Bug Summary

File:lib/Transforms/Scalar/SCCP.cpp
Warning:line 488, column 5
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name SCCP.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 -analyzer-config-compatibility-mode=true -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-9/lib/clang/9.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-9~svn359426/build-llvm/lib/Transforms/Scalar -I /build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar -I /build/llvm-toolchain-snapshot-9~svn359426/build-llvm/include -I /build/llvm-toolchain-snapshot-9~svn359426/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/9.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-9/lib/clang/9.0.0/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-9~svn359426/build-llvm/lib/Transforms/Scalar -fdebug-prefix-map=/build/llvm-toolchain-snapshot-9~svn359426=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2019-05-01-032957-29988-1 -x c++ /build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp -faddrsig

/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp

1//===- SCCP.cpp - Sparse Conditional Constant Propagation -----------------===//
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 implements sparse conditional constant propagation and merging:
10//
11// Specifically, this:
12// * Assumes values are constant unless proven otherwise
13// * Assumes BasicBlocks are dead unless proven otherwise
14// * Proves values to be constant, and replaces them with constants
15// * Proves conditional branches to be unconditional
16//
17//===----------------------------------------------------------------------===//
18
19#include "llvm/Transforms/Scalar/SCCP.h"
20#include "llvm/ADT/ArrayRef.h"
21#include "llvm/ADT/DenseMap.h"
22#include "llvm/ADT/DenseSet.h"
23#include "llvm/ADT/PointerIntPair.h"
24#include "llvm/ADT/STLExtras.h"
25#include "llvm/ADT/SmallPtrSet.h"
26#include "llvm/ADT/SmallVector.h"
27#include "llvm/ADT/Statistic.h"
28#include "llvm/Analysis/ConstantFolding.h"
29#include "llvm/Analysis/GlobalsModRef.h"
30#include "llvm/Analysis/TargetLibraryInfo.h"
31#include "llvm/Transforms/Utils/Local.h"
32#include "llvm/Analysis/ValueLattice.h"
33#include "llvm/Analysis/ValueLatticeUtils.h"
34#include "llvm/IR/BasicBlock.h"
35#include "llvm/IR/CallSite.h"
36#include "llvm/IR/Constant.h"
37#include "llvm/IR/Constants.h"
38#include "llvm/IR/DataLayout.h"
39#include "llvm/IR/DerivedTypes.h"
40#include "llvm/IR/Function.h"
41#include "llvm/IR/GlobalVariable.h"
42#include "llvm/IR/InstVisitor.h"
43#include "llvm/IR/InstrTypes.h"
44#include "llvm/IR/Instruction.h"
45#include "llvm/IR/Instructions.h"
46#include "llvm/IR/Module.h"
47#include "llvm/IR/PassManager.h"
48#include "llvm/IR/Type.h"
49#include "llvm/IR/User.h"
50#include "llvm/IR/Value.h"
51#include "llvm/Pass.h"
52#include "llvm/Support/Casting.h"
53#include "llvm/Support/Debug.h"
54#include "llvm/Support/ErrorHandling.h"
55#include "llvm/Support/raw_ostream.h"
56#include "llvm/Transforms/Scalar.h"
57#include "llvm/Transforms/Utils/PredicateInfo.h"
58#include <cassert>
59#include <utility>
60#include <vector>
61
62using namespace llvm;
63
64#define DEBUG_TYPE"sccp" "sccp"
65
66STATISTIC(NumInstRemoved, "Number of instructions removed")static llvm::Statistic NumInstRemoved = {"sccp", "NumInstRemoved"
, "Number of instructions removed", {0}, {false}}
;
67STATISTIC(NumDeadBlocks , "Number of basic blocks unreachable")static llvm::Statistic NumDeadBlocks = {"sccp", "NumDeadBlocks"
, "Number of basic blocks unreachable", {0}, {false}}
;
68
69STATISTIC(IPNumInstRemoved, "Number of instructions removed by IPSCCP")static llvm::Statistic IPNumInstRemoved = {"sccp", "IPNumInstRemoved"
, "Number of instructions removed by IPSCCP", {0}, {false}}
;
70STATISTIC(IPNumArgsElimed ,"Number of arguments constant propagated by IPSCCP")static llvm::Statistic IPNumArgsElimed = {"sccp", "IPNumArgsElimed"
, "Number of arguments constant propagated by IPSCCP", {0}, {
false}}
;
71STATISTIC(IPNumGlobalConst, "Number of globals found to be constant by IPSCCP")static llvm::Statistic IPNumGlobalConst = {"sccp", "IPNumGlobalConst"
, "Number of globals found to be constant by IPSCCP", {0}, {false
}}
;
72
73namespace {
74
75/// LatticeVal class - This class represents the different lattice values that
76/// an LLVM value may occupy. It is a simple class with value semantics.
77///
78class LatticeVal {
79 enum LatticeValueTy {
80 /// unknown - This LLVM Value has no known value yet.
81 unknown,
82
83 /// constant - This LLVM Value has a specific constant value.
84 constant,
85
86 /// forcedconstant - This LLVM Value was thought to be undef until
87 /// ResolvedUndefsIn. This is treated just like 'constant', but if merged
88 /// with another (different) constant, it goes to overdefined, instead of
89 /// asserting.
90 forcedconstant,
91
92 /// overdefined - This instruction is not known to be constant, and we know
93 /// it has a value.
94 overdefined
95 };
96
97 /// Val: This stores the current lattice value along with the Constant* for
98 /// the constant if this is a 'constant' or 'forcedconstant' value.
99 PointerIntPair<Constant *, 2, LatticeValueTy> Val;
100
101 LatticeValueTy getLatticeValue() const {
102 return Val.getInt();
103 }
104
105public:
106 LatticeVal() : Val(nullptr, unknown) {}
107
108 bool isUnknown() const { return getLatticeValue() == unknown; }
109
110 bool isConstant() const {
111 return getLatticeValue() == constant || getLatticeValue() == forcedconstant;
112 }
113
114 bool isOverdefined() const { return getLatticeValue() == overdefined; }
115
116 Constant *getConstant() const {
117 assert(isConstant() && "Cannot get the constant of a non-constant!")((isConstant() && "Cannot get the constant of a non-constant!"
) ? static_cast<void> (0) : __assert_fail ("isConstant() && \"Cannot get the constant of a non-constant!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 117, __PRETTY_FUNCTION__))
;
118 return Val.getPointer();
119 }
120
121 /// markOverdefined - Return true if this is a change in status.
122 bool markOverdefined() {
123 if (isOverdefined())
124 return false;
125
126 Val.setInt(overdefined);
127 return true;
128 }
129
130 /// markConstant - Return true if this is a change in status.
131 bool markConstant(Constant *V) {
132 if (getLatticeValue() == constant) { // Constant but not forcedconstant.
133 assert(getConstant() == V && "Marking constant with different value")((getConstant() == V && "Marking constant with different value"
) ? static_cast<void> (0) : __assert_fail ("getConstant() == V && \"Marking constant with different value\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 133, __PRETTY_FUNCTION__))
;
134 return false;
135 }
136
137 if (isUnknown()) {
138 Val.setInt(constant);
139 assert(V && "Marking constant with NULL")((V && "Marking constant with NULL") ? static_cast<
void> (0) : __assert_fail ("V && \"Marking constant with NULL\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 139, __PRETTY_FUNCTION__))
;
140 Val.setPointer(V);
141 } else {
142 assert(getLatticeValue() == forcedconstant &&((getLatticeValue() == forcedconstant && "Cannot move from overdefined to constant!"
) ? static_cast<void> (0) : __assert_fail ("getLatticeValue() == forcedconstant && \"Cannot move from overdefined to constant!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 143, __PRETTY_FUNCTION__))
143 "Cannot move from overdefined to constant!")((getLatticeValue() == forcedconstant && "Cannot move from overdefined to constant!"
) ? static_cast<void> (0) : __assert_fail ("getLatticeValue() == forcedconstant && \"Cannot move from overdefined to constant!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 143, __PRETTY_FUNCTION__))
;
144 // Stay at forcedconstant if the constant is the same.
145 if (V == getConstant()) return false;
146
147 // Otherwise, we go to overdefined. Assumptions made based on the
148 // forced value are possibly wrong. Assuming this is another constant
149 // could expose a contradiction.
150 Val.setInt(overdefined);
151 }
152 return true;
153 }
154
155 /// getConstantInt - If this is a constant with a ConstantInt value, return it
156 /// otherwise return null.
157 ConstantInt *getConstantInt() const {
158 if (isConstant())
159 return dyn_cast<ConstantInt>(getConstant());
160 return nullptr;
161 }
162
163 /// getBlockAddress - If this is a constant with a BlockAddress value, return
164 /// it, otherwise return null.
165 BlockAddress *getBlockAddress() const {
166 if (isConstant())
167 return dyn_cast<BlockAddress>(getConstant());
168 return nullptr;
169 }
170
171 void markForcedConstant(Constant *V) {
172 assert(isUnknown() && "Can't force a defined value!")((isUnknown() && "Can't force a defined value!") ? static_cast
<void> (0) : __assert_fail ("isUnknown() && \"Can't force a defined value!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 172, __PRETTY_FUNCTION__))
;
173 Val.setInt(forcedconstant);
174 Val.setPointer(V);
175 }
176
177 ValueLatticeElement toValueLattice() const {
178 if (isOverdefined())
179 return ValueLatticeElement::getOverdefined();
180 if (isConstant())
181 return ValueLatticeElement::get(getConstant());
182 return ValueLatticeElement();
183 }
184};
185
186//===----------------------------------------------------------------------===//
187//
188/// SCCPSolver - This class is a general purpose solver for Sparse Conditional
189/// Constant Propagation.
190///
191class SCCPSolver : public InstVisitor<SCCPSolver> {
192 const DataLayout &DL;
193 const TargetLibraryInfo *TLI;
194 SmallPtrSet<BasicBlock *, 8> BBExecutable; // The BBs that are executable.
195 DenseMap<Value *, LatticeVal> ValueState; // The state each value is in.
196 // The state each parameter is in.
197 DenseMap<Value *, ValueLatticeElement> ParamState;
198
199 /// StructValueState - This maintains ValueState for values that have
200 /// StructType, for example for formal arguments, calls, insertelement, etc.
201 DenseMap<std::pair<Value *, unsigned>, LatticeVal> StructValueState;
202
203 /// GlobalValue - If we are tracking any values for the contents of a global
204 /// variable, we keep a mapping from the constant accessor to the element of
205 /// the global, to the currently known value. If the value becomes
206 /// overdefined, it's entry is simply removed from this map.
207 DenseMap<GlobalVariable *, LatticeVal> TrackedGlobals;
208
209 /// TrackedRetVals - If we are tracking arguments into and the return
210 /// value out of a function, it will have an entry in this map, indicating
211 /// what the known return value for the function is.
212 DenseMap<Function *, LatticeVal> TrackedRetVals;
213
214 /// TrackedMultipleRetVals - Same as TrackedRetVals, but used for functions
215 /// that return multiple values.
216 DenseMap<std::pair<Function *, unsigned>, LatticeVal> TrackedMultipleRetVals;
217
218 /// MRVFunctionsTracked - Each function in TrackedMultipleRetVals is
219 /// represented here for efficient lookup.
220 SmallPtrSet<Function *, 16> MRVFunctionsTracked;
221
222 /// MustTailFunctions - Each function here is a callee of non-removable
223 /// musttail call site.
224 SmallPtrSet<Function *, 16> MustTailCallees;
225
226 /// TrackingIncomingArguments - This is the set of functions for whose
227 /// arguments we make optimistic assumptions about and try to prove as
228 /// constants.
229 SmallPtrSet<Function *, 16> TrackingIncomingArguments;
230
231 /// The reason for two worklists is that overdefined is the lowest state
232 /// on the lattice, and moving things to overdefined as fast as possible
233 /// makes SCCP converge much faster.
234 ///
235 /// By having a separate worklist, we accomplish this because everything
236 /// possibly overdefined will become overdefined at the soonest possible
237 /// point.
238 SmallVector<Value *, 64> OverdefinedInstWorkList;
239 SmallVector<Value *, 64> InstWorkList;
240
241 // The BasicBlock work list
242 SmallVector<BasicBlock *, 64> BBWorkList;
243
244 /// KnownFeasibleEdges - Entries in this set are edges which have already had
245 /// PHI nodes retriggered.
246 using Edge = std::pair<BasicBlock *, BasicBlock *>;
247 DenseSet<Edge> KnownFeasibleEdges;
248
249 DenseMap<Function *, AnalysisResultsForFn> AnalysisResults;
250 DenseMap<Value *, SmallPtrSet<User *, 2>> AdditionalUsers;
251
252public:
253 void addAnalysis(Function &F, AnalysisResultsForFn A) {
254 AnalysisResults.insert({&F, std::move(A)});
255 }
256
257 const PredicateBase *getPredicateInfoFor(Instruction *I) {
258 auto A = AnalysisResults.find(I->getParent()->getParent());
259 if (A == AnalysisResults.end())
260 return nullptr;
261 return A->second.PredInfo->getPredicateInfoFor(I);
262 }
263
264 DomTreeUpdater getDTU(Function &F) {
265 auto A = AnalysisResults.find(&F);
266 assert(A != AnalysisResults.end() && "Need analysis results for function.")((A != AnalysisResults.end() && "Need analysis results for function."
) ? static_cast<void> (0) : __assert_fail ("A != AnalysisResults.end() && \"Need analysis results for function.\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 266, __PRETTY_FUNCTION__))
;
267 return {A->second.DT, A->second.PDT, DomTreeUpdater::UpdateStrategy::Lazy};
268 }
269
270 SCCPSolver(const DataLayout &DL, const TargetLibraryInfo *tli)
271 : DL(DL), TLI(tli) {}
272
273 /// MarkBlockExecutable - This method can be used by clients to mark all of
274 /// the blocks that are known to be intrinsically live in the processed unit.
275 ///
276 /// This returns true if the block was not considered live before.
277 bool MarkBlockExecutable(BasicBlock *BB) {
278 if (!BBExecutable.insert(BB).second)
279 return false;
280 LLVM_DEBUG(dbgs() << "Marking Block Executable: " << BB->getName() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "Marking Block Executable: " <<
BB->getName() << '\n'; } } while (false)
;
281 BBWorkList.push_back(BB); // Add the block to the work list!
282 return true;
283 }
284
285 /// TrackValueOfGlobalVariable - Clients can use this method to
286 /// inform the SCCPSolver that it should track loads and stores to the
287 /// specified global variable if it can. This is only legal to call if
288 /// performing Interprocedural SCCP.
289 void TrackValueOfGlobalVariable(GlobalVariable *GV) {
290 // We only track the contents of scalar globals.
291 if (GV->getValueType()->isSingleValueType()) {
292 LatticeVal &IV = TrackedGlobals[GV];
293 if (!isa<UndefValue>(GV->getInitializer()))
294 IV.markConstant(GV->getInitializer());
295 }
296 }
297
298 /// AddTrackedFunction - If the SCCP solver is supposed to track calls into
299 /// and out of the specified function (which cannot have its address taken),
300 /// this method must be called.
301 void AddTrackedFunction(Function *F) {
302 // Add an entry, F -> undef.
303 if (auto *STy = dyn_cast<StructType>(F->getReturnType())) {
304 MRVFunctionsTracked.insert(F);
305 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
306 TrackedMultipleRetVals.insert(std::make_pair(std::make_pair(F, i),
307 LatticeVal()));
308 } else
309 TrackedRetVals.insert(std::make_pair(F, LatticeVal()));
310 }
311
312 /// AddMustTailCallee - If the SCCP solver finds that this function is called
313 /// from non-removable musttail call site.
