File: | lib/CodeGen/LiveDebugValues.cpp |
Warning: | line 660, column 9 Value stored to 'MBBJoined' is never read |
1 | //===------ LiveDebugValues.cpp - Tracking Debug Value MIs ----------------===// |
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 pass implements a data flow analysis that propagates debug location |
11 | /// information by inserting additional DBG_VALUE instructions into the machine |
12 | /// instruction stream. The pass internally builds debug location liveness |
13 | /// ranges to determine the points where additional DBG_VALUEs need to be |
14 | /// inserted. |
15 | /// |
16 | /// This is a separate pass from DbgValueHistoryCalculator to facilitate |
17 | /// testing and improve modularity. |
18 | /// |
19 | //===----------------------------------------------------------------------===// |
20 | |
21 | #include "llvm/ADT/PostOrderIterator.h" |
22 | #include "llvm/ADT/SmallPtrSet.h" |
23 | #include "llvm/ADT/SparseBitVector.h" |
24 | #include "llvm/ADT/Statistic.h" |
25 | #include "llvm/ADT/UniqueVector.h" |
26 | #include "llvm/CodeGen/LexicalScopes.h" |
27 | #include "llvm/CodeGen/MachineFrameInfo.h" |
28 | #include "llvm/CodeGen/MachineFunction.h" |
29 | #include "llvm/CodeGen/MachineFunctionPass.h" |
30 | #include "llvm/CodeGen/MachineInstrBuilder.h" |
31 | #include "llvm/CodeGen/MachineMemOperand.h" |
32 | #include "llvm/CodeGen/Passes.h" |
33 | #include "llvm/IR/DebugInfo.h" |
34 | #include "llvm/Support/Debug.h" |
35 | #include "llvm/Support/raw_ostream.h" |
36 | #include "llvm/Target/TargetFrameLowering.h" |
37 | #include "llvm/Target/TargetInstrInfo.h" |
38 | #include "llvm/Target/TargetLowering.h" |
39 | #include "llvm/Target/TargetRegisterInfo.h" |
40 | #include "llvm/Target/TargetSubtargetInfo.h" |
41 | #include <list> |
42 | #include <queue> |
43 | |
44 | using namespace llvm; |
45 | |
46 | #define DEBUG_TYPE"livedebugvalues" "livedebugvalues" |
47 | |
48 | STATISTIC(NumInserted, "Number of DBG_VALUE instructions inserted")static llvm::Statistic NumInserted = {"livedebugvalues", "NumInserted" , "Number of DBG_VALUE instructions inserted", {0}, false}; |
49 | |
50 | namespace { |
51 | |
52 | // \brief If @MI is a DBG_VALUE with debug value described by a defined |
53 | // register, returns the number of this register. In the other case, returns 0. |
54 | static unsigned isDbgValueDescribedByReg(const MachineInstr &MI) { |
55 | assert(MI.isDebugValue() && "expected a DBG_VALUE")((MI.isDebugValue() && "expected a DBG_VALUE") ? static_cast <void> (0) : __assert_fail ("MI.isDebugValue() && \"expected a DBG_VALUE\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 55, __PRETTY_FUNCTION__)); |
56 | assert(MI.getNumOperands() == 4 && "malformed DBG_VALUE")((MI.getNumOperands() == 4 && "malformed DBG_VALUE") ? static_cast<void> (0) : __assert_fail ("MI.getNumOperands() == 4 && \"malformed DBG_VALUE\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 56, __PRETTY_FUNCTION__)); |
57 | // If location of variable is described using a register (directly |
58 | // or indirectly), this register is always a first operand. |
59 | return MI.getOperand(0).isReg() ? MI.getOperand(0).getReg() : 0; |
60 | } |
61 | |
62 | class LiveDebugValues : public MachineFunctionPass { |
63 | |
64 | private: |
65 | const TargetRegisterInfo *TRI; |
66 | const TargetInstrInfo *TII; |
67 | const TargetFrameLowering *TFI; |
68 | LexicalScopes LS; |
69 | |
70 | /// Keeps track of lexical scopes associated with a user value's source |
71 | /// location. |
72 | class UserValueScopes { |
73 | DebugLoc DL; |
74 | LexicalScopes &LS; |
75 | SmallPtrSet<const MachineBasicBlock *, 4> LBlocks; |
76 | |
77 | public: |
78 | UserValueScopes(DebugLoc D, LexicalScopes &L) : DL(std::move(D)), LS(L) {} |
79 | |
80 | /// Return true if current scope dominates at least one machine |
81 | /// instruction in a given machine basic block. |
82 | bool dominates(MachineBasicBlock *MBB) { |
83 | if (LBlocks.empty()) |
84 | LS.getMachineBasicBlocks(DL, LBlocks); |
85 | return LBlocks.count(MBB) != 0 || LS.dominates(DL, MBB); |
86 | } |
87 | }; |
88 | |
89 | /// Based on std::pair so it can be used as an index into a DenseMap. |
90 | typedef std::pair<const DILocalVariable *, const DILocation *> |
91 | DebugVariableBase; |
92 | /// A potentially inlined instance of a variable. |
93 | struct DebugVariable : public DebugVariableBase { |
94 | DebugVariable(const DILocalVariable *Var, const DILocation *InlinedAt) |
95 | : DebugVariableBase(Var, InlinedAt) {} |
96 | |
97 | const DILocalVariable *getVar() const { return this->first; }; |
98 | const DILocation *getInlinedAt() const { return this->second; }; |
99 | |
100 | bool operator<(const DebugVariable &DV) const { |
