Bug Summary

File:lib/CodeGen/LiveDebugValues.cpp
Warning:line 809, column 9
Value stored to 'MBBJoined' is never read

Annotated Source Code

Press '?' to see keyboard shortcuts

clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name LiveDebugValues.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-8/lib/clang/8.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/lib/CodeGen -I /build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/include -I /build/llvm-toolchain-snapshot-8~svn345461/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/include/clang/8.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-8/lib/clang/8.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/lib/CodeGen -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-10-27-211344-32123-1 -x c++ /build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp -faddrsig
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/DenseMap.h"
22#include "llvm/ADT/PostOrderIterator.h"
23#include "llvm/ADT/SmallPtrSet.h"
24#include "llvm/ADT/SmallVector.h"
25#include "llvm/ADT/SparseBitVector.h"
26#include "llvm/ADT/Statistic.h"
27#include "llvm/ADT/UniqueVector.h"
28#include "llvm/CodeGen/LexicalScopes.h"
29#include "llvm/CodeGen/MachineBasicBlock.h"
30#include "llvm/CodeGen/MachineFrameInfo.h"
31#include "llvm/CodeGen/MachineFunction.h"
32#include "llvm/CodeGen/MachineFunctionPass.h"
33#include "llvm/CodeGen/MachineInstr.h"
34#include "llvm/CodeGen/MachineInstrBuilder.h"
35#include "llvm/CodeGen/MachineMemOperand.h"
36#include "llvm/CodeGen/MachineOperand.h"
37#include "llvm/CodeGen/PseudoSourceValue.h"
38#include "llvm/CodeGen/TargetFrameLowering.h"
39#include "llvm/CodeGen/TargetInstrInfo.h"
40#include "llvm/CodeGen/TargetLowering.h"
41#include "llvm/CodeGen/TargetRegisterInfo.h"
42#include "llvm/CodeGen/TargetSubtargetInfo.h"
43#include "llvm/CodeGen/RegisterScavenging.h"
44#include "llvm/Config/llvm-config.h"
45#include "llvm/IR/DebugInfoMetadata.h"
46#include "llvm/IR/DebugLoc.h"
47#include "llvm/IR/Function.h"
48#include "llvm/IR/Module.h"
49#include "llvm/MC/MCRegisterInfo.h"
50#include "llvm/Pass.h"
51#include "llvm/Support/Casting.h"
52#include "llvm/Support/Compiler.h"
53#include "llvm/Support/Debug.h"
54#include "llvm/Support/raw_ostream.h"
55#include <algorithm>
56#include <cassert>
57#include <cstdint>
58#include <functional>
59#include <queue>
60#include <utility>
61#include <vector>
62
63using namespace llvm;
64
65#define DEBUG_TYPE"livedebugvalues" "livedebugvalues"
66
67STATISTIC(NumInserted, "Number of DBG_VALUE instructions inserted")static llvm::Statistic NumInserted = {"livedebugvalues", "NumInserted"
, "Number of DBG_VALUE instructions inserted", {0}, {false}}
;
68
69// If @MI is a DBG_VALUE with debug value described by a defined
70// register, returns the number of this register. In the other case, returns 0.
71static unsigned isDbgValueDescribedByReg(const MachineInstr &MI) {
72 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\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 72, __PRETTY_FUNCTION__))
;
73 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\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 73, __PRETTY_FUNCTION__))
;
74 // If location of variable is described using a register (directly
75 // or indirectly), this register is always a first operand.
76 return MI.getOperand(0).isReg() ? MI.getOperand(0).getReg() : 0;
77}
78
79namespace {
80
81class LiveDebugValues : public MachineFunctionPass {
82private:
83 const TargetRegisterInfo *TRI;
84 const TargetInstrInfo *TII;
85 const TargetFrameLowering *TFI;
86 BitVector CalleeSavedRegs;
87 LexicalScopes LS;
88
89 /// Keeps track of lexical scopes associated with a user value's source
90 /// location.
91 class UserValueScopes {
92 DebugLoc DL;
93 LexicalScopes &LS;
94 SmallPtrSet<const MachineBasicBlock *, 4> LBlocks;
95
96 public:
97 UserValueScopes(DebugLoc D, LexicalScopes &L) : DL(std::move(D)), LS(L) {}
98
99 /// Return true if current scope dominates at least one machine
100 /// instruction in a given machine basic block.
101 bool dominates(MachineBasicBlock *MBB) {
102 if (LBlocks.empty())
103 LS.getMachineBasicBlocks(DL, LBlocks);
104 return LBlocks.count(MBB) != 0 || LS.dominates(DL, MBB);
105 }
106 };
107
108 /// Based on std::pair so it can be used as an index into a DenseMap.
109 using DebugVariableBase =
110 std::pair<const DILocalVariable *, const DILocation *>;
111 /// A potentially inlined instance of a variable.
112 struct DebugVariable : public DebugVariableBase {
113 DebugVariable(const DILocalVariable *Var, const DILocation *InlinedAt)
114 : DebugVariableBase(Var, InlinedAt) {}
115
116 const DILocalVariable *getVar() const { return this->first; }
117 const DILocation *getInlinedAt() const { return this->second; }
118
119 bool operator<(const DebugVariable &DV) const {
120 if (getVar() == DV.getVar())
121 return getInlinedAt() < DV.getInlinedAt();
122 return getVar() < DV.getVar();
123 }
124 };
125
126 /// A pair of debug variable and value location.
127 struct VarLoc {
128 const DebugVariable Var;
129 const MachineInstr &MI; ///< Only used for cloning a new DBG_VALUE.
