1 //===-- XCoreFrameLowering.cpp - Frame info for XCore Target --------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains XCore frame information that doesn't fit anywhere else
11 // cleanly...
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "XCoreFrameLowering.h"
16 #include "XCore.h"
17 #include "XCoreInstrInfo.h"
18 #include "XCoreMachineFunctionInfo.h"
19 #include "llvm/CodeGen/MachineFrameInfo.h"
20 #include "llvm/CodeGen/MachineFunction.h"
21 #include "llvm/CodeGen/MachineInstrBuilder.h"
22 #include "llvm/CodeGen/MachineModuleInfo.h"
23 #include "llvm/CodeGen/MachineRegisterInfo.h"
24 #include "llvm/CodeGen/RegisterScavenging.h"
25 #include "llvm/IR/DataLayout.h"
26 #include "llvm/IR/Function.h"
27 #include "llvm/Support/ErrorHandling.h"
28 #include "llvm/Target/TargetOptions.h"
29
30 using namespace llvm;
31
32 // helper functions. FIXME: Eliminate.
isImmUs(unsigned val)33 static inline bool isImmUs(unsigned val) {
34 return val <= 11;
35 }
36
isImmU6(unsigned val)37 static inline bool isImmU6(unsigned val) {
38 return val < (1 << 6);
39 }
40
isImmU16(unsigned val)41 static inline bool isImmU16(unsigned val) {
42 return val < (1 << 16);
43 }
44
loadFromStack(MachineBasicBlock & MBB,MachineBasicBlock::iterator I,unsigned DstReg,int Offset,DebugLoc dl,const TargetInstrInfo & TII)45 static void loadFromStack(MachineBasicBlock &MBB,
46 MachineBasicBlock::iterator I,
47 unsigned DstReg, int Offset, DebugLoc dl,
48 const TargetInstrInfo &TII) {
49 assert(Offset%4 == 0 && "Misaligned stack offset");
50 Offset/=4;
51 bool isU6 = isImmU6(Offset);
52 if (!isU6 && !isImmU16(Offset))
53 report_fatal_error("loadFromStack offset too big " + Twine(Offset));
54 int Opcode = isU6 ? XCore::LDWSP_ru6 : XCore::LDWSP_lru6;
55 BuildMI(MBB, I, dl, TII.get(Opcode), DstReg)
56 .addImm(Offset);
57 }
58
59
storeToStack(MachineBasicBlock & MBB,MachineBasicBlock::iterator I,unsigned SrcReg,int Offset,DebugLoc dl,const TargetInstrInfo & TII)60 static void storeToStack(MachineBasicBlock &MBB,
61 MachineBasicBlock::iterator I,
62 unsigned SrcReg, int Offset, DebugLoc dl,
63 const TargetInstrInfo &TII) {
64 assert(Offset%4 == 0 && "Misaligned stack offset");
65 Offset/=4;
66 bool isU6 = isImmU6(Offset);
67 if (!isU6 && !isImmU16(Offset))
68 report_fatal_error("storeToStack offset too big " + Twine(Offset));
69 int Opcode = isU6 ? XCore::STWSP_ru6 : XCore::STWSP_lru6;
70 BuildMI(MBB, I, dl, TII.get(Opcode))
71 .addReg(SrcReg)
72 .addImm(Offset);
73 }
74
75
76 //===----------------------------------------------------------------------===//
77 // XCoreFrameLowering:
78 //===----------------------------------------------------------------------===//
79
XCoreFrameLowering(const XCoreSubtarget & sti)80 XCoreFrameLowering::XCoreFrameLowering(const XCoreSubtarget &sti)
81 : TargetFrameLowering(TargetFrameLowering::StackGrowsDown, 4, 0) {
82 // Do nothing
83 }
84
hasFP(const MachineFunction & MF) const85 bool XCoreFrameLowering::hasFP(const MachineFunction &MF) const {
86 return MF.getTarget().Options.DisableFramePointerElim(MF) ||
87 MF.getFrameInfo()->hasVarSizedObjects();
88 }
89
emitPrologue(MachineFunction & MF) const90 void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
91 MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
92 MachineBasicBlock::iterator MBBI = MBB.begin();
93 MachineFrameInfo *MFI = MF.getFrameInfo();
94 MachineModuleInfo *MMI = &MF.getMMI();
95 const XCoreInstrInfo &TII =
96 *static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
97 XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
98 DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
99
100 bool FP = hasFP(MF);
101 const AttributeSet &PAL = MF.getFunction()->getAttributes();
102
103 if (PAL.hasAttrSomewhere(Attribute::Nest))
104 loadFromStack(MBB, MBBI, XCore::R11, 0, dl, TII);
105
106 // Work out frame sizes.
