1 //===-- SparcFrameLowering.cpp - Sparc Frame Information ------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains the Sparc implementation of TargetFrameLowering class.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "SparcFrameLowering.h"
14 #include "SparcInstrInfo.h"
15 #include "SparcMachineFunctionInfo.h"
16 #include "SparcSubtarget.h"
17 #include "llvm/CodeGen/MachineFrameInfo.h"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/CodeGen/MachineInstrBuilder.h"
20 #include "llvm/CodeGen/MachineModuleInfo.h"
21 #include "llvm/CodeGen/MachineRegisterInfo.h"
22 #include "llvm/IR/DataLayout.h"
23 #include "llvm/IR/Function.h"
24 #include "llvm/Support/CommandLine.h"
25 #include "llvm/Target/TargetOptions.h"
26
27 using namespace llvm;
28
29 static cl::opt<bool>
30 DisableLeafProc("disable-sparc-leaf-proc",
31 cl::init(false),
32 cl::desc("Disable Sparc leaf procedure optimization."),
33 cl::Hidden);
34
SparcFrameLowering(const SparcSubtarget & ST)35 SparcFrameLowering::SparcFrameLowering(const SparcSubtarget &ST)
36 : TargetFrameLowering(TargetFrameLowering::StackGrowsDown,
37 ST.is64Bit() ? Align(16) : Align(8), 0,
38 ST.is64Bit() ? Align(16) : Align(8)) {}
39
emitSPAdjustment(MachineFunction & MF,MachineBasicBlock & MBB,MachineBasicBlock::iterator MBBI,int NumBytes,unsigned ADDrr,unsigned ADDri) const40 void SparcFrameLowering::emitSPAdjustment(MachineFunction &MF,
41 MachineBasicBlock &MBB,
42 MachineBasicBlock::iterator MBBI,
43 int NumBytes,
44 unsigned ADDrr,
45 unsigned ADDri) const {
46
47 DebugLoc dl;
48 const SparcInstrInfo &TII =
49 *static_cast<const SparcInstrInfo *>(MF.getSubtarget().getInstrInfo());
50
51 if (NumBytes >= -4096 && NumBytes < 4096) {
52 BuildMI(MBB, MBBI, dl, TII.get(ADDri), SP::O6)
53 .addReg(SP::O6).addImm(NumBytes);
54 return;
55 }
56
57 // Emit this the hard way. This clobbers G1 which we always know is
58 // available here.
59 if (NumBytes >= 0) {
60 // Emit nonnegative numbers with sethi + or.
61 // sethi %hi(NumBytes), %g1
62 // or %g1, %lo(NumBytes), %g1
63 // add %sp, %g1, %sp
64 BuildMI(MBB, MBBI, dl, TII.get(SP::SETHIi), SP::G1)
65 .addImm(HI22(NumBytes));
66 BuildMI(MBB, MBBI, dl, TII.get(SP::ORri), SP::G1)
67 .addReg(SP::G1).addImm(LO10(NumBytes));
68 BuildMI(MBB, MBBI, dl, TII.get(ADDrr), SP::O6)
69 .addReg(SP::O6).addReg(SP::G1);
70 return ;
71 }
72
73 // Emit negative numbers with sethi + xor.
74 // sethi %hix(NumBytes), %g1
75 // xor %g1, %lox(NumBytes), %g1
76 // add %sp, %g1, %sp
77 BuildMI(MBB, MBBI, dl, TII.get(SP::SETHIi), SP::G1)
78 .addImm(HIX22(NumBytes));
79 BuildMI(MBB, MBBI, dl, TII.get(SP::XORri), SP::G1)
80 .addReg(SP::G1).addImm(LOX10(NumBytes));
81 BuildMI(MBB, MBBI, dl, TII.get(ADDrr), SP::O6)
82 .addReg(SP::O6).addReg(SP::G1);
83 }
84
emitPrologue(MachineFunction & MF,MachineBasicBlock & MBB) const85 void SparcFrameLowering::emitPrologue(MachineFunction &MF,
86 MachineBasicBlock &MBB) const {
87 SparcMachineFunctionInfo *FuncInfo = MF.getInfo<SparcMachineFunctionInfo>();
88
89 assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
90 MachineFrameInfo &MFI = MF.getFrameInfo();
91 const SparcSubtarget &Subtarget = MF.getSubtarget<SparcSubtarget>();
92 const SparcInstrInfo &TII =
93 *static_cast<const SparcInstrInfo *>(Subtarget.getInstrInfo());
94 const SparcRegisterInfo &RegInfo =
95 *static_cast<const SparcRegisterInfo *>(Subtarget.getRegisterInfo());
96 MachineBasicBlock::iterator MBBI = MBB.begin();
97 // Debug location must be unknown since the first debug location is used
98 // to determine the end of the prologue.
