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Diffstat (limited to 'lib/Target/AArch64/AArch64ConstantIslandPass.cpp')
| -rw-r--r-- | lib/Target/AArch64/AArch64ConstantIslandPass.cpp | 1423 |
1 files changed, 0 insertions, 1423 deletions
diff --git a/lib/Target/AArch64/AArch64ConstantIslandPass.cpp b/lib/Target/AArch64/AArch64ConstantIslandPass.cpp deleted file mode 100644 index ab482bda6a..0000000000 --- a/lib/Target/AArch64/AArch64ConstantIslandPass.cpp +++ /dev/null @@ -1,1423 +0,0 @@ -//===-- AArch64ConstantIslandPass.cpp - AArch64 constant islands ----------===// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -// -// This file contains a pass that splits the constant pool up into 'islands' -// which are scattered through-out the function. This is required due to the -// limited pc-relative displacements that AArch64 has. -// -//===----------------------------------------------------------------------===// - -#define DEBUG_TYPE "aarch64-cp-islands" -#include "AArch64.h" -#include "AArch64InstrInfo.h" -#include "AArch64MachineFunctionInfo.h" -#include "AArch64Subtarget.h" -#include "AArch64MachineFunctionInfo.h" -#include "Utils/AArch64BaseInfo.h" -#include "llvm/CodeGen/MachineConstantPool.h" -#include "llvm/CodeGen/MachineFunctionPass.h" -#include "llvm/CodeGen/MachineInstrBuilder.h" -#include "llvm/CodeGen/MachineJumpTableInfo.h" -#include "llvm/CodeGen/MachineRegisterInfo.h" -#include "llvm/IR/DataLayout.h" -#include "llvm/Target/TargetMachine.h" -#include "llvm/Support/Debug.h" -#include "llvm/Support/ErrorHandling.h" -#include "llvm/Support/Format.h" -#include "llvm/Support/raw_ostream.h" -#include "llvm/ADT/SmallSet.h" -#include "llvm/ADT/SmallVector.h" -#include "llvm/ADT/STLExtras.h" -#include "llvm/ADT/Statistic.h" -#include "llvm/Support/CommandLine.h" -#include <algorithm> -using namespace llvm; - -STATISTIC(NumCPEs, "Number of constpool entries"); -STATISTIC(NumSplit, "Number of uncond branches inserted"); -STATISTIC(NumCBrFixed, "Number of cond branches fixed"); - -// FIXME: This option should be removed once it has received sufficient testing. -static cl::opt<bool> -AlignConstantIslands("aarch64-align-constant-islands", cl::Hidden, - cl::init(true), - cl::desc("Align constant islands in code")); - -/// Return the worst case padding that could result from unknown offset bits. -/// This does not include alignment padding caused by known offset bits. -/// -/// @param LogAlign log2(alignment) -/// @param KnownBits Number of known low offset bits. -static inline unsigned UnknownPadding(unsigned LogAlign, unsigned KnownBits) { - if (KnownBits < LogAlign) - return (1u << LogAlign) - (1u << KnownBits); - return 0; -} - -namespace { - /// Due to limited PC-relative displacements, AArch64 requires constant pool - /// entries to be scattered among the instructions inside a function. To do - /// this, it completely ignores the normal LLVM constant pool; instead, it - /// places constants wherever it feels like with special instructions. - /// - /// The terminology used in this pass includes: - /// Islands - Clumps of constants placed in the function. - /// Water - Potential places where an island could be formed. - /// CPE - A constant pool entry that has been placed somewhere, which - /// tracks a list of users. - class AArch64ConstantIslands : public MachineFunctionPass { - /// Information about the offset and size of a single basic block. - struct BasicBlockInfo { - /// Distance from the beginning of the function to the beginning of this - /// basic block. - /// - /// Offsets are computed assuming worst case padding before an aligned - /// block. This means that subtracting basic block offsets always gives a - /// conservative estimate of the real distance which may be smaller. - /// - /// Because worst case padding is used, the computed offset of an aligned - /// block may not actually be aligned. - unsigned Offset; - - /// Size of the basic block in bytes. If the block contains inline - /// assembly, this is a worst case estimate. - /// - /// The size does not include any alignment padding whether from the - /// beginning of the block, or from an aligned jump table at the end. - unsigned Size; - - /// The number of low bits in Offset that are known to be exact. The - /// remaining bits of Offset are an upper bound. - uint8_t KnownBits; - - /// When non-zero, the block