlign = std::max(MaxAlign, Align); - - // Adjust to alignment boundary. - Offset = RoundUpToAlignment(Offset, Align, Skew); - - if (StackGrowsDown) { - DEBUG(dbgs() << "alloc FI(" << FrameIdx << ") at SP[" << -Offset << "]\n"); - MFI->setObjectOffset(FrameIdx, -Offset); // Set the computed offset - } else { - DEBUG(dbgs() << "alloc FI(" << FrameIdx << ") at SP[" << Offset << "]\n"); - MFI->setObjectOffset(FrameIdx, Offset); - Offset += MFI->getObjectSize(FrameIdx); - } -} - -/// AssignProtectedObjSet - Helper function to assign large stack objects (i.e., -/// those required to be close to the Stack Protector) to stack offsets. -static void -AssignProtectedObjSet(const StackObjSet &UnassignedObjs, - SmallSet<int, 16> &ProtectedObjs, - MachineFrameInfo *MFI, bool StackGrowsDown, - int64_t &Offset, unsigned &MaxAlign, unsigned Skew) { - - for (StackObjSet::const_iterator I = UnassignedObjs.begin(), - E = UnassignedObjs.end(); I != E; ++I) { - int i = *I; - AdjustStackOffset(MFI, i, StackGrowsDown, Offset, MaxAlign, Skew); - ProtectedObjs.insert(i); - } -} - -/// calculateFrameObjectOffsets - Calculate actual frame offsets for all of the -/// abstract stack objects. -/// -void WasmPEI::calculateFrameObjectOffsets(MachineFunction &Fn) { - const TargetFrameLowering &TFI = *Fn.getSubtarget().getFrameLowering(); - StackProtector *SP = &getAnalysis<StackProtector>(); - - bool StackGrowsDown = - TFI.getStackGrowthDirection() == TargetFrameLowering::StackGrowsDown; - - // Loop over all of the stack objects, assigning sequential addresses... - MachineFrameInfo *MFI = Fn.getFrameInfo(); - - // Start at the beginning of the local area. - // The Offset is the distance from the stack top in the direction - // of stack growth -- so it's always nonnegative. - int LocalAreaOffset = TFI.getOffsetOfLocalArea(); - if (StackGrowsDown) - LocalAreaOffset = -LocalAreaOffset; - assert(LocalAreaOffset >= 0 - && "Local area offset should be in direction of stack growth"); - int64_t Offset = LocalAreaOffset; - - // Skew to be applied to alignment. - unsigned Skew = TFI.getStackAlignmentSkew(Fn); - - // If there are fixed sized objects that are preallocated in the local area, - // non-fixed objects can't be allocated right at the start of local area. - // We currently don't support filling in holes in between fixed sized - // objects, so we adjust 'Offset' to point to the end of last fixed sized - // preallocated object. - for (int i = MFI->getObjectIndexBegin(); i != 0; ++i) { - int64_t FixedOff; - if (StackGrowsDown) { - // The maximum distance from the stack pointer is at lower address of - // the object -- which is given by offset. For down growing stack - // the offset is negative, so we negate the offset to get the distance. - FixedOff = -MFI->getObjectOffset(i); - } else { - // The maximum distance from the start pointer is at the upper - // address of the object. - FixedOff = MFI->getObjectOffset(i) + MFI->getObjectSize(i); - } - if (FixedOff > Offset) Offset = FixedOff; - } - - // First assign frame offsets to stack objects that are used to spill - // callee saved registers. - if (StackGrowsDown) { - for (unsigned i = MinCSFrameIndex; i <= MaxCSFrameIndex; ++i) { - // If the stack grows down, we need to add the size to find the lowest - // address of the object. - Offset += MFI->getObjectSize(i); - - unsigned Align = MFI->getObjectAlignment(i); - // Adjust to alignment boundary - Offset = RoundUpToAlignment(Offset, Align, Skew); - - MFI->setObjectOffset(i, -Offset); // Set the computed offset - } - } else { - int MaxCSFI = MaxCSFrameIndex, MinCSFI = MinCSFrameIndex; - for (int i = MaxCSFI; i >= MinCSFI ; --i) { - unsigned Align = MFI->getObjectAlignment(i); - // Adjust to alignment boundary - Offset = RoundUpToAlignment(Offset, Align, Skew); - - MFI->setObjectOffset(i, Offset); - Offset += MFI->getObjectSize(i); - } - } - - unsigned MaxAlign = MFI->getMaxAlignment(); - - // Make sure the special register scavenging spill slot is closest to the - // incoming stack pointer if a frame pointer is required and is closer - // to the incoming rather than the final stack pointer. - const TargetRegisterInfo *RegInfo = Fn.getSubtarget().getRegisterInfo(); - bool EarlyScavengingSlots = (TFI.hasFP(Fn) && - TFI.isFPCloseToIncomingSP() && - RegInfo->useFPForScavengingIndex(Fn) && - !RegInfo->needsStackRealignment(Fn)); - if (RS && EarlyScavengingSlots) { - SmallVector<int, 2> SFIs; - RS->getScavengingFrameIndices(SFIs); - for (SmallVectorImpl<int>::iterator I = SFIs.begin(), - IE = SFIs.end(); I != IE; ++I) - AdjustStackOffset(MFI, *I, StackGrowsDown, Offset, MaxAlign, Skew); - } - - // FIXME: Once this is working, then enable flag will change to a target - // check for whether the frame is large enough to want to use virtual - // frame index registers. Functions which don't want/need this optimization - // will continue to use the existing code path. - if (MFI->getUseLocalStackAllocationBlock()) { - unsigned Align = MFI->getLocalFrameMaxAlign(); - - // Adjust to alignment boundary. - Offset = RoundUpToAlignment(Offset, Align, Skew); - - DEBUG(dbgs() << "Local frame base offset: " << Offset << "\n"); - - // Resolve offsets for objects in the local block. - for (unsigned i = 0, e = MFI->getLocalFrameObjectCount(); i != e; ++i) { - std::pair<int, int64_t> Entry = MFI->getLocalFrameObjectMap(i); - int64_t FIOffset = (StackGrowsDown ? -Offset : Offset) + Entry.second; - DEBUG(dbgs() << "alloc FI(" << Entry.first << ") at SP[" << - FIOffset << "]\n"); - MFI->setObjectOffset(Entry.first, FIOffset); - } - // Allocate the local block - Offset += MFI->getLocalFrameSize(); - - MaxAlign = std::max(Align, MaxAlign); - } - - // Make sure that the stack protector comes before the local variables on the - // stack. - SmallSet<int, 16> ProtectedObjs; - if (MFI->getStackProtectorIndex() >= 0) { - StackObjSet LargeArrayObjs; - StackObjSet SmallArrayObjs; - StackObjSet AddrOfObjs; - - AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), StackGrowsDown, - Offset, MaxAlign, Skew); - - // Assign large stack objects first. - for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) { - if (MFI->isObjectPreAllocated(i) && - MFI->getUseLocalStackAllocationBlock()) - continue; - if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex) - continue; - if (RS && RS->isScavengingFrameIndex((int)i)) - continue; - if (MFI->isDeadObjectIndex(i)) - continue; - if (MFI->getStackProtectorIndex() == (int)i) - continue; - - switch (SP->getSSPLayout(MFI->getObjectAllocation(i))) { - case StackProtector::SSPLK_None: - continue; - case StackProtector::SSPLK_SmallArray: - SmallArrayObjs.insert(i); - continue; - case StackProtector::SSPLK_AddrOf: - AddrOfObjs.insert(i); - continue; - case StackProtector::SSPLK_LargeArray: - LargeArrayObjs.insert(i); - continue; - } - llvm_unreachable("Unexpected SSPLayoutKind."); - } - - AssignProtectedObjSet(LargeArrayObjs, ProtectedObjs, MFI, StackGrowsDown, - Offset, MaxAlign, Skew); - AssignProtectedObjSet(SmallArrayObjs, ProtectedObjs, MFI, StackGrowsDown, - Offset, MaxAlign, Skew); - AssignProtectedObjSet(AddrOfObjs, ProtectedObjs, MFI, StackGrowsDown, - Offset, MaxAlign, Skew); - } - - // Then assign frame offsets to stack objects that are not used to spill - // callee saved registers. - for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) { - if (MFI->isObjectPreAllocated(i) && - MFI->getUseLocalStackAllocationBlock()) - continue; - if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex) - continue; - if (RS && RS->isScavengingFrameIndex((int)i)) - continue; - if (MFI->isDeadObjectIndex(i)) - continue; - if (MFI->getStackProtectorIndex() == (int)i) - continue; - if (ProtectedObjs.count(i)) - continue; - - AdjustStackOffset(MFI, i, StackGrowsDown, Offset, MaxAlign, Skew); - } - - // Make sure the special register scavenging spill slot is closest to the - // stack pointer. - if (RS && !EarlyScavengingSlots) { - SmallVector<int, 2> SFIs; - RS->getScavengingFrameIndices(SFIs); - for (SmallVectorImpl<int>::iterator I = SFIs.begin(), - IE = SFIs.end(); I != IE; ++I) - AdjustStackOffset(MFI, *I, StackGrowsDown, Offset, MaxAlign, Skew); - } - - if (!TFI.targetHandlesStackFrameRounding()) { - // If we have reserved argument space for call sites in the function - // immediately on entry to the current function, count it as part of the - // overall stack size. - if (MFI->adjustsStack() && TFI.hasReservedCallFrame(Fn)) - Offset += MFI->getMaxCallFrameSize(); - - // Round up the size to a multiple of the alignment. If the function has - // any calls or alloca's, align to the target's StackAlignment value to - // ensure that the callee's frame or the alloca data is suitably aligned; - // otherwise, for leaf functions, align to the TransientStackAlignment - // value. - unsigned StackAlign; - if (MFI->adjustsStack() || MFI->hasVarSizedObjects() || - (RegInfo->needsStackRealignment(Fn) && MFI->getObjectIndexEnd() != 0)) - StackAlign = TFI.getStackAlignment(); - else - StackAlign = TFI.getTransientStackAlignment(); - - // 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); - Offset = RoundUpToAlignment(Offset, StackAlign, Skew); - } - - // Update frame info to pretend that this is part of the stack... - int64_t StackSize = Offset - LocalAreaOffset; - MFI->setStackSize(StackSize); - NumBytesStackSpace += StackSize; -} - -/// insertPrologEpilogCode - Scan the function for modified callee saved -/// registers, insert spill code for these callee saved registers, then add -/// prolog and epilog code to the function. -/// -void WasmPEI::insertPrologEpilogCode(MachineFunction &Fn) { - const TargetFrameLowering &TFI = *Fn.getSubtarget().getFrameLowering(); - - // Add prologue to the function... - for (MachineBasicBlock *SaveBlock : SaveBlocks) - TFI.emitPrologue(Fn, *SaveBlock); - - // Add epilogue to restore the callee-save registers in each exiting block. - for (MachineBasicBlock *RestoreBlock : RestoreBlocks) - TFI.emitEpilogue(Fn, *RestoreBlock); - - for (MachineBasicBlock *SaveBlock : SaveBlocks) - TFI.inlineStackProbe(Fn, *SaveBlock); - - // 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()) { - 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 - // approach is rather similar to that of Segmented Stacks, but it uses a - // different conditional check and another BIF for allocating more stack - // space. - if (Fn.getFunction()->getCallingConv() == CallingConv::HiPE) - for (MachineBasicBlock *SaveBlock : SaveBlocks) - TFI.adjustForHiPEPrologue(Fn, *SaveBlock); -} - -/// replaceFrameIndices - Replace all MO_FrameIndex operands with physical -/// register references and actual offsets. -/// -void WasmPEI::replaceFrameIndices(MachineFunction &Fn) { - const TargetFrameLowering &TFI = *Fn.getSubtarget().getFrameLowering(); - if (!TFI.needsFrameIndexResolution(Fn)) return; - - // Store SPAdj at exit of a basic block. - SmallVector<int, 8> SPState; - SPState.resize(Fn.getNumBlockIDs()); - SmallPtrSet<MachineBasicBlock*, 8> Reachable; - - // Iterate over the reachable blocks in DFS order. - for (auto DFI = df_ext_begin(&Fn, Reachable), DFE = df_ext_end(&Fn, Reachable); - DFI != DFE; ++DFI) { - int SPAdj = 0; - // Check the exit state of the DFS stack predecessor. - if (DFI.getPathLength() >= 2) { - MachineBasicBlock *StackPred = DFI.getPath(DFI.getPathLength() - 2); - assert(Reachable.count(StackPred) && - "DFS stack predecessor is already visited.