#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/MRegisterInfo.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Support/Visibility.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/STLExtras.h"
+#include <climits>
using namespace llvm;
namespace {
struct VISIBILITY_HIDDEN PEI : public MachineFunctionPass {
+ static char ID;
+ PEI() : MachineFunctionPass((intptr_t)&ID) {}
+
const char *getPassName() const {
return "Prolog/Epilog Insertion & Frame Finalization";
}
/// frame indexes with appropriate references.
///
bool runOnMachineFunction(MachineFunction &Fn) {
- // Get MachineDebugInfo so that we can track the construction of the
+ const MRegisterInfo *MRI = Fn.getTarget().getRegisterInfo();
+ RS = MRI->requiresRegisterScavenging(Fn) ? new RegScavenger() : NULL;
+
+ // Get MachineModuleInfo so that we can track the construction of the
// frame.
- if (MachineDebugInfo *DI = getAnalysisToUpdate<MachineDebugInfo>()) {
- Fn.getFrameInfo()->setMachineDebugInfo(DI);
+ if (MachineModuleInfo *MMI = getAnalysisToUpdate<MachineModuleInfo>()) {
+ Fn.getFrameInfo()->setMachineModuleInfo(MMI);
}
-
- // Scan the function for modified caller saved registers and insert spill
- // code for any caller saved registers that are modified. Also calculate
+
+ // Allow the target machine to make some adjustments to the function
+ // e.g. UsedPhysRegs before calculateCalleeSavedRegisters.
+ MRI->processFunctionBeforeCalleeSavedScan(Fn, RS);
+
+ // Scan the function for modified callee saved registers and insert spill
+ // code for any callee saved registers that are modified. Also calculate
// the MaxCallFrameSize and HasCalls variables for the function's frame
// information and eliminates call frame pseudo instructions.
- calculateCallerSavedRegisters(Fn);
+ calculateCalleeSavedRegisters(Fn);
- // Add the code to save and restore the caller saved registers
- saveCallerSavedRegisters(Fn);
+ // Add the code to save and restore the callee saved registers
+ saveCalleeSavedRegisters(Fn);
// Allow the target machine to make final modifications to the function
// before the frame layout is finalized.
// Add prolog and epilog code to the function. This function is required
// to align the stack frame as necessary for any stack variables or
- // called functions. Because of this, calculateCallerSavedRegisters
+ // called functions. Because of this, calculateCalleeSavedRegisters
// must be called before this function in order to set the HasCalls
// and MaxCallFrameSize variables.
insertPrologEpilogCode(Fn);
//
replaceFrameIndices(Fn);
+ delete RS;
return true;
}
private:
- void calculateCallerSavedRegisters(MachineFunction &Fn);
- void saveCallerSavedRegisters(MachineFunction &Fn);
+ RegScavenger *RS;
+
+ // MinCSFrameIndex, MaxCSFrameIndex - Keeps the range of callee saved
+ // stack frame indexes.
+ unsigned MinCSFrameIndex, MaxCSFrameIndex;
+
+ void calculateCalleeSavedRegisters(MachineFunction &Fn);
+ void saveCalleeSavedRegisters(MachineFunction &Fn);
void calculateFrameObjectOffsets(MachineFunction &Fn);
void replaceFrameIndices(MachineFunction &Fn);
void insertPrologEpilogCode(MachineFunction &Fn);
};
+ char PEI::ID = 0;
}
FunctionPass *llvm::createPrologEpilogCodeInserter() { return new PEI(); }
-/// calculateCallerSavedRegisters - Scan the function for modified caller saved
+/// calculateCalleeSavedRegisters - Scan the function for modified callee saved
/// registers. Also calculate the MaxCallFrameSize and HasCalls variables for
/// the function's frame information and eliminates call frame pseudo
/// instructions.
///
-void PEI::calculateCallerSavedRegisters(MachineFunction &Fn) {
+void PEI::calculateCalleeSavedRegisters(MachineFunction &Fn) {
const MRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
const TargetFrameInfo *TFI = Fn.getTarget().getFrameInfo();
// Get the callee saved register list...
