Bug Summary

File:lib/Transforms/IPO/MergeFunctions.cpp
Warning:line 692, column 23
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 MergeFunctions.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-eagerly-assume -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-7/lib/clang/7.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/lib/Transforms/IPO -I /build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO -I /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/include -I /build/llvm-toolchain-snapshot-7~svn338205/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward -internal-isystem /usr/include/clang/7.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-7/lib/clang/7.0.0/include -internal-externc-isystem /usr/lib/gcc/x86_64-linux-gnu/8/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-class-memaccess -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/lib/Transforms/IPO -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-07-29-043837-17923-1 -x c++ /build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO/MergeFunctions.cpp -faddrsig
1//===- MergeFunctions.cpp - Merge identical functions ---------------------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This pass looks for equivalent functions that are mergable and folds them.
11//
12// Order relation is defined on set of functions. It was made through
13// special function comparison procedure that returns
14// 0 when functions are equal,
15// -1 when Left function is less than right function, and
16// 1 for opposite case. We need total-ordering, so we need to maintain
17// four properties on the functions set:
18// a <= a (reflexivity)
19// if a <= b and b <= a then a = b (antisymmetry)
20// if a <= b and b <= c then a <= c (transitivity).
21// for all a and b: a <= b or b <= a (totality).
22//
23// Comparison iterates through each instruction in each basic block.
24// Functions are kept on binary tree. For each new function F we perform
25// lookup in binary tree.
26// In practice it works the following way:
27// -- We define Function* container class with custom "operator<" (FunctionPtr).
28// -- "FunctionPtr" instances are stored in std::set collection, so every
29// std::set::insert operation will give you result in log(N) time.
30//
31// As an optimization, a hash of the function structure is calculated first, and
32// two functions are only compared if they have the same hash. This hash is
33// cheap to compute, and has the property that if function F == G according to
34// the comparison function, then hash(F) == hash(G). This consistency property
35// is critical to ensuring all possible merging opportunities are exploited.
36// Collisions in the hash affect the speed of the pass but not the correctness
37// or determinism of the resulting transformation.
38//
39// When a match is found the functions are folded. If both functions are
40// overridable, we move the functionality into a new internal function and
41// leave two overridable thunks to it.
42//
43//===----------------------------------------------------------------------===//
44//
45// Future work:
46//
47// * virtual functions.
48//
49// Many functions have their address taken by the virtual function table for
50// the object they belong to. However, as long as it's only used for a lookup
51// and call, this is irrelevant, and we'd like to fold such functions.
52//
53// * be smarter about bitcasts.
54//
55// In order to fold functions, we will sometimes add either bitcast instructions
56// or bitcast constant expressions. Unfortunately, this can confound further
57// analysis since the two functions differ where one has a bitcast and the
58// other doesn't. We should learn to look through bitcasts.
59//
60// * Compare complex types with pointer types inside.
61// * Compare cross-reference cases.
62// * Compare complex expressions.
63//
64// All the three issues above could be described as ability to prove that
65// fA == fB == fC == fE == fF == fG in example below:
66//
67// void fA() {
68// fB();
69// }
70// void fB() {
71// fA();
72// }
73//
74// void fE() {
75// fF();
76// }
77// void fF() {
78// fG();
79// }
80// void fG() {
81// fE();
82// }
83//
84// Simplest cross-reference case (fA <--> fB) was implemented in previous
85// versions of MergeFunctions, though it presented only in two function pairs
86// in test-suite (that counts >50k functions)
87// Though possibility to detect complex cross-referencing (e.g.: A->B->C->D->A)
88// could cover much more cases.
