diff options
Diffstat (limited to 'lib/CodeGen/LocalStackSlotAllocation.cpp')
| -rw-r--r-- | lib/CodeGen/LocalStackSlotAllocation.cpp | 182 |
1 files changed, 109 insertions, 73 deletions
diff --git a/lib/CodeGen/LocalStackSlotAllocation.cpp b/lib/CodeGen/LocalStackSlotAllocation.cpp index 8bb802fa16..7e366f0cee 100644 --- a/lib/CodeGen/LocalStackSlotAllocation.cpp +++ b/lib/CodeGen/LocalStackSlotAllocation.cpp @@ -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" @@ -42,6 +43,18 @@ 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<int64_t,16> LocalOffsets; @@ -217,22 +230,24 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) { const TargetFrameInfo &TFI = *Fn.getTarget().getFrameInfo(); bool StackGrowsDown = TFI.getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown; + MachineBasicBlock::iterator InsertionPt = Fn.begin()->begin(); - for (MachineFunction::iterator BB = Fn.begin(), - E = Fn.end(); BB != E; ++BB) { - // A base register definition is a register+offset pair. - SmallVector<std::pair<unsigned, int64_t>, 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<FrameRef, 64> FrameReferenceInsns; + // A base register definition is a register+offset pair. + SmallVector<std::pair<unsigned, int64_t>, 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; - // For now, allocate the base register(s) within the basic block // where they're used, and don't try to keep them around outside // of that. It may be beneficial to try sharing them more broadly @@ -243,73 +258,94 @@ 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, 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<unsigned, int64_t> 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, 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; - - int64_t BaseOffset = FrameSizeAdjust + LocalOffsets[FrameIdx] + - InstrOffset; - BaseRegisters.push_back( - std::pair<unsigned, int64_t>(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; + 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()); + + + // Loop throught 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<unsigned, int64_t> 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 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(InsertionPt, 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<unsigned, int64_t>(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; } } } |