- const unsigned *CSRegs = RegInfo->getCalleeSaveRegs();
+ const unsigned *CSRegs = RegInfo->getCalleeSavedRegs(&Fn);
// Get the function call frame set-up and tear-down instruction opcode
int FrameSetupOpcode = RegInfo->getCallFrameSetupOpcode();
int FrameDestroyOpcode = RegInfo->getCallFrameDestroyOpcode();
+ // 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 and no call
// frame setup/destroy pseudo instructions.
if ((CSRegs == 0 || CSRegs[0] == 0) &&
unsigned MaxCallFrameSize = 0;
bool HasCalls = false;
+ std::vector<MachineBasicBlock::iterator> FrameSDOps;
for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB)
- for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); )
+ for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I)
if (I->getOpcode() == FrameSetupOpcode ||
I->getOpcode() == FrameDestroyOpcode) {
assert(I->getNumOperands() >= 1 && "Call Frame Setup/Destroy Pseudo"
unsigned Size = I->getOperand(0).getImmedValue();
if (Size > MaxCallFrameSize) MaxCallFrameSize = Size;
HasCalls = true;
- RegInfo->eliminateCallFramePseudoInstr(Fn, *BB, I++);
- } else {
- ++I;
+ FrameSDOps.push_back(I);
}
MachineFrameInfo *FFI = Fn.getFrameInfo();
FFI->setHasCalls(HasCalls);
FFI->setMaxCallFrameSize(MaxCallFrameSize);
+ for (unsigned i = 0, e = FrameSDOps.size(); i != e; ++i) {
+ MachineBasicBlock::iterator I = FrameSDOps[i];
+ // If call frames are not being included as part of the stack frame,
+ // and there is no dynamic allocation (therefore referencing frame slots
+ // off sp), leave the pseudo ops alone. We'll eliminate them later.
+ if (RegInfo->hasReservedCallFrame(Fn) || RegInfo->hasFP(Fn))
+ RegInfo->eliminateCallFramePseudoInstr(Fn, *I->getParent(), I);
+ }
+
// Now figure out which *callee saved* registers are modified by the current
// function, thus needing to be saved and restored in the prolog/epilog.
//
- const bool *PhysRegsUsed = Fn.getUsedPhysregs();
const TargetRegisterClass* const *CSRegClasses =
- RegInfo->getCalleeSaveRegClasses();
+ RegInfo->getCalleeSavedRegClasses(&Fn);
std::vector<CalleeSavedInfo> CSI;
for (unsigned i = 0; CSRegs[i]; ++i) {
unsigned Reg = CSRegs[i];
- if (PhysRegsUsed[Reg]) {
+ if (Fn.isPhysRegUsed(Reg)) {
// If the reg is modified, save it!
CSI.push_back(CalleeSavedInfo(Reg, CSRegClasses[i]));
} else {
for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
*AliasSet; ++AliasSet) { // Check alias registers too.
- if (PhysRegsUsed[*AliasSet]) {
+ if (Fn.isPhysRegUsed(*AliasSet)) {
CSI.push_back(CalleeSavedInfo(Reg, CSRegClasses[i]));
break;
}
}
if (CSI.empty())
- return; // Early exit if no caller saved registers are modified!
+ return; // Early exit if no callee saved registers are modified!
unsigned NumFixedSpillSlots;
const std::pair<unsigned,int> *FixedSpillSlots =
- TFI->getCalleeSaveSpillSlots(NumFixedSpillSlots);
+ TFI->getCalleeSavedSpillSlots(NumFixedSpillSlots);
// Now that we know which registers need to be saved and restored, allocate
// stack slots for them.
int FrameIdx;
if (FixedSlot == FixedSpillSlots+NumFixedSpillSlots) {
// Nope, just spill it anywhere convenient.