314 void AddMustTailCallee(Function *F) {
315 MustTailCallees.insert(F);
316 }
317
318 /// Returns true if the given function is called from non-removable musttail
319 /// call site.
320 bool isMustTailCallee(Function *F) {
321 return MustTailCallees.count(F);
322 }
323
324 void AddArgumentTrackedFunction(Function *F) {
325 TrackingIncomingArguments.insert(F);
326 }
327
328 /// Returns true if the given function is in the solver's set of
329 /// argument-tracked functions.
330 bool isArgumentTrackedFunction(Function *F) {
331 return TrackingIncomingArguments.count(F);
332 }
333
334 /// Solve - Solve for constants and executable blocks.
335 void Solve();
336
337 /// ResolvedUndefsIn - While solving the dataflow for a function, we assume
338 /// that branches on undef values cannot reach any of their successors.
339 /// However, this is not a safe assumption. After we solve dataflow, this
340 /// method should be use to handle this. If this returns true, the solver
341 /// should be rerun.
342 bool ResolvedUndefsIn(Function &F);
343
344 bool isBlockExecutable(BasicBlock *BB) const {
345 return BBExecutable.count(BB);
346 }
347
348 // isEdgeFeasible - Return true if the control flow edge from the 'From' basic
349 // block to the 'To' basic block is currently feasible.
350 bool isEdgeFeasible(BasicBlock *From, BasicBlock *To);
351
352 std::vector<LatticeVal> getStructLatticeValueFor(Value *V) const {
353 std::vector<LatticeVal> StructValues;
354 auto *STy = dyn_cast<StructType>(V->getType());
355 assert(STy && "getStructLatticeValueFor() can be called only on structs")((STy && "getStructLatticeValueFor() can be called only on structs"
) ? static_cast<void> (0) : __assert_fail ("STy && \"getStructLatticeValueFor() can be called only on structs\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 355, __PRETTY_FUNCTION__))
;
356 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
357 auto I = StructValueState.find(std::make_pair(V, i));
358 assert(I != StructValueState.end() && "Value not in valuemap!")((I != StructValueState.end() && "Value not in valuemap!"
) ? static_cast<void> (0) : __assert_fail ("I != StructValueState.end() && \"Value not in valuemap!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 358, __PRETTY_FUNCTION__))
;
359 StructValues.push_back(I->second);
360 }
361 return StructValues;
362 }
363
364 const LatticeVal &getLatticeValueFor(Value *V) const {
365 assert(!V->getType()->isStructTy() &&((!V->getType()->isStructTy() && "Should use getStructLatticeValueFor"
) ? static_cast<void> (0) : __assert_fail ("!V->getType()->isStructTy() && \"Should use getStructLatticeValueFor\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 366, __PRETTY_FUNCTION__))
366 "Should use getStructLatticeValueFor")((!V->getType()->isStructTy() && "Should use getStructLatticeValueFor"
) ? static_cast<void> (0) : __assert_fail ("!V->getType()->isStructTy() && \"Should use getStructLatticeValueFor\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 366, __PRETTY_FUNCTION__))
;
367 DenseMap<Value *, LatticeVal>::const_iterator I = ValueState.find(V);
368 assert(I != ValueState.end() &&((I != ValueState.end() && "V not found in ValueState nor Paramstate map!"
) ? static_cast<void> (0) : __assert_fail ("I != ValueState.end() && \"V not found in ValueState nor Paramstate map!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 369, __PRETTY_FUNCTION__))
369 "V not found in ValueState nor Paramstate map!")((I != ValueState.end() && "V not found in ValueState nor Paramstate map!"
) ? static_cast<void> (0) : __assert_fail ("I != ValueState.end() && \"V not found in ValueState nor Paramstate map!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 369, __PRETTY_FUNCTION__))
;
370 return I->second;
371 }
372
373 /// getTrackedRetVals - Get the inferred return value map.
374 const DenseMap<Function*, LatticeVal> &getTrackedRetVals() {
375 return TrackedRetVals;
376 }
377
378 /// getTrackedGlobals - Get and return the set of inferred initializers for
379 /// global variables.
380 const DenseMap<GlobalVariable*, LatticeVal> &getTrackedGlobals() {
381 return TrackedGlobals;
382 }
383
384 /// getMRVFunctionsTracked - Get the set of functions which return multiple
385 /// values tracked by the pass.
386 const SmallPtrSet<Function *, 16> getMRVFunctionsTracked() {
387 return MRVFunctionsTracked;
388 }
389
390 /// getMustTailCallees - Get the set of functions which are called
391 /// from non-removable musttail call sites.
392 const SmallPtrSet<Function *, 16> getMustTailCallees() {
393 return MustTailCallees;
394 }
395
396 /// markOverdefined - Mark the specified value overdefined. This
397 /// works with both scalars and structs.
398 void markOverdefined(Value *V) {
399 if (auto *STy = dyn_cast<StructType>(V->getType()))
400 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
401 markOverdefined(getStructValueState(V, i), V);
402 else
403 markOverdefined(ValueState[V], V);
404 }
405
406 // isStructLatticeConstant - Return true if all the lattice values
407 // corresponding to elements of the structure are not overdefined,
408 // false otherwise.
409 bool isStructLatticeConstant(Function *F, StructType *STy) {
410 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
411 const auto &It = TrackedMultipleRetVals.find(std::make_pair(F, i));
412 assert(It != TrackedMultipleRetVals.end())((It != TrackedMultipleRetVals.end()) ? static_cast<void>
(0) : __assert_fail ("It != TrackedMultipleRetVals.end()", "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 412, __PRETTY_FUNCTION__))
;
413 LatticeVal LV = It->second;
414 if (LV.isOverdefined())
415 return false;
416 }
417 return true;
418 }
419
420private:
421 // pushToWorkList - Helper for markConstant/markForcedConstant/markOverdefined
422 void pushToWorkList(LatticeVal &IV, Value *V) {
423 if (IV.isOverdefined())
424 return OverdefinedInstWorkList.push_back(V);
425 InstWorkList.push_back(V);
426 }
427
428 // markConstant - Make a value be marked as "constant". If the value
429 // is not already a constant, add it to the instruction work list so that
430 // the users of the instruction are updated later.
431 bool markConstant(LatticeVal &IV, Value *V, Constant *C) {
432 if (!IV.markConstant(C)) return false;
433 LLVM_DEBUG(dbgs() << "markConstant: " << *C << ": " << *V << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "markConstant: " << *C <<
": " << *V << '\n'; } } while (false)
;
434 pushToWorkList(IV, V);
435 return true;
436 }
437
438 bool markConstant(Value *V, Constant *C) {
439 assert(!V->getType()->isStructTy() && "structs should use mergeInValue")((!V->getType()->isStructTy() && "structs should use mergeInValue"
) ? static_cast<void> (0) : __assert_fail ("!V->getType()->isStructTy() && \"structs should use mergeInValue\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 439, __PRETTY_FUNCTION__))
;
440 return markConstant(ValueState[V], V, C);
441 }
442
443 void markForcedConstant(Value *V, Constant *C) {
444 assert(!V->getType()->isStructTy() && "structs should use mergeInValue")((!V->getType()->isStructTy() && "structs should use mergeInValue"
) ? static_cast<void> (0) : __assert_fail ("!V->getType()->isStructTy() && \"structs should use mergeInValue\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 444, __PRETTY_FUNCTION__))
;
445 LatticeVal &IV = ValueState[V];
446 IV.markForcedConstant(C);
447 LLVM_DEBUG(dbgs() << "markForcedConstant: " << *C << ": " << *V << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "markForcedConstant: " << *
C << ": " << *V << '\n'; } } while (false)
;
448 pushToWorkList(IV, V);
449 }
450
451 // markOverdefined - Make a value be marked as "overdefined". If the
452 // value is not already overdefined, add it to the overdefined instruction
453 // work list so that the users of the instruction are updated later.
454 bool markOverdefined(LatticeVal &IV, Value *V) {
455 if (!IV.markOverdefined()) return false;
456
457 LLVM_DEBUG(dbgs() << "markOverdefined: ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "markOverdefined: "; if (auto *F =
dyn_cast<Function>(V)) dbgs() << "Function '" <<
F->getName() << "'\n"; else dbgs() << *V <<
'\n'; } } while (false)
458 if (auto *F = dyn_cast<Function>(V)) dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "markOverdefined: "; if (auto *F =
dyn_cast<Function>(V)) dbgs() << "Function '" <<
F->getName() << "'\n"; else dbgs() << *V <<
'\n'; } } while (false)
459 << "Function '" << F->getName() << "'\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "markOverdefined: "; if (auto *F =
dyn_cast<Function>(V)) dbgs() << "Function '" <<
F->getName() << "'\n"; else dbgs() << *V <<
'\n'; } } while (false)
460 else dbgs() << *V << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "markOverdefined: "; if (auto *F =
dyn_cast<Function>(V)) dbgs() << "Function '" <<
F->getName() << "'\n"; else dbgs() << *V <<
'\n'; } } while (false)
;
461 // Only instructions go on the work list
462 pushToWorkList(IV, V);
463 return true;
464 }
465
466 bool mergeInValue(LatticeVal &IV, Value *V, LatticeVal MergeWithV) {
467 if (IV.isOverdefined() || MergeWithV.isUnknown())
468 return false; // Noop.
469 if (MergeWithV.isOverdefined())
470 return markOverdefined(IV, V);
471 if (IV.isUnknown())
472 return markConstant(IV, V, MergeWithV.getConstant());
473 if (IV.getConstant() != MergeWithV.getConstant())
474 return markOverdefined(IV, V);
475 return false;
476 }
477
478 bool mergeInValue(Value *V, LatticeVal MergeWithV) {
479 assert(!V->getType()->isStructTy() &&((!V->getType()->isStructTy() && "non-structs should use markConstant"
) ? static_cast<void> (0) : __assert_fail ("!V->getType()->isStructTy() && \"non-structs should use markConstant\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 480, __PRETTY_FUNCTION__))
480 "non-structs should use markConstant")((!V->getType()->isStructTy() && "non-structs should use markConstant"
) ? static_cast<void> (0) : __assert_fail ("!V->getType()->isStructTy() && \"non-structs should use markConstant\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 480, __PRETTY_FUNCTION__))
;
481 return mergeInValue(ValueState[V], V, MergeWithV);
482 }
483
484 /// getValueState - Return the LatticeVal object that corresponds to the
485 /// value. This function handles the case when the value hasn't been seen yet
486 /// by properly seeding constants etc.
487 LatticeVal &getValueState(Value *V) {
488 assert(!V->getType()->isStructTy() && "Should use getStructValueState")((!V->getType()->isStructTy() && "Should use getStructValueState"
) ? static_cast<void> (0) : __assert_fail ("!V->getType()->isStructTy() && \"Should use getStructValueState\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 488, __PRETTY_FUNCTION__))
;
24
Called C++ object pointer is null
489
490 std::pair<DenseMap<Value*, LatticeVal>::iterator, bool> I =
491 ValueState.insert(std::make_pair(V, LatticeVal()));
492 LatticeVal &LV = I.first->second;
493
494 if (!I.second)
495 return LV; // Common case, already in the map.
496
497 if (auto *C = dyn_cast<Constant>(V)) {
498 // Undef values remain unknown.
499 if (!isa<UndefValue>(V))
500 LV.markConstant(C); // Constants are constant
501 }
502
503 // All others are underdefined by default.
504 return LV;
505 }
506
507 ValueLatticeElement &getParamState(Value *V) {
508 assert(!V->getType()->isStructTy() && "Should use getStructValueState")((!V->getType()->isStructTy() && "Should use getStructValueState"
) ? static_cast<void> (0) : __assert_fail ("!V->getType()->isStructTy() && \"Should use getStructValueState\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 508, __PRETTY_FUNCTION__))
;
509
510 std::pair<DenseMap<Value*, ValueLatticeElement>::iterator, bool>
511 PI = ParamState.insert(std::make_pair(V, ValueLatticeElement()));
512 ValueLatticeElement &LV = PI.first->second;
513 if (PI.second)
514 LV = getValueState(V).toValueLattice();
515
516 return LV;
517 }
518
519 /// getStructValueState - Return the LatticeVal object that corresponds to the
520 /// value/field pair. This function handles the case when the value hasn't
521 /// been seen yet by properly seeding constants etc.
522 LatticeVal &getStructValueState(Value *V, unsigned i) {
523 assert(V->getType()->isStructTy() && "Should use getValueState")((V->getType()->isStructTy() && "Should use getValueState"
) ? static_cast<void> (0) : __assert_fail ("V->getType()->isStructTy() && \"Should use getValueState\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 523, __PRETTY_FUNCTION__))
;
524 assert(i < cast<StructType>(V->getType())->getNumElements() &&((i < cast<StructType>(V->getType())->getNumElements
() && "Invalid element #") ? static_cast<void> (
0) : __assert_fail ("i < cast<StructType>(V->getType())->getNumElements() && \"Invalid element #\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 525, __PRETTY_FUNCTION__))
525 "Invalid element #")((i < cast<StructType>(V->getType())->getNumElements
() && "Invalid element #") ? static_cast<void> (
0) : __assert_fail ("i < cast<StructType>(V->getType())->getNumElements() && \"Invalid element #\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 525, __PRETTY_FUNCTION__))
;
526
527 std::pair<DenseMap<std::pair<Value*, unsigned>, LatticeVal>::iterator,
528 bool> I = StructValueState.insert(
529 std::make_pair(std::make_pair(V, i), LatticeVal()));
530 LatticeVal &LV = I.first->second;
531
532 if (!I.second)
533 return LV; // Common case, already in the map.
534
535 if (auto *C = dyn_cast<Constant>(V)) {
536 Constant *Elt = C->getAggregateElement(i);
537
538 if (!Elt)
539 LV.markOverdefined(); // Unknown sort of constant.
540 else if (isa<UndefValue>(Elt))
541 ; // Undef values remain unknown.
542 else
543 LV.markConstant(Elt); // Constants are constant.
544 }
545
546 // All others are underdefined by default.
547 return LV;
548 }
549
550 /// markEdgeExecutable - Mark a basic block as executable, adding it to the BB
551 /// work list if it is not already executable.
552 bool markEdgeExecutable(BasicBlock *Source, BasicBlock *Dest) {
553 if (!KnownFeasibleEdges.insert(Edge(Source, Dest)).second)
554 return false; // This edge is already known to be executable!
555
556 if (!MarkBlockExecutable(Dest)) {
557 // If the destination is already executable, we just made an *edge*
558 // feasible that wasn't before. Revisit the PHI nodes in the block
559 // because they have potentially new operands.
560 LLVM_DEBUG(dbgs() << "Marking Edge Executable: " << Source->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "Marking Edge Executable: " <<
Source->getName() << " -> " << Dest->getName
() << '\n'; } } while (false)
561 << " -> " << Dest->getName() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "Marking Edge Executable: " <<
Source->getName() << " -> " << Dest->getName
() << '\n'; } } while (false)
;
562
563 for (PHINode &PN : Dest->phis())
564 visitPHINode(PN);
565 }
566 return true;
567 }
568
569 // getFeasibleSuccessors - Return a vector of booleans to indicate which
570 // successors are reachable from a given terminator instruction.
571 void getFeasibleSuccessors(Instruction &TI, SmallVectorImpl<bool> &Succs);
572
573 // OperandChangedState - This method is invoked on all of the users of an
574 // instruction that was just changed state somehow. Based on this
575 // information, we need to update the specified user of this instruction.
576 void OperandChangedState(Instruction *I) {
577 if (BBExecutable.count(I->getParent())) // Inst is executable?
578 visit(*I);
579 }
580
581 // Add U as additional user of V.