89//
90//===----------------------------------------------------------------------===//
91
92#include "llvm/ADT/ArrayRef.h"
93#include "llvm/ADT/SmallPtrSet.h"
94#include "llvm/ADT/SmallVector.h"
95#include "llvm/ADT/Statistic.h"
96#include "llvm/IR/Argument.h"
97#include "llvm/IR/Attributes.h"
98#include "llvm/IR/BasicBlock.h"
99#include "llvm/IR/CallSite.h"
100#include "llvm/IR/Constant.h"
101#include "llvm/IR/Constants.h"
102#include "llvm/IR/DebugInfoMetadata.h"
103#include "llvm/IR/DebugLoc.h"
104#include "llvm/IR/DerivedTypes.h"
105#include "llvm/IR/Function.h"
106#include "llvm/IR/GlobalValue.h"
107#include "llvm/IR/IRBuilder.h"
108#include "llvm/IR/InstrTypes.h"
109#include "llvm/IR/Instruction.h"
110#include "llvm/IR/Instructions.h"
111#include "llvm/IR/IntrinsicInst.h"
112#include "llvm/IR/Module.h"
113#include "llvm/IR/Type.h"
114#include "llvm/IR/Use.h"
115#include "llvm/IR/User.h"
116#include "llvm/IR/Value.h"
117#include "llvm/IR/ValueHandle.h"
118#include "llvm/IR/ValueMap.h"
119#include "llvm/Pass.h"
120#include "llvm/Support/Casting.h"
121#include "llvm/Support/CommandLine.h"
122#include "llvm/Support/Debug.h"
123#include "llvm/Support/raw_ostream.h"
124#include "llvm/Transforms/IPO.h"
125#include "llvm/Transforms/Utils/FunctionComparator.h"
126#include <algorithm>
127#include <cassert>
128#include <iterator>
129#include <set>
130#include <utility>
131#include <vector>
132
133using namespace llvm;
134
135#define DEBUG_TYPE"mergefunc" "mergefunc"
136
137STATISTIC(NumFunctionsMerged, "Number of functions merged")static llvm::Statistic NumFunctionsMerged = {"mergefunc", "NumFunctionsMerged"
, "Number of functions merged", {0}, {false}}
;
138STATISTIC(NumThunksWritten, "Number of thunks generated")static llvm::Statistic NumThunksWritten = {"mergefunc", "NumThunksWritten"
, "Number of thunks generated", {0}, {false}}
;
139STATISTIC(NumDoubleWeak, "Number of new functions created")static llvm::Statistic NumDoubleWeak = {"mergefunc", "NumDoubleWeak"
, "Number of new functions created", {0}, {false}}
;
140
141static cl::opt<unsigned> NumFunctionsForSanityCheck(
142 "mergefunc-sanity",
143 cl::desc("How many functions in module could be used for "
144 "MergeFunctions pass sanity check. "
145 "'0' disables this check. Works only with '-debug' key."),
146 cl::init(0), cl::Hidden);
147
148// Under option -mergefunc-preserve-debug-info we:
149// - Do not create a new function for a thunk.
150// - Retain the debug info for a thunk's parameters (and associated
151// instructions for the debug info) from the entry block.
152// Note: -debug will display the algorithm at work.
153// - Create debug-info for the call (to the shared implementation) made by
154// a thunk and its return value.
155// - Erase the rest of the function, retaining the (minimally sized) entry
156// block to create a thunk.
157// - Preserve a thunk's call site to point to the thunk even when both occur
158// within the same translation unit, to aid debugability. Note that this
159// behaviour differs from the underlying -mergefunc implementation which
160// modifies the thunk's call site to point to the shared implementation
161// when both occur within the same translation unit.
162static cl::opt<bool>
163 MergeFunctionsPDI("mergefunc-preserve-debug-info", cl::Hidden,
164 cl::init(false),
165 cl::desc("Preserve debug info in thunk when mergefunc "
166 "transformations are made."));
167
168namespace {
169
170class FunctionNode {
171 mutable AssertingVH<Function> F;
172 FunctionComparator::FunctionHash Hash;
173
174public:
175 // Note the hash is recalculated potentially multiple times, but it is cheap.
176 FunctionNode(Function *F)
177 : F(F), Hash(FunctionComparator::functionHash(*F)) {}
178
179 Function *getFunc() const { return F; }
180 FunctionComparator::FunctionHash getHash() const { return Hash; }
181
182 /// Replace the reference to the function F by the function G, assuming their
183 /// implementations are equal.