130 mutable UserValueScopes UVS;
131 enum { InvalidKind = 0, RegisterKind } Kind = InvalidKind;
132
133 /// The value location. Stored separately to avoid repeatedly
134 /// extracting it from MI.
135 union {
136 uint64_t RegNo;
137 uint64_t Hash;
138 } Loc;
139
140 VarLoc(const MachineInstr &MI, LexicalScopes &LS)
141 : Var(MI.getDebugVariable(), MI.getDebugLoc()->getInlinedAt()), MI(MI),
142 UVS(MI.getDebugLoc(), LS) {
143 static_assert((sizeof(Loc) == sizeof(uint64_t)),
144 "hash does not cover all members of Loc");
145 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\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 145, __PRETTY_FUNCTION__))
;
146 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\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 146, __PRETTY_FUNCTION__))
;
147 if (int RegNo = isDbgValueDescribedByReg(MI)) {
148 Kind = RegisterKind;
149 Loc.RegNo = RegNo;
150 }
151 }
152
153 /// If this variable is described by a register, return it,
154 /// otherwise return 0.
155 unsigned isDescribedByReg() const {
156 if (Kind == RegisterKind)
157 return Loc.RegNo;
158 return 0;
159 }
160
161 /// Determine whether the lexical scope of this value's debug location
162 /// dominates MBB.
163 bool dominates(MachineBasicBlock &MBB) const { return UVS.dominates(&MBB); }
164
165#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
166 LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void dump() const { MI.dump(); }
167#endif
168
169 bool operator==(const VarLoc &Other) const {
170 return Var == Other.Var && Loc.Hash == Other.Loc.Hash;
171 }
172
173 /// This operator guarantees that VarLocs are sorted by Variable first.
174 bool operator<(const VarLoc &Other) const {
175 if (Var == Other.Var)
176 return Loc.Hash < Other.Loc.Hash;
177 return Var < Other.Var;
178 }
179 };
180
181 using VarLocMap = UniqueVector<VarLoc>;
182 using VarLocSet = SparseBitVector<>;
183 using VarLocInMBB = SmallDenseMap<const MachineBasicBlock *, VarLocSet>;
184 struct TransferDebugPair {
185 MachineInstr *TransferInst;
186 MachineInstr *DebugInst;
187 };
188 using TransferMap = SmallVector<TransferDebugPair, 4>;
189
190 /// This holds the working set of currently open ranges. For fast
191 /// access, this is done both as a set of VarLocIDs, and a map of
192 /// DebugVariable to recent VarLocID. Note that a DBG_VALUE ends all
193 /// previous open ranges for the same variable.
194 class OpenRangesSet {
195 VarLocSet VarLocs;
196 SmallDenseMap<DebugVariableBase, unsigned, 8> Vars;
197
198 public:
199 const VarLocSet &getVarLocs() const { return VarLocs; }
200
201 /// Terminate all open ranges for Var by removing it from the set.
202 void erase(DebugVariable Var) {
203 auto It = Vars.find(Var);
204 if (It != Vars.end()) {
205 unsigned ID = It->second;
206 VarLocs.reset(ID);
207 Vars.erase(It);
208 }
209 }
210
211 /// Terminate all open ranges listed in \c KillSet by removing
212 /// them from the set.
213 void erase(const VarLocSet &KillSet, const VarLocMap &VarLocIDs) {
214 VarLocs.intersectWithComplement(KillSet);
215 for (unsigned ID : KillSet)
216 Vars.erase(VarLocIDs[ID].Var);
217 }
218
219 /// Insert a new range into the set.
220 void insert(unsigned VarLocID, DebugVariableBase Var) {
221 VarLocs.set(VarLocID);
222 Vars.insert({Var, VarLocID});
223 }
224
225 /// Empty the set.
226 void clear() {
227 VarLocs.clear();
228 Vars.clear();
229 }
230
231 /// Return whether the set is empty or not.
232 bool empty() const {
233 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\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 233, __PRETTY_FUNCTION__))
;
234 return VarLocs.empty();
235 }
236 };
237
238 bool isSpillInstruction(const MachineInstr &MI, MachineFunction *MF,
239 unsigned &Reg);
240 int extractSpillBaseRegAndOffset(const MachineInstr &MI, unsigned &Reg);
241 void insertTransferDebugPair(MachineInstr &MI, OpenRangesSet &OpenRanges,
242 TransferMap &Transfers, VarLocMap &VarLocIDs,
243 unsigned OldVarID, unsigned NewReg = 0);
244
245 void transferDebugValue(const MachineInstr &MI, OpenRangesSet &OpenRanges,
246 VarLocMap &VarLocIDs);
247 void transferSpillInst(MachineInstr &MI, OpenRangesSet &OpenRanges,
248 VarLocMap &VarLocIDs, TransferMap &Transfers);
249 void transferRegisterCopy(MachineInstr &MI, OpenRangesSet &OpenRanges,
250 VarLocMap &VarLocIDs, TransferMap &Transfers);
251 void transferRegisterDef(MachineInstr &MI, OpenRangesSet &OpenRanges,
252 const VarLocMap &VarLocIDs);
253 bool transferTerminatorInst(MachineInstr &MI, OpenRangesSet &OpenRanges,
254 VarLocInMBB &OutLocs, const VarLocMap &VarLocIDs);
255 bool process(MachineInstr &MI, OpenRangesSet &OpenRanges,
256 VarLocInMBB &OutLocs, VarLocMap &VarLocIDs,
257 TransferMap &Transfers, bool transferChanges);
258
259 bool join(MachineBasicBlock &MBB, VarLocInMBB &OutLocs, VarLocInMBB &InLocs,
260 const VarLocMap &VarLocIDs,
261 SmallPtrSet<const MachineBasicBlock *, 16> &Visited,
262 SmallPtrSetImpl<const MachineBasicBlock *> &ArtificialBlocks);
263
264 bool ExtendRanges(MachineFunction &MF);
265
266public:
267 static char ID;
268
269 /// Default construct and initialize the pass.