101 | if (getVar() == DV.getVar()) |
102 | return getInlinedAt() < DV.getInlinedAt(); |
103 | return getVar() < DV.getVar(); |
104 | } |
105 | }; |
106 | |
107 | /// A pair of debug variable and value location. |
108 | struct VarLoc { |
109 | const DebugVariable Var; |
110 | const MachineInstr &MI; ///< Only used for cloning a new DBG_VALUE. |
111 | mutable UserValueScopes UVS; |
112 | enum { InvalidKind = 0, RegisterKind } Kind; |
113 | |
114 | /// The value location. Stored separately to avoid repeatedly |
115 | /// extracting it from MI. |
116 | union { |
117 | struct { |
118 | uint32_t RegNo; |
119 | uint32_t Offset; |
120 | } RegisterLoc; |
121 | uint64_t Hash; |
122 | } Loc; |
123 | |
124 | VarLoc(const MachineInstr &MI, LexicalScopes &LS) |
125 | : Var(MI.getDebugVariable(), MI.getDebugLoc()->getInlinedAt()), MI(MI), |
126 | UVS(MI.getDebugLoc(), LS), Kind(InvalidKind) { |
127 | static_assert((sizeof(Loc) == sizeof(uint64_t)), |
128 | "hash does not cover all members of Loc"); |
129 | assert(MI.isDebugValue() && "not a DBG_VALUE")((MI.isDebugValue() && "not a DBG_VALUE") ? static_cast <void> (0) : __assert_fail ("MI.isDebugValue() && \"not a DBG_VALUE\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 129, __PRETTY_FUNCTION__)); |
130 | assert(MI.getNumOperands() == 4 && "malformed DBG_VALUE")((MI.getNumOperands() == 4 && "malformed DBG_VALUE") ? static_cast<void> (0) : __assert_fail ("MI.getNumOperands() == 4 && \"malformed DBG_VALUE\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 130, __PRETTY_FUNCTION__)); |
131 | if (int RegNo = isDbgValueDescribedByReg(MI)) { |
132 | Kind = RegisterKind; |
133 | Loc.RegisterLoc.RegNo = RegNo; |
134 | int64_t Offset = |
135 | MI.isIndirectDebugValue() ? MI.getOperand(1).getImm() : 0; |
136 | // We don't support offsets larger than 4GiB here. They are |
137 | // slated to be replaced with DIExpressions anyway. |
138 | // With indirect debug values used for spill locations, Offset |
139 | // can be negative. |
140 | if (Offset == INT64_MIN(-9223372036854775807L -1) || std::abs(Offset) >= (1LL << 32)) |
141 | Kind = InvalidKind; |
142 | else |
143 | Loc.RegisterLoc.Offset = Offset; |
144 | } |
145 | } |
146 | |
147 | /// If this variable is described by a register, return it, |
148 | /// otherwise return 0. |
149 | unsigned isDescribedByReg() const { |
150 | if (Kind == RegisterKind) |
151 | return Loc.RegisterLoc.RegNo; |
152 | return 0; |
153 | } |
154 | |
155 | /// Determine whether the lexical scope of this value's debug location |
156 | /// dominates MBB. |
157 | bool dominates(MachineBasicBlock &MBB) const { return UVS.dominates(&MBB); } |
158 | |
159 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) |
160 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void dump() const { MI.dump(); } |
161 | #endif |
162 | |
163 | bool operator==(const VarLoc &Other) const { |
164 | return Var == Other.Var && Loc.Hash == Other.Loc.Hash; |
165 | } |
166 | |
167 | /// This operator guarantees that VarLocs are sorted by Variable first. |
168 | bool operator<(const VarLoc &Other) const { |
169 | if (Var == Other.Var) |
170 | return Loc.Hash < Other.Loc.Hash; |
171 | return Var < Other.Var; |
172 | } |
173 | }; |
174 | |
175 | typedef UniqueVector<VarLoc> VarLocMap; |
176 | typedef SparseBitVector<> VarLocSet; |
177 | typedef SmallDenseMap<const MachineBasicBlock *, VarLocSet> VarLocInMBB; |
178 | struct SpillDebugPair { |
179 | MachineInstr *SpillInst; |
180 | MachineInstr *DebugInst; |
181 | }; |
182 | typedef SmallVector<SpillDebugPair, 4> SpillMap; |
183 | |
184 | /// This holds the working set of currently open ranges. For fast |
185 | /// access, this is done both as a set of VarLocIDs, and a map of |
186 | /// DebugVariable to recent VarLocID. Note that a DBG_VALUE ends all |
187 | /// previous open ranges for the same variable. |
188 | class OpenRangesSet { |
189 | VarLocSet VarLocs; |
190 | SmallDenseMap<DebugVariableBase, unsigned, 8> Vars; |
191 | |
192 | public: |
193 | const VarLocSet &getVarLocs() const { return VarLocs; } |
194 | |
195 | /// Terminate all open ranges for Var by removing it from the set. |
196 | void erase(DebugVariable Var) { |
197 | auto It = Vars.find(Var); |
198 | if (It != Vars.end()) { |
199 | unsigned ID = It->second; |
200 | VarLocs.reset(ID); |
201 | Vars.erase(It); |
202 | } |
203 | } |
204 | |
205 | /// Terminate all open ranges listed in \c KillSet by removing |
206 | /// them from the set. |
207 | void erase(const VarLocSet &KillSet, const VarLocMap &VarLocIDs) { |
208 | VarLocs.intersectWithComplement(KillSet); |
209 | for (unsigned ID : KillSet) |
210 | Vars.erase(VarLocIDs[ID].Var); |
211 | } |
212 | |