\n"); - SPAdj = SPState[StackPred->getNumber()]; - } - MachineBasicBlock *BB = *DFI; - replaceFrameIndices(BB, Fn, SPAdj); - SPState[BB->getNumber()] = SPAdj; - } - - // Handle the unreachable blocks. - for (auto &BB : Fn) { - if (Reachable.count(&BB)) - // Already handled in DFS traversal. - continue; - int SPAdj = 0; - replaceFrameIndices(&BB, Fn, SPAdj); - } -} - -void WasmPEI::replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &Fn, - int &SPAdj) { - assert(Fn.getSubtarget().getRegisterInfo() && - "getRegisterInfo() must be implemented!"); - const TargetInstrInfo &TII = *Fn.getSubtarget().getInstrInfo(); - const TargetRegisterInfo &TRI = *Fn.getSubtarget().getRegisterInfo(); - const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering(); - unsigned FrameSetupOpcode = TII.getCallFrameSetupOpcode(); - unsigned FrameDestroyOpcode = TII.getCallFrameDestroyOpcode(); - - if (RS && !FrameIndexVirtualScavenging) RS->enterBasicBlock(BB); - - bool InsideCallSequence = false; - - for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) { - - if (I->getOpcode() == FrameSetupOpcode || - I->getOpcode() == FrameDestroyOpcode) { - InsideCallSequence = (I->getOpcode() == FrameSetupOpcode); - SPAdj += TII.getSPAdjust(I); - - MachineBasicBlock::iterator PrevI = BB->end(); - if (I != BB->begin()) PrevI = std::prev(I); - TFI->eliminateCallFramePseudoInstr(Fn, *BB, I); - - // Visit the instructions created by eliminateCallFramePseudoInstr(). - if (PrevI == BB->end()) - I = BB->begin(); // The replaced instr was the first in the block. - else - I = std::next(PrevI); - continue; - } - - MachineInstr *MI = I; - bool DoIncr = true; - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - if (!MI->getOperand(i).isFI()) - continue; - - // 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 indices can only appear as the first " - "operand of a DBG_VALUE machine instruction"); - unsigned Reg; - MachineOperand &Offset = MI->getOperand(1); - Offset.setImm(Offset.getImm() + - TFI->getFrameIndexReference( - Fn, MI->getOperand(0).getIndex(), Reg)); - MI->getOperand(0).ChangeToRegister(Reg, false /*isDef*/); - continue; - } - - // TODO: This code should be commoned with the code for - // PATCHPOINT. There's no good reason for the difference in - // implementation other than historical accident. The only - // remaining difference is the unconditional use of the stack - // pointer as the base register. - if (MI->getOpcode() == TargetOpcode::STATEPOINT) { - assert((!MI->isDebugValue() || i == 0) && - "Frame indicies can only appear as the first operand of a " - "DBG_VALUE machine instruction"); - unsigned Reg; - MachineOperand &Offset = MI->getOperand(i + 1); - const unsigned refOffset = - TFI->getFrameIndexReferenceFromSP(Fn, MI->getOperand(i).getIndex(), - Reg); - - Offset.setImm(Offset.getImm() + refOffset); - MI->getOperand(i).ChangeToRegister(Reg, false /*isDef*/); - 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 - // scavenger to go through all of these instructions so that - // it can update its register information. We keep the - // iterator at the point before insertion so that we can - // revisit them in full. - bool AtBeginning = (I == BB->begin()); - if (!AtBeginning) --I; - - // If this instruction has a FrameIndex operand, we need to - // use that target machine register info object to eliminate - // it. - TRI.eliminateFrameIndex(MI, SPAdj, i, - FrameIndexVirtualScavenging ? nullptr : RS); - - // Reset the iterator if we were at the beginning of the BB. - if (AtBeginning) { - I = BB->begin(); - DoIncr = false; - } - - MI = nullptr; - break; - } - - // If we are looking at a call sequence, we need to keep track of - // the SP adjustment