99 DebugLoc dl;
100 bool NeedsStackRealignment = RegInfo.shouldRealignStack(MF);
101
102 if (NeedsStackRealignment && !RegInfo.canRealignStack(MF))
103 report_fatal_error("Function \"" + Twine(MF.getName()) + "\" required "
104 "stack re-alignment, but LLVM couldn't handle it "
105 "(probably because it has a dynamic alloca).");
106
107 // Get the number of bytes to allocate from the FrameInfo
108 int NumBytes = (int) MFI.getStackSize();
109
110 unsigned SAVEri = SP::SAVEri;
111 unsigned SAVErr = SP::SAVErr;
112 if (FuncInfo->isLeafProc()) {
113 if (NumBytes == 0)
114 return;
115 SAVEri = SP::ADDri;
116 SAVErr = SP::ADDrr;
117 }
118
119 // The SPARC ABI is a bit odd in that it requires a reserved 92-byte
120 // (128 in v9) area in the user's stack, starting at %sp. Thus, the
121 // first part of the stack that can actually be used is located at
122 // %sp + 92.
123 //
124 // We therefore need to add that offset to the total stack size
125 // after all the stack objects are placed by
126 // PrologEpilogInserter calculateFrameObjectOffsets. However, since the stack needs to be
127 // aligned *after* the extra size is added, we need to disable
128 // calculateFrameObjectOffsets's built-in stack alignment, by having
129 // targetHandlesStackFrameRounding return true.
130
131
132 // Add the extra call frame stack size, if needed. (This is the same
133 // code as in PrologEpilogInserter, but also gets disabled by
134 // targetHandlesStackFrameRounding)
135 if (MFI.adjustsStack() && hasReservedCallFrame(MF))
136 NumBytes += MFI.getMaxCallFrameSize();
137
138 // Adds the SPARC subtarget-specific spill area to the stack
139 // size. Also ensures target-required alignment.
140 NumBytes = Subtarget.getAdjustedFrameSize(NumBytes);
141
142 // Finally, ensure that the size is sufficiently aligned for the
143 // data on the stack.
144 NumBytes = alignTo(NumBytes, MFI.getMaxAlign());
145
146 // Update stack size with corrected value.
147 MFI.setStackSize(NumBytes);
148
149 emitSPAdjustment(MF, MBB, MBBI, -NumBytes, SAVErr, SAVEri);
150
151 unsigned regFP = RegInfo.getDwarfRegNum(SP::I6, true);
152
153 // Emit ".cfi_def_cfa_register 30".
154 unsigned CFIIndex =
155 MF.addFrameInst(MCCFIInstruction::createDefCfaRegister(nullptr, regFP));
156 BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
157 .addCFIIndex(CFIIndex);
158
159 // Emit ".cfi_window_save".
160 CFIIndex = MF.addFrameInst(MCCFIInstruction::createWindowSave(nullptr));
161 BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
162 .addCFIIndex(CFIIndex);
163
164 unsigned regInRA = RegInfo.getDwarfRegNum(SP::I7, true);
165 unsigned regOutRA = RegInfo.getDwarfRegNum(SP::O7, true);
166 // Emit ".cfi_register 15, 31".
167 CFIIndex = MF.addFrameInst(
168 MCCFIInstruction::createRegister(nullptr, regOutRA, regInRA));
169 BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
170 .addCFIIndex(CFIIndex);
171
172 if (NeedsStackRealignment) {
173 int64_t Bias = Subtarget.getStackPointerBias();
174 unsigned regUnbiased;
175 if (Bias) {
176 // This clobbers G1 which we always know is available here.