107 int FrameSize = MFI->getStackSize();
108 assert(FrameSize%4 == 0 && "Misaligned frame size");
109 FrameSize/=4;
110
111 bool isU6 = isImmU6(FrameSize);
112
113 if (!isU6 && !isImmU16(FrameSize)) {
114 // FIXME could emit multiple instructions.
115 report_fatal_error("emitPrologue Frame size too big: " + Twine(FrameSize));
116 }
117 bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(MF);
118
119 bool saveLR = XFI->getUsesLR();
120 // Do we need to allocate space on the stack?
121 if (FrameSize) {
122 int Opcode;
123 if (saveLR && (MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0)) {
124 Opcode = (isU6) ? XCore::ENTSP_u6 : XCore::ENTSP_lu6;
125 MBB.addLiveIn(XCore::LR);
126 saveLR = false;
127 } else {
128 Opcode = (isU6) ? XCore::EXTSP_u6 : XCore::EXTSP_lu6;
129 }
130 BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addImm(FrameSize);
131
132 if (emitFrameMoves) {
133
134 // Show update of SP.
135 MCSymbol *FrameLabel = MMI->getContext().CreateTempSymbol();
136 BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(FrameLabel);
137 }
138 }
139 if (saveLR) {
140 int LRSpillOffset = MFI->getObjectOffset(XFI->getLRSpillSlot());
141 storeToStack(MBB, MBBI, XCore::LR, LRSpillOffset + FrameSize*4, dl, TII);
142 MBB.addLiveIn(XCore::LR);
143
144 if (emitFrameMoves) {
145 MCSymbol *SaveLRLabel = MMI->getContext().CreateTempSymbol();
146 BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(SaveLRLabel);
147 }
148 }
149
150 if (FP) {
151 // Save R10 to the stack.
152 int FPSpillOffset = MFI->getObjectOffset(XFI->getFPSpillSlot());
153 storeToStack(MBB, MBBI, XCore::R10, FPSpillOffset + FrameSize*4, dl, TII);
154 // R10 is live-in. It is killed at the spill.
155 MBB.addLiveIn(XCore::R10);
156 if (emitFrameMoves) {
157 MCSymbol *SaveR10Label = MMI->getContext().CreateTempSymbol();
158 BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(SaveR10Label);
159 }
160 // Set the FP from the SP.
161 unsigned FramePtr = XCore::R10;
162 BuildMI(MBB, MBBI, dl, TII.get(XCore::LDAWSP_ru6), FramePtr)
163 .addImm(0);
164 if (emitFrameMoves) {
165 // Show FP is now valid.
166 MCSymbol *FrameLabel = MMI->getContext().CreateTempSymbol();
167 BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(FrameLabel);
168 }
169 }
170 }
171
emitEpilogue(MachineFunction & MF,MachineBasicBlock & MBB) const172 void XCoreFrameLowering::emitEpilogue(MachineFunction &MF,
173 MachineBasicBlock &MBB) const {
174 MachineFrameInfo *MFI = MF.getFrameInfo();
175 MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
176 const XCoreInstrInfo &TII =
177 *static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
178 XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
179 DebugLoc dl = MBBI->getDebugLoc();
180
181 bool FP = hasFP(MF);
182 if (FP) {
183 // Restore the stack pointer.
184 unsigned FramePtr = XCore::R10;
185 BuildMI(MBB, MBBI, dl, TII.get(XCore::SETSP_1r))
186 .addReg(FramePtr);
187 }
188
189 // Work out frame sizes.
190 int FrameSize = MFI->getStackSize();
191
192 assert(FrameSize%4 == 0 && "Misaligned frame size");
193
194 FrameSize/=4;
195
196 bool isU6 = isImmU6(FrameSize);
197
198 if (!isU6 && !isImmU16(FrameSize)) {
199 // FIXME could emit multiple instructions.