made by each instruction in the sequence. - // This includes both the frame setup/destroy pseudos (handled above), - // as well as other instructions that have side effects w.r.t the SP. - // Note that this must come after eliminateFrameIndex, because - // if I itself referred to a frame index, we shouldn't count its own - // adjustment. - if (MI && InsideCallSequence) - SPAdj += TII.getSPAdjust(MI); - - if (DoIncr && I != BB->end()) ++I; - - // Update register states. - if (RS && !FrameIndexVirtualScavenging && MI) RS->forward(MI); - } -} - -/// scavengeFrameVirtualRegs - Replace all frame index virtual registers -/// with physical registers. Use the register scavenger to find an -/// appropriate register to use. -/// -/// FIXME: Iterating over the instruction stream is unnecessary. We can simply -/// iterate over the vreg use list, which at this point only contains machine -/// operands for which eliminateFrameIndex need a new scratch reg. -void -WasmPEI::scavengeFrameVirtualRegs(MachineFunction &Fn) { - // Run through the instructions and find any virtual registers. - for (MachineFunction::iterator BB = Fn.begin(), - E = Fn.end(); BB != E; ++BB) { - RS->enterBasicBlock(&*BB); - - int SPAdj = 0; - - // The instruction stream may change in the loop, so check BB->end() - // directly. - for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) { - // We might end up here again with a NULL iterator if we scavenged a - // register for which we inserted spill code for definition by what was - // originally the first instruction in BB. - if (I == MachineBasicBlock::iterator(nullptr)) - I = BB->begin(); - - MachineInstr *MI = I; - MachineBasicBlock::iterator J = std::next(I); - MachineBasicBlock::iterator P = - I == BB->begin() ? MachineBasicBlock::iterator(nullptr) - : std::prev(I); - - // RS should process this instruction before we might scavenge at this - // location. This is because we might be replacing a virtual register - // defined by this instruction, and if so, registers killed by this - // instruction are available, and defined registers are not. - RS->forward(I); - - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - if (MI->getOperand(i).isReg()) { - MachineOperand &MO = MI->getOperand(i); - unsigned Reg = MO.getReg(); - if (Reg == 0) - continue; - if (!TargetRegisterInfo::isVirtualRegister(Reg)) - continue; - - // When we first encounter a new virtual register, it - // must be a definition. - assert(MI->getOperand(i).isDef() && - "frame index virtual missing def!"); - // Scavenge a new scratch register - const TargetRegisterClass *RC = Fn.getRegInfo().getRegClass(Reg); - unsigned ScratchReg = RS->scavengeRegister(RC, J, SPAdj); - - ++NumScavengedRegs; - - // Replace this reference to the virtual register with the - // scratch register. - assert (ScratchReg && "Missing scratch register!"); - Fn.getRegInfo().replaceRegWith(Reg, 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. - RS->setRegUsed(ScratchReg); - } - } - - // If the scavenger needed to use one of its spill slots, the - // spill code will have been inserted in between I and J. This is a - // problem because we need the spill code before I: Move I to just - // prior to J. - if (I != std::prev(J)) { - BB->splice(J, &*BB, I); - - // Before we move I, we need to prepare the RS to visit I again. - // Specifically, RS will assert if it sees uses of registers that - // it believes are undefined. Because we have already processed - // register kills in I, when it visits I again, it will believe that - // those registers are undefined. To avoid this situation, unprocess - // the instruction I. - assert(RS->getCurrentPosition() == I && - "The register scavenger has an unexpected position"); - I = P; - RS->unprocess(P); - } else - ++I; - } - } -} |