270 LiveDebugValues();
271
272 /// Tell the pass manager which passes we depend on and what
273 /// information we preserve.
274 void getAnalysisUsage(AnalysisUsage &AU) const override;
275
276 MachineFunctionProperties getRequiredProperties() const override {
277 return MachineFunctionProperties().set(
278 MachineFunctionProperties::Property::NoVRegs);
279 }
280
281 /// Print to ostream with a message.
282 void printVarLocInMBB(const MachineFunction &MF, const VarLocInMBB &V,
283 const VarLocMap &VarLocIDs, const char *msg,
284 raw_ostream &Out) const;
285
286 /// Calculate the liveness information for the given machine function.
287 bool runOnMachineFunction(MachineFunction &MF) override;
288};
289
290} // end anonymous namespace
291
292//===----------------------------------------------------------------------===//
293// Implementation
294//===----------------------------------------------------------------------===//
295
296char LiveDebugValues::ID = 0;
297
298char &llvm::LiveDebugValuesID = LiveDebugValues::ID;
299
300INITIALIZE_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)); }
301 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)); }
302
303/// Default construct and initialize the pass.
304LiveDebugValues::LiveDebugValues() : MachineFunctionPass(ID) {
305 initializeLiveDebugValuesPass(*PassRegistry::getPassRegistry());
306}
307
308/// Tell the pass manager which passes we depend on and what information we
309/// preserve.
310void LiveDebugValues::getAnalysisUsage(AnalysisUsage &AU) const {
311 AU.setPreservesCFG();
312 MachineFunctionPass::getAnalysisUsage(AU);
313}
314
315//===----------------------------------------------------------------------===//
316// Debug Range Extension Implementation
317//===----------------------------------------------------------------------===//
318
319#ifndef NDEBUG
320void LiveDebugValues::printVarLocInMBB(const MachineFunction &MF,
321 const VarLocInMBB &V,
322 const VarLocMap &VarLocIDs,
323 const char *msg,
324 raw_ostream &Out) const {
325 Out << '\n' << msg << '\n';
326 for (const MachineBasicBlock &BB : MF) {
327 const VarLocSet &L = V.lookup(&BB);
328 if (L.empty())
329 continue;
330 Out << "MBB: " << BB.getNumber() << ":\n";
331 for (unsigned VLL : L) {
332 const VarLoc &VL = VarLocIDs[VLL];
333 Out << " Var: " << VL.Var.getVar()->getName();
334 Out << " MI: ";
335 VL.dump();
336 }
337 }
338 Out << "\n";
339}
340#endif
341
342/// Given a spill instruction, extract the register and offset used to
343/// address the spill location in a target independent way.
344int LiveDebugValues::extractSpillBaseRegAndOffset(const MachineInstr &MI,
345 unsigned &Reg) {
346 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?\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 347, __PRETTY_FUNCTION__))
347 "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?\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 347, __PRETTY_FUNCTION__))
;
348 auto MMOI = MI.memoperands_begin();
349 const PseudoSourceValue *PVal = (*MMOI)->getPseudoValue();
350 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\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 351, __PRETTY_FUNCTION__))
351 "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\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 351, __PRETTY_FUNCTION__))
;
352 int FI = cast<FixedStackPseudoSourceValue>(PVal)->getFrameIndex();
353 const MachineBasicBlock *MBB = MI.getParent();
354 return TFI->getFrameIndexReference(*MBB->getParent(), FI, Reg);
355}
356
357/// End all previous ranges related to @MI and start a new range from @MI
358/// if it is a DBG_VALUE instr.
359void LiveDebugValues::transferDebugValue(const MachineInstr &MI,
360 OpenRangesSet &OpenRanges,
361 VarLocMap &VarLocIDs) {
362 if (!MI.isDebugValue())
363 return;
364 const DILocalVariable *Var = MI.getDebugVariable();
365 const DILocation *DebugLoc = MI.getDebugLoc();
366 const DILocation *InlinedAt = DebugLoc->getInlinedAt();
367 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\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 368, __PRETTY_FUNCTION__))
368 "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\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 368, __PRETTY_FUNCTION__))
;
369
370 // End all previous ranges of Var.
371 DebugVariable V(Var, InlinedAt);
372 OpenRanges.erase(V);
373
374 // Add the VarLoc to OpenRanges from this DBG_VALUE.
375 // TODO: Currently handles DBG_VALUE which has only reg as location.
376 if (isDbgValueDescribedByReg(MI)) {
377 VarLoc VL(MI, LS);
378 unsigned ID = VarLocIDs.insert(VL);
379 OpenRanges.insert(ID, VL.Var);
380 }
381}
382
383/// Create new TransferDebugPair and insert it in \p Transfers. The VarLoc
384/// with \p OldVarID should be deleted form \p OpenRanges and replaced with
385/// new VarLoc. If \p NewReg is different than default zero value then the
386/// new location will be register location created by the copy like instruction,
387/// otherwise it is variable's location on the stack.
