X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FLocalStackSlotAllocation.cpp;h=fbc9e20517c2c4c90d7b6382bec24792ae1804d4;hb=a4b5050cf5af18ac18565073fecbfcb95f93556b;hp=962c7c3a15afe8cec58536e00908ca6c48ae25e7;hpb=2d16f5b0cb5ae03c4b4ff6711d543552d97243a0;p=oota-llvm.git diff --git a/lib/CodeGen/LocalStackSlotAllocation.cpp b/lib/CodeGen/LocalStackSlotAllocation.cpp index 962c7c3a15a..fbc9e20517c 100644 --- a/lib/CodeGen/LocalStackSlotAllocation.cpp +++ b/lib/CodeGen/LocalStackSlotAllocation.cpp @@ -9,7 +9,7 @@ // // This pass assigns local frame indices to stack slots relative to one another // and allocates additional base registers to access them when the target -// estimates the are likely to be out of range of stack pointer and frame +// estimates they are likely to be out of range of stack pointer and frame // pointer relative addressing. // //===----------------------------------------------------------------------===// @@ -24,6 +24,7 @@ #include "llvm/Pass.h" #include "llvm/ADT/SmallSet.h" #include "llvm/ADT/Statistic.h" +#include "llvm/ADT/STLExtras.h" #include "llvm/CodeGen/MachineFrameInfo.h" #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineFunctionPass.h" @@ -33,7 +34,7 @@ #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Target/TargetRegisterInfo.h" -#include "llvm/Target/TargetFrameInfo.h" +#include "llvm/Target/TargetFrameLowering.h" using namespace llvm; @@ -42,11 +43,23 @@ STATISTIC(NumBaseRegisters, "Number of virtual frame base registers allocated"); STATISTIC(NumReplacements, "Number of frame indices references replaced"); namespace { + class FrameRef { + MachineBasicBlock::iterator MI; // Instr referencing the frame + int64_t LocalOffset; // Local offset of the frame idx referenced + public: + FrameRef(MachineBasicBlock::iterator I, int64_t Offset) : + MI(I), LocalOffset(Offset) {} + bool operator<(const FrameRef &RHS) const { + return LocalOffset < RHS.LocalOffset; + } + MachineBasicBlock::iterator getMachineInstr() { return MI; } + }; + class LocalStackSlotPass: public MachineFunctionPass { SmallVector LocalOffsets; void AdjustStackOffset(MachineFrameInfo *MFI, int FrameIdx, int64_t &Offset, - unsigned &MaxAlign); + bool StackGrowsDown, unsigned &MaxAlign); void calculateFrameObjectOffsets(MachineFunction &Fn); bool insertFrameReferenceRegisters(MachineFunction &Fn); public: @@ -58,26 +71,24 @@ namespace { AU.setPreservesCFG(); MachineFunctionPass::getAnalysisUsage(AU); } - const char *getPassName() const { - return "Local Stack Slot Allocation"; - } private: }; } // end anonymous namespace char LocalStackSlotPass::ID = 0; - -FunctionPass *llvm::createLocalStackSlotAllocationPass() { - return new LocalStackSlotPass(); -} +char &llvm::LocalStackSlotAllocationID = LocalStackSlotPass::ID; +INITIALIZE_PASS(LocalStackSlotPass, "localstackalloc", + "Local Stack Slot Allocation", false, false) bool LocalStackSlotPass::runOnMachineFunction(MachineFunction &MF) { MachineFrameInfo *MFI = MF.getFrameInfo(); + const TargetRegisterInfo *TRI = MF.getTarget().getRegisterInfo(); unsigned LocalObjectCount = MFI->getObjectIndexEnd(); - // Early exit if there are no locals to consider - if (!LocalObjectCount) + // If the target doesn't want/need this pass, or if there are no locals + // to consider, early exit. + if (!TRI->requiresVirtualBaseRegisters(MF) || LocalObjectCount == 0) return true; // Make sure we have enough space to store the local offsets. @@ -102,7 +113,12 @@ bool LocalStackSlotPass::runOnMachineFunction(MachineFunction &MF) { /// AdjustStackOffset - Helper function used to adjust the stack frame offset. void LocalStackSlotPass::AdjustStackOffset(MachineFrameInfo *MFI, int FrameIdx, int64_t &Offset, + bool StackGrowsDown, unsigned &MaxAlign) { + // 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 @@ -112,13 +128,16 @@ void LocalStackSlotPass::AdjustStackOffset(MachineFrameInfo *MFI, // Adjust to alignment boundary. Offset = (Offset + Align - 1) / Align * Align; + int64_t LocalOffset = StackGrowsDown ? -Offset : Offset; DEBUG(dbgs() << "Allocate FI(" << FrameIdx << ") to local offset " - << Offset << "\n"); + << LocalOffset << "\n"); // Keep the offset available for base register allocation - LocalOffsets[FrameIdx] = Offset; + LocalOffsets[FrameIdx] = LocalOffset; // And tell MFI about it for PEI to use later - MFI->mapLocalFrameObject(FrameIdx, Offset); - Offset += MFI->getObjectSize(FrameIdx); + MFI->mapLocalFrameObject(FrameIdx, LocalOffset); + + if (!StackGrowsDown) + Offset += MFI->getObjectSize(FrameIdx); ++NumAllocations; } @@ -129,6 +148,9 @@ void LocalStackSlotPass::AdjustStackOffset(MachineFrameInfo *MFI, void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) { // Loop over all of the stack objects, assigning sequential addresses... MachineFrameInfo *MFI = Fn.getFrameInfo(); + const TargetFrameLowering &TFI = *Fn.getTarget().getFrameLowering(); + bool StackGrowsDown = + TFI.getStackGrowthDirection() == TargetFrameLowering::StackGrowsDown; int64_t Offset = 0; unsigned MaxAlign = 0; @@ -136,7 +158,8 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) { // stack. SmallSet LargeStackObjs; if (MFI->getStackProtectorIndex() >= 0) { - AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), Offset, MaxAlign); + AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), Offset, + StackGrowsDown, MaxAlign); // Assign large stack objects first. for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) { @@ -147,7 +170,7 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) { if (!MFI->MayNeedStackProtector(i)) continue; - AdjustStackOffset(MFI, i, Offset, MaxAlign); + AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign); LargeStackObjs.insert(i); } } @@ -162,7 +185,7 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) { if (LargeStackObjs.count(i)) continue; - AdjustStackOffset(MFI, i, Offset, MaxAlign); + AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign); } // Remember how big this blob of stack space is @@ -173,6 +196,7 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) { static inline bool lookupCandidateBaseReg(const SmallVector, 8> &Regs, std::pair &RegOffset, + int64_t FrameSizeAdjust, int64_t LocalFrameOffset, const MachineInstr *MI, const TargetRegisterInfo *TRI) { @@ -181,7 +205,7 @@ lookupCandidateBaseReg(const SmallVector, 8> &Regs, RegOffset = Regs[i]; // Check if the relative offset from the where the base register references // to the target address is in range for the instruction. - int64_t Offset = LocalFrameOffset - RegOffset.second; + int64_t Offset = FrameSizeAdjust + LocalFrameOffset - RegOffset.second; if (TRI->isFrameOffsetLegal(MI, Offset)) return true; } @@ -199,19 +223,25 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) { MachineFrameInfo *MFI = Fn.getFrameInfo(); const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo(); + const TargetFrameLowering &TFI = *Fn.getTarget().getFrameLowering(); + bool StackGrowsDown = + TFI.getStackGrowthDirection() == TargetFrameLowering::StackGrowsDown; - for (MachineFunction::iterator BB = Fn.begin(), - E = Fn.end(); BB != E; ++BB) { - // A base register definition is a register+offset pair. - SmallVector, 8> BaseRegisters; + // Collect all of the instructions in the block that reference + // a frame index. Also store the frame index referenced to ease later + // lookup. (For any insn that has more than one FI reference, we arbitrarily + // choose the first one). + SmallVector FrameReferenceInsns; + // A base register definition is a register + offset pair. + SmallVector, 8> BaseRegisters; + + for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) { for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) { MachineInstr *MI = I; + // Debug value instructions can't be out of range, so they don't need // any updates. - // FIXME: When we extend this stuff to handle functions with both - // VLAs and dynamic realignment, we should update the debug values - // to reference the new base pointer when possible. if (MI->isDebugValue()) continue; @@ -225,67 +255,99 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) { // Consider replacing all frame index operands that reference // an object allocated in the local block. if (MI->getOperand(i).isFI()) { - int FrameIdx = MI->getOperand(i).getIndex(); - // Don't try this with values not in the local block. - if (!MFI->isObjectPreAllocated(FrameIdx)) - continue; - - DEBUG(dbgs() << "Considering: " << *MI); - if (TRI->needsFrameBaseReg(MI, i)) { - unsigned BaseReg = 0; - int64_t Offset = 0; - - DEBUG(dbgs() << " Replacing FI in: " << *MI); - - // If we have a suitable base register available, use it; otherwise - // create a new one. Note that any offset encoded in the - // instruction itself will be taken into account by the target, - // so we don't have to adjust for it here when reusing a base - // register. - std::pair RegOffset; - if (lookupCandidateBaseReg(BaseRegisters, RegOffset, - LocalOffsets[FrameIdx], MI, TRI)) { - DEBUG(dbgs() << " Reusing base