- FrameIdx = FFI->CreateStackObject(RC->getSize(), RC->getAlignment());
+ unsigned Align = RC->getAlignment();
+ unsigned StackAlign = TFI->getStackAlignment();
+ // We may not be able to sastify the desired alignment specification of
+ // the TargetRegisterClass if the stack alignment is smaller. Use the min.
+ Align = std::min(Align, StackAlign);
+ FrameIdx = FFI->CreateStackObject(RC->getSize(), Align);
+ if ((unsigned)FrameIdx < MinCSFrameIndex) MinCSFrameIndex = FrameIdx;
+ if ((unsigned)FrameIdx > MaxCSFrameIndex) MaxCSFrameIndex = FrameIdx;
} else {
// Spill it to the stack where we must.
FrameIdx = FFI->CreateFixedObject(RC->getSize(), FixedSlot->second);
FFI->setCalleeSavedInfo(CSI);
}
-/// saveCallerSavedRegisters - Insert spill code for any caller saved registers
+/// saveCalleeSavedRegisters - Insert spill code for any callee saved registers
/// that are modified in the function.
///
-void PEI::saveCallerSavedRegisters(MachineFunction &Fn) {
+void PEI::saveCalleeSavedRegisters(MachineFunction &Fn) {
// Get callee saved register information.
MachineFrameInfo *FFI = Fn.getFrameInfo();
const std::vector<CalleeSavedInfo> &CSI = FFI->getCalleeSavedInfo();
- // Early exit if no caller saved registers are modified!
+ // Early exit if no callee saved registers are modified!
if (CSI.empty())
return;
// code into the entry block.
MachineBasicBlock *MBB = Fn.begin();
MachineBasicBlock::iterator I = MBB->begin();
- for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
- // Insert the spill to the stack frame.
- RegInfo->storeRegToStackSlot(*MBB, I, CSI[i].getReg(), CSI[i].getFrameIdx(),
- CSI[i].getRegClass());
+ if (!RegInfo->spillCalleeSavedRegisters(*MBB, I, CSI)) {
+ for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+ // Add the callee-saved register as live-in. It's killed at the spill.
+ MBB->addLiveIn(CSI[i].getReg());
+
+ // Insert the spill to the stack frame.
+ RegInfo->storeRegToStackSlot(*MBB, I, CSI[i].getReg(),
+ CSI[i].getFrameIdx(), CSI[i].getRegClass());
+ }
}
// Add code to restore the callee-save registers in each exiting block.
// Restore all registers immediately before the return and any terminators
// that preceed it.
- for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
- RegInfo->loadRegFromStackSlot(*MBB, I, CSI[i].getReg(),
- CSI[i].getFrameIdx(),
- CSI[i].getRegClass());
- assert(I != MBB->begin() &&
- "loadRegFromStackSlot didn't insert any code!");
- // Insert in reverse order. loadRegFromStackSlot can insert multiple
- // instructions.
- if (AtStart)
- I = MBB->begin();
- else {
- I = BeforeI;
- ++I;
+ if (!RegInfo->restoreCalleeSavedRegisters(*MBB, I, CSI)) {
+ for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+ RegInfo->loadRegFromStackSlot(*MBB, I, CSI[i].getReg(),
+ CSI[i].getFrameIdx(),
+ CSI[i].getRegClass());
+ assert(I != MBB->begin() &&
+ "loadRegFromStackSlot didn't insert any code!");
+ // Insert in reverse order. loadRegFromStackSlot can insert multiple
+ // instructions.
+ if (AtStart)
+ I = MBB->begin();
+ else {
+ I = BeforeI;
+ ++I;
+ }
}
}
}
// Loop over all of the stack objects, assigning sequential addresses...
MachineFrameInfo *FFI = Fn.getFrameInfo();
- unsigned StackAlignment = TFI.getStackAlignment();
unsigned MaxAlign = 0;
// Start at the beginning of the local area.
// The Offset is the distance from the stack top in the direction
// of stack growth -- so it's always positive.