582 void addAdditionalUser(Value *V, User *U) {
583 auto Iter = AdditionalUsers.insert({V, {}});
584 Iter.first->second.insert(U);
585 }
586
587 // Mark I's users as changed, including AdditionalUsers.
588 void markUsersAsChanged(Value *I) {
589 for (User *U : I->users())
590 if (auto *UI = dyn_cast<Instruction>(U))
591 OperandChangedState(UI);
592
593 auto Iter = AdditionalUsers.find(I);
594 if (Iter != AdditionalUsers.end()) {
595 for (User *U : Iter->second)
596 if (auto *UI = dyn_cast<Instruction>(U))
597 OperandChangedState(UI);
598 }
599 }
600
601private:
602 friend class InstVisitor<SCCPSolver>;
603
604 // visit implementations - Something changed in this instruction. Either an
605 // operand made a transition, or the instruction is newly executable. Change
606 // the value type of I to reflect these changes if appropriate.
607 void visitPHINode(PHINode &I);
608
609 // Terminators
610
611 void visitReturnInst(ReturnInst &I);
612 void visitTerminator(Instruction &TI);
613
614 void visitCastInst(CastInst &I);
615 void visitSelectInst(SelectInst &I);
616 void visitBinaryOperator(Instruction &I);
617 void visitCmpInst(CmpInst &I);
618 void visitExtractValueInst(ExtractValueInst &EVI);
619 void visitInsertValueInst(InsertValueInst &IVI);
620
621 void visitCatchSwitchInst(CatchSwitchInst &CPI) {
622 markOverdefined(&CPI);
623 visitTerminator(CPI);
624 }
625
626 // Instructions that cannot be folded away.
627
628 void visitStoreInst (StoreInst &I);
629 void visitLoadInst (LoadInst &I);
630 void visitGetElementPtrInst(GetElementPtrInst &I);
631
632 void visitCallInst (CallInst &I) {
633 visitCallSite(&I);
1
Calling 'SCCPSolver::visitCallSite'
634 }
635
636 void visitInvokeInst (InvokeInst &II) {
637 visitCallSite(&II);
638 visitTerminator(II);
639 }
640
641 void visitCallBrInst (CallBrInst &CBI) {
642 visitCallSite(&CBI);
643 visitTerminator(CBI);
644 }
645
646 void visitCallSite (CallSite CS);
647 void visitResumeInst (ResumeInst &I) { /*returns void*/ }
648 void visitUnreachableInst(UnreachableInst &I) { /*returns void*/ }
649 void visitFenceInst (FenceInst &I) { /*returns void*/ }
650
651 void visitInstruction(Instruction &I) {
652 // All the instructions we don't do any special handling for just
653 // go to overdefined.
654 LLVM_DEBUG(dbgs() << "SCCP: Don't know how to handle: " << I << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "SCCP: Don't know how to handle: "
<< I << '\n'; } } while (false)
;
655 markOverdefined(&I);
656 }
657};
658
659} // end anonymous namespace
660
661// getFeasibleSuccessors - Return a vector of booleans to indicate which
662// successors are reachable from a given terminator instruction.
663void SCCPSolver::getFeasibleSuccessors(Instruction &TI,
664 SmallVectorImpl<bool> &Succs) {
665 Succs.resize(TI.getNumSuccessors());
666 if (auto *BI = dyn_cast<BranchInst>(&TI)) {
667 if (BI->isUnconditional()) {
668 Succs[0] = true;
669 return;
670 }
671
672 LatticeVal BCValue = getValueState(BI->getCondition());
673 ConstantInt *CI = BCValue.getConstantInt();
674 if (!CI) {
675 // Overdefined condition variables, and branches on unfoldable constant
676 // conditions, mean the branch could go either way.
677 if (!BCValue.isUnknown())
678 Succs[0] = Succs[1] = true;
679 return;
680 }
681
682 // Constant condition variables mean the branch can only go a single way.
683 Succs[CI->isZero()] = true;
684 return;
685 }
686
687 // Unwinding instructions successors are always executable.
688 if (TI.isExceptionalTerminator()) {
689 Succs.assign(TI.getNumSuccessors(), true);
690 return;
691 }
692
693 if (auto *SI = dyn_cast<SwitchInst>(&TI)) {
694 if (!SI->getNumCases()) {
695 Succs[0] = true;
696 return;
697 }
698 LatticeVal SCValue = getValueState(SI->getCondition());
699 ConstantInt *CI = SCValue.getConstantInt();
700
701 if (!CI) { // Overdefined or unknown condition?
702 // All destinations are executable!
703 if (!SCValue.isUnknown())
704 Succs.assign(TI.getNumSuccessors(), true);
705 return;
706 }
707
708 Succs[SI->findCaseValue(CI)->getSuccessorIndex()] = true;
709 return;
710 }
711
712 // In case of indirect branch and its address is a blockaddress, we mark
713 // the target as executable.
714 if (auto *IBR = dyn_cast<IndirectBrInst>(&TI)) {
715 // Casts are folded by visitCastInst.
716 LatticeVal IBRValue = getValueState(IBR->getAddress());
717 BlockAddress *Addr = IBRValue.getBlockAddress();
718 if (!Addr) { // Overdefined or unknown condition?
719 // All destinations are executable!
720 if (!IBRValue.isUnknown())
721 Succs.assign(TI.getNumSuccessors(), true);
722 return;
723 }
724
725 BasicBlock* T = Addr->getBasicBlock();
726 assert(Addr->getFunction() == T->getParent() &&((Addr->getFunction() == T->getParent() && "Block address of a different function ?"
) ? static_cast<void> (0) : __assert_fail ("Addr->getFunction() == T->getParent() && \"Block address of a different function ?\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 727, __PRETTY_FUNCTION__))
727 "Block address of a different function ?")((Addr->getFunction() == T->getParent() && "Block address of a different function ?"
) ? static_cast<void> (0) : __assert_fail ("Addr->getFunction() == T->getParent() && \"Block address of a different function ?\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 727, __PRETTY_FUNCTION__))
;
728 for (unsigned i = 0; i < IBR->getNumSuccessors(); ++i) {
729 // This is the target.
730 if (IBR->getDestination(i) == T) {
731 Succs[i] = true;
732 return;
733 }
734 }
735
736 // If we didn't find our destination in the IBR successor list, then we
737 // have undefined behavior. Its ok to assume no successor is executable.
738 return;
739 }
740
741 // In case of callbr, we pessimistically assume that all successors are
742 // feasible.
743 if (isa<CallBrInst>(&TI)) {
744 Succs.assign(TI.getNumSuccessors(), true);
745 return;
746 }
747
748 LLVM_DEBUG(dbgs() << "Unknown terminator instruction: " << TI << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "Unknown terminator instruction: "
<< TI << '\n'; } } while (false)
;
749 llvm_unreachable("SCCP: Don't know how to handle this terminator!")::llvm::llvm_unreachable_internal("SCCP: Don't know how to handle this terminator!"
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 749)
;
750}
751
752// isEdgeFeasible - Return true if the control flow edge from the 'From' basic
753// block to the 'To' basic block is currently feasible.
754bool SCCPSolver::isEdgeFeasible(BasicBlock *From, BasicBlock *To) {
755 // Check if we've called markEdgeExecutable on the edge yet. (We could
756 // be more aggressive and try to consider edges which haven't been marked
757 // yet, but there isn't any need.)
758 return KnownFeasibleEdges.count(Edge(From, To));
759}
760
761// visit Implementations - Something changed in this instruction, either an
762// operand made a transition, or the instruction is newly executable. Change
763// the value type of I to reflect these changes if appropriate. This method
764// makes sure to do the following actions:
765//
766// 1. If a phi node merges two constants in, and has conflicting value coming
767// from different branches, or if the PHI node merges in an overdefined
768// value, then the PHI node becomes overdefined.
769// 2. If a phi node merges only constants in, and they all agree on value, the
770// PHI node becomes a constant value equal to that.
771// 3. If V <- x (op) y && isConstant(x) && isConstant(y) V = Constant
772// 4. If V <- x (op) y && (isOverdefined(x) || isOverdefined(y)) V = Overdefined
773// 5. If V <- MEM or V <- CALL or V <- (unknown) then V = Overdefined
774// 6. If a conditional branch has a value that is constant, make the selected
775// destination executable
776// 7. If a conditional branch has a value that is overdefined, make all
777// successors executable.
778void SCCPSolver::visitPHINode(PHINode &PN) {
779 // If this PN returns a struct, just mark the result overdefined.
780 // TODO: We could do a lot better than this if code actually uses this.
781 if (PN.getType()->isStructTy())
782 return (void)markOverdefined(&PN);
783
784 if (getValueState(&PN).isOverdefined())
785 return; // Quick exit
786
787 // Super-extra-high-degree PHI nodes are unlikely to ever be marked constant,
788 // and slow us down a lot. Just mark them overdefined.
789 if (PN.getNumIncomingValues() > 64)
790 return (void)markOverdefined(&PN);
791
792 // Look at all of the executable operands of the PHI node. If any of them
793 // are overdefined, the PHI becomes overdefined as well. If they are all
794 // constant, and they agree with each other, the PHI becomes the identical
795 // constant. If they are constant and don't agree, the PHI is overdefined.
796 // If there are no executable operands, the PHI remains unknown.
797 Constant *OperandVal = nullptr;
798 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
799 LatticeVal IV = getValueState(PN.getIncomingValue(i));
800 if (IV.isUnknown()) continue; // Doesn't influence PHI node.
801
802 if (!isEdgeFeasible(PN.getIncomingBlock(i), PN.getParent()))
803 continue;
804
805 if (IV.isOverdefined()) // PHI node becomes overdefined!
806 return (void)markOverdefined(&PN);
807
808 if (!OperandVal) { // Grab the first value.
809 OperandVal = IV.getConstant();
810 continue;
811 }
812
813 // There is already a reachable operand. If we conflict with it,
814 // then the PHI node becomes overdefined. If we agree with it, we
815 // can continue on.
816
817 // Check to see if there are two different constants merging, if so, the PHI
818 // node is overdefined.
819 if (IV.getConstant() != OperandVal)
820 return (void)markOverdefined(&PN);
821 }
822
823 // If we exited the loop, this means that the PHI node only has constant
824 // arguments that agree with each other(and OperandVal is the constant) or
825 // OperandVal is null because there are no defined incoming arguments. If
826 // this is the case, the PHI remains unknown.
827 if (OperandVal)
828 markConstant(&PN, OperandVal); // Acquire operand value
829}
830
831void SCCPSolver::visitReturnInst(ReturnInst &I) {
832 if (I.getNumOperands() == 0) return; // ret void
833
834 Function *F = I.getParent()->getParent();
835 Value *ResultOp = I.getOperand(0);
836
837 // If we are tracking the return value of this function, merge it in.
838 if (!TrackedRetVals.empty() && !ResultOp->getType()->isStructTy()) {
839 DenseMap<Function*, LatticeVal>::iterator TFRVI =
840 TrackedRetVals.find(F);
841 if (TFRVI != TrackedRetVals.end()) {
842 mergeInValue(TFRVI->second, F, getValueState(ResultOp));
843 return;
844 }
845 }
846
847 // Handle functions that return multiple values.
848 if (!TrackedMultipleRetVals.empty()) {
849 if (auto *STy = dyn_cast<StructType>(ResultOp->getType()))
850 if (MRVFunctionsTracked.count(F))
851 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
852 mergeInValue(TrackedMultipleRetVals[std::make_pair(F, i)], F,
853 getStructValueState(ResultOp, i));
854 }
855}
856
857void SCCPSolver::visitTerminator(Instruction &TI) {
858 SmallVector<bool, 16> SuccFeasible;
859 getFeasibleSuccessors(TI, SuccFeasible);
860
861 BasicBlock *BB = TI.getParent();
862
863 // Mark all feasible successors executable.
864 for (unsigned i = 0, e = SuccFeasible.size(); i != e; ++i)
865 if (SuccFeasible[i])
866 markEdgeExecutable(BB, TI.getSuccessor(i));
867}
868
869void SCCPSolver::visitCastInst(CastInst &I) {
870 LatticeVal OpSt = getValueState(I.getOperand(0));
871 if (OpSt.isOverdefined()) // Inherit overdefinedness of operand
872 markOverdefined(&I);
873 else if (OpSt.isConstant()) {
874 // Fold the constant as we build.
875 Constant *C = ConstantFoldCastOperand(I.getOpcode(), OpSt.getConstant(),
876 I.getType(), DL);
877 if (isa<UndefValue>(C))
878 return;
879 // Propagate constant value
880 markConstant(&I, C);
881 }
882}
883
884void SCCPSolver::visitExtractValueInst(ExtractValueInst &EVI) {
885 // If this returns a struct, mark all elements over defined, we don't track
886 // structs in structs.
887 if (EVI.getType()->isStructTy())
888 return (void)markOverdefined(&EVI);
889
890 // If this is extracting from more than one level of struct, we don't know.
891 if (EVI.getNumIndices() != 1)
892 return (void)markOverdefined(&EVI);
893
894 Value *AggVal = EVI.getAggregateOperand();
895 if (AggVal->getType()->isStructTy()) {
896 unsigned i = *EVI.idx_begin();
897 LatticeVal EltVal = getStructValueState(AggVal, i);
898 mergeInValue(getValueState(&EVI), &EVI, EltVal);
899 } else {
900 // Otherwise, must be extracting from an array.
901 return (void)markOverdefined(&EVI);
902 }
903}
904
905void SCCPSolver::visitInsertValueInst(InsertValueInst &IVI) {
906 auto *STy = dyn_cast<StructType>(IVI.getType());
907 if (!STy)
908 return (void)markOverdefined(&IVI);
909
910 // If this has more than one index, we can't handle it, drive all results to
911 // undef.
912 if (IVI.getNumIndices() != 1)
913 return (void)markOverdefined(&IVI);
914
915 Value *Aggr = IVI.getAggregateOperand();
916 unsigned Idx = *IVI.idx_begin();
917
918 // Compute the result based on what we're inserting.
919 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
920 // This passes through all values that aren't the inserted element.
921 if (i != Idx) {
922 LatticeVal EltVal = getStructValueState(Aggr, i);
923 mergeInValue(getStructValueState(&IVI, i), &IVI, EltVal);
924 continue;
925 }
926
927 Value *Val = IVI.getInsertedValueOperand();
928 if (Val->getType()->isStructTy())
929 // We don't track structs in structs.
930 markOverdefined(getStructValueState(&IVI, i), &IVI);
931 else {
932 LatticeVal InVal = getValueState(Val);
933 mergeInValue(getStructValueState(&IVI, i), &IVI, InVal);
934 }
935 }
936}
937
938void SCCPSolver::visitSelectInst(SelectInst &I) {
939 // If this select returns a struct, just mark the result overdefined.
940 // TODO: We could do a lot better than this if code actually uses this.
941 if (I.getType()->isStructTy())
942 return (void)markOverdefined(&I);
943
944 LatticeVal CondValue = getValueState(I.getCondition());
945 if (CondValue.isUnknown())
946 return;
947
948 if (ConstantInt *CondCB = CondValue.getConstantInt()) {
949 Value *OpVal = CondCB->isZero() ? I.getFalseValue() : I.getTrueValue();
950 mergeInValue(&I, getValueState(OpVal));
951 return;
952 }
953
954 // Otherwise, the condition is overdefined or a constant we can't evaluate.
955 // See if we can produce something better than overdefined based on the T/F
956 // value.
957 LatticeVal TVal = getValueState(I.getTrueValue());
958 LatticeVal FVal = getValueState(I.getFalseValue());
959
960 // select ?, C, C -> C.
961 if (TVal.isConstant() && FVal.isConstant() &&
962 TVal.getConstant() == FVal.getConstant())
963 return (void)markConstant(&I, FVal.getConstant());
964
965 if (TVal.isUnknown()) // select ?, undef, X -> X.
