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XCore target: Refactor LR handling 

We also narrow the liveness of FP & LR during the prologue to
reflect the actual usage of the registers.
I have been unable to construct a test to prove the previous live
range was too large.

llvm-svn: 198611
This commit is contained in:
Robert Lytton 2014-01-06 14:20:41 +00:00
parent 9288eea910
commit a53360a339
3 changed files with 72 additions and 48 deletions
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56
llvm/lib/Target/XCore/XCoreFrameLowering.cpp
View File

@ -170,7 +170,7 @@ void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
const int FrameSize = MFI->getStackSize() / 4;
int Adjusted = 0;
bool saveLR = XFI->getUsesLR();
bool saveLR = XFI->hasLRSpillSlot();
bool UseENTSP = saveLR && FrameSize
&& (MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0);
if (UseENTSP)
@ -182,8 +182,10 @@ void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
// Allocate space on the stack at the same time as saving LR.
Adjusted = (FrameSize > MaxImmU16) ? MaxImmU16 : FrameSize;
int Opcode = isImmU6(Adjusted) ? XCore::ENTSP_u6 : XCore::ENTSP_lu6;
BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addImm(Adjusted);
MBB.addLiveIn(XCore::LR);
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opcode));
MIB.addImm(Adjusted);
MIB->addRegisterKilled(XCore::LR, MF.getTarget().getRegisterInfo(), true);
if (emitFrameMoves) {
EmitDefCfaOffset(MBB, MBBI, dl, TII, MMI, Adjusted*4);
unsigned DRegNum = MRI->getDwarfRegNum(XCore::LR, true);
@ -204,8 +206,9 @@ void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
emitFrameMoves);
int Offset = Adjusted - OffsetFromTop;
int Opcode = isImmU6(Offset) ? XCore::STWSP_ru6 : XCore::STWSP_lru6;
BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addReg(SpillReg).addImm(Offset);
MBB.addLiveIn(SpillReg);
BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addReg(SpillReg, RegState::Kill)
.addImm(Offset);
if (emitFrameMoves) {
unsigned DRegNum = MRI->getDwarfRegNum(SpillReg, true);
EmitCfiOffset(MBB, MBBI, dl, TII, MMI, DRegNum, SpillOffset, NULL);
@ -241,12 +244,13 @@ void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
void XCoreFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
const XCoreInstrInfo &TII =
*static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
DebugLoc dl = MBBI->getDebugLoc();
unsigned RetOpcode = MBBI->getOpcode();
// Work out frame sizes.
// We will adjust the SP in stages towards the final FrameSize.
@ -254,7 +258,7 @@ void XCoreFrameLowering::emitEpilogue(MachineFunction &MF,
assert(RemainingAdj%4 == 0 && "Misaligned frame size");
RemainingAdj /= 4;
bool restoreLR = XFI->getUsesLR();
bool restoreLR = XFI->hasLRSpillSlot();
bool UseRETSP = restoreLR && RemainingAdj
&& (MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0);
if (UseRETSP)
@ -285,8 +289,8 @@ void XCoreFrameLowering::emitEpilogue(MachineFunction &MF,
IfNeededLDAWSP(MBB, MBBI, dl, TII, 0, RemainingAdj);
if (UseRETSP) {
// Fold prologue into return instruction
assert(MBBI->getOpcode() == XCore::RETSP_u6
|| MBBI->getOpcode() == XCore::RETSP_lu6);
assert(RetOpcode == XCore::RETSP_u6
|| RetOpcode == XCore::RETSP_lu6);
int Opcode = isImmU6(RemainingAdj) ? XCore::RETSP_u6 : XCore::RETSP_lu6;
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opcode))
.addImm(RemainingAdj);
@ -312,7 +316,6 @@ spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineFunction *MF = MBB.getParent();
const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
XCoreFunctionInfo *XFI = MF->getInfo<XCoreFunctionInfo>();
bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(*MF);
@ -322,13 +325,11 @@ spillCalleeSavedRegisters(MachineBasicBlock &MBB,
for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
it != CSI.end(); ++it) {
// Add the callee-saved register as live-in. It's killed at the spill.
MBB.addLiveIn(it->getReg());
unsigned Reg = it->getReg();
// Add the callee-saved register as live-in. It's killed at the spill.
MBB.addLiveIn(Reg);
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.storeRegToStackSlot(MBB, MI, Reg, true,
it->getFrameIdx(), RC, TRI);
TII.storeRegToStackSlot(MBB, MI, Reg, true, it->getFrameIdx(), RC, TRI);
if (emitFrameMoves) {
MCSymbol *SaveLabel = MF->getContext().CreateTempSymbol();
BuildMI(MBB, MI, DL, TII.get(XCore::PROLOG_LABEL)).addSym(SaveLabel);
@ -354,8 +355,7 @@ restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
it != CSI.end(); ++it) {
unsigned Reg = it->getReg();
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.loadRegFromStackSlot(MBB, MI, it->getReg(), it->getFrameIdx(),
RC, TRI);
TII.loadRegFromStackSlot(MBB, MI, Reg, it->getFrameIdx(), RC, TRI);
assert(MI != MBB.begin() &&
"loadRegFromStackSlot didn't insert any code!");
// Insert in reverse order. loadRegFromStackSlot can insert multiple
@ -425,32 +425,18 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
void XCoreFrameLowering::
processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
RegScavenger *RS) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
bool LRUsed = MF.getRegInfo().isPhysRegUsed(XCore::LR);
const TargetRegisterClass *RC = &XCore::GRRegsRegClass;
XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
if (LRUsed) {
// We will handling LR in the prologue/epilogue
// and space on the stack ourselves.
if (MF.getRegInfo().isPhysRegUsed(XCore::LR)) {
MF.getRegInfo().setPhysRegUnused(XCore::LR);
bool isVarArg = MF.getFunction()->isVarArg();
int FrameIdx;
if (! isVarArg) {
// A fixed offset of 0 allows us to save/restore LR using entsp/retsp.
FrameIdx = MFI->CreateFixedObject(RC->getSize(), 0, true);
} else {
FrameIdx = MFI->CreateStackObject(RC->getSize(), RC->getAlignment(),
false);
}
XFI->setUsesLR(FrameIdx);
XFI->setLRSpillSlot(FrameIdx);
XFI->createLRSpillSlot(MF);
}
// A callee save register is used to hold the FP.
// This needs saving / restoring in the epilogue / prologue.
if (hasFP(MF))
XFI->setFPSpillSlot(MFI->CreateStackObject(RC->getSize(),
RC->getAlignment(),
false));
XFI->createFPSpillSlot(MF);
}
void XCoreFrameLowering::