contains instructions (inline asm) of unknown - /// size. The real size may be smaller than Size bytes by a multiple of 1 - /// << Unalign. - uint8_t Unalign; - - BasicBlockInfo() : Offset(0), Size(0), KnownBits(0), Unalign(0) {} - - /// Compute the number of known offset bits internally to this block. - /// This number should be used to predict worst case padding when - /// splitting the block. - unsigned internalKnownBits() const { - unsigned Bits = Unalign ? Unalign : KnownBits; - // If the block size isn't a multiple of the known bits, assume the - // worst case padding. - if (Size & ((1u << Bits) - 1)) - Bits = CountTrailingZeros_32(Size); - return Bits; - } - - /// Compute the offset immediately following this block. If LogAlign is - /// specified, return the offset the successor block will get if it has - /// this alignment. - unsigned postOffset(unsigned LogAlign = 0) const { - unsigned PO = Offset + Size; - if (!LogAlign) - return PO; - // Add alignment padding from the terminator. - return PO + UnknownPadding(LogAlign, internalKnownBits()); - } - - /// Compute the number of known low bits of postOffset. If this block - /// contains inline asm, the number of known bits drops to the - /// instruction alignment. An aligned terminator may increase the number - /// of know bits. - /// If LogAlign is given, also consider the alignment of the next block. - unsigned postKnownBits(unsigned LogAlign = 0) const { - return std::max(LogAlign, internalKnownBits()); - } - }; - - std::vector<BasicBlockInfo> BBInfo; - - /// A sorted list of basic blocks where islands could be placed (i.e. blocks - /// that don't fall through to the following block, due to a return, - /// unreachable, or unconditional branch). - std::vector<MachineBasicBlock*> WaterList; - - /// The subset of WaterList that was created since the previous iteration by - /// inserting unconditional branches. - SmallSet<MachineBasicBlock*, 4> NewWaterList; - - typedef std::vector<MachineBasicBlock*>::iterator water_iterator; - - /// One user of a constant pool, keeping the machine instruction pointer, - /// the constant pool being referenced, and the number of bits used by the - /// instruction for displacement. The HighWaterMark records the highest - /// basic block where a new CPEntry can be placed. To ensure this pass - /// terminates, the CP entries are initially placed at the end of the - /// function and then move monotonically to lower addresses. The exception - /// to this rule is when the current CP entry for a particular CPUser is out - /// of range, but there is another CP entry for the same constant value in - /// range. We want to use the existing in-range CP entry, but if it later - /// moves out of range, the search for new water should resume where it left - /// off. The HighWaterMark is used to record that point. - struct CPUser { - MachineInstr *MI; - MachineInstr *CPEMI; - MachineBasicBlock *HighWaterMark; - private: - unsigned OffsetBits; - public: - CPUser(MachineInstr *mi, MachineInstr *cpemi, unsigned offsetbits) - : MI(mi), CPEMI(cpemi), OffsetBits(offsetbits) { - HighWaterMark = CPEMI->getParent(); - } - /// Returns the number of bits used to specify the offset. - unsigned getOffsetBits() const { - return OffsetBits; - } - - /// Returns the maximum positive displacement possible from this CPUser - /// (essentially INT<N>_MAX * 4). - unsigned getMaxPosDisp() const { - return (1 << (OffsetBits - 1)) - 1; - } - }; - - /// Keep track of all of the machine instructions that use various constant - /// pools and their max displacement. - std::vector<CPUser> CPUsers; - - /// One per constant pool entry, keeping the machine instruction pointer, - /// the constpool index, and the number of CPUser's which reference this - /// entry. - struct CPEntry { - MachineInstr *CPEMI; - unsigned CPI; - unsigned RefCount; - CPEntry(MachineInstr *cpemi, unsigned cpi, unsigned rc = 0) - : CPEMI(cpemi), CPI(cpi), RefCount(rc) {} - }; - - /// Keep track of all of the constant pool entry machine instructions. For - /// each original constpool index (i.e. those that existed upon entry to - /// this pass), it keeps a vector of entries. Original elements are cloned - /// as we go along; the clones are put in the vector of the original - /// element, but have distinct CPIs. - std::vector<std::vector<CPEntry> > CPEntries; - - /// One per