966 return (void)mergeInValue(&I, FVal);
967 if (FVal.isUnknown()) // select ?, X, undef -> X.
968 return (void)mergeInValue(&I, TVal);
969 markOverdefined(&I);
970}
971
972// Handle Binary Operators.
973void SCCPSolver::visitBinaryOperator(Instruction &I) {
974 LatticeVal V1State = getValueState(I.getOperand(0));
975 LatticeVal V2State = getValueState(I.getOperand(1));
976
977 LatticeVal &IV = ValueState[&I];
978 if (IV.isOverdefined()) return;
979
980 if (V1State.isConstant() && V2State.isConstant()) {
981 Constant *C = ConstantExpr::get(I.getOpcode(), V1State.getConstant(),
982 V2State.getConstant());
983 // X op Y -> undef.
984 if (isa<UndefValue>(C))
985 return;
986 return (void)markConstant(IV, &I, C);
987 }
988
989 // If something is undef, wait for it to resolve.
990 if (!V1State.isOverdefined() && !V2State.isOverdefined())
991 return;
992
993 // Otherwise, one of our operands is overdefined. Try to produce something
994 // better than overdefined with some tricks.
995 // If this is 0 / Y, it doesn't matter that the second operand is
996 // overdefined, and we can replace it with zero.
997 if (I.getOpcode() == Instruction::UDiv || I.getOpcode() == Instruction::SDiv)
998 if (V1State.isConstant() && V1State.getConstant()->isNullValue())
999 return (void)markConstant(IV, &I, V1State.getConstant());
1000
1001 // If this is:
1002 // -> AND/MUL with 0
1003 // -> OR with -1
1004 // it doesn't matter that the other operand is overdefined.
1005 if (I.getOpcode() == Instruction::And || I.getOpcode() == Instruction::Mul ||
1006 I.getOpcode() == Instruction::Or) {
1007 LatticeVal *NonOverdefVal = nullptr;
1008 if (!V1State.isOverdefined())
1009 NonOverdefVal = &V1State;
1010 else if (!V2State.isOverdefined())
1011 NonOverdefVal = &V2State;
1012
1013 if (NonOverdefVal) {
1014 if (NonOverdefVal->isUnknown())
1015 return;
1016
1017 if (I.getOpcode() == Instruction::And ||
1018 I.getOpcode() == Instruction::Mul) {
1019 // X and 0 = 0
1020 // X * 0 = 0
1021 if (NonOverdefVal->getConstant()->isNullValue())
1022 return (void)markConstant(IV, &I, NonOverdefVal->getConstant());
1023 } else {
1024 // X or -1 = -1
1025 if (ConstantInt *CI = NonOverdefVal->getConstantInt())
1026 if (CI->isMinusOne())
1027 return (void)markConstant(IV, &I, NonOverdefVal->getConstant());
1028 }
1029 }
1030 }
1031
1032 markOverdefined(&I);
1033}
1034
1035// Handle ICmpInst instruction.
1036void SCCPSolver::visitCmpInst(CmpInst &I) {
1037 // Do not cache this lookup, getValueState calls later in the function might
1038 // invalidate the reference.
1039 if (ValueState[&I].isOverdefined()) return;
1040
1041 Value *Op1 = I.getOperand(0);
1042 Value *Op2 = I.getOperand(1);
1043
1044 // For parameters, use ParamState which includes constant range info if
1045 // available.
1046 auto V1Param = ParamState.find(Op1);
1047 ValueLatticeElement V1State = (V1Param != ParamState.end())
1048 ? V1Param->second
1049 : getValueState(Op1).toValueLattice();
1050
1051 auto V2Param = ParamState.find(Op2);
1052 ValueLatticeElement V2State = V2Param != ParamState.end()
1053 ? V2Param->second
1054 : getValueState(Op2).toValueLattice();
1055
1056 Constant *C = V1State.getCompare(I.getPredicate(), I.getType(), V2State);
1057 if (C) {
1058 if (isa<UndefValue>(C))
1059 return;
1060 LatticeVal CV;
1061 CV.markConstant(C);
1062 mergeInValue(&I, CV);
1063 return;
1064 }
1065
1066 // If operands are still unknown, wait for it to resolve.
1067 if (!V1State.isOverdefined() && !V2State.isOverdefined() &&
1068 !ValueState[&I].isConstant())
1069 return;
1070
1071 markOverdefined(&I);
1072}
1073
1074// Handle getelementptr instructions. If all operands are constants then we
1075// can turn this into a getelementptr ConstantExpr.
1076void SCCPSolver::visitGetElementPtrInst(GetElementPtrInst &I) {
1077 if (ValueState[&I].isOverdefined()) return;
1078
1079 SmallVector<Constant*, 8> Operands;
1080 Operands.reserve(I.getNumOperands());
1081
1082 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) {
1083 LatticeVal State = getValueState(I.getOperand(i));
1084 if (State.isUnknown())
1085 return; // Operands are not resolved yet.
1086
1087 if (State.isOverdefined())
1088 return (void)markOverdefined(&I);
1089
1090 assert(State.isConstant() && "Unknown state!")((State.isConstant() && "Unknown state!") ? static_cast
<void> (0) : __assert_fail ("State.isConstant() && \"Unknown state!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 1090, __PRETTY_FUNCTION__))
;
1091 Operands.push_back(State.getConstant());
1092 }
1093
1094 Constant *Ptr = Operands[0];
1095 auto Indices = makeArrayRef(Operands.begin() + 1, Operands.end());
1096 Constant *C =
1097 ConstantExpr::getGetElementPtr(I.getSourceElementType(), Ptr, Indices);
1098 if (isa<UndefValue>(C))
1099 return;
1100 markConstant(&I, C);
1101}
1102
1103void SCCPSolver::visitStoreInst(StoreInst &SI) {
1104 // If this store is of a struct, ignore it.
1105 if (SI.getOperand(0)->getType()->isStructTy())
1106 return;
1107
1108 if (TrackedGlobals.empty() || !isa<GlobalVariable>(SI.getOperand(1)))
1109 return;
1110
1111 GlobalVariable *GV = cast<GlobalVariable>(SI.getOperand(1));
1112 DenseMap<GlobalVariable*, LatticeVal>::iterator I = TrackedGlobals.find(GV);
1113 if (I == TrackedGlobals.end() || I->second.isOverdefined()) return;
1114
1115 // Get the value we are storing into the global, then merge it.
1116 mergeInValue(I->second, GV, getValueState(SI.getOperand(0)));
1117 if (I->second.isOverdefined())
1118 TrackedGlobals.erase(I); // No need to keep tracking this!
1119}
1120
1121// Handle load instructions. If the operand is a constant pointer to a constant
1122// global, we can replace the load with the loaded constant value!
1123void SCCPSolver::visitLoadInst(LoadInst &I) {
1124 // If this load is of a struct, just mark the result overdefined.
1125 if (I.getType()->isStructTy())
1126 return (void)markOverdefined(&I);
1127
1128 LatticeVal PtrVal = getValueState(I.getOperand(0));
1129 if (PtrVal.isUnknown()) return; // The pointer is not resolved yet!
1130
1131 LatticeVal &IV = ValueState[&I];
1132 if (IV.isOverdefined()) return;
1133
1134 if (!PtrVal.isConstant() || I.isVolatile())
1135 return (void)markOverdefined(IV, &I);
1136
1137 Constant *Ptr = PtrVal.getConstant();
1138
1139 // load null is undefined.
1140 if (isa<ConstantPointerNull>(Ptr)) {
1141 if (NullPointerIsDefined(I.getFunction(), I.getPointerAddressSpace()))
1142 return (void)markOverdefined(IV, &I);
1143 else
1144 return;
1145 }
1146
1147 // Transform load (constant global) into the value loaded.
1148 if (auto *GV = dyn_cast<GlobalVariable>(Ptr)) {
1149 if (!TrackedGlobals.empty()) {
1150 // If we are tracking this global, merge in the known value for it.
1151 DenseMap<GlobalVariable*, LatticeVal>::iterator It =
1152 TrackedGlobals.find(GV);
1153 if (It != TrackedGlobals.end()) {
1154 mergeInValue(IV, &I, It->second);
1155 return;
1156 }
1157 }
1158 }
1159
1160 // Transform load from a constant into a constant if possible.
1161 if (Constant *C = ConstantFoldLoadFromConstPtr(Ptr, I.getType(), DL)) {
1162 if (isa<UndefValue>(C))
1163 return;
1164 return (void)markConstant(IV, &I, C);
1165 }
1166
1167 // Otherwise we cannot say for certain what value this load will produce.
1168 // Bail out.
1169 markOverdefined(IV, &I);
1170}
1171
1172void SCCPSolver::visitCallSite(CallSite CS) {
1173 Function *F = CS.getCalledFunction();
1174 Instruction *I = CS.getInstruction();
1175
1176 if (auto *II = dyn_cast<IntrinsicInst>(I)) {
2
Taking true branch
1177 if (II->getIntrinsicID() == Intrinsic::ssa_copy) {
3
Assuming the condition is true
4
Taking true branch
1178 if (ValueState[I].isOverdefined())
5
Taking false branch
1179 return;
1180
1181 auto *PI = getPredicateInfoFor(I);
1182 if (!PI)
6
Assuming 'PI' is non-null
7
Taking false branch
1183 return;
1184
1185 Value *CopyOf = I->getOperand(0);
8
Calling 'User::getOperand'
15
Returning from 'User::getOperand'
16
'CopyOf' initialized here
1186 auto *PBranch = dyn_cast<PredicateBranch>(PI);
1187 if (!PBranch) {
17
Taking false branch
1188 mergeInValue(ValueState[I], I, getValueState(CopyOf));
1189 return;
1190 }
1191
1192 Value *Cond = PBranch->Condition;
1193
1194 // Everything below relies on the condition being a comparison.
1195 auto *Cmp = dyn_cast<CmpInst>(Cond);
1196 if (!Cmp) {
18
Taking false branch
1197 mergeInValue(ValueState[I], I, getValueState(CopyOf));
1198 return;
1199 }
1200
1201 Value *CmpOp0 = Cmp->getOperand(0);
1202 Value *CmpOp1 = Cmp->getOperand(1);
1203 if (CopyOf != CmpOp0 && CopyOf != CmpOp1) {
19
Assuming pointer value is null
20
Assuming 'CopyOf' is equal to 'CmpOp0'
1204 mergeInValue(ValueState[I], I, getValueState(CopyOf));
1205 return;
1206 }
1207
1208 if (CmpOp0 != CopyOf)
21
Taking false branch
1209 std::swap(CmpOp0, CmpOp1);
1210
1211 LatticeVal OriginalVal = getValueState(CopyOf);
22
Passing null pointer value via 1st parameter 'V'
23
Calling 'SCCPSolver::getValueState'
1212 LatticeVal EqVal = getValueState(CmpOp1);
1213 LatticeVal &IV = ValueState[I];
1214 if (PBranch->TrueEdge && Cmp->getPredicate() == CmpInst::ICMP_EQ) {
1215 addAdditionalUser(CmpOp1, I);
1216 if (OriginalVal.isConstant())
1217 mergeInValue(IV, I, OriginalVal);
1218 else
1219 mergeInValue(IV, I, EqVal);
1220 return;
1221 }
1222 if (!PBranch->TrueEdge && Cmp->getPredicate() == CmpInst::ICMP_NE) {
1223 addAdditionalUser(CmpOp1, I);
1224 if (OriginalVal.isConstant())
1225 mergeInValue(IV, I, OriginalVal);
1226 else
1227 mergeInValue(IV, I, EqVal);
1228 return;
1229 }
1230
1231 return (void)mergeInValue(IV, I, getValueState(CopyOf));
1232 }
1233 }
1234
1235 // The common case is that we aren't tracking the callee, either because we
1236 // are not doing interprocedural analysis or the callee is indirect, or is
1237 // external. Handle these cases first.
1238 if (!F || F->isDeclaration()) {
1239CallOverdefined:
1240 // Void return and not tracking callee, just bail.
1241 if (I->getType()->isVoidTy()) return;
1242
1243 // Otherwise, if we have a single return value case, and if the function is
1244 // a declaration, maybe we can constant fold it.
1245 if (F && F->isDeclaration() && !I->getType()->isStructTy() &&
1246 canConstantFoldCallTo(cast<CallBase>(CS.getInstruction()), F)) {
1247 SmallVector<Constant*, 8> Operands;
1248 for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
1249 AI != E; ++AI) {
1250 if (AI->get()->getType()->isStructTy())
1251 return markOverdefined(I); // Can't handle struct args.
1252 LatticeVal State = getValueState(*AI);
1253
1254 if (State.isUnknown())
1255 return; // Operands are not resolved yet.
1256 if (State.isOverdefined())
1257 return (void)markOverdefined(I);
1258 assert(State.isConstant() && "Unknown state!")((State.isConstant() && "Unknown state!") ? static_cast
<void> (0) : __assert_fail ("State.isConstant() && \"Unknown state!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 1258, __PRETTY_FUNCTION__))
;
1259 Operands.push_back(State.getConstant());
1260 }
1261
1262 if (getValueState(I).isOverdefined())
1263 return;
1264
1265 // If we can constant fold this, mark the result of the call as a
1266 // constant.
1267 if (Constant *C = ConstantFoldCall(cast<CallBase>(CS.getInstruction()), F,
1268 Operands, TLI)) {
1269 // call -> undef.
1270 if (isa<UndefValue>(C))
1271 return;
1272 return (void)markConstant(I, C);
1273 }
1274 }
1275
1276 // Otherwise, we don't know anything about this call, mark it overdefined.
1277 return (void)markOverdefined(I);
1278 }
1279
1280 // If this is a local function that doesn't have its address taken, mark its
1281 // entry block executable and merge in the actual arguments to the call into
1282 // the formal arguments of the function.
1283 if (!TrackingIncomingArguments.empty() && TrackingIncomingArguments.count(F)){
1284 MarkBlockExecutable(&F->front());
1285
1286 // Propagate information from this call site into the callee.
1287 CallSite::arg_iterator CAI = CS.arg_begin();
1288 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
1289 AI != E; ++AI, ++CAI) {
1290 // If this argument is byval, and if the function is not readonly, there
1291 // will be an implicit copy formed of the input aggregate.
1292 if (AI->hasByValAttr() && !F->onlyReadsMemory()) {
1293 markOverdefined(&*AI);
1294 continue;
1295 }
1296
1297 if (auto *STy = dyn_cast<StructType>(AI->getType())) {
1298 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
1299 LatticeVal CallArg = getStructValueState(*CAI, i);
1300 mergeInValue(getStructValueState(&*AI, i), &*AI, CallArg);
1301 }
1302 } else {
1303 // Most other parts of the Solver still only use the simpler value
1304 // lattice, so we propagate changes for parameters to both lattices.
1305 LatticeVal ConcreteArgument = getValueState(*CAI);
1306 bool ParamChanged =
1307 getParamState(&*AI).mergeIn(ConcreteArgument.toValueLattice(), DL);
1308 bool ValueChanged = mergeInValue(&*AI, ConcreteArgument);
1309 // Add argument to work list, if the state of a parameter changes but
1310 // ValueState does not change (because it is already overdefined there),
1311 // We have to take changes in ParamState into account, as it is used
1312 // when evaluating Cmp instructions.
1313 if (!ValueChanged && ParamChanged)
1314 pushToWorkList(ValueState[&*AI], &*AI);
1315 }
1316 }
1317 }
1318
1319 // If this is a single/zero retval case, see if we're tracking the function.
1320 if (auto *STy = dyn_cast<StructType>(F->getReturnType())) {
1321 if (!MRVFunctionsTracked.count(F))
1322 goto CallOverdefined; // Not tracking this callee.