388void LiveDebugValues::insertTransferDebugPair(
389 MachineInstr &MI, OpenRangesSet &OpenRanges, TransferMap &Transfers,
390 VarLocMap &VarLocIDs, unsigned OldVarID, unsigned NewReg) {
391 const MachineInstr *DMI = &VarLocIDs[OldVarID].MI;
392 MachineFunction *MF = MI.getParent()->getParent();
393 MachineInstr *NewDMI;
394 if (NewReg) {
395 // Create a DBG_VALUE instruction to describe the Var in its new
396 // register location.
397 NewDMI = BuildMI(*MF, DMI->getDebugLoc(), DMI->getDesc(),
398 DMI->isIndirectDebugValue(), NewReg,
399 DMI->getDebugVariable(), DMI->getDebugExpression());
400 if (DMI->isIndirectDebugValue())
401 NewDMI->getOperand(1).setImm(DMI->getOperand(1).getImm());
402 LLVM_DEBUG(dbgs() << "Creating DBG_VALUE inst for register copy: ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { dbgs() << "Creating DBG_VALUE inst for register copy: "
; NewDMI->print(dbgs(), false, false, false, TII); } } while
(false)
403 NewDMI->print(dbgs(), false, false, false, TII))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { dbgs() << "Creating DBG_VALUE inst for register copy: "
; NewDMI->print(dbgs(), false, false, false, TII); } } while
(false)
;
404 } else {
405 // Create a DBG_VALUE instruction to describe the Var in its spilled
406 // location.
407 unsigned SpillBase;
408 int SpillOffset = extractSpillBaseRegAndOffset(MI, SpillBase);
409 auto *SpillExpr = DIExpression::prepend(DMI->getDebugExpression(),
410 DIExpression::NoDeref, SpillOffset);
411 NewDMI = BuildMI(*MF, DMI->getDebugLoc(), DMI->getDesc(), true, SpillBase,
412 DMI->getDebugVariable(), SpillExpr);
413 LLVM_DEBUG(dbgs() << "Creating DBG_VALUE inst for spill: ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { dbgs() << "Creating DBG_VALUE inst for spill: "
; NewDMI->print(dbgs(), false, false, false, TII); } } while
(false)
414 NewDMI->print(dbgs(), false, false, false, TII))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { dbgs() << "Creating DBG_VALUE inst for spill: "
; NewDMI->print(dbgs(), false, false, false, TII); } } while
(false)
;
415 }
416
417 // The newly created DBG_VALUE instruction NewDMI must be inserted after
418 // MI. Keep track of the pairing.
419 TransferDebugPair MIP = {&MI, NewDMI};
420 Transfers.push_back(MIP);
421
422 // End all previous ranges of Var.
423 OpenRanges.erase(VarLocIDs[OldVarID].Var);
424
425 // Add the VarLoc to OpenRanges.
426 VarLoc VL(*NewDMI, LS);
427 unsigned LocID = VarLocIDs.insert(VL);
428 OpenRanges.insert(LocID, VL.Var);
429}
430
431/// A definition of a register may mark the end of a range.
432void LiveDebugValues::transferRegisterDef(MachineInstr &MI,
433 OpenRangesSet &OpenRanges,
434 const VarLocMap &VarLocIDs) {
435 MachineFunction *MF = MI.getMF();
436 const TargetLowering *TLI = MF->getSubtarget().getTargetLowering();
437 unsigned SP = TLI->getStackPointerRegisterToSaveRestore();
438 SparseBitVector<> KillSet;
439 for (const MachineOperand &MO : MI.operands()) {
440 // Determine whether the operand is a register def. Assume that call
441 // instructions never clobber SP, because some backends (e.g., AArch64)
442 // never list SP in the regmask.
443 if (MO.isReg() && MO.isDef() && MO.getReg() &&
444 TRI->isPhysicalRegister(MO.getReg()) &&
445 !(MI.isCall() && MO.getReg() == SP)) {
446 // Remove ranges of all aliased registers.
447 for (MCRegAliasIterator RAI(MO.getReg(), TRI, true); RAI.isValid(); ++RAI)
448 for (unsigned ID : OpenRanges.getVarLocs())
449 if (VarLocIDs[ID].isDescribedByReg() == *RAI)
450 KillSet.set(ID);
451 } else if (MO.isRegMask()) {
452 // Remove ranges of all clobbered registers. Register masks don't usually
453 // list SP as preserved. While the debug info may be off for an
454 // instruction or two around callee-cleanup calls, transferring the
455 // DEBUG_VALUE across the call is still a better user experience.
456 for (unsigned ID : OpenRanges.getVarLocs()) {
457 unsigned Reg = VarLocIDs[ID].isDescribedByReg();
458 if (Reg && Reg != SP && MO.clobbersPhysReg(Reg))
459 KillSet.set(ID);
460 }
461 }
462 }
463 OpenRanges.erase(KillSet, VarLocIDs);
464}
465
466/// Decide if @MI is a spill instruction and return true if it is. We use 2
467/// criteria to make this decision:
468/// - Is this instruction a store to a spill slot?
469/// - Is there a register operand that is both used and killed?
470/// TODO: Store optimization can fold spills into other stores (including
471/// other spills). We do not handle this yet (more than one memory operand).
472bool LiveDebugValues::isSpillInstruction(const MachineInstr &MI,
473 MachineFunction *MF, unsigned &Reg) {
474 const MachineFrameInfo &FrameInfo = MF->getFrameInfo();
475 int FI;
476 SmallVector<const MachineMemOperand*, 1> Accesses;
477
478 // TODO: Handle multiple stores folded into one.
479 if (!MI.hasOneMemOperand())
480 return false;
481
482 // To identify a spill instruction, use the same criteria as in AsmPrinter.
