//
//===----------------------------------------------------------------------===//
-#include "PrologEpilogInserter.h"
#include "llvm/ADT/IndexedMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetVector.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"
#define DEBUG_TYPE "pei"
+namespace {
+class PEI : public MachineFunctionPass {
+public:
+ static char ID;
+ PEI() : MachineFunctionPass(ID) {
+ initializePEIPass(*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 PEI::ID = 0;
char &llvm::PrologEpilogCodeInserterID = PEI::ID;
MachineFunctionPass::getAnalysisUsage(AU);
}
-bool PEI::isReturnBlock(MachineBasicBlock* MBB) {
- return (MBB && !MBB->empty() && MBB->back().isReturn());
-}
-
/// Compute the set of return blocks
void PEI::calculateSets(MachineFunction &Fn) {
- // Sets used to compute spill, restore placement sets.
- const std::vector<CalleeSavedInfo> &CSI =
- Fn.getFrameInfo()->getCalleeSavedInfo();
-
- // If no CSRs used, we are done.
- if (CSI.empty())
+ 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.
- EntryBlock = Fn.begin();
- for (MachineFunction::iterator MBB = Fn.begin(), E = Fn.end();
- MBB != E; ++MBB)
- if (isReturnBlock(MBB))
- ReturnBlocks.push_back(MBB);
-
- return;
+ 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
// instructions.
calculateCallsInformation(Fn);
- // Allow the target machine to make some adjustments to the function
- // e.g. UsedPhysRegs before calculateCalleeSavedRegisters.
- TFI->processFunctionBeforeCalleeSavedScan(Fn, RS);
+ // Determine which of the registers in the callee save list should be saved.
+ BitVector SavedRegs;
+ TFI->determineCalleeSaves(Fn, SavedRegs, RS);
- // Scan the function for modified callee saved registers and insert spill code
- // for any callee saved registers that are modified.
- calculateCalleeSavedRegisters(Fn);
+ // 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
+ // Add the code to save and restore the callee saved registers.
if (!F->hasFnAttribute(Attribute::Naked))
insertCSRSpillsAndRestores(Fn);
}
delete RS;
- ReturnBlocks.clear();
+ SaveBlocks.clear();
+ RestoreBlocks.clear();
return true;
}
bool AdjustsStack = MFI->adjustsStack();
// Get the function call frame set-up and tear-down instruction opcode
- int FrameSetupOpcode = TII.getCallFrameSetupOpcode();
- int FrameDestroyOpcode = TII.getCallFrameDestroyOpcode();
+ unsigned FrameSetupOpcode = TII.getCallFrameSetupOpcode();
+ unsigned FrameDestroyOpcode = TII.getCallFrameDestroyOpcode();
// Early exit for targets which have no call frame setup/destroy pseudo
// instructions.
- if (FrameSetupOpcode == -1 && FrameDestroyOpcode == -1)
+ if (FrameSetupOpcode == ~0u && FrameDestroyOpcode == ~0u)
return;
std::vector<MachineBasicBlock::iterator> FrameSDOps;
}
}
-
-/// calculateCalleeSavedRegisters - Scan the function for modified callee saved
-/// registers.
-void PEI::calculateCalleeSavedRegisters(MachineFunction &F) {
- const TargetRegisterInfo *RegInfo = F.getSubtarget().getRegisterInfo();
- const TargetFrameLowering *TFI = F.getSubtarget().getFrameLowering();
- MachineFrameInfo *MFI = F.getFrameInfo();
-
- // Get the callee saved register list...
- const MCPhysReg *CSRegs = RegInfo->getCalleeSavedRegs(&F);
-
+void PEI::assignCalleeSavedSpillSlots(MachineFunction &F,
+ const BitVector &SavedRegs) {
// These are used to keep track the callee-save area. Initialize them.
MinCSFrameIndex = INT_MAX;
MaxCSFrameIndex = 0;
- // Early exit for targets which have no callee saved registers.
- if (!CSRegs || CSRegs[0] == 0)
+ if (SavedRegs.empty())
return;
- // In Naked functions we aren't going to save any registers.
- if (F.getFunction()->hasFnAttribute(Attribute::Naked))
- 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];
- // Functions which call __builtin_unwind_init get all their registers saved.
- if (F.getRegInfo().isPhysRegUsed(Reg) || F.getMMI().callsUnwindInit()) {
- // If the reg is modified, save it!
+ 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.
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.