1323
1324 // If we are tracking this callee, propagate the result of the function
1325 // into this call site.
1326 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
1327 mergeInValue(getStructValueState(I, i), I,
1328 TrackedMultipleRetVals[std::make_pair(F, i)]);
1329 } else {
1330 DenseMap<Function*, LatticeVal>::iterator TFRVI = TrackedRetVals.find(F);
1331 if (TFRVI == TrackedRetVals.end())
1332 goto CallOverdefined; // Not tracking this callee.
1333
1334 // If so, propagate the return value of the callee into this call result.
1335 mergeInValue(I, TFRVI->second);
1336 }
1337}
1338
1339void SCCPSolver::Solve() {
1340 // Process the work lists until they are empty!
1341 while (!BBWorkList.empty() || !InstWorkList.empty() ||
1342 !OverdefinedInstWorkList.empty()) {
1343 // Process the overdefined instruction's work list first, which drives other
1344 // things to overdefined more quickly.
1345 while (!OverdefinedInstWorkList.empty()) {
1346 Value *I = OverdefinedInstWorkList.pop_back_val();
1347
1348 LLVM_DEBUG(dbgs() << "\nPopped off OI-WL: " << *I << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "\nPopped off OI-WL: " << *
I << '\n'; } } while (false)
;
1349
1350 // "I" got into the work list because it either made the transition from
1351 // bottom to constant, or to overdefined.
1352 //
1353 // Anything on this worklist that is overdefined need not be visited
1354 // since all of its users will have already been marked as overdefined
1355 // Update all of the users of this instruction's value.
1356 //
1357 markUsersAsChanged(I);
1358 }
1359
1360 // Process the instruction work list.
1361 while (!InstWorkList.empty()) {
1362 Value *I = InstWorkList.pop_back_val();
1363
1364 LLVM_DEBUG(dbgs() << "\nPopped off I-WL: " << *I << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "\nPopped off I-WL: " << *I
<< '\n'; } } while (false)
;
1365
1366 // "I" got into the work list because it made the transition from undef to
1367 // constant.
1368 //
1369 // Anything on this worklist that is overdefined need not be visited
1370 // since all of its users will have already been marked as overdefined.
1371 // Update all of the users of this instruction's value.
1372 //
1373 if (I->getType()->isStructTy() || !getValueState(I).isOverdefined())
1374 markUsersAsChanged(I);
1375 }
1376
1377 // Process the basic block work list.
1378 while (!BBWorkList.empty()) {
1379 BasicBlock *BB = BBWorkList.back();
1380 BBWorkList.pop_back();
1381
1382 LLVM_DEBUG(dbgs() << "\nPopped off BBWL: " << *BB << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "\nPopped off BBWL: " << *BB
<< '\n'; } } while (false)
;
1383
1384 // Notify all instructions in this basic block that they are newly
1385 // executable.
1386 visit(BB);
1387 }
1388 }
1389}
1390
1391/// ResolvedUndefsIn - While solving the dataflow for a function, we assume
1392/// that branches on undef values cannot reach any of their successors.
1393/// However, this is not a safe assumption. After we solve dataflow, this
1394/// method should be use to handle this. If this returns true, the solver
1395/// should be rerun.
1396///
1397/// This method handles this by finding an unresolved branch and marking it one
1398/// of the edges from the block as being feasible, even though the condition
1399/// doesn't say it would otherwise be. This allows SCCP to find the rest of the
1400/// CFG and only slightly pessimizes the analysis results (by marking one,
1401/// potentially infeasible, edge feasible). This cannot usefully modify the
1402/// constraints on the condition of the branch, as that would impact other users
1403/// of the value.
1404///
1405/// This scan also checks for values that use undefs, whose results are actually
1406/// defined. For example, 'zext i8 undef to i32' should produce all zeros
1407/// conservatively, as "(zext i8 X -> i32) & 0xFF00" must always return zero,
1408/// even if X isn't defined.
1409bool SCCPSolver::ResolvedUndefsIn(Function &F) {
1410 for (BasicBlock &BB : F) {
1411 if (!BBExecutable.count(&BB))
1412 continue;
1413
1414 for (Instruction &I : BB) {
1415 // Look for instructions which produce undef values.
1416 if (I.getType()->isVoidTy()) continue;
1417
1418 if (auto *STy = dyn_cast<StructType>(I.getType())) {
1419 // Only a few things that can be structs matter for undef.
1420
1421 // Tracked calls must never be marked overdefined in ResolvedUndefsIn.
1422 if (CallSite CS = CallSite(&I))
1423 if (Function *F = CS.getCalledFunction())
1424 if (MRVFunctionsTracked.count(F))
1425 continue;
1426
1427 // extractvalue and insertvalue don't need to be marked; they are
1428 // tracked as precisely as their operands.
1429 if (isa<ExtractValueInst>(I) || isa<InsertValueInst>(I))
1430 continue;
1431
1432 // Send the results of everything else to overdefined. We could be
1433 // more precise than this but it isn't worth bothering.
1434 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
1435 LatticeVal &LV = getStructValueState(&I, i);
1436 if (LV.isUnknown())
1437 markOverdefined(LV, &I);
1438 }
1439 continue;
1440 }
1441
1442 LatticeVal &LV = getValueState(&I);
1443 if (!LV.isUnknown()) continue;
1444
1445 // extractvalue is safe; check here because the argument is a struct.
1446 if (isa<ExtractValueInst>(I))
1447 continue;
1448
1449 // Compute the operand LatticeVals, for convenience below.
1450 // Anything taking a struct is conservatively assumed to require
1451 // overdefined markings.
1452 if (I.getOperand(0)->getType()->isStructTy()) {
1453 markOverdefined(&I);
1454 return true;
1455 }
1456 LatticeVal Op0LV = getValueState(I.getOperand(0));
1457 LatticeVal Op1LV;
1458 if (I.getNumOperands() == 2) {
1459 if (I.getOperand(1)->getType()->isStructTy()) {
1460 markOverdefined(&I);
1461 return true;
1462 }
1463
1464 Op1LV = getValueState(I.getOperand(1));
1465 }
1466 // If this is an instructions whose result is defined even if the input is
1467 // not fully defined, propagate the information.
1468 Type *ITy = I.getType();
1469 switch (I.getOpcode()) {
1470 case Instruction::Add:
1471 case Instruction::Sub:
1472 case Instruction::Trunc:
1473 case Instruction::FPTrunc:
1474 case Instruction::BitCast:
1475 break; // Any undef -> undef
1476 case Instruction::FSub:
1477 case Instruction::FAdd:
1478 case Instruction::FMul:
1479 case Instruction::FDiv:
1480 case Instruction::FRem:
1481 // Floating-point binary operation: be conservative.
1482 if (Op0LV.isUnknown() && Op1LV.isUnknown())
1483 markForcedConstant(&I, Constant::getNullValue(ITy));
1484 else
1485 markOverdefined(&I);
1486 return true;
1487 case Instruction::ZExt:
1488 case Instruction::SExt:
1489 case Instruction::FPToUI:
1490 case Instruction::FPToSI:
1491 case Instruction::FPExt:
1492 case Instruction::PtrToInt:
1493 case Instruction::IntToPtr:
1494 case Instruction::SIToFP:
1495 case Instruction::UIToFP:
1496 // undef -> 0; some outputs are impossible
1497 markForcedConstant(&I, Constant::getNullValue(ITy));
1498 return true;
1499 case Instruction::Mul:
1500 case Instruction::And:
1501 // Both operands undef -> undef
1502 if (Op0LV.isUnknown() && Op1LV.isUnknown())
1503 break;
1504 // undef * X -> 0. X could be zero.
1505 // undef & X -> 0. X could be zero.
1506 markForcedConstant(&I, Constant::getNullValue(ITy));
1507 return true;
1508 case Instruction::Or:
1509 // Both operands undef -> undef
1510 if (Op0LV.isUnknown() && Op1LV.isUnknown())
1511 break;
1512 // undef | X -> -1. X could be -1.
1513 markForcedConstant(&I, Constant::getAllOnesValue(ITy));
1514 return true;
1515 case Instruction::Xor:
1516 // undef ^ undef -> 0; strictly speaking, this is not strictly
1517 // necessary, but we try to be nice to people who expect this
1518 // behavior in simple cases
1519 if (Op0LV.isUnknown() && Op1LV.isUnknown()) {
1520 markForcedConstant(&I, Constant::getNullValue(ITy));
1521 return true;
1522 }
1523 // undef ^ X -> undef
1524 break;
1525 case Instruction::SDiv:
1526 case Instruction::UDiv:
1527 case Instruction::SRem:
1528 case Instruction::URem:
1529 // X / undef -> undef. No change.
1530 // X % undef -> undef. No change.
1531 if (Op1LV.isUnknown()) break;
1532
1533 // X / 0 -> undef. No change.
1534 // X % 0 -> undef. No change.
1535 if (Op1LV.isConstant() && Op1LV.getConstant()->isZeroValue())
1536 break;
1537
1538 // undef / X -> 0. X could be maxint.
1539 // undef % X -> 0. X could be 1.
1540 markForcedConstant(&I, Constant::getNullValue(ITy));
1541 return true;
1542 case Instruction::AShr:
1543 // X >>a undef -> undef.
1544 if (Op1LV.isUnknown()) break;
1545
1546 // Shifting by the bitwidth or more is undefined.
1547 if (Op1LV.isConstant()) {
1548 if (auto *ShiftAmt = Op1LV.getConstantInt())
1549 if (ShiftAmt->getLimitedValue() >=
1550 ShiftAmt->getType()->getScalarSizeInBits())
1551 break;
1552 }
1553
1554 // undef >>a X -> 0
1555 markForcedConstant(&I, Constant::getNullValue(ITy));
1556 return true;
1557 case Instruction::LShr:
1558 case Instruction::Shl:
1559 // X << undef -> undef.
1560 // X >> undef -> undef.
1561 if (Op1LV.isUnknown()) break;
1562
1563 // Shifting by the bitwidth or more is undefined.
1564 if (Op1LV.isConstant()) {
1565 if (auto *ShiftAmt = Op1LV.getConstantInt())
1566 if (ShiftAmt->getLimitedValue() >=
1567 ShiftAmt->getType()->getScalarSizeInBits())
1568 break;
1569 }
1570
1571 // undef << X -> 0
1572 // undef >> X -> 0
1573 markForcedConstant(&I, Constant::getNullValue(ITy));
1574 return true;
1575 case Instruction::Select:
1576 Op1LV = getValueState(I.getOperand(1));
1577 // undef ? X : Y -> X or Y. There could be commonality between X/Y.
1578 if (Op0LV.isUnknown()) {
1579 if (!Op1LV.isConstant()) // Pick the constant one if there is any.
1580 Op1LV = getValueState(I.getOperand(2));
1581 } else if (Op1LV.isUnknown()) {
1582 // c ? undef : undef -> undef. No change.
1583 Op1LV = getValueState(I.getOperand(2));
1584 if (Op1LV.isUnknown())
1585 break;
1586 // Otherwise, c ? undef : x -> x.
1587 } else {
1588 // Leave Op1LV as Operand(1)'s LatticeValue.
1589 }
1590
1591 if (Op1LV.isConstant())
1592 markForcedConstant(&I, Op1LV.getConstant());
1593 else
1594 markOverdefined(&I);
1595 return true;
1596 case Instruction::Load:
1597 // A load here means one of two things: a load of undef from a global,
1598 // a load from an unknown pointer. Either way, having it return undef
1599 // is okay.
1600 break;
1601 case Instruction::ICmp:
1602 // X == undef -> undef. Other comparisons get more complicated.
1603 Op0LV = getValueState(I.getOperand(0));
1604 Op1LV = getValueState(I.getOperand(1));
1605
1606 if ((Op0LV.isUnknown() || Op1LV.isUnknown()) &&
1607 cast<ICmpInst>(&I)->isEquality())
1608 break;
1609 markOverdefined(&I);
1610 return true;
1611 case Instruction::Call:
1612 case Instruction::Invoke:
1613 case Instruction::CallBr:
1614 // There are two reasons a call can have an undef result
1615 // 1. It could be tracked.
1616 // 2. It could be constant-foldable.
1617 // Because of the way we solve return values, tracked calls must
1618 // never be marked overdefined in ResolvedUndefsIn.
1619 if (Function *F = CallSite(&I).getCalledFunction())
1620 if (TrackedRetVals.count(F))
1621 break;
1622
1623 // If the call is constant-foldable, we mark it overdefined because
1624 // we do not know what return values are valid.
1625 markOverdefined(&I);
1626 return true;
1627 default:
1628 // If we don't know what should happen here, conservatively mark it
1629 // overdefined.
1630 markOverdefined(&I);
1631 return true;
1632 }
1633 }
1634
1635 // Check to see if we have a branch or switch on an undefined value. If so
1636 // we force the branch to go one way or the other to make the successor
1637 // values live. It doesn't really matter which way we force it.
1638 Instruction *TI = BB.getTerminator();
1639 if (auto *BI = dyn_cast<BranchInst>(TI)) {
1640 if (!BI->isConditional()) continue;
1641 if (!getValueState(BI->getCondition()).isUnknown())
1642 continue;
1643
1644 // If the input to SCCP is actually branch on undef, fix the undef to
1645 // false.
1646 if (isa<UndefValue>(BI->getCondition())) {
1647 BI->setCondition(ConstantInt::getFalse(BI->getContext()));
1648 markEdgeExecutable(&BB, TI->getSuccessor(1));
1649 return true;
1650 }
1651
1652 // Otherwise, it is a branch on a symbolic value which is currently
1653 // considered to be undef. Make sure some edge is executable, so a
1654 // branch on "undef" always flows somewhere.
1655 // FIXME: Distinguish between dead code and an LLVM "undef" value.
1656 BasicBlock *DefaultSuccessor = TI->getSuccessor(1);
1657 if (markEdgeExecutable(&BB, DefaultSuccessor))
1658 return true;
1659
1660 continue;
1661 }
1662
1663 if (auto *IBR = dyn_cast<IndirectBrInst>(TI)) {
1664 // Indirect branch with no successor ?. Its ok to assume it branches
1665 // to no target.
1666 if (IBR->getNumSuccessors() < 1)
1667 continue;
1668
1669 if (!getValueState(IBR->getAddress()).isUnknown())
1670 continue;
1671
1672 // If the input to SCCP is actually branch on undef, fix the undef to
1673 // the first successor of the indirect branch.
1674 if (isa<UndefValue>(IBR->getAddress())) {
1675 IBR->setAddress(BlockAddress::get(IBR->getSuccessor(0)));
1676 markEdgeExecutable(&BB, IBR->getSuccessor(0));
1677 return true;
1678 }
1679
1680 // Otherwise, it is a branch on a symbolic value which is currently
1681 // considered to be undef. Make sure some edge is executable, so a
1682 // branch on "undef" always flows somewhere.
1683 // FIXME: IndirectBr on "undef" doesn't actually need to go anywhere:
1684 // we can assume the branch has undefined behavior instead.
1685 BasicBlock *DefaultSuccessor = IBR->getSuccessor(0);
1686 if (markEdgeExecutable(&BB, DefaultSuccessor))
1687 return true;
1688
1689 continue;
1690 }
1691
1692 if (auto *SI = dyn_cast<SwitchInst>(TI)) {
1693 if (!SI->getNumCases() || !getValueState(SI->getCondition()).isUnknown())
1694 continue;
1695
1696 // If the input to SCCP is actually switch on undef, fix the undef to
1697 // the first constant.