177 regUnbiased = SP::G1;
178 // add %o6, BIAS, %g1
179 BuildMI(MBB, MBBI, dl, TII.get(SP::ADDri), regUnbiased)
180 .addReg(SP::O6).addImm(Bias);
181 } else
182 regUnbiased = SP::O6;
183
184 // andn %regUnbiased, MaxAlign-1, %regUnbiased
185 Align MaxAlign = MFI.getMaxAlign();
186 BuildMI(MBB, MBBI, dl, TII.get(SP::ANDNri), regUnbiased)
187 .addReg(regUnbiased)
188 .addImm(MaxAlign.value() - 1U);
189
190 if (Bias) {
191 // add %g1, -BIAS, %o6
192 BuildMI(MBB, MBBI, dl, TII.get(SP::ADDri), SP::O6)
193 .addReg(regUnbiased).addImm(-Bias);
194 }
195 }
196 }
197
198 MachineBasicBlock::iterator SparcFrameLowering::
eliminateCallFramePseudoInstr(MachineFunction & MF,MachineBasicBlock & MBB,MachineBasicBlock::iterator I) const199 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
200 MachineBasicBlock::iterator I) const {
201 if (!hasReservedCallFrame(MF)) {
202 MachineInstr &MI = *I;
203 int Size = MI.getOperand(0).getImm();
204 if (MI.getOpcode() == SP::ADJCALLSTACKDOWN)
205 Size = -Size;
206
207 if (Size)
208 emitSPAdjustment(MF, MBB, I, Size, SP::ADDrr, SP::ADDri);
209 }
210 return MBB.erase(I);
211 }
212
213
emitEpilogue(MachineFunction & MF,MachineBasicBlock & MBB) const214 void SparcFrameLowering::emitEpilogue(MachineFunction &MF,
215 MachineBasicBlock &MBB) const {
216 SparcMachineFunctionInfo *FuncInfo = MF.getInfo<SparcMachineFunctionInfo>();
217 MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
218 const SparcInstrInfo &TII =
219 *static_cast<const SparcInstrInfo *>(MF.getSubtarget().getInstrInfo());
220 DebugLoc dl = MBBI->getDebugLoc();
221 assert((MBBI->getOpcode() == SP::RETL || MBBI->getOpcode() == SP::TAIL_CALL ||
222 MBBI->getOpcode() == SP::TAIL_CALLri) &&
223 "Can only put epilog before 'retl' or 'tail_call' instruction!");
224 if (!FuncInfo->isLeafProc()) {
225 BuildMI(MBB, MBBI, dl, TII.get(SP::RESTORErr), SP::G0).addReg(SP::G0)
226 .addReg(SP::G0);
227 return;
228 }
229 MachineFrameInfo &MFI = MF.getFrameInfo();
230
231 int NumBytes = (int) MFI.getStackSize();
232 if (NumBytes != 0)
233 emitSPAdjustment(MF, MBB, MBBI, NumBytes, SP::ADDrr, SP::ADDri);
234
235 // Preserve return address in %o7
236 if (MBBI->getOpcode() == SP::TAIL_CALL) {
237 MBB.addLiveIn(SP::O7);
238 BuildMI(MBB, MBBI, dl, TII.get(SP::ORrr), SP::G1)
239 .addReg(SP::G0)
240 .addReg(SP::O7);
241 BuildMI(MBB, MBBI, dl, TII.get(SP::ORrr), SP::O7)
242 .addReg(SP::G0)
243 .addReg(SP::G1);
244 }
245 }
246
hasReservedCallFrame(const MachineFunction & MF) const247 bool SparcFrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
248 // Reserve call frame if there are no variable sized objects on the stack.
249 return !MF.getFrameInfo().hasVarSizedObjects();
250 }
251
252 // hasFP - Return true if the specified function should have a dedicated frame
253 // pointer register. This is true if the function has variable sized allocas or
254 // if frame pointer elimination is disabled.
hasFP(const MachineFunction & MF) const255 bool SparcFrameLowering::hasFP(const MachineFunction &MF) const {
256 const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
257
258 const MachineFrameInfo &MFI = MF.getFrameInfo();
259 return MF.getTarget().Options.DisableFramePointerElim(MF) ||
260 RegInfo->hasStackRealignment(MF) || MFI.hasVarSizedObjects() ||
261 MFI.isFrameAddressTaken();
262 }
263
264 StackOffset
getFrameIndexReference(const MachineFunction & MF,int FI,Register & FrameReg) const265 SparcFrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI,
266 Register &FrameReg) const {
267 const SparcSubtarget &Subtarget = MF.getSubtarget<SparcSubtarget>();
268 const MachineFrameInfo &MFI = MF.getFrameInfo();
269 const SparcRegisterInfo *RegInfo = Subtarget.getRegisterInfo();
270 const SparcMachineFunctionInfo *FuncInfo = MF.getInfo<SparcMachineFunctionInfo>();
271 bool isFixed = MFI.isFixedObjectIndex(FI);
272
273 // Addressable stack objects are accessed using neg. offsets from
274 // %fp, or positive offsets from %sp.
275 bool UseFP;
276
277 // Sparc uses FP-based references in general, even when "hasFP" is
278 // false. That function is rather a misnomer, because %fp is
279 // actually always available, unless isLeafProc.
280 if (FuncInfo->isLeafProc()) {
281 // If there's a leaf proc, all offsets need to be %sp-based,
282 // because we haven't caused %fp to actually point to our frame.