immediate branch, keeping the machine instruction pointer, - /// conditional or unconditional, the max displacement, and (if IsCond is - /// true) the corresponding inverted branch opcode. - struct ImmBranch { - MachineInstr *MI; - unsigned OffsetBits : 31; - bool IsCond : 1; - ImmBranch(MachineInstr *mi, unsigned offsetbits, bool cond) - : MI(mi), OffsetBits(offsetbits), IsCond(cond) {} - }; - - /// Keep track of all the immediate branch instructions. - /// - std::vector<ImmBranch> ImmBranches; - - MachineFunction *MF; - MachineConstantPool *MCP; - const AArch64InstrInfo *TII; - const AArch64Subtarget *STI; - AArch64MachineFunctionInfo *AFI; - public: - static char ID; - AArch64ConstantIslands() : MachineFunctionPass(ID) {} - - virtual bool runOnMachineFunction(MachineFunction &MF); - - virtual const char *getPassName() const { - return "AArch64 constant island placement pass"; - } - - private: - void doInitialPlacement(std::vector<MachineInstr*> &CPEMIs); - CPEntry *findConstPoolEntry(unsigned CPI, const MachineInstr *CPEMI); - unsigned getCPELogAlign(const MachineInstr *CPEMI); - void scanFunctionJumpTables(); - void initializeFunctionInfo(const std::vector<MachineInstr*> &CPEMIs); - MachineBasicBlock *splitBlockBeforeInstr(MachineInstr *MI); - void updateForInsertedWaterBlock(MachineBasicBlock *NewBB); - void adjustBBOffsetsAfter(MachineBasicBlock *BB); - bool decrementCPEReferenceCount(unsigned CPI, MachineInstr* CPEMI); - int findInRangeCPEntry(CPUser& U, unsigned UserOffset); - bool findAvailableWater(CPUser&U, unsigned UserOffset, - water_iterator &WaterIter); - void createNewWater(unsigned CPUserIndex, unsigned UserOffset, - MachineBasicBlock *&NewMBB); - bool handleConstantPoolUser(unsigned CPUserIndex); - void removeDeadCPEMI(MachineInstr *CPEMI); - bool removeUnusedCPEntries(); - bool isCPEntryInRange(MachineInstr *MI, unsigned UserOffset, - MachineInstr *CPEMI, unsigned OffsetBits, - bool DoDump = false); - bool isWaterInRange(unsigned UserOffset, MachineBasicBlock *Water, - CPUser &U, unsigned &Growth); - bool isBBInRange(MachineInstr *MI, MachineBasicBlock *BB, - unsigned OffsetBits); - bool fixupImmediateBr(ImmBranch &Br); - bool fixupConditionalBr(ImmBranch &Br); - - void computeBlockSize(MachineBasicBlock *MBB); - unsigned getOffsetOf(MachineInstr *MI) const; - unsigned getUserOffset(CPUser&) const; - void dumpBBs(); - void verify(); - - bool isOffsetInRange(unsigned UserOffset, unsigned TrialOffset, - unsigned BitsAvailable); - bool isOffsetInRange(unsigned UserOffset, unsigned TrialOffset, - const CPUser &U) { - return isOffsetInRange(UserOffset, TrialOffset, U.getOffsetBits()); - } - }; - char AArch64ConstantIslands::ID = 0; -} - -/// check BBOffsets, BBSizes, alignment of islands -void AArch64ConstantIslands::verify() { -#ifndef NDEBUG - for (MachineFunction::iterator MBBI = MF->begin(), E = MF->end(); - MBBI != E; ++MBBI) { - MachineBasicBlock *MBB = MBBI; - unsigned MBBId = MBB->getNumber(); - assert(!MBBId || BBInfo[MBBId - 1].postOffset() <= BBInfo[MBBId].Offset); - } - DEBUG(dbgs() << "Verifying " << CPUsers.size() << " CP users.\n"); - for (unsigned i = 0, e = CPUsers.size(); i != e; ++i) { - CPUser &U = CPUsers[i]; - unsigned UserOffset = getUserOffset(U); - // Verify offset using the real max displacement without the safety - // adjustment. - if (isCPEntryInRange(U.MI, UserOffset, U.CPEMI, U.getOffsetBits(), - /* DoDump = */ true)) { - DEBUG(dbgs() << "OK\n"); - continue; - } - DEBUG(dbgs() << "Out of range.\n"); - dumpBBs(); - DEBUG(MF->dump()); - llvm_unreachable("Constant pool entry out of range!"); - } -#endif -} - -/// print block size and offset information - debugging -void AArch64ConstantIslands::dumpBBs() { - DEBUG({ - for (unsigned J = 0, E = BBInfo.size(); J !