1698 if (isa<UndefValue>(SI->getCondition())) {
1699 SI->setCondition(SI->case_begin()->getCaseValue());
1700 markEdgeExecutable(&BB, SI->case_begin()->getCaseSuccessor());
1701 return true;
1702 }
1703
1704 // Otherwise, it is a branch on a symbolic value which is currently
1705 // considered to be undef. Make sure some edge is executable, so a
1706 // branch on "undef" always flows somewhere.
1707 // FIXME: Distinguish between dead code and an LLVM "undef" value.
1708 BasicBlock *DefaultSuccessor = SI->case_begin()->getCaseSuccessor();
1709 if (markEdgeExecutable(&BB, DefaultSuccessor))
1710 return true;
1711
1712 continue;
1713 }
1714 }
1715
1716 return false;
1717}
1718
1719static bool tryToReplaceWithConstant(SCCPSolver &Solver, Value *V) {
1720 Constant *Const = nullptr;
1721 if (V->getType()->isStructTy()) {
1722 std::vector<LatticeVal> IVs = Solver.getStructLatticeValueFor(V);
1723 if (llvm::any_of(IVs,
1724 [](const LatticeVal &LV) { return LV.isOverdefined(); }))
1725 return false;
1726 std::vector<Constant *> ConstVals;
1727 auto *ST = dyn_cast<StructType>(V->getType());
1728 for (unsigned i = 0, e = ST->getNumElements(); i != e; ++i) {
1729 LatticeVal V = IVs[i];
1730 ConstVals.push_back(V.isConstant()
1731 ? V.getConstant()
1732 : UndefValue::get(ST->getElementType(i)));
1733 }
1734 Const = ConstantStruct::get(ST, ConstVals);
1735 } else {
1736 const LatticeVal &IV = Solver.getLatticeValueFor(V);
1737 if (IV.isOverdefined())
1738 return false;
1739
1740 Const = IV.isConstant() ? IV.getConstant() : UndefValue::get(V->getType());
1741 }
1742 assert(Const && "Constant is nullptr here!")((Const && "Constant is nullptr here!") ? static_cast
<void> (0) : __assert_fail ("Const && \"Constant is nullptr here!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 1742, __PRETTY_FUNCTION__))
;
1743
1744 // Replacing `musttail` instructions with constant breaks `musttail` invariant
1745 // unless the call itself can be removed
1746 CallInst *CI = dyn_cast<CallInst>(V);
1747 if (CI && CI->isMustTailCall() && !CI->isSafeToRemove()) {
1748 CallSite CS(CI);
1749 Function *F = CS.getCalledFunction();
1750
1751 // Don't zap returns of the callee
1752 if (F)
1753 Solver.AddMustTailCallee(F);
1754
1755 LLVM_DEBUG(dbgs() << " Can\'t treat the result of musttail call : " << *CIdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << " Can\'t treat the result of musttail call : "
<< *CI << " as a constant\n"; } } while (false)
1756 << " as a constant\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << " Can\'t treat the result of musttail call : "
<< *CI << " as a constant\n"; } } while (false)
;
1757 return false;
1758 }
1759
1760 LLVM_DEBUG(dbgs() << " Constant: " << *Const << " = " << *V << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << " Constant: " << *Const <<
" = " << *V << '\n'; } } while (false)
;
1761
1762 // Replaces all of the uses of a variable with uses of the constant.
1763 V->replaceAllUsesWith(Const);
1764 return true;
1765}
1766
1767// runSCCP() - Run the Sparse Conditional Constant Propagation algorithm,
1768// and return true if the function was modified.
1769static bool runSCCP(Function &F, const DataLayout &DL,
1770 const TargetLibraryInfo *TLI) {
1771 LLVM_DEBUG(dbgs() << "SCCP on function '" << F.getName() << "'\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "SCCP on function '" << F.getName
() << "'\n"; } } while (false)
;
1772 SCCPSolver Solver(DL, TLI);
1773
1774 // Mark the first block of the function as being executable.
1775 Solver.MarkBlockExecutable(&F.front());
1776
1777 // Mark all arguments to the function as being overdefined.
1778 for (Argument &AI : F.args())
1779 Solver.markOverdefined(&AI);
1780
1781 // Solve for constants.
1782 bool ResolvedUndefs = true;
1783 while (ResolvedUndefs) {
1784 Solver.Solve();
1785 LLVM_DEBUG(dbgs() << "RESOLVING UNDEFs\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "RESOLVING UNDEFs\n"; } } while (
false)
;
1786 ResolvedUndefs = Solver.ResolvedUndefsIn(F);
1787 }
1788
1789 bool MadeChanges = false;
1790
1791 // If we decided that there are basic blocks that are dead in this function,
1792 // delete their contents now. Note that we cannot actually delete the blocks,
1793 // as we cannot modify the CFG of the function.
1794
1795 for (BasicBlock &BB : F) {
1796 if (!Solver.isBlockExecutable(&BB)) {
1797 LLVM_DEBUG(dbgs() << " BasicBlock Dead:" << BB)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << " BasicBlock Dead:" << BB;
} } while (false)
;
1798
1799 ++NumDeadBlocks;
1800 NumInstRemoved += removeAllNonTerminatorAndEHPadInstructions(&BB);
1801
1802 MadeChanges = true;
1803 continue;
1804 }
1805
1806 // Iterate over all of the instructions in a function, replacing them with
1807 // constants if we have found them to be of constant values.
1808 for (BasicBlock::iterator BI = BB.begin(), E = BB.end(); BI != E;) {
1809 Instruction *Inst = &*BI++;
1810 if (Inst->getType()->isVoidTy() || Inst->isTerminator())
1811 continue;
1812
1813 if (tryToReplaceWithConstant(Solver, Inst)) {
1814 if (isInstructionTriviallyDead(Inst))
1815 Inst->eraseFromParent();
1816 // Hey, we just changed something!
1817 MadeChanges = true;
1818 ++NumInstRemoved;
1819 }
1820 }
1821 }
1822
1823 return MadeChanges;
1824}
1825
1826PreservedAnalyses SCCPPass::run(Function &F, FunctionAnalysisManager &AM) {
1827 const DataLayout &DL = F.getParent()->getDataLayout();
1828 auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
1829 if (!runSCCP(F, DL, &TLI))
1830 return PreservedAnalyses::all();
1831
1832 auto PA = PreservedAnalyses();
1833 PA.preserve<GlobalsAA>();
1834 PA.preserveSet<CFGAnalyses>();
1835 return PA;
1836}
1837
1838namespace {
1839
1840//===--------------------------------------------------------------------===//
1841//
1842/// SCCP Class - This class uses the SCCPSolver to implement a per-function
1843/// Sparse Conditional Constant Propagator.
1844///
1845class SCCPLegacyPass : public FunctionPass {
1846public:
1847 // Pass identification, replacement for typeid
1848 static char ID;
1849
1850 SCCPLegacyPass() : FunctionPass(ID) {
1851 initializeSCCPLegacyPassPass(*PassRegistry::getPassRegistry());
1852 }
1853
1854 void getAnalysisUsage(AnalysisUsage &AU) const override {
1855 AU.addRequired<TargetLibraryInfoWrapperPass>();
1856 AU.addPreserved<GlobalsAAWrapperPass>();
1857 AU.setPreservesCFG();
1858 }
1859
1860 // runOnFunction - Run the Sparse Conditional Constant Propagation
1861 // algorithm, and return true if the function was modified.
1862 bool runOnFunction(Function &F) override {
1863 if (skipFunction(F))
1864 return false;
1865 const DataLayout &DL = F.getParent()->getDataLayout();
1866 const TargetLibraryInfo *TLI =
1867 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1868 return runSCCP(F, DL, TLI);
1869 }
1870};
1871
1872} // end anonymous namespace
1873
1874char SCCPLegacyPass::ID = 0;
1875
1876INITIALIZE_PASS_BEGIN(SCCPLegacyPass, "sccp",static void *initializeSCCPLegacyPassPassOnce(PassRegistry &
Registry) {
1877 "Sparse Conditional Constant Propagation", false, false)static void *initializeSCCPLegacyPassPassOnce(PassRegistry &
Registry) {
1878INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
1879INITIALIZE_PASS_END(SCCPLegacyPass, "sccp",PassInfo *PI = new PassInfo( "Sparse Conditional Constant Propagation"
, "sccp", &SCCPLegacyPass::ID, PassInfo::NormalCtor_t(callDefaultCtor
<SCCPLegacyPass>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeSCCPLegacyPassPassFlag
; void llvm::initializeSCCPLegacyPassPass(PassRegistry &Registry
) { llvm::call_once(InitializeSCCPLegacyPassPassFlag, initializeSCCPLegacyPassPassOnce
, std::ref(Registry)); }
1880 "Sparse Conditional Constant Propagation", false, false)PassInfo *PI = new PassInfo( "Sparse Conditional Constant Propagation"
, "sccp", &SCCPLegacyPass::ID, PassInfo::NormalCtor_t(callDefaultCtor
<SCCPLegacyPass>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeSCCPLegacyPassPassFlag
; void llvm::initializeSCCPLegacyPassPass(PassRegistry &Registry
) { llvm::call_once(InitializeSCCPLegacyPassPassFlag, initializeSCCPLegacyPassPassOnce
, std::ref(Registry)); }
1881
1882// createSCCPPass - This is the public interface to this file.
1883FunctionPass *llvm::createSCCPPass() { return new SCCPLegacyPass(); }
1884
1885static void findReturnsToZap(Function &F,
1886 SmallVector<ReturnInst *, 8> &ReturnsToZap,
1887 SCCPSolver &Solver) {
1888 // We can only do this if we know that nothing else can call the function.
1889 if (!Solver.isArgumentTrackedFunction(&F))
1890 return;
1891
1892 // There is a non-removable musttail call site of this function. Zapping
1893 // returns is not allowed.
1894 if (Solver.isMustTailCallee(&F)) {
1895 LLVM_DEBUG(dbgs() << "Can't zap returns of the function : " << F.getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "Can't zap returns of the function : "
<< F.getName() << " due to present musttail call of it\n"
; } } while (false)
1896 << " due to present musttail call of it\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "Can't zap returns of the function : "
<< F.getName() << " due to present musttail call of it\n"
; } } while (false)
;
1897 return;
1898 }
1899
1900 for (BasicBlock &BB : F) {
1901 if (CallInst *CI = BB.getTerminatingMustTailCall()) {
1902 LLVM_DEBUG(dbgs() << "Can't zap return of the block due to present "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "Can't zap return of the block due to present "
<< "musttail call : " << *CI << "\n"; } } while
(false)
1903 << "musttail call : " << *CI << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "Can't zap return of the block due to present "
<< "musttail call : " << *CI << "\n"; } } while
(false)
;
1904 (void)CI;
1905 return;
1906 }
1907
1908 if (auto *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1909 if (!isa<UndefValue>(RI->getOperand(0)))
1910 ReturnsToZap.push_back(RI);
1911 }
1912}
1913
1914// Update the condition for terminators that are branching on indeterminate
1915// values, forcing them to use a specific edge.
1916static void forceIndeterminateEdge(Instruction* I, SCCPSolver &Solver) {
1917 BasicBlock *Dest = nullptr;
1918 Constant *C = nullptr;
1919 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
1920 if (!isa<ConstantInt>(SI->getCondition())) {
1921 // Indeterminate switch; use first case value.
1922 Dest = SI->case_begin()->getCaseSuccessor();
1923 C = SI->case_begin()->getCaseValue();
1924 }
1925 } else if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
1926 if (!isa<ConstantInt>(BI->getCondition())) {
1927 // Indeterminate branch; use false.
1928 Dest = BI->getSuccessor(1);
1929 C = ConstantInt::getFalse(BI->getContext());
1930 }
1931 } else if (IndirectBrInst *IBR = dyn_cast<IndirectBrInst>(I)) {
1932 if (!isa<BlockAddress>(IBR->getAddress()->stripPointerCasts())) {
1933 // Indeterminate indirectbr; use successor 0.
1934 Dest = IBR->getSuccessor(0);
1935 C = BlockAddress::get(IBR->getSuccessor(0));
1936 }
1937 } else {
1938 llvm_unreachable("Unexpected terminator instruction")::llvm::llvm_unreachable_internal("Unexpected terminator instruction"
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 1938)
;
1939 }
1940 if (C) {
1941 assert(Solver.isEdgeFeasible(I->getParent(), Dest) &&((Solver.isEdgeFeasible(I->getParent(), Dest) && "Didn't find feasible edge?"
) ? static_cast<void> (0) : __assert_fail ("Solver.isEdgeFeasible(I->getParent(), Dest) && \"Didn't find feasible edge?\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 1942, __PRETTY_FUNCTION__))
1942 "Didn't find feasible edge?")((Solver.isEdgeFeasible(I->getParent(), Dest) && "Didn't find feasible edge?"
) ? static_cast<void> (0) : __assert_fail ("Solver.isEdgeFeasible(I->getParent(), Dest) && \"Didn't find feasible edge?\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 1942, __PRETTY_FUNCTION__))
;
1943 (void)Dest;
1944
1945 I->setOperand(0, C);
1946 }
1947}
1948
1949bool llvm::runIPSCCP(
1950 Module &M, const DataLayout &DL, const TargetLibraryInfo *TLI,
1951 function_ref<AnalysisResultsForFn(Function &)> getAnalysis) {
1952 SCCPSolver Solver(DL, TLI);
1953
1954 // Loop over all functions, marking arguments to those with their addresses
1955 // taken or that are external as overdefined.
1956 for (Function &F : M) {
1957 if (F.isDeclaration())
1958 continue;
1959
1960 Solver.addAnalysis(F, getAnalysis(F));
1961
1962 // Determine if we can track the function's return values. If so, add the
1963 // function to the solver's set of return-tracked functions.
1964 if (canTrackReturnsInterprocedurally(&F))
1965 Solver.AddTrackedFunction(&F);
1966
1967 // Determine if we can track the function's arguments. If so, add the
1968 // function to the solver's set of argument-tracked functions.
1969 if (canTrackArgumentsInterprocedurally(&F)) {
1970 Solver.AddArgumentTrackedFunction(&F);
1971 continue;
1972 }
1973
1974 // Assume the function is called.
1975 Solver.MarkBlockExecutable(&F.front());
1976
1977 // Assume nothing about the incoming arguments.
1978 for (Argument &AI : F.args())
1979 Solver.markOverdefined(&AI);
1980 }
1981
1982 // Determine if we can track any of the module's global variables. If so, add
1983 // the global variables we can track to the solver's set of tracked global
1984 // variables.
1985 for (GlobalVariable &G : M.globals()) {
1986 G.removeDeadConstantUsers();
1987 if (canTrackGlobalVariableInterprocedurally(&G))
1988 Solver.TrackValueOfGlobalVariable(&G);
1989 }
1990
1991 // Solve for constants.
1992 bool ResolvedUndefs = true;
1993 Solver.Solve();
1994 while (ResolvedUndefs) {
1995 LLVM_DEBUG(dbgs() << "RESOLVING UNDEFS\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "RESOLVING UNDEFS\n"; } } while (
false)
;
1996 ResolvedUndefs = false;
1997 for (Function &F : M)
1998 if (Solver.ResolvedUndefsIn(F)) {
1999 // We run Solve() after we resolved an undef in a function, because
2000 // we might deduce a fact that eliminates an undef in another function.
2001 Solver.Solve();
2002 ResolvedUndefs = true;
2003 }
2004 }
2005
2006 bool MadeChanges = false;
2007
2008 // Iterate over all of the instructions in the module, replacing them with
2009 // constants if we have found them to be of constant values.