30
llvm/lib/Target/XCore/XCoreMachineFunctionInfo.cpp
View File

@ -8,6 +8,8 @@
//===----------------------------------------------------------------------===//
#include "XCoreMachineFunctionInfo.h"
#include "XCoreInstrInfo.h"
#include "llvm/IR/Function.h"
using namespace llvm;
@ -28,3 +30,31 @@ bool XCoreFunctionInfo::isLargeFrame(const MachineFunction &MF) const {
// 16KB of function arguments.
return CachedEStackSize > 0xf000;
}
int XCoreFunctionInfo::createLRSpillSlot(MachineFunction &MF) {
if (LRSpillSlotSet) {
return LRSpillSlot;
}
const TargetRegisterClass *RC = &XCore::GRRegsRegClass;
MachineFrameInfo *MFI = MF.getFrameInfo();
if (! MF.getFunction()->isVarArg()) {
// A fixed offset of 0 allows us to save / restore LR using entsp / retsp.
LRSpillSlot = MFI->CreateFixedObject(RC->getSize(), 0, true);
} else {
LRSpillSlot = MFI->CreateStackObject(RC->getSize(), RC->getAlignment(), true);
}
LRSpillSlotSet = true;
return LRSpillSlot;
}
int XCoreFunctionInfo::createFPSpillSlot(MachineFunction &MF) {
if (FPSpillSlotSet) {
return FPSpillSlot;
}
const TargetRegisterClass *RC = &XCore::GRRegsRegClass;
MachineFrameInfo *MFI = MF.getFrameInfo();
FPSpillSlot = MFI->CreateStackObject(RC->getSize(), RC->getAlignment(), true);
FPSpillSlotSet = true;
return FPSpillSlot;
}

34
llvm/lib/Target/XCore/XCoreMachineFunctionInfo.h
View File

@ -27,8 +27,9 @@ class Function;
/// XCore target-specific information for each MachineFunction.
class XCoreFunctionInfo : public MachineFunctionInfo {
virtual void anchor();
bool UsesLR;
bool LRSpillSlotSet;
int LRSpillSlot;
bool FPSpillSlotSet;
int FPSpillSlot;
int VarArgsFrameIndex;
mutable int CachedEStackSize;
@ -36,15 +37,17 @@ class XCoreFunctionInfo : public MachineFunctionInfo {
public:
XCoreFunctionInfo() :
UsesLR(false),
LRSpillSlotSet(false),
LRSpillSlot(0),
FPSpillSlotSet(false),
FPSpillSlot(0),
VarArgsFrameIndex(0),
CachedEStackSize(-1) {}
explicit XCoreFunctionInfo(MachineFunction &MF) :
UsesLR(false),
LRSpillSlotSet(false),
LRSpillSlot(0),
FPSpillSlotSet(false),
FPSpillSlot(0),
VarArgsFrameIndex(0),
CachedEStackSize(-1) {}
@ -53,16 +56,21 @@ public:
void setVarArgsFrameIndex(int off) { VarArgsFrameIndex = off; }
int getVarArgsFrameIndex() const { return VarArgsFrameIndex; }
void setUsesLR(bool val) { UsesLR = val; }
bool getUsesLR() const { return UsesLR; }
void setLRSpillSlot(int off) { LRSpillSlot = off; }
int getLRSpillSlot() const { return LRSpillSlot; }
void setFPSpillSlot(int off) { FPSpillSlot = off; }
int getFPSpillSlot() const { return FPSpillSlot; }
int createLRSpillSlot(MachineFunction &MF);
bool hasLRSpillSlot() { return LRSpillSlotSet; }
int getLRSpillSlot() const {
assert(LRSpillSlotSet && "LR Spill slot no set");
return LRSpillSlot;
}
int createFPSpillSlot(MachineFunction &MF);
bool hasFPSpillSlot() { return FPSpillSlotSet; }
int getFPSpillSlot() const {
assert(FPSpillSlotSet && "FP Spill slot no set");
return FPSpillSlot;
}
bool isLargeFrame(const MachineFunction &MF) const;
std::vector<std::pair<MCSymbol*, CalleeSavedInfo> > &getSpillLabels() {