- int Offset = TFI.getOffsetOfLocalArea();
+ int64_t Offset = TFI.getOffsetOfLocalArea();
if (StackGrowsDown)
Offset = -Offset;
assert(Offset >= 0
// so we adjust 'Offset' to point to the end of last fixed sized
// preallocated object.
for (int i = FFI->getObjectIndexBegin(); i != 0; ++i) {
- int FixedOff;
+ int64_t FixedOff;
if (StackGrowsDown) {
// The maximum distance from the stack pointer is at lower address of
// the object -- which is given by offset. For down growing stack
if (FixedOff > Offset) Offset = FixedOff;
}
+ // First assign frame offsets to stack objects that are used to spill
+ // callee saved registers.
+ if (StackGrowsDown) {
+ for (unsigned i = MinCSFrameIndex; i <= MaxCSFrameIndex; ++i) {
+ // If stack grows down, we need to add size of find the lowest
+ // address of the object.
+ Offset += FFI->getObjectSize(i);
+
+ unsigned Align = FFI->getObjectAlignment(i);
+ // If the alignment of this object is greater than that of the stack, then
+ // increase the stack alignment to match.
+ MaxAlign = std::max(MaxAlign, Align);
+ // Adjust to alignment boundary
+ Offset = (Offset+Align-1)/Align*Align;
+
+ FFI->setObjectOffset(i, -Offset); // Set the computed offset
+ }
+ } else {
+ for (unsigned i = MaxCSFrameIndex; i >= MinCSFrameIndex; --i) {
+ unsigned Align = FFI->getObjectAlignment(i);
+ // If the alignment of this object is greater than that of the stack, then
+ // increase the stack alignment to match.
+ MaxAlign = std::max(MaxAlign, Align);
+ // Adjust to alignment boundary
+ Offset = (Offset+Align-1)/Align*Align;
+
+ FFI->setObjectOffset(i, Offset);
+ Offset += FFI->getObjectSize(i);
+ }
+ }
+
+ // Make sure the special register scavenging spill slot is closest to the
+ // frame pointer if a frame pointer is required.
+ const MRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
+ if (RS && RegInfo->hasFP(Fn)) {
+ int SFI = RS->getScavengingFrameIndex();
+ if (SFI >= 0) {
+ // If stack grows down, we need to add size of the lowest
+ // address of the object.
+ if (StackGrowsDown)
+ Offset += FFI->getObjectSize(SFI);
+
+ unsigned Align = FFI->getObjectAlignment(SFI);
+ // Adjust to alignment boundary
+ Offset = (Offset+Align-1)/Align*Align;
+
+ if (StackGrowsDown) {
+ FFI->setObjectOffset(SFI, -Offset); // Set the computed offset
+ } else {
+ FFI->setObjectOffset(SFI, Offset);
+ Offset += FFI->getObjectSize(SFI);
+ }
+ }
+ }
+
+ // Then assign frame offsets to stack objects that are not used to spill
+ // callee saved registers.
for (unsigned i = 0, e = FFI->getObjectIndexEnd(); i != e; ++i) {
+ if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex)
+ continue;
+ if (RS && (int)i == RS->getScavengingFrameIndex())
+ continue;
+
// If stack grows down, we need to add size of find the lowest
// address of the object.
if (StackGrowsDown)
}
}
- // Align the final stack pointer offset, but only if there are calls in the
- // function. This ensures that any calls to subroutines have their stack
- // frames suitable aligned.
- if (FFI->hasCalls())
- Offset = (Offset+StackAlignment-1)/StackAlignment*StackAlignment;
+ // Make sure the special register scavenging spill slot is closest to the
+ // stack pointer.
+ if (RS && !RegInfo->hasFP(Fn)) {
+ int SFI = RS->getScavengingFrameIndex();
+ if (SFI >= 0) {
+ // If stack grows down, we need to add size of find the lowest
+ // address of the object.