2010
2011 for (Function &F : M) {
2012 if (F.isDeclaration())
2013 continue;
2014
2015 SmallVector<BasicBlock *, 512> BlocksToErase;
2016
2017 if (Solver.isBlockExecutable(&F.front()))
2018 for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end(); AI != E;
2019 ++AI) {
2020 if (!AI->use_empty() && tryToReplaceWithConstant(Solver, &*AI)) {
2021 ++IPNumArgsElimed;
2022 continue;
2023 }
2024 }
2025
2026 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
2027 if (!Solver.isBlockExecutable(&*BB)) {
2028 LLVM_DEBUG(dbgs() << " BasicBlock Dead:" << *BB)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << " BasicBlock Dead:" << *BB
; } } while (false)
;
2029 ++NumDeadBlocks;
2030
2031 MadeChanges = true;
2032
2033 if (&*BB != &F.front())
2034 BlocksToErase.push_back(&*BB);
2035 continue;
2036 }
2037
2038 for (BasicBlock::iterator BI = BB->begin(), E = BB->end(); BI != E; ) {
2039 Instruction *Inst = &*BI++;
2040 if (Inst->getType()->isVoidTy())
2041 continue;
2042 if (tryToReplaceWithConstant(Solver, Inst)) {
2043 if (Inst->isSafeToRemove())
2044 Inst->eraseFromParent();
2045 // Hey, we just changed something!
2046 MadeChanges = true;
2047 ++IPNumInstRemoved;
2048 }
2049 }
2050 }
2051
2052 DomTreeUpdater DTU = Solver.getDTU(F);
2053 // Change dead blocks to unreachable. We do it after replacing constants
2054 // in all executable blocks, because changeToUnreachable may remove PHI
2055 // nodes in executable blocks we found values for. The function's entry
2056 // block is not part of BlocksToErase, so we have to handle it separately.
2057 for (BasicBlock *BB : BlocksToErase) {
2058 NumInstRemoved +=
2059 changeToUnreachable(BB->getFirstNonPHI(), /*UseLLVMTrap=*/false,
2060 /*PreserveLCSSA=*/false, &DTU);
2061 }
2062 if (!Solver.isBlockExecutable(&F.front()))
2063 NumInstRemoved += changeToUnreachable(F.front().getFirstNonPHI(),
2064 /*UseLLVMTrap=*/false,
2065 /*PreserveLCSSA=*/false, &DTU);
2066
2067 // Now that all instructions in the function are constant folded,
2068 // use ConstantFoldTerminator to get rid of in-edges, record DT updates and
2069 // delete dead BBs.
2070 for (BasicBlock *DeadBB : BlocksToErase) {
2071 // If there are any PHI nodes in this successor, drop entries for BB now.
2072 for (Value::user_iterator UI = DeadBB->user_begin(),
2073 UE = DeadBB->user_end();
2074 UI != UE;) {
2075 // Grab the user and then increment the iterator early, as the user
2076 // will be deleted. Step past all adjacent uses from the same user.
2077 auto *I = dyn_cast<Instruction>(*UI);
2078 do { ++UI; } while (UI != UE && *UI == I);
2079
2080 // Ignore blockaddress users; BasicBlock's dtor will handle them.
2081 if (!I) continue;
2082
2083 // If we have forced an edge for an indeterminate value, then force the
2084 // terminator to fold to that edge.
2085 forceIndeterminateEdge(I, Solver);
2086 bool Folded = ConstantFoldTerminator(I->getParent(),
2087 /*DeleteDeadConditions=*/false,
2088 /*TLI=*/nullptr, &DTU);
2089 assert(Folded &&((Folded && "Expect TermInst on constantint or blockaddress to be folded"
) ? static_cast<void> (0) : __assert_fail ("Folded && \"Expect TermInst on constantint or blockaddress to be folded\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 2090, __PRETTY_FUNCTION__))
2090 "Expect TermInst on constantint or blockaddress to be folded")((Folded && "Expect TermInst on constantint or blockaddress to be folded"
) ? static_cast<void> (0) : __assert_fail ("Folded && \"Expect TermInst on constantint or blockaddress to be folded\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 2090, __PRETTY_FUNCTION__))
;
2091 (void) Folded;
2092 }
2093 // Mark dead BB for deletion.
2094 DTU.deleteBB(DeadBB);
2095 }
2096
2097 for (BasicBlock &BB : F) {
2098 for (BasicBlock::iterator BI = BB.begin(), E = BB.end(); BI != E;) {
2099 Instruction *Inst = &*BI++;
2100 if (Solver.getPredicateInfoFor(Inst)) {
2101 if (auto *II = dyn_cast<IntrinsicInst>(Inst)) {
2102 if (II->getIntrinsicID() == Intrinsic::ssa_copy) {
2103 Value *Op = II->getOperand(0);
2104 Inst->replaceAllUsesWith(Op);
2105 Inst->eraseFromParent();
2106 }
2107 }
2108 }
2109 }
2110 }
2111 }
2112
2113 // If we inferred constant or undef return values for a function, we replaced
2114 // all call uses with the inferred value. This means we don't need to bother
2115 // actually returning anything from the function. Replace all return
2116 // instructions with return undef.
2117 //
2118 // Do this in two stages: first identify the functions we should process, then
2119 // actually zap their returns. This is important because we can only do this
2120 // if the address of the function isn't taken. In cases where a return is the
2121 // last use of a function, the order of processing functions would affect
2122 // whether other functions are optimizable.
2123 SmallVector<ReturnInst*, 8> ReturnsToZap;
2124
2125 const DenseMap<Function*, LatticeVal> &RV = Solver.getTrackedRetVals();
2126 for (const auto &I : RV) {
2127 Function *F = I.first;
2128 if (I.second.isOverdefined() || F->getReturnType()->isVoidTy())
2129 continue;
2130 findReturnsToZap(*F, ReturnsToZap, Solver);
2131 }
2132
2133 for (const auto &F : Solver.getMRVFunctionsTracked()) {
2134 assert(F->getReturnType()->isStructTy() &&((F->getReturnType()->isStructTy() && "The return type should be a struct"
) ? static_cast<void> (0) : __assert_fail ("F->getReturnType()->isStructTy() && \"The return type should be a struct\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 2135, __PRETTY_FUNCTION__))
2135 "The return type should be a struct")((F->getReturnType()->isStructTy() && "The return type should be a struct"
) ? static_cast<void> (0) : __assert_fail ("F->getReturnType()->isStructTy() && \"The return type should be a struct\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 2135, __PRETTY_FUNCTION__))
;
2136 StructType *STy = cast<StructType>(F->getReturnType());
2137 if (Solver.isStructLatticeConstant(F, STy))
2138 findReturnsToZap(*F, ReturnsToZap, Solver);
2139 }
2140
2141 // Zap all returns which we've identified as zap to change.
2142 for (unsigned i = 0, e = ReturnsToZap.size(); i != e; ++i) {
2143 Function *F = ReturnsToZap[i]->getParent()->getParent();
2144 ReturnsToZap[i]->setOperand(0, UndefValue::get(F->getReturnType()));
2145 }
2146
2147 // If we inferred constant or undef values for globals variables, we can
2148 // delete the global and any stores that remain to it.
2149 const DenseMap<GlobalVariable*, LatticeVal> &TG = Solver.getTrackedGlobals();
2150 for (DenseMap<GlobalVariable*, LatticeVal>::const_iterator I = TG.begin(),
2151 E = TG.end(); I != E; ++I) {
2152 GlobalVariable *GV = I->first;
2153 assert(!I->second.isOverdefined() &&((!I->second.isOverdefined() && "Overdefined values should have been taken out of the map!"
) ? static_cast<void> (0) : __assert_fail ("!I->second.isOverdefined() && \"Overdefined values should have been taken out of the map!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 2154, __PRETTY_FUNCTION__))
2154 "Overdefined values should have been taken out of the map!")((!I->second.isOverdefined() && "Overdefined values should have been taken out of the map!"
) ? static_cast<void> (0) : __assert_fail ("!I->second.isOverdefined() && \"Overdefined values should have been taken out of the map!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/lib/Transforms/Scalar/SCCP.cpp"
, 2154, __PRETTY_FUNCTION__))
;
2155 LLVM_DEBUG(dbgs() << "Found that GV '" << GV->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "Found that GV '" << GV->
getName() << "' is constant!\n"; } } while (false)
2156 << "' is constant!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sccp")) { dbgs() << "Found that GV '" << GV->
getName() << "' is constant!\n"; } } while (false)
;
2157 while (!GV->use_empty()) {
2158 StoreInst *SI = cast<StoreInst>(GV->user_back());
2159 SI->eraseFromParent();
2160 }
2161 M.getGlobalList().erase(GV);
2162 ++IPNumGlobalConst;
2163 }
2164
2165 return MadeChanges;
2166}

/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h

1//===- llvm/User.h - User class definition ----------------------*- C++ -*-===//
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 class defines the interface that one who uses a Value must implement.
10// Each instance of the Value class keeps track of what User's have handles
11// to it.
12//
13// * Instructions are the largest class of Users.
14// * Constants may be users of other constants (think arrays and stuff)
15//
16//===----------------------------------------------------------------------===//
17
18#ifndef LLVM_IR_USER_H
19#define LLVM_IR_USER_H
20
21#include "llvm/ADT/iterator.h"
22#include "llvm/ADT/iterator_range.h"
23#include "llvm/IR/Use.h"
24#include "llvm/IR/Value.h"
25#include "llvm/Support/Casting.h"
26#include "llvm/Support/Compiler.h"
27#include "llvm/Support/ErrorHandling.h"
28#include <cassert>
29#include <cstddef>
30#include <cstdint>
31#include <iterator>
32
33namespace llvm {
34
35template <typename T> class ArrayRef;
36template <typename T> class MutableArrayRef;
37
38/// Compile-time customization of User operands.
39///
40/// Customizes operand-related allocators and accessors.
41template <class>
42struct OperandTraits;
43
44class User : public Value {
45 template <unsigned>
46 friend struct HungoffOperandTraits;
47
48 LLVM_ATTRIBUTE_ALWAYS_INLINE__attribute__((always_inline)) inline static void *
49 allocateFixedOperandUser(size_t, unsigned, unsigned);
50
51protected:
52 /// Allocate a User with an operand pointer co-allocated.
53 ///
54 /// This is used for subclasses which need to allocate a variable number
55 /// of operands, ie, 'hung off uses'.
56 void *operator new(size_t Size);
57
58 /// Allocate a User with the operands co-allocated.
59 ///
60 /// This is used for subclasses which have a fixed number of operands.
61 void *operator new(size_t Size, unsigned Us);
62
63 /// Allocate a User with the operands co-allocated. If DescBytes is non-zero
64 /// then allocate an additional DescBytes bytes before the operands. These
65 /// bytes can be accessed by calling getDescriptor.
66 ///
67 /// DescBytes needs to be divisible by sizeof(void *). The allocated
68 /// descriptor, if any, is aligned to sizeof(void *) bytes.
69 ///
70 /// This is used for subclasses which have a fixed number of operands.
71 void *operator new(size_t Size, unsigned Us, unsigned DescBytes);
72
73 User(Type *ty, unsigned vty, Use *, unsigned NumOps)
74 : Value(ty, vty) {
75 assert(NumOps < (1u << NumUserOperandsBits) && "Too many operands")((NumOps < (1u << NumUserOperandsBits) && "Too many operands"
) ? static_cast<void> (0) : __assert_fail ("NumOps < (1u << NumUserOperandsBits) && \"Too many operands\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 75, __PRETTY_FUNCTION__))
;
76 NumUserOperands = NumOps;
77 // If we have hung off uses, then the operand list should initially be
78 // null.
79 assert((!HasHungOffUses || !getOperandList()) &&(((!HasHungOffUses || !getOperandList()) && "Error in initializing hung off uses for User"
) ? static_cast<void> (0) : __assert_fail ("(!HasHungOffUses || !getOperandList()) && \"Error in initializing hung off uses for User\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 80, __PRETTY_FUNCTION__))
80 "Error in initializing hung off uses for User")(((!HasHungOffUses || !getOperandList()) && "Error in initializing hung off uses for User"
) ? static_cast<void> (0) : __assert_fail ("(!HasHungOffUses || !getOperandList()) && \"Error in initializing hung off uses for User\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 80, __PRETTY_FUNCTION__))
;
81 }
82
83 /// Allocate the array of Uses, followed by a pointer
84 /// (with bottom bit set) to the User.
85 /// \param IsPhi identifies callers which are phi nodes and which need
86 /// N BasicBlock* allocated along with N
87 void allocHungoffUses(unsigned N, bool IsPhi = false);
88
89 /// Grow the number of hung off uses. Note that allocHungoffUses
90 /// should be called if there are no uses.
91 void growHungoffUses(unsigned N, bool IsPhi = false);
92
93protected:
94 ~User() = default; // Use deleteValue() to delete a generic Instruction.
95
96public:
97 User(const User &) = delete;
98
99 /// Free memory allocated for User and Use objects.
100 void operator delete(void *Usr);
101 /// Placement delete - required by std, called if the ctor throws.
102 void operator delete(void *Usr, unsigned) {
103 // Note: If a subclass manipulates the information which is required to calculate the
104 // Usr memory pointer, e.g. NumUserOperands, the operator delete of that subclass has
105 // to restore the changed information to the original value, since the dtor of that class
106 // is not called if the ctor fails.
107 User::operator delete(Usr);
108
109#ifndef LLVM_ENABLE_EXCEPTIONS
110 llvm_unreachable("Constructor throws?")::llvm::llvm_unreachable_internal("Constructor throws?", "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 110)
;
111#endif
112 }
113 /// Placement delete - required by std, called if the ctor throws.
114 void operator delete(void *Usr, unsigned, bool) {
115 // Note: If a subclass manipulates the information which is required to calculate the
116 // Usr memory pointer, e.g. NumUserOperands, the operator delete of that subclass has
117 // to restore the changed information to the original value, since the dtor of that class
118 // is not called if the ctor fails.
119 User::operator delete(Usr);
120
121#ifndef LLVM_ENABLE_EXCEPTIONS
122 llvm_unreachable("Constructor throws?")::llvm::llvm_unreachable_internal("Constructor throws?", "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 122)
;
123#endif
124 }
125
126protected:
127 template <int Idx, typename U> static Use &OpFrom(const U *that) {
128 return Idx < 0
129 ? OperandTraits<U>::op_end(const_cast<U*>(that))[Idx]
130 : OperandTraits<U>::op_begin(const_cast<U*>(that))[Idx];
131 }
132
133 template <int Idx> Use &Op() {
134 return OpFrom<Idx>(this);
135 }
136 template <int Idx> const Use &Op() const {
137 return OpFrom<Idx>(this);
138 }
139
140private:
141 const Use *getHungOffOperands() const {
142 return *(reinterpret_cast<const Use *const *>(this) - 1);
143 }
144
145 Use *&getHungOffOperands() { return *(reinterpret_cast<Use **>(this) - 1); }
146
147 const Use *getIntrusiveOperands() const {
148 return reinterpret_cast<const Use *>(this) - NumUserOperands;
149 }
150
151 Use *getIntrusiveOperands() {
152 return reinterpret_cast<Use *>(this) - NumUserOperands;
153 }
154
155 void setOperandList(Use *NewList) {
156 assert(HasHungOffUses &&((HasHungOffUses && "Setting operand list only required for hung off uses"
) ? static_cast<void> (0) : __assert_fail ("HasHungOffUses && \"Setting operand list only required for hung off uses\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 157, __PRETTY_FUNCTION__))
157 "Setting operand list only required for hung off uses")((HasHungOffUses && "Setting operand list only required for hung off uses"
) ? static_cast<void> (0) : __assert_fail ("HasHungOffUses && \"Setting operand list only required for hung off uses\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 157, __PRETTY_FUNCTION__))
;
158 getHungOffOperands() = NewList;
159 }
160
161public:
162 const Use *getOperandList() const {
163 return HasHungOffUses ? getHungOffOperands() : getIntrusiveOperands();
164 }
165 Use *getOperandList() {
166 return const_cast<Use *>(static_cast<const User *>(this)->getOperandList());
167 }
168
169 Value *getOperand(unsigned i) const {
170 assert(i < NumUserOperands && "getOperand() out of range!")((i < NumUserOperands && "getOperand() out of range!"
