//
// 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.
//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "localstackalloc"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Instructions.h"
-#include "llvm/Intrinsics.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Module.h"
-#include "llvm/Pass.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/StackProtector.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetFrameLowering.h"
#include "llvm/Target/TargetRegisterInfo.h"
-#include "llvm/Target/TargetFrameInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
using namespace llvm;
+#define DEBUG_TYPE "localstackalloc"
+
STATISTIC(NumAllocations, "Number of frame indices allocated into local block");
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
+ int FrameIdx; // The frame index
+ public:
+ FrameRef(MachineBasicBlock::iterator I, int64_t Offset, int Idx) :
+ MI(I), LocalOffset(Offset), FrameIdx(Idx) {}
+ bool operator<(const FrameRef &RHS) const {
+ return LocalOffset < RHS.LocalOffset;
+ }
+ MachineBasicBlock::iterator getMachineInstr() const { return MI; }
+ int64_t getLocalOffset() const { return LocalOffset; }
+ int getFrameIndex() const { return FrameIdx; }
+ };
+
class LocalStackSlotPass: public MachineFunctionPass {
SmallVector<int64_t,16> LocalOffsets;
+ /// StackObjSet - A set of stack object indexes
+ typedef SmallSetVector<int, 8> StackObjSet;
void AdjustStackOffset(MachineFrameInfo *MFI, int FrameIdx, int64_t &Offset,
bool StackGrowsDown, unsigned &MaxAlign);
+ void AssignProtectedObjSet(const StackObjSet &UnassignedObjs,
+ SmallSet<int, 16> &ProtectedObjs,
+ MachineFrameInfo *MFI, bool StackGrowsDown,
+ int64_t &Offset, unsigned &MaxAlign);
void calculateFrameObjectOffsets(MachineFunction &Fn);
bool insertFrameReferenceRegisters(MachineFunction &Fn);
public:
static char ID; // Pass identification, replacement for typeid
- explicit LocalStackSlotPass() : MachineFunctionPass(ID) { }
- bool runOnMachineFunction(MachineFunction &MF);
+ explicit LocalStackSlotPass() : MachineFunctionPass(ID) {
+ initializeLocalStackSlotPassPass(*PassRegistry::getPassRegistry());
+ }
+ bool runOnMachineFunction(MachineFunction &MF) override;
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
+ AU.addRequired<StackProtector>();
MachineFunctionPass::getAnalysisUsage(AU);
}
- const char *getPassName() const {
- return "Local Stack Slot Allocation";
- }
private:
};
} // end anonymous namespace
char LocalStackSlotPass::ID = 0;
+char &llvm::LocalStackSlotAllocationID = LocalStackSlotPass::ID;
+INITIALIZE_PASS_BEGIN(LocalStackSlotPass, "localstackalloc",
+ "Local Stack Slot Allocation", false, false)
+INITIALIZE_PASS_DEPENDENCY(StackProtector)
+INITIALIZE_PASS_END(LocalStackSlotPass, "localstackalloc",
+ "Local Stack Slot Allocation", false, false)
-FunctionPass *llvm::createLocalStackSlotAllocationPass() {
- return new LocalStackSlotPass();
-}
bool LocalStackSlotPass::runOnMachineFunction(MachineFunction &MF) {
MachineFrameInfo *MFI = MF.getFrameInfo();
+ const TargetRegisterInfo *TRI = MF.getSubtarget().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.
++NumAllocations;
}
+/// AssignProtectedObjSet - Helper function to assign large stack objects (i.e.,
+/// those required to be close to the Stack Protector) to stack offsets.
+void LocalStackSlotPass::AssignProtectedObjSet(const StackObjSet &UnassignedObjs,
+ SmallSet<int, 16> &ProtectedObjs,
+ MachineFrameInfo *MFI,
+ bool StackGrowsDown, int64_t &Offset,
+ unsigned &MaxAlign) {
+
+ for (StackObjSet::const_iterator I = UnassignedObjs.begin(),
+ E = UnassignedObjs.end(); I != E; ++I) {
+ int i = *I;
+ AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign);
+ ProtectedObjs.insert(i);
+ }
+}
+
/// calculateFrameObjectOffsets - Calculate actual frame offsets for all of the
/// abstract stack objects.
///
void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
// Loop over all of the stack objects, assigning sequential addresses...
MachineFrameInfo *MFI = Fn.getFrameInfo();
- const TargetFrameInfo &TFI = *Fn.getTarget().getFrameInfo();
+ const TargetFrameLowering &TFI = *Fn.getSubtarget().getFrameLowering();
bool StackGrowsDown =
- TFI.getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
+ TFI.getStackGrowthDirection() == TargetFrameLowering::StackGrowsDown;
int64_t Offset = 0;
unsigned MaxAlign = 0;
+ StackProtector *SP = &getAnalysis<StackProtector>();
// Make sure that the stack protector comes before the local variables on the
// stack.