213 | /// Insert a new range into the set. |
214 | void insert(unsigned VarLocID, DebugVariableBase Var) { |
215 | VarLocs.set(VarLocID); |
216 | Vars.insert({Var, VarLocID}); |
217 | } |
218 | |
219 | /// Empty the set. |
220 | void clear() { |
221 | VarLocs.clear(); |
222 | Vars.clear(); |
223 | } |
224 | |
225 | /// Return whether the set is empty or not. |
226 | bool empty() const { |
227 | assert(Vars.empty() == VarLocs.empty() && "open ranges are inconsistent")((Vars.empty() == VarLocs.empty() && "open ranges are inconsistent" ) ? static_cast<void> (0) : __assert_fail ("Vars.empty() == VarLocs.empty() && \"open ranges are inconsistent\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 227, __PRETTY_FUNCTION__)); |
228 | return VarLocs.empty(); |
229 | } |
230 | }; |
231 | |
232 | bool isSpillInstruction(const MachineInstr &MI, MachineFunction *MF, |
233 | unsigned &Reg); |
234 | int extractSpillBaseRegAndOffset(const MachineInstr &MI, unsigned &Reg); |
235 | |
236 | void transferDebugValue(const MachineInstr &MI, OpenRangesSet &OpenRanges, |
237 | VarLocMap &VarLocIDs); |
238 | void transferSpillInst(MachineInstr &MI, OpenRangesSet &OpenRanges, |
239 | VarLocMap &VarLocIDs, SpillMap &Spills); |
240 | void transferRegisterDef(MachineInstr &MI, OpenRangesSet &OpenRanges, |
241 | const VarLocMap &VarLocIDs); |
242 | bool transferTerminatorInst(MachineInstr &MI, OpenRangesSet &OpenRanges, |
243 | VarLocInMBB &OutLocs, const VarLocMap &VarLocIDs); |
244 | bool transfer(MachineInstr &MI, OpenRangesSet &OpenRanges, |
245 | VarLocInMBB &OutLocs, VarLocMap &VarLocIDs, SpillMap &Spills, |
246 | bool transferSpills); |
247 | |
248 | bool join(MachineBasicBlock &MBB, VarLocInMBB &OutLocs, VarLocInMBB &InLocs, |
249 | const VarLocMap &VarLocIDs, |
250 | SmallPtrSet<const MachineBasicBlock *, 16> &Visited); |
251 | |
252 | bool ExtendRanges(MachineFunction &MF); |
253 | |
254 | public: |
255 | static char ID; |
256 | |
257 | /// Default construct and initialize the pass. |
258 | LiveDebugValues(); |
259 | |
260 | /// Tell the pass manager which passes we depend on and what |
261 | /// information we preserve. |
262 | void getAnalysisUsage(AnalysisUsage &AU) const override; |
263 | |
264 | MachineFunctionProperties getRequiredProperties() const override { |
265 | return MachineFunctionProperties().set( |
266 | MachineFunctionProperties::Property::NoVRegs); |
267 | } |
268 | |
269 | /// Print to ostream with a message. |
270 | void printVarLocInMBB(const MachineFunction &MF, const VarLocInMBB &V, |
271 | const VarLocMap &VarLocIDs, const char *msg, |
272 | raw_ostream &Out) const; |
273 | |
274 | /// Calculate the liveness information for the given machine function. |
275 | bool runOnMachineFunction(MachineFunction &MF) override; |
276 | }; |
277 | |
278 | } // namespace |
279 | |
280 | //===----------------------------------------------------------------------===// |
281 | // Implementation |
282 | //===----------------------------------------------------------------------===// |
283 | |
284 | char LiveDebugValues::ID = 0; |
285 | char &llvm::LiveDebugValuesID = LiveDebugValues::ID; |
286 | INITIALIZE_PASS(LiveDebugValues, DEBUG_TYPE, "Live DEBUG_VALUE analysis",static void *initializeLiveDebugValuesPassOnce(PassRegistry & Registry) { PassInfo *PI = new PassInfo( "Live DEBUG_VALUE analysis" , "livedebugvalues", &LiveDebugValues::ID, PassInfo::NormalCtor_t (callDefaultCtor<LiveDebugValues>), false, false); Registry .registerPass(*PI, true); return PI; } static llvm::once_flag InitializeLiveDebugValuesPassFlag; void llvm::initializeLiveDebugValuesPass (PassRegistry &Registry) { llvm::call_once(InitializeLiveDebugValuesPassFlag , initializeLiveDebugValuesPassOnce, std::ref(Registry)); } |
287 | false, false)static void *initializeLiveDebugValuesPassOnce(PassRegistry & Registry) { PassInfo *PI = new PassInfo( "Live DEBUG_VALUE analysis" , "livedebugvalues", &LiveDebugValues::ID, PassInfo::NormalCtor_t (callDefaultCtor<LiveDebugValues>), false, false); Registry .registerPass(*PI, true); return PI; } static llvm::once_flag InitializeLiveDebugValuesPassFlag; void llvm::initializeLiveDebugValuesPass (PassRegistry &Registry) { llvm::call_once(InitializeLiveDebugValuesPassFlag , initializeLiveDebugValuesPassOnce, std::ref(Registry)); } |
288 | |
289 | /// Default construct and initialize the pass. |
290 | LiveDebugValues::LiveDebugValues() : MachineFunctionPass(ID) { |
291 | initializeLiveDebugValuesPass(*PassRegistry::getPassRegistry()); |
292 | } |
293 | |
294 | /// Tell the pass manager which passes we depend on and what information we |
295 | /// preserve. |
296 | void LiveDebugValues::getAnalysisUsage(AnalysisUsage &AU) const { |