=E; ++J) { - const BasicBlockInfo &BBI = BBInfo[J]; - dbgs() << format("%08x BB#%u\t", BBI.Offset, J) - << " kb=" << unsigned(BBI.KnownBits) - << " ua=" << unsigned(BBI.Unalign) - << format(" size=%#x\n", BBInfo[J].Size); - } - }); -} - -/// Returns an instance of the constpool island pass. -FunctionPass *llvm::createAArch64ConstantIslandPass() { - return new AArch64ConstantIslands(); -} - -bool AArch64ConstantIslands::runOnMachineFunction(MachineFunction &mf) { - MF = &mf; - MCP = mf.getConstantPool(); - - DEBUG(dbgs() << "***** AArch64ConstantIslands: " - << MCP->getConstants().size() << " CP entries, aligned to " - << MCP->getConstantPoolAlignment() << " bytes *****\n"); - - TII = (const AArch64InstrInfo*)MF->getTarget().getInstrInfo(); - AFI = MF->getInfo<AArch64MachineFunctionInfo>(); - STI = &MF->getTarget().getSubtarget<AArch64Subtarget>(); - - // This pass invalidates liveness information when it splits basic blocks. - MF->getRegInfo().invalidateLiveness(); - - // Renumber all of the machine basic blocks in the function, guaranteeing that - // the numbers agree with the position of the block in the function. - MF->RenumberBlocks(); - - // Perform the initial placement of the constant pool entries. To start with, - // we put them all at the end of the function. - std::vector<MachineInstr*> CPEMIs; - if (!MCP->isEmpty()) - doInitialPlacement(CPEMIs); - - /// The next UID to take is the first unused one. - AFI->initPICLabelUId(CPEMIs.size()); - - // Do the initial scan of the function, building up information about the - // sizes of each block, the location of all the water, and finding all of the - // constant pool users. - initializeFunctionInfo(CPEMIs); - CPEMIs.clear(); - DEBUG(dumpBBs()); - - - /// Remove dead constant pool entries. - bool MadeChange = removeUnusedCPEntries(); - - // Iteratively place constant pool entries and fix up branches until there - // is no change. - unsigned NoCPIters = 0, NoBRIters = 0; - while (true) { - DEBUG(dbgs() << "Beginning CP iteration #" << NoCPIters << '\n'); - bool CPChange = false; - for (unsigned i = 0, e = CPUsers.size(); i != e; ++i) - CPChange |= handleConstantPoolUser(i); - if (CPChange && ++NoCPIters > 30) - report_fatal_error("Constant Island pass failed to converge!"); - DEBUG(dumpBBs()); - - // Clear NewWaterList now. If we split a block for branches, it should - // appear as "new water" for the next iteration of constant pool placement. - NewWaterList.clear(); - - DEBUG(dbgs() << "Beginning BR iteration #" << NoBRIters << '\n'); - bool BRChange = false; - for (unsigned i = 0, e = ImmBranches.size(); i != e; ++i) - BRChange |= fixupImmediateBr(ImmBranches[i]); - if (BRChange && ++NoBRIters > 30) - report_fatal_error("Branch Fix Up pass failed to converge!"); - DEBUG(dumpBBs()); - - if (!CPChange && !BRChange) - break; - MadeChange = true; - } - - // After a while, this might be made debug-only, but it is not expensive. - verify(); - - DEBUG(dbgs() << '\n'; dumpBBs()); - - BBInfo.clear(); - WaterList.clear(); - CPUsers.clear(); - CPEntries.clear(); - ImmBranches.clear(); - - return MadeChange; -} - -/// Perform the initial placement of the constant pool entries. To start with, -/// we put them all at the end of the function. -void -AArch64ConstantIslands::doInitialPlacement(std::vector<MachineInstr*> &CPEMIs) { - // Create the basic block to hold the CPE's. - MachineBasicBlock *BB = MF->CreateMachineBasicBlock(); - MF->push_back(BB); - - // MachineConstantPool measures alignment in bytes. We measure in log2(bytes). - unsigned MaxAlign = Log2_32(MCP->getConstantPoolAlignment()); - - // Mark the basic block as required by the const-pool. - // If AlignConstantIslands isn't set, use 4-byte alignment for everything. - BB->setAlignment(AlignConstantIslands ? MaxAlign : 2); - - // The function needs to be as aligned as the basic blocks. The linker may - // move functions around based on their alignment. - MF->ensureAlignment(BB->getAlignment()); - - // Order the entries in BB by descending alignment. That ensures correct - // alignment of all entries as long as BB is sufficiently aligned. Keep - // track of the insertion point for each alignment. We are going to bucket - // sort the entries as they are created. - SmallVector<MachineBasicBlock::iterator, 8> InsPoint(MaxAlign + 1, BB->end()); - - // Add all of the constants from the constant pool to the end block, use an - // identity mapping of CPI's to CPE's. - const std::vector<MachineConstantPoolEntry> &CPs = MCP->getConstants(); - - const DataLayout &TD = *MF->getTarget().getDataLayout(); - for (unsigned i = 0, e = CPs.size(); i != e; ++i) { - unsigned Size = TD.getTypeAllocSize(CPs[i].getType()); - assert(Size >= 4 && "Too small constant pool entry"); - unsigned Align = CPs[i].getAlignment(); - assert(isPowerOf2_32(Align) && "Invalid alignment"); - // Verify that all constant pool entries are a multiple of their alignment. - // If not, we would have to pad them out so that