283 UseFP = false;
284 } else if (isFixed) {
285 // Otherwise, argument access should always use %fp.
286 UseFP = true;
287 } else if (RegInfo->hasStackRealignment(MF)) {
288 // If there is dynamic stack realignment, all local object
289 // references need to be via %sp, to take account of the
290 // re-alignment.
291 UseFP = false;
292 } else {
293 // Finally, default to using %fp.
294 UseFP = true;
295 }
296
297 int64_t FrameOffset = MF.getFrameInfo().getObjectOffset(FI) +
298 Subtarget.getStackPointerBias();
299
300 if (UseFP) {
301 FrameReg = RegInfo->getFrameRegister(MF);
302 return StackOffset::getFixed(FrameOffset);
303 } else {
304 FrameReg = SP::O6; // %sp
305 return StackOffset::getFixed(FrameOffset + MF.getFrameInfo().getStackSize());
306 }
307 }
308
verifyLeafProcRegUse(MachineRegisterInfo * MRI)309 static bool LLVM_ATTRIBUTE_UNUSED verifyLeafProcRegUse(MachineRegisterInfo *MRI)
310 {
311
312 for (unsigned reg = SP::I0; reg <= SP::I7; ++reg)
313 if (MRI->isPhysRegUsed(reg))
314 return false;
315
316 for (unsigned reg = SP::L0; reg <= SP::L7; ++reg)
317 if (MRI->isPhysRegUsed(reg))
318 return false;
319
320 return true;
321 }
322
isLeafProc(MachineFunction & MF) const323 bool SparcFrameLowering::isLeafProc(MachineFunction &MF) const
324 {
325
326 MachineRegisterInfo &MRI = MF.getRegInfo();
327 MachineFrameInfo &MFI = MF.getFrameInfo();
328
329 return !(MFI.hasCalls() // has calls
330 || MRI.isPhysRegUsed(SP::L0) // Too many registers needed
331 || MRI.isPhysRegUsed(SP::O6) // %sp is used
332 || hasFP(MF) // need %fp
333 || MF.hasInlineAsm()); // has inline assembly
334 }
335
remapRegsForLeafProc(MachineFunction & MF) const336 void SparcFrameLowering::remapRegsForLeafProc(MachineFunction &MF) const {
337 MachineRegisterInfo &MRI = MF.getRegInfo();
338 // Remap %i[0-7] to %o[0-7].
339 for (unsigned reg = SP::I0; reg <= SP::I7; ++reg) {
340 if (!MRI.isPhysRegUsed(reg))
341 continue;
342
343 unsigned mapped_reg = reg - SP::I0 + SP::O0;
344
345 // Replace I register with O register.
346 MRI.replaceRegWith(reg, mapped_reg);
347
348 // Also replace register pair super-registers.
349 if ((reg - SP::I0) % 2 == 0) {
350 unsigned preg = (reg - SP::I0) / 2 + SP::I0_I1;
351 unsigned mapped_preg = preg - SP::I0_I1 + SP::O0_O1;
352 MRI.replaceRegWith(preg, mapped_preg);
353 }
354 }
355
356 // Rewrite MBB's Live-ins.
357 for (MachineBasicBlock &MBB : MF) {
358 for (unsigned reg = SP::I0_I1; reg <= SP::I6_I7; ++reg) {
359 if (!MBB.isLiveIn(reg))
360 continue;
361 MBB.removeLiveIn(reg);
362 MBB.addLiveIn(reg - SP::I0_I1 + SP::O0_O1);
363 }
364 for (unsigned reg = SP::I0; reg <= SP::I7; ++reg) {
365 if (!MBB.isLiveIn(reg))
366 continue;
367 MBB.removeLiveIn(reg);
368 MBB.addLiveIn(reg - SP::I0 + SP::O0);
369 }
370 }
371
372 assert(verifyLeafProcRegUse(&MRI));
373 #ifdef EXPENSIVE_CHECKS
374 MF.verify(0, "After LeafProc Remapping");
375 #endif
376 }
377
determineCalleeSaves(MachineFunction & MF,BitVector & SavedRegs,RegScavenger * RS) const378 void SparcFrameLowering::determineCalleeSaves(MachineFunction &MF,
379 BitVector &SavedRegs,
380 RegScavenger *RS) const {
381 TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
382 if (!DisableLeafProc && isLeafProc(MF)) {
383 SparcMachineFunctionInfo *MFI = MF.getInfo<SparcMachineFunctionInfo>();
384 MFI->setLeafProc(true);
385
386 remapRegsForLeafProc(MF);
387 }
388
389 }
390