297 | AU.setPreservesCFG(); |
298 | MachineFunctionPass::getAnalysisUsage(AU); |
299 | } |
300 | |
301 | //===----------------------------------------------------------------------===// |
302 | // Debug Range Extension Implementation |
303 | //===----------------------------------------------------------------------===// |
304 | |
305 | #ifndef NDEBUG |
306 | void LiveDebugValues::printVarLocInMBB(const MachineFunction &MF, |
307 | const VarLocInMBB &V, |
308 | const VarLocMap &VarLocIDs, |
309 | const char *msg, |
310 | raw_ostream &Out) const { |
311 | Out << '\n' << msg << '\n'; |
312 | for (const MachineBasicBlock &BB : MF) { |
313 | const auto &L = V.lookup(&BB); |
314 | Out << "MBB: " << BB.getName() << ":\n"; |
315 | for (unsigned VLL : L) { |
316 | const VarLoc &VL = VarLocIDs[VLL]; |
317 | Out << " Var: " << VL.Var.getVar()->getName(); |
318 | Out << " MI: "; |
319 | VL.dump(); |
320 | } |
321 | } |
322 | Out << "\n"; |
323 | } |
324 | #endif |
325 | |
326 | /// Given a spill instruction, extract the register and offset used to |
327 | /// address the spill location in a target independent way. |
328 | int LiveDebugValues::extractSpillBaseRegAndOffset(const MachineInstr &MI, |
329 | unsigned &Reg) { |
330 | assert(MI.hasOneMemOperand() &&((MI.hasOneMemOperand() && "Spill instruction does not have exactly one memory operand?" ) ? static_cast<void> (0) : __assert_fail ("MI.hasOneMemOperand() && \"Spill instruction does not have exactly one memory operand?\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 331, __PRETTY_FUNCTION__)) |
331 | "Spill instruction does not have exactly one memory operand?")((MI.hasOneMemOperand() && "Spill instruction does not have exactly one memory operand?" ) ? static_cast<void> (0) : __assert_fail ("MI.hasOneMemOperand() && \"Spill instruction does not have exactly one memory operand?\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 331, __PRETTY_FUNCTION__)); |
332 | auto MMOI = MI.memoperands_begin(); |
333 | const PseudoSourceValue *PVal = (*MMOI)->getPseudoValue(); |
334 | assert(PVal->kind() == PseudoSourceValue::FixedStack &&((PVal->kind() == PseudoSourceValue::FixedStack && "Inconsistent memory operand in spill instruction") ? static_cast <void> (0) : __assert_fail ("PVal->kind() == PseudoSourceValue::FixedStack && \"Inconsistent memory operand in spill instruction\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 335, __PRETTY_FUNCTION__)) |
335 | "Inconsistent memory operand in spill instruction")((PVal->kind() == PseudoSourceValue::FixedStack && "Inconsistent memory operand in spill instruction") ? static_cast <void> (0) : __assert_fail ("PVal->kind() == PseudoSourceValue::FixedStack && \"Inconsistent memory operand in spill instruction\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 335, __PRETTY_FUNCTION__)); |
336 | int FI = cast<FixedStackPseudoSourceValue>(PVal)->getFrameIndex(); |
337 | const MachineBasicBlock *MBB = MI.getParent(); |
338 | return TFI->getFrameIndexReference(*MBB->getParent(), FI, Reg); |
339 | } |
340 | |
341 | /// End all previous ranges related to @MI and start a new range from @MI |
342 | /// if it is a DBG_VALUE instr. |
343 | void LiveDebugValues::transferDebugValue(const MachineInstr &MI, |
344 | OpenRangesSet &OpenRanges, |
345 | VarLocMap &VarLocIDs) { |
346 | if (!MI.isDebugValue()) |
347 | return; |
348 | const DILocalVariable *Var = MI.getDebugVariable(); |
349 | const DILocation *DebugLoc = MI.getDebugLoc(); |
350 | const DILocation *InlinedAt = DebugLoc->getInlinedAt(); |
351 | assert(Var->isValidLocationForIntrinsic(DebugLoc) &&((Var->isValidLocationForIntrinsic(DebugLoc) && "Expected inlined-at fields to agree" ) ? static_cast<void> (0) : __assert_fail ("Var->isValidLocationForIntrinsic(DebugLoc) && \"Expected inlined-at fields to agree\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 352, __PRETTY_FUNCTION__)) |
352 | "Expected inlined-at fields to agree")((Var->isValidLocationForIntrinsic(DebugLoc) && "Expected inlined-at fields to agree" ) ? static_cast<void> (0) : __assert_fail ("Var->isValidLocationForIntrinsic(DebugLoc) && \"Expected inlined-at fields to agree\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 352, __PRETTY_FUNCTION__)); |
353 | |
354 | // End all previous ranges of Var. |
355 | DebugVariable V(Var, InlinedAt); |
356 | OpenRanges.erase(V); |
357 | |
358 | // Add the VarLoc to OpenRanges from this DBG_VALUE. |
359 | // TODO: Currently handles DBG_VALUE which has only reg as location. |
360 | if (isDbgValueDescribedByReg(MI)) { |
361 | VarLoc VL(MI, LS); |
362 | unsigned ID = VarLocIDs.insert(VL); |
363 | OpenRanges.insert(ID, VL.Var); |
364 | } |
365 | } |
366 | |