200 report_fatal_error("emitEpilogue Frame size too big: " + Twine(FrameSize));
201 }
202
203 if (FP) {
204 // Restore R10
205 int FPSpillOffset = MFI->getObjectOffset(XFI->getFPSpillSlot());
206 FPSpillOffset += FrameSize*4;
207 loadFromStack(MBB, MBBI, XCore::R10, FPSpillOffset, dl, TII);
208 }
209
210 bool restoreLR = XFI->getUsesLR();
211 if (restoreLR &&
212 (FrameSize == 0 || MFI->getObjectOffset(XFI->getLRSpillSlot()) != 0)) {
213 int LRSpillOffset = MFI->getObjectOffset(XFI->getLRSpillSlot());
214 LRSpillOffset += FrameSize*4;
215 loadFromStack(MBB, MBBI, XCore::LR, LRSpillOffset, dl, TII);
216 restoreLR = false;
217 }
218
219 if (FrameSize) {
220 if (restoreLR) {
221 // Fold prologue into return instruction
222 assert(MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0);
223 assert(MBBI->getOpcode() == XCore::RETSP_u6
224 || MBBI->getOpcode() == XCore::RETSP_lu6);
225 int Opcode = (isU6) ? XCore::RETSP_u6 : XCore::RETSP_lu6;
226 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addImm(FrameSize);
227 for (unsigned i = 3, e = MBBI->getNumOperands(); i < e; ++i)
228 MIB->addOperand(MBBI->getOperand(i)); // copy any variadic operands
229 MBB.erase(MBBI);
230 } else {
231 int Opcode = (isU6) ? XCore::LDAWSP_ru6 : XCore::LDAWSP_lru6;
232 BuildMI(MBB, MBBI, dl, TII.get(Opcode), XCore::SP).addImm(FrameSize);
233 }
234 }
235 }
236
spillCalleeSavedRegisters(MachineBasicBlock & MBB,MachineBasicBlock::iterator MI,const std::vector<CalleeSavedInfo> & CSI,const TargetRegisterInfo * TRI) const237 bool XCoreFrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
238 MachineBasicBlock::iterator MI,
239 const std::vector<CalleeSavedInfo> &CSI,
240 const TargetRegisterInfo *TRI) const {
241 if (CSI.empty())
242 return true;
243
244 MachineFunction *MF = MBB.getParent();
245 const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
246
247 XCoreFunctionInfo *XFI = MF->getInfo<XCoreFunctionInfo>();
248 bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(*MF);
249
250 DebugLoc DL;
251 if (MI != MBB.end()) DL = MI->getDebugLoc();
252
253 for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
254 it != CSI.end(); ++it) {
255 // Add the callee-saved register as live-in. It's killed at the spill.
256 MBB.addLiveIn(it->getReg());
257
258 unsigned Reg = it->getReg();
259 const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
260 TII.storeRegToStackSlot(MBB, MI, Reg, true,
261 it->getFrameIdx(), RC, TRI);
262 if (emitFrameMoves) {
263 MCSymbol *SaveLabel = MF->getContext().CreateTempSymbol();
264 BuildMI(MBB, MI, DL, TII.get(XCore::PROLOG_LABEL)).addSym(SaveLabel);
265 XFI->getSpillLabels().push_back(std::make_pair(SaveLabel, *it));
266 }
267 }
268 return true;
269 }
270
restoreCalleeSavedRegisters(MachineBasicBlock & MBB,MachineBasicBlock::iterator MI,const std::vector<CalleeSavedInfo> & CSI,const TargetRegisterInfo * TRI) const271 bool XCoreFrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
272 MachineBasicBlock::iterator MI,
273 const std::vector<CalleeSavedInfo> &CSI,
274 const TargetRegisterInfo *TRI) const{
275 MachineFunction *MF = MBB.getParent();
276 const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
277
278 bool AtStart = MI == MBB.begin();
279 MachineBasicBlock::iterator BeforeI = MI;
280 if (!AtStart)
281 --BeforeI;
282 for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
283 it != CSI.end(); ++it) {
284 unsigned Reg = it->getReg();
285 const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
286 TII.loadRegFromStackSlot(MBB, MI, it->getReg(), it->getFrameIdx(),
287 RC, TRI);
288 assert(MI != MBB.begin() &&
289 "loadRegFromStackSlot didn't insert any code!");
290 // Insert in reverse order. loadRegFromStackSlot can insert multiple
291 // instructions.