- SmallSet<int, 16> LargeStackObjs;
+ SmallSet<int, 16> ProtectedObjs;
if (MFI->getStackProtectorIndex() >= 0) {
+ StackObjSet LargeArrayObjs;
+ StackObjSet SmallArrayObjs;
+ StackObjSet AddrOfObjs;
+
AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), Offset,
StackGrowsDown, MaxAlign);
continue;
if (MFI->getStackProtectorIndex() == (int)i)
continue;
- if (!MFI->MayNeedStackProtector(i))
- continue;
- AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign);
- LargeStackObjs.insert(i);
+ 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);
+ AssignProtectedObjSet(SmallArrayObjs, ProtectedObjs, MFI, StackGrowsDown,
+ Offset, MaxAlign);
+ AssignProtectedObjSet(AddrOfObjs, ProtectedObjs, MFI, StackGrowsDown,
+ Offset, MaxAlign);
}
// Then assign frame offsets to stack objects that are not used to spill
continue;
if (MFI->getStackProtectorIndex() == (int)i)
continue;
- if (LargeStackObjs.count(i))
+ if (ProtectedObjs.count(i))
continue;
AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign);
}
static inline bool
-lookupCandidateBaseReg(const SmallVector<std::pair<unsigned, int64_t>, 8> &Regs,
- std::pair<unsigned, int64_t> &RegOffset,
+lookupCandidateBaseReg(unsigned BaseReg,
+ int64_t BaseOffset,
int64_t FrameSizeAdjust,
int64_t LocalFrameOffset,
const MachineInstr *MI,
const TargetRegisterInfo *TRI) {
- unsigned e = Regs.size();
- for (unsigned i = 0; i < e; ++i) {
- 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 = FrameSizeAdjust + LocalFrameOffset - RegOffset.second;
- if (TRI->isFrameOffsetLegal(MI, Offset))
- return true;
- }
- return false;
+ // 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 = FrameSizeAdjust + LocalFrameOffset - BaseOffset;
+ return TRI->isFrameOffsetLegal(MI, BaseReg, Offset);
}
bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
bool UsedBaseReg = false;
MachineFrameInfo *MFI = Fn.getFrameInfo();
- const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
- const TargetFrameInfo &TFI = *Fn.getTarget().getFrameInfo();
+ const TargetRegisterInfo *TRI = Fn.getSubtarget().getRegisterInfo();
+ const TargetFrameLowering &TFI = *Fn.getSubtarget().getFrameLowering();
bool StackGrowsDown =
- TFI.getStackGrowthDirection() == TargetFrameInfo::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<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;
+ 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())
+
+ // Debug value, stackmap and patchpoint instructions can't be out of
+ // range, so they don't need any updates.
+ if (MI->isDebugValue() ||
+ MI->getOpcode() == TargetOpcode::STATEPOINT ||
+ MI->getOpcode() == TargetOpcode::STACKMAP ||
+ MI->getOpcode() == TargetOpcode::PATCHPOINT)
continue;
// For now, allocate the base register(s) within the basic block
// 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;
- 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;
+ int Idx = MI->getOperand(i).getIndex();
+ int64_t LocalOffset = LocalOffsets[Idx];
+ if (!TRI->needsFrameBaseReg(MI, LocalOffset))
+ break;
+ FrameReferenceInsns.
+ push_back(FrameRef(MI, LocalOffset, Idx));
+ break;
}
}
}
}
+
+ // Sort the frame references by local offset
+ array_pod_sort(FrameReferenceInsns.begin(), FrameReferenceInsns.end());
+
+ MachineBasicBlock *Entry = Fn.begin();
+
+ unsigned BaseReg = 0;
+ int64_t BaseOffset = 0;
+
+ // Loop through the frame references and allocate for them as necessary.
+ for (int ref = 0, e = FrameReferenceInsns.size(); ref < e ; ++ref) {
+ FrameRef &FR = FrameReferenceInsns[ref];
+ MachineBasicBlock::iterator I = FR.getMachineInstr();
+ MachineInstr *MI = I;
+ int64_t LocalOffset = FR.getLocalOffset();
+ int FrameIdx = FR.getFrameIndex();
+ assert(MFI->isObjectPreAllocated(FrameIdx) &&
+ "Only pre-allocated locals expected!");
+
+ DEBUG(dbgs() << "Considering: " << *MI);
+
+ unsigned idx = 0;
+ for (unsigned f = MI->getNumOperands(); idx != f; ++idx) {
+ if (!MI->getOperand(idx).isFI())
+ continue;
+
+ if (FrameIdx == I->getOperand(idx).getIndex())
+ break;
+ }
+
+ assert(idx < MI->getNumOperands() && "Cannot find FI operand");
+
+ 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.
+ if (UsedBaseReg && lookupCandidateBaseReg(BaseReg, BaseOffset,
+ FrameSizeAdjust, LocalOffset, MI,
+ TRI)) {
+ DEBUG(dbgs() << " Reusing base register " << BaseReg << "\n");
+ // We found a register to reuse.
+ Offset = FrameSizeAdjust + LocalOffset - BaseOffset;
+ } else {
+ // No previously defined register was in range, so create a // new one.
+
+ int64_t InstrOffset = TRI->getFrameIndexInstrOffset(MI, idx);
+
+ int64_t PrevBaseOffset = BaseOffset;
+ BaseOffset = FrameSizeAdjust + LocalOffset + InstrOffset;
+
+ // We'd like to avoid creating single-use virtual base registers.
+ // Because the FrameRefs are in sorted order, and we've already
+ // processed all FrameRefs before this one, just check whether or not
+ // the next FrameRef will be able to reuse this new register. If not,
+ // then don't bother creating it.
+ if (ref + 1 >= e ||
+ !lookupCandidateBaseReg(
+ BaseReg, BaseOffset, FrameSizeAdjust,
+ FrameReferenceInsns[ref + 1].getLocalOffset(),
+ FrameReferenceInsns[ref + 1].getMachineInstr(), TRI)) {
+ BaseOffset = PrevBaseOffset;
+ continue;
+ }
+
+ 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 " << LocalOffset + 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;
+
+ ++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;
+ }
+
return UsedBaseReg;
}
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