483 if (!((TII->isStoreToStackSlotPostFE(MI, FI) &&
484 FrameInfo.isSpillSlotObjectIndex(FI)) ||
485 (TII->hasStoreToStackSlot(MI, Accesses) &&
486 llvm::any_of(Accesses, [&FrameInfo](const MachineMemOperand *MMO) {
487 return FrameInfo.isSpillSlotObjectIndex(
488 cast<FixedStackPseudoSourceValue>(MMO->getPseudoValue())
489 ->getFrameIndex());
490 }))))
491 return false;
492
493 auto isKilledReg = [&](const MachineOperand MO, unsigned &Reg) {
494 if (!MO.isReg() || !MO.isUse()) {
495 Reg = 0;
496 return false;
497 }
498 Reg = MO.getReg();
499 return MO.isKill();
500 };
501
502 for (const MachineOperand &MO : MI.operands()) {
503 // In a spill instruction generated by the InlineSpiller the spilled
504 // register has its kill flag set.
505 if (isKilledReg(MO, Reg))
506 return true;
507 if (Reg != 0) {
508 // Check whether next instruction kills the spilled register.
509 // FIXME: Current solution does not cover search for killed register in
510 // bundles and instructions further down the chain.
511 auto NextI = std::next(MI.getIterator());
512 // Skip next instruction that points to basic block end iterator.
513 if (MI.getParent()->end() == NextI)
514 continue;
515 unsigned RegNext;
516 for (const MachineOperand &MONext : NextI->operands()) {
517 // Return true if we came across the register from the
518 // previous spill instruction that is killed in NextI.
519 if (isKilledReg(MONext, RegNext) && RegNext == Reg)
520 return true;
521 }
522 }
523 }
524 // Return false if we didn't find spilled register.
525 return false;
526}
527
528/// A spilled register may indicate that we have to end the current range of
529/// a variable and create a new one for the spill location.
530/// We don't want to insert any instructions in process(), so we just create
531/// the DBG_VALUE without inserting it and keep track of it in \p Transfers.
532/// It will be inserted into the BB when we're done iterating over the
533/// instructions.
534void LiveDebugValues::transferSpillInst(MachineInstr &MI,
535 OpenRangesSet &OpenRanges,
536 VarLocMap &VarLocIDs,
537 TransferMap &Transfers) {
538 unsigned Reg;
539 MachineFunction *MF = MI.getMF();
540 if (!isSpillInstruction(MI, MF, Reg))
541 return;
542
543 // Check if the register is the location of a debug value.
544 for (unsigned ID : OpenRanges.getVarLocs()) {
545 if (VarLocIDs[ID].isDescribedByReg() == Reg) {
546 LLVM_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)
547 << 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)
;
548 insertTransferDebugPair(MI, OpenRanges, Transfers, VarLocIDs, ID);
549 return;
550 }
551 }
552}
553
554/// If \p MI is a register copy instruction, that copies a previously tracked
555/// value from one register to another register that is callee saved, we
556/// create new DBG_VALUE instruction described with copy destination register.
557void LiveDebugValues::transferRegisterCopy(MachineInstr &MI,
558 OpenRangesSet &OpenRanges,
559 VarLocMap &VarLocIDs,
560 TransferMap &Transfers) {
561 const MachineOperand *SrcRegOp, *DestRegOp;
562
563 if (!TII->isCopyInstr(MI, SrcRegOp, DestRegOp) || !SrcRegOp->isKill() ||
564 !DestRegOp->isDef())
565 return;
566
567 auto isCalleSavedReg = [&](unsigned Reg) {
568 for (MCRegAliasIterator RAI(Reg, TRI, true); RAI.isValid(); ++RAI)
569 if (CalleeSavedRegs.test(*RAI))
570 return true;
571 return false;
572 };
573
574 unsigned SrcReg = SrcRegOp->getReg();
575 unsigned DestReg = DestRegOp->getReg();
576
577 // We want to recognize instructions where destination register is callee
578 // saved register. If register that could be clobbered by the call is
579 // included, there would be a great chance that it is going to be clobbered
580 // soon. It is more likely that previous register location, which is callee
581 // saved, is going to stay unclobbered longer, even if it is killed.
582 if (!isCalleSavedReg(DestReg))
583 return;
584
585 for (unsigned ID : OpenRanges.getVarLocs()) {
586 if (VarLocIDs[ID].isDescribedByReg() == SrcReg) {
587 insertTransferDebugPair(MI, OpenRanges, Transfers, VarLocIDs, ID,
588 DestReg);
589 return;
590 }
591 }
592}
593
594/// Terminate all open ranges at the end of the current basic block.