register " << - RegOffset.first << "\n"); - // We found a register to reuse. - BaseReg = RegOffset.first; - Offset = LocalOffsets[FrameIdx] - RegOffset.second; - } else { - // No previously defined register was in range, so create a - // new one. - int64_t InstrOffset = TRI->getFrameIndexInstrOffset(MI, i); - const TargetRegisterClass *RC = TRI->getPointerRegClass(); - BaseReg = Fn.getRegInfo().createVirtualRegister(RC); - - DEBUG(dbgs() << " Materializing base register " << BaseReg << - " at frame local offset " << - LocalOffsets[FrameIdx] + InstrOffset << "\n"); - // Tell the target to insert the instruction to initialize - // the base register. - TRI->materializeFrameBaseRegister(I, BaseReg, FrameIdx, - InstrOffset); - - // The base register already includes any offset specified - // by the instruction, so account for that so it doesn't get - // applied twice. - Offset = -InstrOffset; - - BaseRegisters.push_back( - std::pair(BaseReg, - LocalOffsets[FrameIdx] + InstrOffset)); - ++NumBaseRegisters; - UsedBaseReg = true; - } - assert(BaseReg != 0 && "Unable to allocate virtual base register!"); - - // Modify the instruction to use the new base register rather - // than the frame index operand. - TRI->resolveFrameIndex(I, BaseReg, Offset); - - ++NumReplacements; + if (!MFI->isObjectPreAllocated(MI->getOperand(i).getIndex())) + break; + FrameReferenceInsns. + push_back(FrameRef(MI, LocalOffsets[MI->getOperand(i).getIndex()])); + break; + } + } + } + } + + // Sort the frame references by local offset + array_pod_sort(FrameReferenceInsns.begin(), FrameReferenceInsns.end()); + + MachineBasicBlock *Entry = Fn.begin(); + + // Loop through the frame references and allocate for them as necessary. + for (int ref = 0, e = FrameReferenceInsns.size(); ref < e ; ++ref) { + MachineBasicBlock::iterator I = + FrameReferenceInsns[ref].getMachineInstr(); + MachineInstr *MI = I; + for (unsigned idx = 0, e = MI->getNumOperands(); idx != e; ++idx) { + // Consider replacing all frame index operands that reference + // an object allocated in the local block. + if (MI->getOperand(idx).isFI()) { + int FrameIdx = MI->getOperand(idx).getIndex(); + + assert(MFI->isObjectPreAllocated(FrameIdx) && + "Only pre-allocated locals expected!"); + + DEBUG(dbgs() << "Considering: " << *MI); + if (TRI->needsFrameBaseReg(MI, LocalOffsets[FrameIdx])) { + unsigned BaseReg = 0; + int64_t Offset = 0; + int64_t FrameSizeAdjust = + StackGrowsDown ? MFI->getLocalFrameSize() : 0; + + DEBUG(dbgs() << " Replacing FI in: " << *MI); + + // If we have a suitable base register available, use it; otherwise + // create a new one. Note that any offset encoded in the + // instruction itself will be taken into account by the target, + // so we don't have to adjust for it here when reusing a base + // register. + std::pair RegOffset; + if (lookupCandidateBaseReg(BaseRegisters, RegOffset, + FrameSizeAdjust, + LocalOffsets[FrameIdx], + MI, TRI)) { + DEBUG(dbgs() << " Reusing base register " << + RegOffset.first << "\n"); + // We found a register to reuse. + BaseReg = RegOffset.first; + Offset = FrameSizeAdjust + LocalOffsets[FrameIdx] - + RegOffset.second; + } else { + // No previously defined register was in range, so create a + // new one. + int64_t InstrOffset = TRI->getFrameIndexInstrOffset(MI, idx); + const MachineFunction *MF = MI->getParent()->getParent(); + const TargetRegisterClass *RC = TRI->getPointerRegClass(*MF); + BaseReg = Fn.getRegInfo().createVirtualRegister(RC); + + DEBUG(dbgs() << " Materializing base register " << BaseReg << + " at frame local offset " << + LocalOffsets[FrameIdx] + InstrOffset << "\n"); + + // Tell the target to insert the instruction to initialize + // the base register. + // MachineBasicBlock::iterator InsertionPt = Entry->begin(); + TRI->materializeFrameBaseRegister(Entry, BaseReg, FrameIdx, + InstrOffset); + + // The base register already includes any offset specified + // by the instruction, so account for that so it doesn't get + // applied twice. + Offset = -InstrOffset; + + int64_t BaseOffset = FrameSizeAdjust + LocalOffsets[FrameIdx] + + InstrOffset; + BaseRegisters.push_back( + std::pair(BaseReg, BaseOffset)); + ++NumBaseRegisters; + UsedBaseReg = true; } + assert(BaseReg != 0 && "Unable to allocate virtual base register!"); + + // Modify the instruction to use the new base register rather + // than the frame index operand. + TRI->resolveFrameIndex(I, BaseReg, Offset); + DEBUG(dbgs() << "Resolved: " << *MI); + ++NumReplacements; } } }