+ if (StackGrowsDown)
+ Offset += FFI->getObjectSize(SFI);
+
+ unsigned Align = FFI->getObjectAlignment(SFI);
+ // Adjust to alignment boundary
+ Offset = (Offset+Align-1)/Align*Align;
+
+ if (StackGrowsDown) {
+ FFI->setObjectOffset(SFI, -Offset); // Set the computed offset
+ } else {
+ FFI->setObjectOffset(SFI, Offset);
+ Offset += FFI->getObjectSize(SFI);
+ }
+ }
+ }
+
+ // Round up the size to a multiple of the alignment, but only if there are
+ // calls or alloca's in the function. This ensures that any calls to
+ // subroutines have their stack frames suitable aligned.
+ if (!RegInfo->targetHandlesStackFrameRounding() &&
+ (FFI->hasCalls() || FFI->hasVarSizedObjects())) {
+ // If we have reserved argument space for call sites in the function
+ // immediately on entry to the current function, count it as part of the
+ // overall stack size.
+ if (RegInfo->hasReservedCallFrame(Fn))
+ Offset += FFI->getMaxCallFrameSize();
+
+ unsigned AlignMask = TFI.getStackAlignment() - 1;
+ Offset = (Offset + AlignMask) & ~uint64_t(AlignMask);
+ }
- // Set the final value of the stack pointer...
+ // Update frame info to pretend that this is part of the stack...
FFI->setStackSize(Offset+TFI.getOffsetOfLocalArea());
// Remember the required stack alignment in case targets need it to perform
}
-/// insertPrologEpilogCode - Scan the function for modified caller saved
-/// registers, insert spill code for these caller saved registers, then add
+/// insertPrologEpilogCode - Scan the function for modified callee saved
+/// registers, insert spill code for these callee saved registers, then add
/// prolog and epilog code to the function.
///
void PEI::insertPrologEpilogCode(MachineFunction &Fn) {
const TargetMachine &TM = Fn.getTarget();
assert(TM.getRegisterInfo() && "TM::getRegisterInfo() must be implemented!");
const MRegisterInfo &MRI = *TM.getRegisterInfo();
+ const TargetFrameInfo *TFI = TM.getFrameInfo();
+ bool StackGrowsDown =
+ TFI->getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
+ int FrameSetupOpcode = MRI.getCallFrameSetupOpcode();
+ int FrameDestroyOpcode = MRI.getCallFrameDestroyOpcode();
- for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB)
- for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I)
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
- if (I->getOperand(i).isFrameIndex()) {
- // If this instruction has a FrameIndex operand, we need to use that
- // target machine register info object to eliminate it.
- MRI.eliminateFrameIndex(I);
- break;
- }
+ for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
+ int SPAdj = 0; // SP offset due to call frame setup / destroy.
+ if (RS) RS->enterBasicBlock(BB);
+ for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
+ MachineInstr *MI = I;
+
+ // Remember how much SP has been adjustment to create the call frame.
+ if (I->getOpcode() == FrameSetupOpcode ||
+ I->getOpcode() == FrameDestroyOpcode) {
+ int Size = I->getOperand(0).getImmedValue();
+ if ((!StackGrowsDown && I->getOpcode() == FrameSetupOpcode) ||
+ (StackGrowsDown && I->getOpcode() == FrameDestroyOpcode))
+ Size = -Size;
+ SPAdj += Size;
+ MachineBasicBlock::iterator PrevI = prior(I);
+ MRI.eliminateCallFramePseudoInstr(Fn, *BB, I);
+ // Visit the instructions created by eliminateCallFramePseudoInstr().
+ I = next(PrevI);
+ MI = NULL;
+ } else {
+ I++;
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
+ if (MI->getOperand(i).isFrameIndex()) {
+ // If this instruction has a FrameIndex operand, we need to use that
+ // target machine register info object to eliminate it.
+ MRI.eliminateFrameIndex(MI, SPAdj, RS);
+
+ // Revisit the instruction in full. Some instructions (e.g. inline
+ // asm instructions) can have multiple frame indices.
+ --I;
+ MI = 0;
+ break;
+ }
+ }
+ // Update register states.
+ if (RS && MI) RS->forward(MI);
+ }
+ assert(SPAdj == 0 && "Unbalanced call frame setup / destroy pairs?");
+ }
}
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