367 | /// A definition of a register may mark the end of a range. |
368 | void LiveDebugValues::transferRegisterDef(MachineInstr &MI, |
369 | OpenRangesSet &OpenRanges, |
370 | const VarLocMap &VarLocIDs) { |
371 | MachineFunction *MF = MI.getParent()->getParent(); |
372 | const TargetLowering *TLI = MF->getSubtarget().getTargetLowering(); |
373 | unsigned SP = TLI->getStackPointerRegisterToSaveRestore(); |
374 | SparseBitVector<> KillSet; |
375 | for (const MachineOperand &MO : MI.operands()) { |
376 | // Determine whether the operand is a register def. Assume that call |
377 | // instructions never clobber SP, because some backends (e.g., AArch64) |
378 | // never list SP in the regmask. |
379 | if (MO.isReg() && MO.isDef() && MO.getReg() && |
380 | TRI->isPhysicalRegister(MO.getReg()) && |
381 | !(MI.isCall() && MO.getReg() == SP)) { |
382 | // Remove ranges of all aliased registers. |
383 | for (MCRegAliasIterator RAI(MO.getReg(), TRI, true); RAI.isValid(); ++RAI) |
384 | for (unsigned ID : OpenRanges.getVarLocs()) |
385 | if (VarLocIDs[ID].isDescribedByReg() == *RAI) |
386 | KillSet.set(ID); |
387 | } else if (MO.isRegMask()) { |
388 | // Remove ranges of all clobbered registers. Register masks don't usually |
389 | // list SP as preserved. While the debug info may be off for an |
390 | // instruction or two around callee-cleanup calls, transferring the |
391 | // DEBUG_VALUE across the call is still a better user experience. |
392 | for (unsigned ID : OpenRanges.getVarLocs()) { |
393 | unsigned Reg = VarLocIDs[ID].isDescribedByReg(); |
394 | if (Reg && Reg != SP && MO.clobbersPhysReg(Reg)) |
395 | KillSet.set(ID); |
396 | } |
397 | } |
398 | } |
399 | OpenRanges.erase(KillSet, VarLocIDs); |
400 | } |
401 | |
402 | /// Decide if @MI is a spill instruction and return true if it is. We use 2 |
403 | /// criteria to make this decision: |
404 | /// - Is this instruction a store to a spill slot? |
405 | /// - Is there a register operand that is both used and killed? |
406 | /// TODO: Store optimization can fold spills into other stores (including |
407 | /// other spills). We do not handle this yet (more than one memory operand). |
408 | bool LiveDebugValues::isSpillInstruction(const MachineInstr &MI, |
409 | MachineFunction *MF, unsigned &Reg) { |
410 | const MachineFrameInfo &FrameInfo = MF->getFrameInfo(); |
411 | int FI; |
412 | const MachineMemOperand *MMO; |
413 | |
414 | // TODO: Handle multiple stores folded into one. |
415 | if (!MI.hasOneMemOperand()) |
416 | return false; |
417 | |
418 | // To identify a spill instruction, use the same criteria as in AsmPrinter. |
419 | if (!((TII->isStoreToStackSlotPostFE(MI, FI) || |
420 | TII->hasStoreToStackSlot(MI, MMO, FI)) && |
421 | FrameInfo.isSpillSlotObjectIndex(FI))) |
422 | return false; |
423 | |
424 | // In a spill instruction generated by the InlineSpiller the spilled register |
425 | // has its kill flag set. Return false if we don't find such a register. |
426 | Reg = 0; |
427 | for (const MachineOperand &MO : MI.operands()) { |
428 | if (MO.isReg() && MO.isUse() && MO.isKill()) { |
429 | Reg = MO.getReg(); |
430 | break; |
431 | } |
432 | } |
433 | return Reg != 0; |
434 | } |
435 | |
436 | /// A spilled register may indicate that we have to end the current range of |
437 | /// a variable and create a new one for the spill location. |
438 | /// We don't want to insert any instructions in transfer(), so we just create |
439 | /// the DBG_VALUE witout inserting it and keep track of it in @Spills. |
440 | /// It will be inserted into the BB when we're done iterating over the |
441 | /// instructions. |
442 | void LiveDebugValues::transferSpillInst(MachineInstr &MI, |
443 | OpenRangesSet &OpenRanges, |
444 | VarLocMap &VarLocIDs, |
445 | SpillMap &Spills) { |
446 | unsigned Reg; |
447 | MachineFunction *MF = MI.getParent()->getParent(); |
448 | if (!isSpillInstruction(MI, MF, Reg)) |
449 | return; |
450 | |
451 | // Check if the register is the location of a debug value. |
452 | for (unsigned ID : OpenRanges.getVarLocs()) { |
453 | if (VarLocIDs[ID].isDescribedByReg() == Reg) { |
454 | DEBUG(dbgs() << "Spilling Register " << PrintReg(Reg, TRI) << '('do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { dbgs() << "Spilling Register " << PrintReg(Reg, TRI) << '(' << VarLocIDs[ID].Var.getVar ()->getName() << ")\n"; } } while (false) |
455 | << VarLocIDs[ID].Var.getVar()->getName() << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { dbgs() << "Spilling Register " << PrintReg(Reg, TRI) << '(' << VarLocIDs[ID].Var.getVar ()->getName() << ")\n"; } } while (false); |
456 | |
457 | // Create a DBG_VALUE instruction to describe the Var in its spilled |