) ? static_cast<void> (0) : __assert_fail ("i < NumUserOperands && \"getOperand() out of range!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 170, __PRETTY_FUNCTION__))
;
9
Assuming the condition is true
10
'?' condition is true
171 return getOperandList()[i];
11
Calling 'Use::operator llvm::Value *'
13
Returning from 'Use::operator llvm::Value *'
14
Returning pointer
172 }
173
174 void setOperand(unsigned i, Value *Val) {
175 assert(i < NumUserOperands && "setOperand() out of range!")((i < NumUserOperands && "setOperand() out of range!"
) ? static_cast<void> (0) : __assert_fail ("i < NumUserOperands && \"setOperand() out of range!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 175, __PRETTY_FUNCTION__))
;
176 assert((!isa<Constant>((const Value*)this) ||(((!isa<Constant>((const Value*)this) || isa<GlobalValue
>((const Value*)this)) && "Cannot mutate a constant with setOperand!"
) ? static_cast<void> (0) : __assert_fail ("(!isa<Constant>((const Value*)this) || isa<GlobalValue>((const Value*)this)) && \"Cannot mutate a constant with setOperand!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 178, __PRETTY_FUNCTION__))
177 isa<GlobalValue>((const Value*)this)) &&(((!isa<Constant>((const Value*)this) || isa<GlobalValue
>((const Value*)this)) && "Cannot mutate a constant with setOperand!"
) ? static_cast<void> (0) : __assert_fail ("(!isa<Constant>((const Value*)this) || isa<GlobalValue>((const Value*)this)) && \"Cannot mutate a constant with setOperand!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 178, __PRETTY_FUNCTION__))
178 "Cannot mutate a constant with setOperand!")(((!isa<Constant>((const Value*)this) || isa<GlobalValue
>((const Value*)this)) && "Cannot mutate a constant with setOperand!"
) ? static_cast<void> (0) : __assert_fail ("(!isa<Constant>((const Value*)this) || isa<GlobalValue>((const Value*)this)) && \"Cannot mutate a constant with setOperand!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 178, __PRETTY_FUNCTION__))
;
179 getOperandList()[i] = Val;
180 }
181
182 const Use &getOperandUse(unsigned i) const {
183 assert(i < NumUserOperands && "getOperandUse() out of range!")((i < NumUserOperands && "getOperandUse() out of range!"
) ? static_cast<void> (0) : __assert_fail ("i < NumUserOperands && \"getOperandUse() out of range!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 183, __PRETTY_FUNCTION__))
;
184 return getOperandList()[i];
185 }
186 Use &getOperandUse(unsigned i) {
187 assert(i < NumUserOperands && "getOperandUse() out of range!")((i < NumUserOperands && "getOperandUse() out of range!"
) ? static_cast<void> (0) : __assert_fail ("i < NumUserOperands && \"getOperandUse() out of range!\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 187, __PRETTY_FUNCTION__))
;
188 return getOperandList()[i];
189 }
190
191 unsigned getNumOperands() const { return NumUserOperands; }
192
193 /// Returns the descriptor co-allocated with this User instance.
194 ArrayRef<const uint8_t> getDescriptor() const;
195
196 /// Returns the descriptor co-allocated with this User instance.
197 MutableArrayRef<uint8_t> getDescriptor();
198
199 /// Set the number of operands on a GlobalVariable.
200 ///
201 /// GlobalVariable always allocates space for a single operands, but
202 /// doesn't always use it.
203 ///
204 /// FIXME: As that the number of operands is used to find the start of
205 /// the allocated memory in operator delete, we need to always think we have
206 /// 1 operand before delete.
207 void setGlobalVariableNumOperands(unsigned NumOps) {
208 assert(NumOps <= 1 && "GlobalVariable can only have 0 or 1 operands")((NumOps <= 1 && "GlobalVariable can only have 0 or 1 operands"
) ? static_cast<void> (0) : __assert_fail ("NumOps <= 1 && \"GlobalVariable can only have 0 or 1 operands\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 208, __PRETTY_FUNCTION__))
;
209 NumUserOperands = NumOps;
210 }
211
212 /// Subclasses with hung off uses need to manage the operand count
213 /// themselves. In these instances, the operand count isn't used to find the
214 /// OperandList, so there's no issue in having the operand count change.
215 void setNumHungOffUseOperands(unsigned NumOps) {
216 assert(HasHungOffUses && "Must have hung off uses to use this method")((HasHungOffUses && "Must have hung off uses to use this method"
) ? static_cast<void> (0) : __assert_fail ("HasHungOffUses && \"Must have hung off uses to use this method\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 216, __PRETTY_FUNCTION__))
;
217 assert(NumOps < (1u << NumUserOperandsBits) && "Too many operands")((NumOps < (1u << NumUserOperandsBits) && "Too many operands"
) ? static_cast<void> (0) : __assert_fail ("NumOps < (1u << NumUserOperandsBits) && \"Too many operands\""
, "/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/User.h"
, 217, __PRETTY_FUNCTION__))
;
218 NumUserOperands = NumOps;
219 }
220
221 // ---------------------------------------------------------------------------
222 // Operand Iterator interface...
223 //
224 using op_iterator = Use*;
225 using const_op_iterator = const Use*;
226 using op_range = iterator_range<op_iterator>;
227 using const_op_range = iterator_range<const_op_iterator>;
228
229 op_iterator op_begin() { return getOperandList(); }
230 const_op_iterator op_begin() const { return getOperandList(); }
231 op_iterator op_end() {
232 return getOperandList() + NumUserOperands;
233 }
234 const_op_iterator op_end() const {
235 return getOperandList() + NumUserOperands;
236 }
237 op_range operands() {
238 return op_range(op_begin(), op_end());
239 }
240 const_op_range operands() const {
241 return const_op_range(op_begin(), op_end());
242 }
243
244 /// Iterator for directly iterating over the operand Values.
245 struct value_op_iterator
246 : iterator_adaptor_base<value_op_iterator, op_iterator,
247 std::random_access_iterator_tag, Value *,
248 ptrdiff_t, Value *, Value *> {
249 explicit value_op_iterator(Use *U = nullptr) : iterator_adaptor_base(U) {}
250
251 Value *operator*() const { return *I; }
252 Value *operator->() const { return operator*(); }
253 };
254
255 value_op_iterator value_op_begin() {
256 return value_op_iterator(op_begin());
257 }
258 value_op_iterator value_op_end() {
259 return value_op_iterator(op_end());
260 }
261 iterator_range<value_op_iterator> operand_values() {
262 return make_range(value_op_begin(), value_op_end());
263 }
264
265 struct const_value_op_iterator
266 : iterator_adaptor_base<const_value_op_iterator, const_op_iterator,
267 std::random_access_iterator_tag, const Value *,
268 ptrdiff_t, const Value *, const Value *> {
269 explicit const_value_op_iterator(const Use *U = nullptr) :
270 iterator_adaptor_base(U) {}
271
272 const Value *operator*() const { return *I; }
273 const Value *operator->() const { return operator*(); }
274 };
275
276 const_value_op_iterator value_op_begin() const {
277 return const_value_op_iterator(op_begin());
278 }
279 const_value_op_iterator value_op_end() const {
280 return const_value_op_iterator(op_end());
281 }
282 iterator_range<const_value_op_iterator> operand_values() const {
283 return make_range(value_op_begin(), value_op_end());
284 }
285
286 /// Drop all references to operands.
287 ///
288 /// This function is in charge of "letting go" of all objects that this User
289 /// refers to. This allows one to 'delete' a whole class at a time, even
290 /// though there may be circular references... First all references are
291 /// dropped, and all use counts go to zero. Then everything is deleted for
292 /// real. Note that no operations are valid on an object that has "dropped
293 /// all references", except operator delete.
294 void dropAllReferences() {
295 for (Use &U : operands())
296 U.set(nullptr);
297 }
298
299 /// Replace uses of one Value with another.
300 ///
301 /// Replaces all references to the "From" definition with references to the
302 /// "To" definition.
303 void replaceUsesOfWith(Value *From, Value *To);
304
305 // Methods for support type inquiry through isa, cast, and dyn_cast:
306 static bool classof(const Value *V) {
307 return isa<Instruction>(V) || isa<Constant>(V);
308 }
309};
310
311// Either Use objects, or a Use pointer can be prepended to User.
312static_assert(alignof(Use) >= alignof(User),
313 "Alignment is insufficient after objects prepended to User");
314static_assert(alignof(Use *) >= alignof(User),
315 "Alignment is insufficient after objects prepended to User");
316
317template<> struct simplify_type<User::op_iterator> {
318 using SimpleType = Value*;
319
320 static SimpleType getSimplifiedValue(User::op_iterator &Val) {
321 return Val->get();
322 }
323};
324template<> struct simplify_type<User::const_op_iterator> {
325 using SimpleType = /*const*/ Value*;
326
327 static SimpleType getSimplifiedValue(User::const_op_iterator &Val) {
328 return Val->get();
329 }
330};
331
332} // end namespace llvm
333
334#endif // LLVM_IR_USER_H

/build/llvm-toolchain-snapshot-9~svn359426/include/llvm/IR/Use.h

1//===- llvm/Use.h - Definition of the Use class -----------------*- C++ -*-===//
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/// \file
9///
10/// This defines the Use class. The Use class represents the operand of an
11/// instruction or some other User instance which refers to a Value. The Use
12/// class keeps the "use list" of the referenced value up to date.
13///
14/// Pointer tagging is used to efficiently find the User corresponding to a Use
15/// without having to store a User pointer in every Use. A User is preceded in
16/// memory by all the Uses corresponding to its operands, and the low bits of
17/// one of the fields (Prev) of the Use class are used to encode offsets to be
18/// able to find that User given a pointer to any Use. For details, see:
19///
20/// http://www.llvm.org/docs/ProgrammersManual.html#UserLayout
21///
22//===----------------------------------------------------------------------===//
23
24#ifndef LLVM_IR_USE_H
25#define LLVM_IR_USE_H
26
27#include "llvm-c/Types.h"
28#include "llvm/ADT/PointerIntPair.h"
29#include "llvm/Support/CBindingWrapping.h"
30#include "llvm/Support/Compiler.h"
31
32namespace llvm {
33
34template <typename> struct simplify_type;
35class User;
36class Value;
37
38/// A Use represents the edge between a Value definition and its users.
39///
40/// This is notionally a two-dimensional linked list. It supports traversing
41/// all of the uses for a particular value definition. It also supports jumping
42/// directly to the used value when we arrive from the User's operands, and
43/// jumping directly to the User when we arrive from the Value's uses.
44///
45/// The pointer to the used Value is explicit, and the pointer to the User is
46/// implicit. The implicit pointer is found via a waymarking algorithm
47/// described in the programmer's manual:
48///
49/// http://www.llvm.org/docs/ProgrammersManual.html#the-waymarking-algorithm
50///
51/// This is essentially the single most memory intensive object in LLVM because
52/// of the number of uses in the system. At the same time, the constant time
53/// operations it allows are essential to many optimizations having reasonable
54/// time complexity.
55class Use {
56public:
57 Use(const Use &U) = delete;
58
59 /// Provide a fast substitute to std::swap<Use>
60 /// that also works with less standard-compliant compilers
61 void swap(Use &RHS);
62
63 /// Pointer traits for the UserRef PointerIntPair. This ensures we always
64 /// use the LSB regardless of pointer alignment on different targets.
65 struct UserRefPointerTraits {
66 static inline void *getAsVoidPointer(User *P) { return P; }
67
68 static inline User *getFromVoidPointer(void *P) {
69 return (User *)P;
70 }
71
72 enum { NumLowBitsAvailable = 1 };
73 };
74
75 // A type for the word following an array of hung-off Uses in memory, which is
76 // a pointer back to their User with the bottom bit set.
77 using UserRef = PointerIntPair<User *, 1, unsigned, UserRefPointerTraits>;
78
79 /// Pointer traits for the Prev PointerIntPair. This ensures we always use
80 /// the two LSBs regardless of pointer alignment on different targets.
81 struct PrevPointerTraits {
82 static inline void *getAsVoidPointer(Use **P) { return P; }
83
84 static inline Use **getFromVoidPointer(void *P) {
85 return (Use **)P;
86 }
87
88 enum { NumLowBitsAvailable = 2 };
89 };
90
91private:
92 /// Destructor - Only for zap()
93 ~Use() {
94 if (Val)
95 removeFromList();
96 }
97
98 enum PrevPtrTag { zeroDigitTag, oneDigitTag, stopTag, fullStopTag };
99
100 /// Constructor
101 Use(PrevPtrTag tag) { Prev.setInt(tag); }
102
103public:
104 friend class Value;
105
106 operator Value *() const { return Val; }
12
Returning pointer
107 Value *get() const { return Val; }
108
109 /// Returns the User that contains this Use.
110 ///
111 /// For an instruction operand, for example, this will return the
112 /// instruction.
113 User *getUser() const LLVM_READONLY__attribute__((__pure__));
114
115 inline void set(Value *Val);
116
117 inline Value *operator=(Value *RHS);
118 inline const Use &operator=(const Use &RHS);
119
120 Value *operator->() { return Val; }
121 const Value *operator->() const { return Val; }
122
123 Use *getNext() const { return Next; }
124
125 /// Return the operand # of this use in its User.
126 unsigned getOperandNo() const;
127
128 /// Initializes the waymarking tags on an array of Uses.
129 ///
130 /// This sets up the array of Uses such that getUser() can find the User from
131 /// any of those Uses.
132 static Use *initTags(Use *Start, Use *Stop);
133
134 /// Destroys Use operands when the number of operands of
135 /// a User changes.
136 static void zap(Use *Start, const Use *Stop, bool del = false);
137
138private:
139 const Use *getImpliedUser() const LLVM_READONLY__attribute__((__pure__));
140
141 Value *Val = nullptr;
142 Use *Next;
143 PointerIntPair<Use **, 2, PrevPtrTag, PrevPointerTraits> Prev;
144
145 void setPrev(Use **NewPrev) { Prev.setPointer(NewPrev); }
146
147 void addToList(Use **List) {
148 Next = *List;
149 if (Next)
150 Next->setPrev(&Next);
151 setPrev(List);
152 *List = this;
153 }
154
155 void removeFromList() {
156 Use **StrippedPrev = Prev.getPointer();
157 *StrippedPrev = Next;
158 if (Next)
159 Next->setPrev(StrippedPrev);
160 }
161};
162
163/// Allow clients to treat uses just like values when using
164/// casting operators.
165template <> struct simplify_type<Use> {
166 using SimpleType = Value *;
167
168 static SimpleType getSimplifiedValue(Use &Val) { return Val.get(); }
169};
170template <> struct simplify_type<const Use> {
171 using SimpleType = /*const*/ Value *;
172
173 static SimpleType getSimplifiedValue(const Use &Val) { return Val.get(); }
174};
175
176// Create wrappers for C Binding types (see CBindingWrapping.h).
177DEFINE_SIMPLE_CONVERSION_FUNCTIONS(Use, LLVMUseRef)inline Use *unwrap(LLVMUseRef P) { return reinterpret_cast<
Use*>(P); } inline LLVMUseRef wrap(const Use *P) { return reinterpret_cast
<LLVMUseRef>(const_cast<Use*>(P)); }
178
179} // end namespace llvm
180
181#endif // LLVM_IR_USE_H