///
MachineBasicBlock::iterator I;
// Spill using target interface.
- I = EntryBlock->begin();
- if (!TFI->spillCalleeSavedRegisters(*EntryBlock, I, CSI, TRI)) {
- for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
- // Add the callee-saved register as live-in.
- // It's killed at the spill.
- EntryBlock->addLiveIn(CSI[i].getReg());
-
- // Insert the spill to the stack frame.
- unsigned Reg = CSI[i].getReg();
- const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
- TII.storeRegToStackSlot(*EntryBlock, I, Reg, true, CSI[i].getFrameIdx(),
- RC, TRI);
+ 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 (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri) {
- MachineBasicBlock *MBB = ReturnBlocks[ri];
+ for (MachineBasicBlock *MBB : RestoreBlocks) {
I = MBB->end();
- --I;
// Skip over all terminator instructions, which are part of the return
// sequence.
static inline void
AdjustStackOffset(MachineFrameInfo *MFI, int FrameIdx,
bool StackGrowsDown, int64_t &Offset,
- unsigned &MaxAlign) {
+ unsigned &MaxAlign, unsigned Skew) {
// If the stack grows down, add the object size to find the lowest address.
if (StackGrowsDown)
Offset += MFI->getObjectSize(FrameIdx);
MaxAlign = std::max(MaxAlign, Align);
// Adjust to alignment boundary.
- Offset = (Offset + Align - 1) / Align * Align;
+ Offset = RoundUpToAlignment(Offset, Align, Skew);
if (StackGrowsDown) {
DEBUG(dbgs() << "alloc FI(" << FrameIdx << ") at SP[" << -Offset << "]\n");
AssignProtectedObjSet(const StackObjSet &UnassignedObjs,
SmallSet<int, 16> &ProtectedObjs,
MachineFrameInfo *MFI, bool StackGrowsDown,
- int64_t &Offset, unsigned &MaxAlign) {
+ 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);
+ AdjustStackOffset(MFI, i, StackGrowsDown, Offset, MaxAlign, Skew);
ProtectedObjs.insert(i);
}
}
&& "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
unsigned Align = MFI->getObjectAlignment(i);
// Adjust to alignment boundary
- Offset = (Offset+Align-1)/Align*Align;
+ Offset = RoundUpToAlignment(Offset, Align, Skew);
MFI->setObjectOffset(i, -Offset); // Set the computed offset
}
for (int i = MaxCSFI; i >= MinCSFI ; --i) {
unsigned Align = MFI->getObjectAlignment(i);
// Adjust to alignment boundary
- Offset = (Offset+Align-1)/Align*Align;
+ Offset = RoundUpToAlignment(Offset, Align, Skew);
MFI->setObjectOffset(i, Offset);
Offset += MFI->getObjectSize(i);
RS->getScavengingFrameIndices(SFIs);
for (SmallVectorImpl<int>::iterator I = SFIs.begin(),
IE = SFIs.end(); I != IE; ++I)
- AdjustStackOffset(MFI, *I, StackGrowsDown, Offset, MaxAlign);
+ AdjustStackOffset(MFI, *I, StackGrowsDown, Offset, MaxAlign, Skew);
}
// FIXME: Once this is working, then enable flag will change to a target
unsigned Align = MFI->getLocalFrameMaxAlign();
// Adjust to alignment boundary.
- Offset = (Offset + Align - 1) / Align * Align;
+ Offset = RoundUpToAlignment(Offset, Align, Skew);
DEBUG(dbgs() << "Local frame base offset: " << Offset << "\n");
StackObjSet AddrOfObjs;
AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), StackGrowsDown,
- Offset, MaxAlign);
+ Offset, MaxAlign, Skew);
// Assign large stack objects first.