458 | // location, but don't insert it yet to avoid invalidating the |
459 | // iterator in our caller. |
460 | unsigned SpillBase; |
461 | int SpillOffset = extractSpillBaseRegAndOffset(MI, SpillBase); |
462 | const MachineInstr *DMI = &VarLocIDs[ID].MI; |
463 | MachineInstr *SpDMI = |
464 | BuildMI(*MF, DMI->getDebugLoc(), DMI->getDesc(), true, SpillBase, 0, |
465 | DMI->getDebugVariable(), DMI->getDebugExpression()); |
466 | SpDMI->getOperand(1).setImm(SpillOffset); |
467 | DEBUG(dbgs() << "Creating DBG_VALUE inst for spill: ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { dbgs() << "Creating DBG_VALUE inst for spill: " ; SpDMI->print(dbgs(), false, TII); } } while (false) |
468 | SpDMI->print(dbgs(), false, TII))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { dbgs() << "Creating DBG_VALUE inst for spill: " ; SpDMI->print(dbgs(), false, TII); } } while (false); |
469 | |
470 | // The newly created DBG_VALUE instruction SpDMI must be inserted after |
471 | // MI. Keep track of the pairing. |
472 | SpillDebugPair MIP = {&MI, SpDMI}; |
473 | Spills.push_back(MIP); |
474 | |
475 | // End all previous ranges of Var. |
476 | OpenRanges.erase(VarLocIDs[ID].Var); |
477 | |
478 | // Add the VarLoc to OpenRanges. |
479 | VarLoc VL(*SpDMI, LS); |
480 | unsigned SpillLocID = VarLocIDs.insert(VL); |
481 | OpenRanges.insert(SpillLocID, VL.Var); |
482 | return; |
483 | } |
484 | } |
485 | } |
486 | |
487 | /// Terminate all open ranges at the end of the current basic block. |
488 | bool LiveDebugValues::transferTerminatorInst(MachineInstr &MI, |
489 | OpenRangesSet &OpenRanges, |
490 | VarLocInMBB &OutLocs, |
491 | const VarLocMap &VarLocIDs) { |
492 | bool Changed = false; |
493 | const MachineBasicBlock *CurMBB = MI.getParent(); |
494 | if (!(MI.isTerminator() || (&MI == &CurMBB->instr_back()))) |
495 | return false; |
496 | |
497 | if (OpenRanges.empty()) |
498 | return false; |
499 | |
500 | DEBUG(for (unsigned ID : OpenRanges.getVarLocs()) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { for (unsigned ID : OpenRanges.getVarLocs ()) { dbgs() << "Add to OutLocs: "; VarLocIDs[ID].dump( ); }; } } while (false) |
501 | // Copy OpenRanges to OutLocs, if not already present.do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { for (unsigned ID : OpenRanges.getVarLocs ()) { dbgs() << "Add to OutLocs: "; VarLocIDs[ID].dump( ); }; } } while (false) |
502 | dbgs() << "Add to OutLocs: "; VarLocIDs[ID].dump();do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { for (unsigned ID : OpenRanges.getVarLocs ()) { dbgs() << "Add to OutLocs: "; VarLocIDs[ID].dump( ); }; } } while (false) |
503 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { for (unsigned ID : OpenRanges.getVarLocs ()) { dbgs() << "Add to OutLocs: "; VarLocIDs[ID].dump( ); }; } } while (false); |
504 | VarLocSet &VLS = OutLocs[CurMBB]; |
505 | Changed = VLS |= OpenRanges.getVarLocs(); |
506 | OpenRanges.clear(); |
507 | return Changed; |
508 | } |
509 | |
510 | /// This routine creates OpenRanges and OutLocs. |
511 | bool LiveDebugValues::transfer(MachineInstr &MI, OpenRangesSet &OpenRanges, |
512 | VarLocInMBB &OutLocs, VarLocMap &VarLocIDs, |
513 | SpillMap &Spills, bool transferSpills) { |
514 | bool Changed = false; |
515 | transferDebugValue(MI, OpenRanges, VarLocIDs); |
516 | transferRegisterDef(MI, OpenRanges, VarLocIDs); |
517 | if (transferSpills) |
518 | transferSpillInst(MI, OpenRanges, VarLocIDs, Spills); |
519 | Changed = transferTerminatorInst(MI, OpenRanges, OutLocs, VarLocIDs); |
520 | return Changed; |
521 | } |
522 | |
523 | /// This routine joins the analysis results of all incoming edges in @MBB by |
524 | /// inserting a new DBG_VALUE instruction at the start of the @MBB - if the same |
525 | /// source variable in all the predecessors of @MBB reside in the same location. |
526 | bool LiveDebugValues::join(MachineBasicBlock &MBB, VarLocInMBB &OutLocs, |
527 | VarLocInMBB &InLocs, const VarLocMap &VarLocIDs, |
528 | SmallPtrSet<const MachineBasicBlock *, 16> &Visited) { |
529 | DEBUG(dbgs() << "join MBB: " << MBB.getName() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { dbgs() << "join MBB: " << MBB .getName() << "\n"; } } while (false); |
530 | bool Changed = false; |
531 | |
532 | VarLocSet InLocsT; // Temporary incoming locations. |
533 | |
534 | // For all predecessors of this MBB, find the set of VarLocs that |
535 | // can be joined. |
536 | int NumVisited = 0; |
537 | for (auto p : MBB.predecessors()) { |
538 | // Ignore unvisited predecessor blocks. As we are processing |
539 | // the blocks in reverse post-order any unvisited block can |
540 | // be considered to not remove any incoming values. |
541 | if (!Visited.count(p)) |
542 | continue; |