595bool LiveDebugValues::transferTerminatorInst(MachineInstr &MI,
596 OpenRangesSet &OpenRanges,
597 VarLocInMBB &OutLocs,
598 const VarLocMap &VarLocIDs) {
599 bool Changed = false;
600 const MachineBasicBlock *CurMBB = MI.getParent();
601 if (!(MI.isTerminator() || (&MI == &CurMBB->back())))
602 return false;
603
604 if (OpenRanges.empty())
605 return false;
606
607 LLVM_DEBUG(for (unsigned IDdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { for (unsigned ID : OpenRanges.getVarLocs
()) { dbgs() << "Add to OutLocs in MBB #" << CurMBB
->getNumber() << ": "; VarLocIDs[ID].dump(); }; } }
while (false)
608 : OpenRanges.getVarLocs()) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { for (unsigned ID : OpenRanges.getVarLocs
()) { dbgs() << "Add to OutLocs in MBB #" << CurMBB
->getNumber() << ": "; VarLocIDs[ID].dump(); }; } }
while (false)
609 // Copy OpenRanges to OutLocs, if not already present.do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { for (unsigned ID : OpenRanges.getVarLocs
()) { dbgs() << "Add to OutLocs in MBB #" << CurMBB
->getNumber() << ": "; VarLocIDs[ID].dump(); }; } }
while (false)
610 dbgs() << "Add to OutLocs in MBB #" << CurMBB->getNumber() << ": ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { for (unsigned ID : OpenRanges.getVarLocs
()) { dbgs() << "Add to OutLocs in MBB #" << CurMBB
->getNumber() << ": "; VarLocIDs[ID].dump(); }; } }
while (false)
611 VarLocIDs[ID].dump();do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { for (unsigned ID : OpenRanges.getVarLocs
()) { dbgs() << "Add to OutLocs in MBB #" << CurMBB
->getNumber() << ": "; VarLocIDs[ID].dump(); }; } }
while (false)
612 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { for (unsigned ID : OpenRanges.getVarLocs
()) { dbgs() << "Add to OutLocs in MBB #" << CurMBB
->getNumber() << ": "; VarLocIDs[ID].dump(); }; } }
while (false)
;
613 VarLocSet &VLS = OutLocs[CurMBB];
614 Changed = VLS |= OpenRanges.getVarLocs();
615 OpenRanges.clear();
616 return Changed;
617}
618
619/// This routine creates OpenRanges and OutLocs.
620bool LiveDebugValues::process(MachineInstr &MI, OpenRangesSet &OpenRanges,
621 VarLocInMBB &OutLocs, VarLocMap &VarLocIDs,
622 TransferMap &Transfers, bool transferChanges) {
623 bool Changed = false;
624 transferDebugValue(MI, OpenRanges, VarLocIDs);
625 transferRegisterDef(MI, OpenRanges, VarLocIDs);
626 if (transferChanges) {
627 transferRegisterCopy(MI, OpenRanges, VarLocIDs, Transfers);
628 transferSpillInst(MI, OpenRanges, VarLocIDs, Transfers);
629 }
630 Changed = transferTerminatorInst(MI, OpenRanges, OutLocs, VarLocIDs);
631 return Changed;
632}
633
634/// This routine joins the analysis results of all incoming edges in @MBB by
635/// inserting a new DBG_VALUE instruction at the start of the @MBB - if the same
636/// source variable in all the predecessors of @MBB reside in the same location.
637bool LiveDebugValues::join(
638 MachineBasicBlock &MBB, VarLocInMBB &OutLocs, VarLocInMBB &InLocs,
639 const VarLocMap &VarLocIDs,
640 SmallPtrSet<const MachineBasicBlock *, 16> &Visited,
641 SmallPtrSetImpl<const MachineBasicBlock *> &ArtificialBlocks) {
642 LLVM_DEBUG(dbgs() << "join MBB: " << MBB.getNumber() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { dbgs() << "join MBB: " << MBB
.getNumber() << "\n"; } } while (false)
;
643 bool Changed = false;
644
645 VarLocSet InLocsT; // Temporary incoming locations.
646
647 // For all predecessors of this MBB, find the set of VarLocs that
648 // can be joined.
649 int NumVisited = 0;
650 for (auto p : MBB.predecessors()) {
651 // Ignore unvisited predecessor blocks. As we are processing
652 // the blocks in reverse post-order any unvisited block can
653 // be considered to not remove any incoming values.
654 if (!Visited.count(p)) {
655 LLVM_DEBUG(dbgs() << " ignoring unvisited pred MBB: " << p->getNumber()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { dbgs() << " ignoring unvisited pred MBB: "
<< p->getNumber() << "\n"; } } while (false)
656 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { dbgs() << " ignoring unvisited pred MBB: "
<< p->getNumber() << "\n"; } } while (false)
;
657 continue;
658 }
659 auto OL = OutLocs.find(p);
660 // Join is null in case of empty OutLocs from any of the pred.
661 if (OL == OutLocs.end())
662 return false;
663
664 // Just copy over the Out locs to incoming locs for the first visited
665 // predecessor, and for all other predecessors join the Out locs.
666 if (!NumVisited)
667 InLocsT = OL->second;
668 else
669 InLocsT &= OL->second;
670
671 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { { if (!InLocsT.empty()) { for (auto ID
: InLocsT) dbgs() << " gathered candidate incoming var: "
<< VarLocIDs[ID].Var.getVar()->getName() << "\n"
; } }; } } while (false)
672 if (!InLocsT.empty()) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { { if (!InLocsT.empty()) { for (auto ID
: InLocsT) dbgs() << " gathered candidate incoming var: "
<< VarLocIDs[ID].Var.getVar()->getName() << "\n"
; } }; } } while (false)
673 for (auto ID : InLocsT)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { { if (!InLocsT.empty()) { for (auto ID
: InLocsT) dbgs() << " gathered candidate incoming var: "
<< VarLocIDs[ID].Var.getVar()->getName() << "\n"
; } }; } } while (false)
674 dbgs() << " gathered candidate incoming var: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { { if (!InLocsT.empty()) { for (auto ID
: InLocsT) dbgs() << " gathered candidate incoming var: "
<< VarLocIDs[ID].Var.getVar()->getName() << "\n"
; } }; } } while (false)
675 << VarLocIDs[ID].Var.getVar()->getName() << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { { if (!InLocsT.empty()) { for (auto ID
: InLocsT) dbgs() << " gathered candidate incoming var: "
<< VarLocIDs[ID].Var.getVar()->getName() << "\n"
; } }; } } while (false)
676 }do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { { if (!InLocsT.empty()) { for (auto ID
: InLocsT) dbgs() << " gathered candidate incoming var: "
<< VarLocIDs[ID].Var.getVar()->getName() << "\n"
; } }; } } while (false)
677 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { { if (!InLocsT.empty()) { for (auto ID
: InLocsT) dbgs() << " gathered candidate incoming var: "
<< VarLocIDs[ID].Var.getVar()->getName() << "\n"
; } }; } } while (false)
;
678
679 NumVisited++;
680 }
681
682 // Filter out DBG_VALUES that are out of scope.