for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
}
AssignProtectedObjSet(LargeArrayObjs, ProtectedObjs, MFI, StackGrowsDown,
- Offset, MaxAlign);
+ Offset, MaxAlign, Skew);
AssignProtectedObjSet(SmallArrayObjs, ProtectedObjs, MFI, StackGrowsDown,
- Offset, MaxAlign);
+ Offset, MaxAlign, Skew);
AssignProtectedObjSet(AddrOfObjs, ProtectedObjs, MFI, StackGrowsDown,
- Offset, MaxAlign);
+ Offset, MaxAlign, Skew);
}
// Then assign frame offsets to stack objects that are not used to spill
if (ProtectedObjs.count(i))
continue;
- AdjustStackOffset(MFI, i, StackGrowsDown, Offset, MaxAlign);
+ AdjustStackOffset(MFI, i, StackGrowsDown, Offset, MaxAlign, Skew);
}
// Make sure the special register scavenging spill slot is closest to the
RS->getScavengingFrameIndices(SFIs);
for (SmallVectorImpl<int>::iterator I = SFIs.begin(),
IE = SFIs.end(); I != IE; ++I)
- AdjustStackOffset(MFI, *I, StackGrowsDown, Offset, MaxAlign);
+ AdjustStackOffset(MFI, *I, StackGrowsDown, Offset, MaxAlign, Skew);
}
if (!TFI.targetHandlesStackFrameRounding()) {
// 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);
- unsigned AlignMask = StackAlign - 1;
- Offset = (Offset + AlignMask) & ~uint64_t(AlignMask);
+ Offset = RoundUpToAlignment(Offset, StackAlign, Skew);
}
// Update frame info to pretend that this is part of the stack...
const TargetFrameLowering &TFI = *Fn.getSubtarget().getFrameLowering();
// Add prologue to the function...
- TFI.emitPrologue(Fn);
+ for (MachineBasicBlock *SaveBlock : SaveBlocks)
+ TFI.emitPrologue(Fn, *SaveBlock);
- // Add epilogue to restore the callee-save registers in each exiting block
- for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
- // If last instruction is a return instruction, add an epilogue
- if (!I->empty() && I->back().isReturn())
- TFI.emitEpilogue(Fn, *I);
- }
+ // 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())
- TFI.adjustForSegmentedStacks(Fn);
+ 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
// different conditional check and another BIF for allocating more stack
// space.
if (Fn.getFunction()->getCallingConv() == CallingConv::HiPE)
- TFI.adjustForHiPEPrologue(Fn);
+ for (MachineBasicBlock *SaveBlock : SaveBlocks)
+ TFI.adjustForHiPEPrologue(Fn, *SaveBlock);
}
/// replaceFrameIndices - Replace all MO_FrameIndex operands with physical
}
// Handle the unreachable blocks.
- for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
- if (Reachable.count(BB))
+ for (auto &BB : Fn) {
+ if (Reachable.count(&BB))
// Already handled in DFS traversal.
continue;
int SPAdj = 0;
- replaceFrameIndices(BB, Fn, SPAdj);
+ replaceFrameIndices(&BB, Fn, SPAdj);
}
}
const TargetInstrInfo &TII = *Fn.getSubtarget().getInstrInfo();
const TargetRegisterInfo &TRI = *Fn.getSubtarget().getRegisterInfo();
const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering();
- int FrameSetupOpcode = TII.getCallFrameSetupOpcode();
- int FrameDestroyOpcode = TII.getCallFrameDestroyOpcode();
+ unsigned FrameSetupOpcode = TII.getCallFrameSetupOpcode();
+ unsigned FrameDestroyOpcode = TII.getCallFrameDestroyOpcode();
if (RS && !FrameIndexVirtualScavenging) RS->enterBasicBlock(BB);
if (!MI->getOperand(i).isFI())
continue;
- // Frame indicies in debug values are encoded in a target independent
+ // 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 indicies can only appear as the first "
+ 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);
continue;
}
- // Frame allocations are target independent. Simply swap the index with
- // the offset.
- if (MI->getOpcode() == TargetOpcode::FRAME_ALLOC) {
- assert(TFI->hasFP(Fn) && "frame alloc requires FP");
- MachineOperand &FI = MI->getOperand(i);
- unsigned Reg;
- int FrameOffset = TFI->getFrameIndexReference(Fn, FI.getIndex(), Reg);
- FI.ChangeToImmediate(FrameOffset);
- 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
// Run through the instructions and find any virtual registers.
for (MachineFunction::iterator BB = Fn.begin(),
E = Fn.end(); BB != E; ++BB) {
- RS->enterBasicBlock(BB);
+ RS->enterBasicBlock(&*BB);
int SPAdj = 0;
// Replace this reference to the virtual register with the
// scratch register.
assert (ScratchReg && "Missing scratch register!");
- MachineRegisterInfo &MRI = Fn.getRegInfo();
Fn.getRegInfo().replaceRegWith(Reg, ScratchReg);
- // Make sure MRI now accounts this register as used.
- MRI.setPhysRegUsed(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.
// 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);
+ 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
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