instructions stay aligned. - assert((Size % Align) == 0 && "CP Entry not multiple of 4 bytes!"); - - // Insert CONSTPOOL_ENTRY before entries with a smaller alignment. - unsigned LogAlign = Log2_32(Align); - MachineBasicBlock::iterator InsAt = InsPoint[LogAlign]; - MachineInstr *CPEMI = - BuildMI(*BB, InsAt, DebugLoc(), TII->get(AArch64::CONSTPOOL_ENTRY)) - .addImm(i).addConstantPoolIndex(i).addImm(Size); - CPEMIs.push_back(CPEMI); - - // Ensure that future entries with higher alignment get inserted before - // CPEMI. This is bucket sort with iterators. - for (unsigned a = LogAlign + 1; a <= MaxAlign; ++a) - if (InsPoint[a] == InsAt) - InsPoint[a] = CPEMI; - - // Add a new CPEntry, but no corresponding CPUser yet. - std::vector<CPEntry> CPEs; - CPEs.push_back(CPEntry(CPEMI, i)); - CPEntries.push_back(CPEs); - ++NumCPEs; - DEBUG(dbgs() << "Moved CPI#" << i << " to end of function, size = " - << Size << ", align = " << Align <<'\n'); - } - DEBUG(BB->dump()); -} - -/// Return true if the specified basic block can fallthrough into the block -/// immediately after it. -static bool BBHasFallthrough(MachineBasicBlock *MBB) { - // Get the next machine basic block in the function. - MachineFunction::iterator MBBI = MBB; - // Can't fall off end of function. - if (llvm::next(MBBI) == MBB->getParent()->end()) - return false; - - MachineBasicBlock *NextBB = llvm::next(MBBI); - for (MachineBasicBlock::succ_iterator I = MBB->succ_begin(), - E = MBB->succ_end(); I != E; ++I) - if (*I == NextBB) - return true; - - return false; -} - -/// Given the constpool index and CONSTPOOL_ENTRY MI, look up the corresponding -/// CPEntry. -AArch64ConstantIslands::CPEntry -*AArch64ConstantIslands::findConstPoolEntry(unsigned CPI, - const MachineInstr *CPEMI) { - std::vector<CPEntry> &CPEs = CPEntries[CPI]; - // Number of entries per constpool index should be small, just do a - // linear search. - for (unsigned i = 0, e = CPEs.size(); i != e; ++i) { - if (CPEs[i].CPEMI == CPEMI) - return &CPEs[i]; - } - return NULL; -} - -/// Returns the required alignment of the constant pool entry represented by -/// CPEMI. Alignment is measured in log2(bytes) units. -unsigned AArch64ConstantIslands::getCPELogAlign(const MachineInstr *CPEMI) { - assert(CPEMI && CPEMI->getOpcode() == AArch64::CONSTPOOL_ENTRY); - - // Everything is 4-byte aligned unless AlignConstantIslands is set. - if (!AlignConstantIslands) - return 2; - - unsigned CPI = CPEMI->getOperand(1).getIndex(); - assert(CPI < MCP->getConstants().size() && "Invalid constant pool index."); - unsigned Align = MCP->getConstants()[CPI].getAlignment(); - assert(isPowerOf2_32(Align) && "Invalid CPE alignment"); - return Log2_32(Align); -} - -/// Do the initial scan of the function, building up information about the sizes -/// of each block, the location of all the water, and finding all of the -/// constant pool users. -void AArch64ConstantIslands:: -initializeFunctionInfo(const std::vector<MachineInstr*> &CPEMIs) { - BBInfo.clear(); - BBInfo.resize(MF->getNumBlockIDs()); - - // First thing, compute the size of all basic blocks, and see if the function - // has any inline assembly in it. If so, we have to be conservative about - // alignment assumptions, as we don't know for sure the size of any - // instructions in the inline assembly. - for (MachineFunction::iterator I = MF->begin(), E = MF->end(); I != E; ++I) - computeBlockSize(I); - - // The known bits of the entry block offset are determined by the function - // alignment. - BBInfo.front().KnownBits = MF->getAlignment(); - - // Compute block offsets and known bits. - adjustBBOffsetsAfter(MF->begin()); - - // Now go back through the instructions and build up our data structures. - for (MachineFunction::iterator MBBI = MF->begin(), E = MF->end(); - MBBI != E; ++MBBI) { - MachineBasicBlock &MBB = *MBBI; - - // If this block doesn't fall through into the next MBB, then this is - // 'water' that a constant pool island could be placed. - if (!BBHasFallthrough(&MBB)) - WaterList.push_back(&MBB); - - for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); - I != E; ++I) { - if (I->isDebugValue()) - continue; - - int Opc = I->getOpcode(); - if (I->isBranch()) { - bool IsCond = false; - - // The offsets encoded in instructions here scale by the instruction - // size (4 bytes), effectively increasing their range by 2 bits. - unsigned