292 if (AtStart)
293 MI = MBB.begin();
294 else {
295 MI = BeforeI;
296 ++MI;
297 }
298 }
299 return true;
300 }
301
302 // This function eliminates ADJCALLSTACKDOWN,
303 // ADJCALLSTACKUP pseudo instructions
304 void XCoreFrameLowering::
eliminateCallFramePseudoInstr(MachineFunction & MF,MachineBasicBlock & MBB,MachineBasicBlock::iterator I) const305 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
306 MachineBasicBlock::iterator I) const {
307 const XCoreInstrInfo &TII =
308 *static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
309 if (!hasReservedCallFrame(MF)) {
310 // Turn the adjcallstackdown instruction into 'extsp <amt>' and the
311 // adjcallstackup instruction into 'ldaw sp, sp[<amt>]'
312 MachineInstr *Old = I;
313 uint64_t Amount = Old->getOperand(0).getImm();
314 if (Amount != 0) {
315 // We need to keep the stack aligned properly. To do this, we round the
316 // amount of space needed for the outgoing arguments up to the next
317 // alignment boundary.
318 unsigned Align = getStackAlignment();
319 Amount = (Amount+Align-1)/Align*Align;
320
321 assert(Amount%4 == 0);
322 Amount /= 4;
323
324 bool isU6 = isImmU6(Amount);
325 if (!isU6 && !isImmU16(Amount)) {
326 // FIX could emit multiple instructions in this case.
327 #ifndef NDEBUG
328 errs() << "eliminateCallFramePseudoInstr size too big: "
329 << Amount << "\n";
330 #endif
331 llvm_unreachable(0);
332 }
333
334 MachineInstr *New;
335 if (Old->getOpcode() == XCore::ADJCALLSTACKDOWN) {
336 int Opcode = isU6 ? XCore::EXTSP_u6 : XCore::EXTSP_lu6;
337 New=BuildMI(MF, Old->getDebugLoc(), TII.get(Opcode))
338 .addImm(Amount);
339 } else {
340 assert(Old->getOpcode() == XCore::ADJCALLSTACKUP);
341 int Opcode = isU6 ? XCore::LDAWSP_ru6 : XCore::LDAWSP_lru6;
342 New=BuildMI(MF, Old->getDebugLoc(), TII.get(Opcode), XCore::SP)
343 .addImm(Amount);
344 }
345
346 // Replace the pseudo instruction with a new instruction...
347 MBB.insert(I, New);
348 }
349 }
350
351 MBB.erase(I);
352 }
353
354 void
processFunctionBeforeCalleeSavedScan(MachineFunction & MF,RegScavenger * RS) const355 XCoreFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
356 RegScavenger *RS) const {
357 MachineFrameInfo *MFI = MF.getFrameInfo();
358 const TargetRegisterInfo *RegInfo = MF.getTarget().getRegisterInfo();
359 bool LRUsed = MF.getRegInfo().isPhysRegUsed(XCore::LR);
360 const TargetRegisterClass *RC = &XCore::GRRegsRegClass;
361 XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
362 if (LRUsed) {
363 MF.getRegInfo().setPhysRegUnused(XCore::LR);
364
365 bool isVarArg = MF.getFunction()->isVarArg();
366 int FrameIdx;
367 if (! isVarArg) {
368 // A fixed offset of 0 allows us to save / restore LR using entsp / retsp.
369 FrameIdx = MFI->CreateFixedObject(RC->getSize(), 0, true);
370 } else {
371 FrameIdx = MFI->CreateStackObject(RC->getSize(), RC->getAlignment(),
372 false);
373 }
374 XFI->setUsesLR(FrameIdx);
375 XFI->setLRSpillSlot(FrameIdx);
376 }
377 if (RegInfo->requiresRegisterScavenging(MF)) {
378 // Reserve a slot close to SP or frame pointer.
379 RS->addScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
380 RC->getAlignment(),
381 false));
382 }
383 if (hasFP(MF)) {
384 // A callee save register is used to hold the FP.
385 // This needs saving / restoring in the epilogue / prologue.
386 XFI->setFPSpillSlot(MFI->CreateStackObject(RC->getSize(),
387 RC->getAlignment(),
388 false));
389 }
390 }
391