543 | auto OL = OutLocs.find(p); |
544 | // Join is null in case of empty OutLocs from any of the pred. |
545 | if (OL == OutLocs.end()) |
546 | return false; |
547 | |
548 | // Just copy over the Out locs to incoming locs for the first visited |
549 | // predecessor, and for all other predecessors join the Out locs. |
550 | if (!NumVisited) |
551 | InLocsT = OL->second; |
552 | else |
553 | InLocsT &= OL->second; |
554 | NumVisited++; |
555 | } |
556 | |
557 | // Filter out DBG_VALUES that are out of scope. |
558 | VarLocSet KillSet; |
559 | for (auto ID : InLocsT) |
560 | if (!VarLocIDs[ID].dominates(MBB)) |
561 | KillSet.set(ID); |
562 | InLocsT.intersectWithComplement(KillSet); |
563 | |
564 | // As we are processing blocks in reverse post-order we |
565 | // should have processed at least one predecessor, unless it |
566 | // is the entry block which has no predecessor. |
567 | assert((NumVisited || MBB.pred_empty()) &&(((NumVisited || MBB.pred_empty()) && "Should have processed at least one predecessor" ) ? static_cast<void> (0) : __assert_fail ("(NumVisited || MBB.pred_empty()) && \"Should have processed at least one predecessor\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 568, __PRETTY_FUNCTION__)) |
568 | "Should have processed at least one predecessor")(((NumVisited || MBB.pred_empty()) && "Should have processed at least one predecessor" ) ? static_cast<void> (0) : __assert_fail ("(NumVisited || MBB.pred_empty()) && \"Should have processed at least one predecessor\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 568, __PRETTY_FUNCTION__)); |
569 | if (InLocsT.empty()) |
570 | return false; |
571 | |
572 | VarLocSet &ILS = InLocs[&MBB]; |
573 | |
574 | // Insert DBG_VALUE instructions, if not already inserted. |
575 | VarLocSet Diff = InLocsT; |
576 | Diff.intersectWithComplement(ILS); |
577 | for (auto ID : Diff) { |
578 | // This VarLoc is not found in InLocs i.e. it is not yet inserted. So, a |
579 | // new range is started for the var from the mbb's beginning by inserting |
580 | // a new DBG_VALUE. transfer() will end this range however appropriate. |
581 | const VarLoc &DiffIt = VarLocIDs[ID]; |
582 | const MachineInstr *DMI = &DiffIt.MI; |
583 | MachineInstr *MI = |
584 | BuildMI(MBB, MBB.instr_begin(), DMI->getDebugLoc(), DMI->getDesc(), |
585 | DMI->isIndirectDebugValue(), DMI->getOperand(0).getReg(), 0, |
586 | DMI->getDebugVariable(), DMI->getDebugExpression()); |
587 | if (DMI->isIndirectDebugValue()) |
588 | MI->getOperand(1).setImm(DMI->getOperand(1).getImm()); |
589 | DEBUG(dbgs() << "Inserted: "; MI->dump();)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { dbgs() << "Inserted: "; MI->dump ();; } } while (false); |
590 | ILS.set(ID); |
591 | ++NumInserted; |
592 | Changed = true; |
593 | } |
594 | return Changed; |
595 | } |
596 | |
597 | /// Calculate the liveness information for the given machine function and |
598 | /// extend ranges across basic blocks. |
599 | bool LiveDebugValues::ExtendRanges(MachineFunction &MF) { |
600 | |
601 | DEBUG(dbgs() << "\nDebug Range Extension\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { dbgs() << "\nDebug Range Extension\n" ; } } while (false); |
602 | |
603 | bool Changed = false; |
604 | bool OLChanged = false; |
605 | bool MBBJoined = false; |
606 | |
607 | VarLocMap VarLocIDs; // Map VarLoc<>unique ID for use in bitvectors. |
608 | OpenRangesSet OpenRanges; // Ranges that are open until end of bb. |
609 | VarLocInMBB OutLocs; // Ranges that exist beyond bb. |
610 | VarLocInMBB InLocs; // Ranges that are incoming after joining. |
611 | SpillMap Spills; // DBG_VALUEs associated with spills. |
612 | |
613 | DenseMap<unsigned int, MachineBasicBlock *> OrderToBB; |
614 | DenseMap<MachineBasicBlock *, unsigned int> BBToOrder; |
615 | std::priority_queue<unsigned int, std::vector<unsigned int>, |
616 | std::greater<unsigned int>> |
617 | Worklist; |
618 | std::priority_queue<unsigned int, std::vector<unsigned int>, |
619 | std::greater<unsigned int>> |
620 | Pending; |
621 | |
622 | // Initialize every mbb with OutLocs. |
623 | // We are not looking at any spill instructions during the initial pass |
624 | // over the BBs. The LiveDebugVariables pass has already created DBG_VALUE |
625 | // instructions for spills of registers that are known to be user variables |
626 | // within the BB in which the spill occurs. |
627 | for (auto &MBB : MF) |
628 | for (auto &MI : MBB) |
629 | transfer(MI, OpenRanges, OutLocs, VarLocIDs, Spills, |
630 | /*transferSpills=*/false); |
631 | |
632 | DEBUG(printVarLocInMBB(MF, OutLocs, VarLocIDs, "OutLocs after initialization",do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { printVarLocInMBB(MF, OutLocs, VarLocIDs , "OutLocs after initialization", dbgs()); } } while (false) |