Bits = 0; - switch (Opc) { - default: - continue; // Ignore other JT branches - case AArch64::TBZxii: - case AArch64::TBZwii: - case AArch64::TBNZxii: - case AArch64::TBNZwii: - IsCond = true; - Bits = 14 + 2; - break; - case AArch64::Bcc: - case AArch64::CBZx: - case AArch64::CBZw: - case AArch64::CBNZx: - case AArch64::CBNZw: - IsCond = true; - Bits = 19 + 2; - break; - case AArch64::Bimm: - Bits = 26 + 2; - break; - } - - // Record this immediate branch. - ImmBranches.push_back(ImmBranch(I, Bits, IsCond)); - } - - if (Opc == AArch64::CONSTPOOL_ENTRY) - continue; - - // Scan the instructions for constant pool operands. - for (unsigned op = 0, e = I->getNumOperands(); op != e; ++op) - if (I->getOperand(op).isCPI()) { - // We found one. The addressing mode tells us the max displacement - // from the PC that this instruction permits. - - // The offsets encoded in instructions here scale by the instruction - // size (4 bytes), effectively increasing their range by 2 bits. - unsigned Bits = 0; - - switch (Opc) { - default: - llvm_unreachable("Unknown addressing mode for CP reference!"); - - case AArch64::LDRw_lit: - case AArch64::LDRx_lit: - case AArch64::LDRs_lit: - case AArch64::LDRd_lit: - case AArch64::LDRq_lit: - case AArch64::LDRSWx_lit: - case AArch64::PRFM_lit: - Bits = 19 + 2; - } - - // Remember that this is a user of a CP entry. - unsigned CPI = I->getOperand(op).getIndex(); - MachineInstr *CPEMI = CPEMIs[CPI]; - CPUsers.push_back(CPUser(I, CPEMI, Bits)); - - // Increment corresponding CPEntry reference count. - CPEntry *CPE = findConstPoolEntry(CPI, CPEMI); - assert(CPE && "Cannot find a corresponding CPEntry!"); - CPE->RefCount++; - - // Instructions can only use one CP entry, don't bother scanning the - // rest of the operands. - break; - } - } - } -} - -/// Compute the size and some alignment information for MBB. This function -/// updates BBInfo directly. -void AArch64ConstantIslands::computeBlockSize(MachineBasicBlock *MBB) { - BasicBlockInfo &BBI = BBInfo[MBB->getNumber()]; - BBI.Size = 0; - BBI.Unalign = 0; - - for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E; - ++I) { - BBI.Size += TII->getInstSizeInBytes(*I); - // For inline asm, GetInstSizeInBytes returns a conservative estimate. - // The actual size may be smaller, but still a multiple of the instr size. - if (I->isInlineAsm()) - BBI.Unalign = 2; - } -} - -/// Return the current offset of the specified machine instruction from the -/// start of the function. This offset changes as stuff is moved around inside -/// the function. -unsigned AArch64ConstantIslands::getOffsetOf(MachineInstr *MI) const { - MachineBasicBlock *MBB = MI->getParent(); - - // The offset is composed of two things: the sum of the sizes of all MBB's - // before this instruction's block, and the offset from the start of the block - // it is in. - unsigned Offset = BBInfo[MBB->getNumber()].Offset; - - // Sum instructions before MI in MBB. - for (MachineBasicBlock::iterator I = MBB->begin(); &*I != MI; ++I) { - assert(I != MBB->end() && "Didn't find MI in its own basic block?"); - Offset += TII->getInstSizeInBytes(*I); - } - return Offset; -} - -/// Little predicate function to sort the WaterList by MBB ID. -static bool CompareMBBNumbers(const MachineBasicBlock *LHS, - const MachineBasicBlock *RHS) { - return LHS->getNumber() < RHS->getNumber(); -} - -/// When a block is newly inserted into the machine function, it upsets all of -/// the block numbers. Renumber the blocks and update the arrays that parallel -/// this numbering. -void AArch64ConstantIslands:: -updateForInsertedWaterBlock(MachineBasicBlock *NewBB) { - // Renumber the MBB's to keep them consecutive. - NewBB->getParent()->RenumberBlocks(NewBB); - - // Insert an entry into BBInfo to align it properly with the (newly - // renumbered) block numbers. - BBInfo.insert(BBInfo.begin() + NewBB->getNumber(), BasicBlockInfo()); - - // Next, update WaterList. Specifically, we need to add NewMBB as having - // available water after it. - water_iterator IP = - std::lower_bound(WaterList.begin(), WaterList.end(), NewBB, - CompareMBBNumbers); - WaterList.insert(IP, NewBB); -} - - -/// Split the basic block containing MI into two blocks, which are joined by -/// an unconditional branch. Update data structures and renumber blocks to -/// account for this change and returns the newly created