683 VarLocSet KillSet;
684 bool IsArtificial = ArtificialBlocks.count(&MBB);
685 if (!IsArtificial) {
686 for (auto ID : InLocsT) {
687 if (!VarLocIDs[ID].dominates(MBB)) {
688 KillSet.set(ID);
689 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { { auto Name = VarLocIDs[ID].Var.getVar
()->getName(); dbgs() << " killing " << Name <<
", it doesn't dominate MBB\n"; }; } } while (false)
690 auto Name = VarLocIDs[ID].Var.getVar()->getName();do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { { auto Name = VarLocIDs[ID].Var.getVar
()->getName(); dbgs() << " killing " << Name <<
", it doesn't dominate MBB\n"; }; } } while (false)
691 dbgs() << " killing " << Name << ", it doesn't dominate MBB\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { { auto Name = VarLocIDs[ID].Var.getVar
()->getName(); dbgs() << " killing " << Name <<
", it doesn't dominate MBB\n"; }; } } while (false)
692 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { { auto Name = VarLocIDs[ID].Var.getVar
()->getName(); dbgs() << " killing " << Name <<
", it doesn't dominate MBB\n"; }; } } while (false)
;
693 }
694 }
695 }
696 InLocsT.intersectWithComplement(KillSet);
697
698 // As we are processing blocks in reverse post-order we
699 // should have processed at least one predecessor, unless it
700 // is the entry block which has no predecessor.
701 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\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 702, __PRETTY_FUNCTION__))
702 "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\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 702, __PRETTY_FUNCTION__))
;
703 if (InLocsT.empty())
704 return false;
705
706 VarLocSet &ILS = InLocs[&MBB];
707
708 // Insert DBG_VALUE instructions, if not already inserted.
709 VarLocSet Diff = InLocsT;
710 Diff.intersectWithComplement(ILS);
711 for (auto ID : Diff) {
712 // This VarLoc is not found in InLocs i.e. it is not yet inserted. So, a
713 // new range is started for the var from the mbb's beginning by inserting
714 // a new DBG_VALUE. process() will end this range however appropriate.
715 const VarLoc &DiffIt = VarLocIDs[ID];
716 const MachineInstr *DMI = &DiffIt.MI;
717 MachineInstr *MI =
718 BuildMI(MBB, MBB.instr_begin(), DMI->getDebugLoc(), DMI->getDesc(),
719 DMI->isIndirectDebugValue(), DMI->getOperand(0).getReg(),
720 DMI->getDebugVariable(), DMI->getDebugExpression());
721 if (DMI->isIndirectDebugValue())
722 MI->getOperand(1).setImm(DMI->getOperand(1).getImm());
723 LLVM_DEBUG(dbgs() << "Inserted: "; MI->dump();)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { dbgs() << "Inserted: "; MI->dump
();; } } while (false)
;
724 ILS.set(ID);
725 ++NumInserted;
726 Changed = true;
727 }
728 return Changed;
729}
730
731/// Calculate the liveness information for the given machine function and
732/// extend ranges across basic blocks.
733bool LiveDebugValues::ExtendRanges(MachineFunction &MF) {
734 LLVM_DEBUG(dbgs() << "\nDebug Range Extension\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { dbgs() << "\nDebug Range Extension\n"
; } } while (false)
;
735
736 bool Changed = false;
737 bool OLChanged = false;
738 bool MBBJoined = false;
739
740 VarLocMap VarLocIDs; // Map VarLoc<>unique ID for use in bitvectors.
741 OpenRangesSet OpenRanges; // Ranges that are open until end of bb.
742 VarLocInMBB OutLocs; // Ranges that exist beyond bb.
743 VarLocInMBB InLocs; // Ranges that are incoming after joining.
744 TransferMap Transfers; // DBG_VALUEs associated with spills.
745
746 // Blocks which are artificial, i.e. blocks which exclusively contain
747 // instructions without locations, or with line 0 locations.
748 SmallPtrSet<const MachineBasicBlock *, 16> ArtificialBlocks;
749
750 DenseMap<unsigned int, MachineBasicBlock *> OrderToBB;
751 DenseMap<MachineBasicBlock *, unsigned int> BBToOrder;
752 std::priority_queue<unsigned int, std::vector<unsigned int>,
753 std::greater<unsigned int>>
754 Worklist;
755 std::priority_queue<unsigned int, std::vector<unsigned int>,
756 std::greater<unsigned int>>
757 Pending;
758
759 enum : bool { dontTransferChanges = false, transferChanges = true };
760
761 // Initialize every mbb with OutLocs.
762 // We are not looking at any spill instructions during the initial pass
763 // over the BBs. The LiveDebugVariables pass has already created DBG_VALUE
764 // instructions for spills of registers that are known to be user variables
765 // within the BB in which the spill occurs.