633 | dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { printVarLocInMBB(MF, OutLocs, VarLocIDs , "OutLocs after initialization", dbgs()); } } while (false); |
634 | |
635 | ReversePostOrderTraversal<MachineFunction *> RPOT(&MF); |
636 | unsigned int RPONumber = 0; |
637 | for (auto RI = RPOT.begin(), RE = RPOT.end(); RI != RE; ++RI) { |
638 | OrderToBB[RPONumber] = *RI; |
639 | BBToOrder[*RI] = RPONumber; |
640 | Worklist.push(RPONumber); |
641 | ++RPONumber; |
642 | } |
643 | // This is a standard "union of predecessor outs" dataflow problem. |
644 | // To solve it, we perform join() and transfer() using the two worklist method |
645 | // until the ranges converge. |
646 | // Ranges have converged when both worklists are empty. |
647 | SmallPtrSet<const MachineBasicBlock *, 16> Visited; |
648 | while (!Worklist.empty() || !Pending.empty()) { |
649 | // We track what is on the pending worklist to avoid inserting the same |
650 | // thing twice. We could avoid this with a custom priority queue, but this |
651 | // is probably not worth it. |
652 | SmallPtrSet<MachineBasicBlock *, 16> OnPending; |
653 | DEBUG(dbgs() << "Processing Worklist\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { dbgs() << "Processing Worklist\n" ; } } while (false); |
654 | while (!Worklist.empty()) { |
655 | MachineBasicBlock *MBB = OrderToBB[Worklist.top()]; |
656 | Worklist.pop(); |
657 | MBBJoined = join(*MBB, OutLocs, InLocs, VarLocIDs, Visited); |
658 | Visited.insert(MBB); |
659 | if (MBBJoined) { |
660 | MBBJoined = false; |
Value stored to 'MBBJoined' is never read | |
661 | Changed = true; |
662 | // Now that we have started to extend ranges across BBs we need to |
663 | // examine spill instructions to see whether they spill registers that |
664 | // correspond to user variables. |
665 | for (auto &MI : *MBB) |
666 | OLChanged |= transfer(MI, OpenRanges, OutLocs, VarLocIDs, Spills, |
667 | /*transferSpills=*/true); |
668 | |
669 | // Add any DBG_VALUE instructions necessitated by spills. |
670 | for (auto &SP : Spills) |
671 | MBB->insertAfter(MachineBasicBlock::iterator(*SP.SpillInst), |
672 | SP.DebugInst); |
673 | Spills.clear(); |
674 | |
675 | DEBUG(printVarLocInMBB(MF, OutLocs, VarLocIDs,do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { printVarLocInMBB(MF, OutLocs, VarLocIDs , "OutLocs after propagating", dbgs()); } } while (false) |
676 | "OutLocs after propagating", dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { printVarLocInMBB(MF, OutLocs, VarLocIDs , "OutLocs after propagating", dbgs()); } } while (false); |
677 | DEBUG(printVarLocInMBB(MF, InLocs, VarLocIDs,do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { printVarLocInMBB(MF, InLocs, VarLocIDs , "InLocs after propagating", dbgs()); } } while (false) |
678 | "InLocs after propagating", dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { printVarLocInMBB(MF, InLocs, VarLocIDs , "InLocs after propagating", dbgs()); } } while (false); |
679 | |
680 | if (OLChanged) { |
681 | OLChanged = false; |
682 | for (auto s : MBB->successors()) |
683 | if (OnPending.insert(s).second) { |
684 | Pending.push(BBToOrder[s]); |
685 | } |
686 | } |
687 | } |
688 | } |
689 | Worklist.swap(Pending); |
690 | // At this point, pending must be empty, since it was just the empty |
691 | // worklist |
692 | assert(Pending.empty() && "Pending should be empty")((Pending.empty() && "Pending should be empty") ? static_cast <void> (0) : __assert_fail ("Pending.empty() && \"Pending should be empty\"" , "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/CodeGen/LiveDebugValues.cpp" , 692, __PRETTY_FUNCTION__)); |
693 | } |
694 | |
695 | DEBUG(printVarLocInMBB(MF, OutLocs, VarLocIDs, "Final OutLocs", dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { printVarLocInMBB(MF, OutLocs, VarLocIDs , "Final OutLocs", dbgs()); } } while (false); |
696 | DEBUG(printVarLocInMBB(MF, InLocs, VarLocIDs, "Final InLocs", dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("livedebugvalues")) { printVarLocInMBB(MF, InLocs, VarLocIDs , "Final InLocs", dbgs()); } } while (false); |
697 | return Changed; |
698 | } |
699 | |
700 | bool LiveDebugValues::runOnMachineFunction(MachineFunction &MF) { |
701 | if (!MF.getFunction()->getSubprogram()) |
702 | // LiveDebugValues will already have removed all DBG_VALUEs. |
703 | return false; |
704 | |
705 | TRI = MF.getSubtarget().getRegisterInfo(); |
706 | TII = MF.getSubtarget().getInstrInfo(); |
707 | TFI = MF.getSubtarget().getFrameLowering(); |
708 | LS.initialize(MF); |
709 | |
710 | bool Changed = ExtendRanges(MF); |
711 | return Changed; |
712 | } |