block. -MachineBasicBlock * -AArch64ConstantIslands::splitBlockBeforeInstr(MachineInstr *MI) { - MachineBasicBlock *OrigBB = MI->getParent(); - - // Create a new MBB for the code after the OrigBB. - MachineBasicBlock *NewBB = - MF->CreateMachineBasicBlock(OrigBB->getBasicBlock()); - MachineFunction::iterator MBBI = OrigBB; ++MBBI; - MF->insert(MBBI, NewBB); - - // Splice the instructions starting with MI over to NewBB. - NewBB->splice(NewBB->end(), OrigBB, MI, OrigBB->end()); - - // Add an unconditional branch from OrigBB to NewBB. - // Note the new unconditional branch is not being recorded. - // There doesn't seem to be meaningful DebugInfo available; this doesn't - // correspond to anything in the source. - BuildMI(OrigBB, DebugLoc(), TII->get(AArch64::Bimm)).addMBB(NewBB); - ++NumSplit; - - // Update the CFG. All succs of OrigBB are now succs of NewBB. - NewBB->transferSuccessors(OrigBB); - - // OrigBB branches to NewBB. - OrigBB->addSuccessor(NewBB); - - // Update internal data structures to account for the newly inserted MBB. - // This is almost the same as updateForInsertedWaterBlock, except that - // the Water goes after OrigBB, not NewBB. - MF->RenumberBlocks(NewBB); - - // Insert an entry into BBInfo to align it properly with the (newly - // renumbered) block numbers. - BBInfo.insert(BBInfo.begin() + NewBB->getNumber(), BasicBlockInfo()); - - // Next, update WaterList. Specifically, we need to add OrigMBB as having - // available water after it (but not if it's already there, which happens - // when splitting before a conditional branch that is followed by an - // unconditional branch - in that case we want to insert NewBB). - water_iterator IP = - std::lower_bound(WaterList.begin(), WaterList.end(), OrigBB, - CompareMBBNumbers); - MachineBasicBlock* WaterBB = *IP; - if (WaterBB == OrigBB) - WaterList.insert(llvm::next(IP), NewBB); - else - WaterList.insert(IP, OrigBB); - NewWaterList.insert(OrigBB); - - // Figure out how large the OrigBB is. As the first half of the original - // block, it cannot contain a tablejump. The size includes - // the new jump we added. (It should be possible to do this without - // recounting everything, but it's very confusing, and this is rarely - // executed.) - computeBlockSize(OrigBB); - - // Figure out how large the NewMBB is. As the second half of the original - // block, it may contain a tablejump. - computeBlockSize(NewBB); - - // All BBOffsets following these blocks must be modified. - adjustBBOffsetsAfter(OrigBB); - - return NewBB; -} - -/// Compute the offset of U.MI as seen by the hardware displacement computation. -unsigned AArch64ConstantIslands::getUserOffset(CPUser &U) const { - return getOffsetOf(U.MI); -} - -/// Checks whether UserOffset (the location of a constant pool reference) is -/// within OffsetBits of TrialOffset (a proposed location of a constant pool -/// entry). -bool AArch64ConstantIslands::isOffsetInRange(unsigned UserOffset, - unsigned TrialOffset, - unsigned OffsetBits) { - return isIntN(OffsetBits, static_cast<int64_t>(TrialOffset) - UserOffset); -} - -/// Returns true if a CPE placed after the specified Water (a basic block) will -/// be in range for the specific MI. -/// -/// Compute how much the function will grow by inserting a CPE after Water. -bool AArch64ConstantIslands::isWaterInRange(unsigned UserOffset, - MachineBasicBlock* Water, CPUser &U, - unsigned &Growth) { - unsigned CPELogAlign = getCPELogAlign(U.CPEMI); - unsigned CPEOffset = BBInfo[Water->getNumber()].postOffset(CPELogAlign); - unsigned NextBlockOffset, NextBlockAlignment; - MachineFunction::const_iterator NextBlock = Water; - if (++NextBlock == MF->end()) { - NextBlockOffset = BBInfo[Water->getNumber()].postOffset(); - NextBlockAlignment = 0; - } else { - NextBlockOffset = BBInfo[NextBlock->getNumber()].Offset; - NextBlockAlignment = NextBlock->getAlignment(); - } - unsigned Size = U.CPEMI->getOperand(2).getImm(); - unsigned CPEEnd = CPEOffset + Size; - - // The CPE may be able to hide in the alignment padding before the next - // block. It may also cause more padding to be required if it is more aligned - // that the next block. - if (CPEEnd > NextBlockOffset) { - Growth = CPEEnd - NextBlockOffset; - // Compute the padding that would go at the end of the CPE to align the next - // block. - Growth += OffsetToAlignment(CPEEnd, 1u << NextBlockAlignment); - - // If