766 for (auto &MBB : MF)
767 for (auto &MI : MBB)
768 process(MI, OpenRanges, OutLocs, VarLocIDs, Transfers,
769 dontTransferChanges);
770
771 auto hasNonArtificialLocation = [](const MachineInstr &MI) -> bool {
772 if (const DebugLoc &DL = MI.getDebugLoc())
773 return DL.getLine() != 0;
774 return false;
775 };
776 for (auto &MBB : MF)
777 if (none_of(MBB.instrs(), hasNonArtificialLocation))
778 ArtificialBlocks.insert(&MBB);
779
780 LLVM_DEBUG(printVarLocInMBB(MF, OutLocs, VarLocIDs,do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { printVarLocInMBB(MF, OutLocs, VarLocIDs
, "OutLocs after initialization", dbgs()); } } while (false)
781 "OutLocs after initialization", dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { printVarLocInMBB(MF, OutLocs, VarLocIDs
, "OutLocs after initialization", dbgs()); } } while (false)
;
782
783 ReversePostOrderTraversal<MachineFunction *> RPOT(&MF);
784 unsigned int RPONumber = 0;
785 for (auto RI = RPOT.begin(), RE = RPOT.end(); RI != RE; ++RI) {
786 OrderToBB[RPONumber] = *RI;
787 BBToOrder[*RI] = RPONumber;
788 Worklist.push(RPONumber);
789 ++RPONumber;
790 }
791 // This is a standard "union of predecessor outs" dataflow problem.
792 // To solve it, we perform join() and process() using the two worklist method
793 // until the ranges converge.
794 // Ranges have converged when both worklists are empty.
795 SmallPtrSet<const MachineBasicBlock *, 16> Visited;
796 while (!Worklist.empty() || !Pending.empty()) {
797 // We track what is on the pending worklist to avoid inserting the same
798 // thing twice. We could avoid this with a custom priority queue, but this
799 // is probably not worth it.
800 SmallPtrSet<MachineBasicBlock *, 16> OnPending;
801 LLVM_DEBUG(dbgs() << "Processing Worklist\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { dbgs() << "Processing Worklist\n"
; } } while (false)
;
802 while (!Worklist.empty()) {
803 MachineBasicBlock *MBB = OrderToBB[Worklist.top()];
804 Worklist.pop();
805 MBBJoined =
806 join(*MBB, OutLocs, InLocs, VarLocIDs, Visited, ArtificialBlocks);
807 Visited.insert(MBB);
808 if (MBBJoined) {
809 MBBJoined = false;
Value stored to 'MBBJoined' is never read
810 Changed = true;
811 // Now that we have started to extend ranges across BBs we need to
812 // examine spill instructions to see whether they spill registers that
813 // correspond to user variables.
814 for (auto &MI : *MBB)
815 OLChanged |= process(MI, OpenRanges, OutLocs, VarLocIDs, Transfers,
816 transferChanges);
817
818 // Add any DBG_VALUE instructions necessitated by spills.
819 for (auto &TR : Transfers)
820 MBB->insertAfter(MachineBasicBlock::iterator(*TR.TransferInst),
821 TR.DebugInst);
822 Transfers.clear();
823
824 LLVM_DEBUG(printVarLocInMBB(MF, OutLocs, VarLocIDs,do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { printVarLocInMBB(MF, OutLocs, VarLocIDs
, "OutLocs after propagating", dbgs()); } } while (false)
825 "OutLocs after propagating", dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { printVarLocInMBB(MF, OutLocs, VarLocIDs
, "OutLocs after propagating", dbgs()); } } while (false)
;
826 LLVM_DEBUG(printVarLocInMBB(MF, InLocs, VarLocIDs,do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { printVarLocInMBB(MF, InLocs, VarLocIDs
, "InLocs after propagating", dbgs()); } } while (false)
827 "InLocs after propagating", dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { printVarLocInMBB(MF, InLocs, VarLocIDs
, "InLocs after propagating", dbgs()); } } while (false)
;
828
829 if (OLChanged) {
830 OLChanged = false;
831 for (auto s : MBB->successors())
832 if (OnPending.insert(s).second) {
833 Pending.push(BBToOrder[s]);
834 }
835 }
836 }
837 }
838 Worklist.swap(Pending);
839 // At this point, pending must be empty, since it was just the empty
840 // worklist
841 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\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/CodeGen/LiveDebugValues.cpp"
, 841, __PRETTY_FUNCTION__))
;
842 }
843
844 LLVM_DEBUG(printVarLocInMBB(MF, OutLocs, VarLocIDs, "Final OutLocs", dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { printVarLocInMBB(MF, OutLocs, VarLocIDs
, "Final OutLocs", dbgs()); } } while (false)
;
845 LLVM_DEBUG(printVarLocInMBB(MF, InLocs, VarLocIDs, "Final InLocs", dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("livedebugvalues")) { printVarLocInMBB(MF, InLocs, VarLocIDs
, "Final InLocs", dbgs()); } } while (false)
;
846 return Changed;
847}
848
849bool LiveDebugValues::runOnMachineFunction(MachineFunction &MF) {
850 if (!MF.getFunction().getSubprogram())
851 // LiveDebugValues will already have removed all DBG_VALUEs.
852 return false;
853
854 // Skip functions from NoDebug compilation units.
855 if (MF.getFunction().getSubprogram()->getUnit()->getEmissionKind() ==
856 DICompileUnit::NoDebug)
857 return false;
858
859 TRI = MF.getSubtarget().getRegisterInfo();
860 TII = MF.getSubtarget().getInstrInfo();
861 TFI = MF.getSubtarget().getFrameLowering();
862 TFI->determineCalleeSaves(MF, CalleeSavedRegs,
863 make_unique<RegScavenger>().get());
864 LS.initialize(MF);
865
866 bool Changed = ExtendRanges(MF);
867 return Changed;
868}