the CPE is to be inserted before the instruction, that will raise - // the offset of the instruction. Also account for unknown alignment padding - // in blocks between CPE and the user. - if (CPEOffset < UserOffset) - UserOffset += Growth + UnknownPadding(MF->getAlignment(), CPELogAlign); - } else - // CPE fits in existing padding. - Growth = 0; - - return isOffsetInRange(UserOffset, CPEOffset, U); -} - -/// Returns true if the distance between specific MI and specific ConstPool -/// entry instruction can fit in MI's displacement field. -bool AArch64ConstantIslands::isCPEntryInRange(MachineInstr *MI, - unsigned UserOffset, - MachineInstr *CPEMI, - unsigned OffsetBits, - bool DoDump) { - unsigned CPEOffset = getOffsetOf(CPEMI); - - if (DoDump) { - DEBUG({ - unsigned Block = MI->getParent()->getNumber(); - const BasicBlockInfo &BBI = BBInfo[Block]; - dbgs() << "User of CPE#" << CPEMI->getOperand(0).getImm() - << " bits available=" << OffsetBits - << format(" insn address=%#x", UserOffset) - << " in BB#" << Block << ": " - << format("%#x-%x\t", BBI.Offset, BBI.postOffset()) << *MI - << format("CPE address=%#x offset=%+d: ", CPEOffset, - int(CPEOffset-UserOffset)); - }); - } - - return isOffsetInRange(UserOffset, CPEOffset, OffsetBits); -} - -#ifndef NDEBUG -/// Return true of the specified basic block's only predecessor unconditionally -/// branches to its only successor. -static bool BBIsJumpedOver(MachineBasicBlock *MBB) { - if (MBB->pred_size() != 1 || MBB->succ_size() != 1) - return false; - - MachineBasicBlock *Succ = *MBB->succ_begin(); - MachineBasicBlock *Pred = *MBB->pred_begin(); - MachineInstr *PredMI = &Pred->back(); - if (PredMI->getOpcode() == AArch64::Bimm) - return PredMI->getOperand(0).getMBB() == Succ; - return false; -} -#endif // NDEBUG - -void AArch64ConstantIslands::adjustBBOffsetsAfter(MachineBasicBlock *BB) { - unsigned BBNum = BB->getNumber(); - for(unsigned i = BBNum + 1, e = MF->getNumBlockIDs(); i < e; ++i) { - // Get the offset and known bits at the end of the layout predecessor. - // Include the alignment of the current block. - unsigned LogAlign = MF->getBlockNumbered(i)->getAlignment(); - unsigned Offset = BBInfo[i - 1].postOffset(LogAlign); - unsigned KnownBits = BBInfo[i - 1].postKnownBits(LogAlign); - - // This is where block i begins. Stop if the offset is already correct, - // and we have updated 2 blocks. This is the maximum number of blocks - // changed before calling this function. - if (i > BBNum + 2 && - BBInfo[i].Offset == Offset && - BBInfo[i].KnownBits == KnownBits) - break; - - BBInfo[i].Offset = Offset; - BBInfo[i].KnownBits = KnownBits; - } -} - -/// Find the constant pool entry with index CPI and instruction CPEMI, and -/// decrement its refcount. If the refcount becomes 0 remove the entry and -/// instruction. Returns true if we removed the entry, false if we didn't. -bool AArch64ConstantIslands::decrementCPEReferenceCount(unsigned CPI, - MachineInstr *CPEMI) { - // Find the old entry. Eliminate it if it is no longer used. - CPEntry *CPE = findConstPoolEntry(CPI, CPEMI); - assert(CPE && "Unexpected!"); - if (--CPE->RefCount == 0) { - removeDeadCPEMI(CPEMI); - CPE->CPEMI = NULL; - --NumCPEs; - return true; - } - return false; -} - -/// See if the currently referenced CPE is in range; if not, see if an in-range -/// clone of the CPE is in range, and if so, change the data structures so the -/// user references the clone. Returns: -/// 0 = no existing entry found -/// 1 = entry found, and there were no code insertions or deletions -/// 2 = entry found, and there were code insertions or deletions -int AArch64ConstantIslands::findInRangeCPEntry(CPUser& U, unsigned UserOffset) -{ - MachineInstr *UserMI = U.MI; - MachineInstr *CPEMI = U.CPEMI; - - // Check to see if the CPE is already in-range. - if (isCPEntryInRange(UserMI, UserOffset, CPEMI, U.getOffsetBits(), true)) { - DEBUG(dbgs() << "In range\n"); - return 1; - } - - // No. Look for previously created clones of the CPE that are in range. - unsigned CPI = CPEMI->getOperand(1).getIndex(); - std::vector<CPEntry> &CPEs = CPEntries[CPI]; - for (unsigned i = 0, e = CPEs.size(); i != e; ++i) { - // We already tried this one - if (CPEs[i].CPEMI == CPEMI) - continue; - // Removing CPEs can leave empty entries, skip - if (CPEs[i].CPEMI == NULL) - continue; - if (isCPEntryInRange(UserMI, User |