184 void replaceBy(Function *G) const {
185 F = G;
186 }
187
188 void release() { F = nullptr; }
189};
190
191/// MergeFunctions finds functions which will generate identical machine code,
192/// by considering all pointer types to be equivalent. Once identified,
193/// MergeFunctions will fold them by replacing a call to one to a call to a
194/// bitcast of the other.
195class MergeFunctions : public ModulePass {
196public:
197 static char ID;
198
199 MergeFunctions()
200 : ModulePass(ID), FnTree(FunctionNodeCmp(&GlobalNumbers)) {
201 initializeMergeFunctionsPass(*PassRegistry::getPassRegistry());
202 }
203
204 bool runOnModule(Module &M) override;
205
206private:
207 // The function comparison operator is provided here so that FunctionNodes do
208 // not need to become larger with another pointer.
209 class FunctionNodeCmp {
210 GlobalNumberState* GlobalNumbers;
211
212 public:
213 FunctionNodeCmp(GlobalNumberState* GN) : GlobalNumbers(GN) {}
214
215 bool operator()(const FunctionNode &LHS, const FunctionNode &RHS) const {
216 // Order first by hashes, then full function comparison.
217 if (LHS.getHash() != RHS.getHash())
218 return LHS.getHash() < RHS.getHash();
219 FunctionComparator FCmp(LHS.getFunc(), RHS.getFunc(), GlobalNumbers);
220 return FCmp.compare() == -1;
221 }
222 };
223 using FnTreeType = std::set<FunctionNode, FunctionNodeCmp>;
224
225 GlobalNumberState GlobalNumbers;
226
227 /// A work queue of functions that may have been modified and should be
228 /// analyzed again.
229 std::vector<WeakTrackingVH> Deferred;
230
231#ifndef NDEBUG
232 /// Checks the rules of order relation introduced among functions set.
233 /// Returns true, if sanity check has been passed, and false if failed.
234 bool doSanityCheck(std::vector<WeakTrackingVH> &Worklist);
235#endif
236
237 /// Insert a ComparableFunction into the FnTree, or merge it away if it's
238 /// equal to one that's already present.
239 bool insert(Function *NewFunction);
240
241 /// Remove a Function from the FnTree and queue it up for a second sweep of
242 /// analysis.
243 void remove(Function *F);
244
245 /// Find the functions that use this Value and remove them from FnTree and
246 /// queue the functions.
247 void removeUsers(Value *V);
248
249 /// Replace all direct calls of Old with calls of New. Will bitcast New if
250 /// necessary to make types match.
251 void replaceDirectCallers(Function *Old, Function *New);
252
253 /// Merge two equivalent functions. Upon completion, G may be deleted, or may
254 /// be converted into a thunk. In either case, it should never be visited
255 /// again.
256 void mergeTwoFunctions(Function *F, Function *G);
257
258 /// Fill PDIUnrelatedWL with instructions from the entry block that are
259 /// unrelated to parameter related debug info.
260 void filterInstsUnrelatedToPDI(BasicBlock *GEntryBlock,
261 std::vector<Instruction *> &PDIUnrelatedWL);
262
263 /// Erase the rest of the CFG (i.e. barring the entry block).
264 void eraseTail(Function *G);
265
266 /// Erase the instructions in PDIUnrelatedWL as they are unrelated to the
267 /// parameter debug info, from the entry block.
268 void eraseInstsUnrelatedToPDI(std::vector<Instruction *> &PDIUnrelatedWL);
269
270 /// Replace G with a simple tail call to bitcast(F). Also (unless
271 /// MergeFunctionsPDI holds) replace direct uses of G with bitcast(F),
272 /// delete G.
273 void writeThunk(Function *F, Function *G);
274
275 /// Replace function F with function G in the function tree.
276 void replaceFunctionInTree(const FunctionNode &FN, Function *G);
277
278 /// The set of all distinct functions. Use the insert() and remove() methods
279 /// to modify it. The map allows efficient lookup and deferring of Functions.
280 FnTreeType FnTree;
281
282 // Map functions to the iterators of the FunctionNode which contains them
283 // in the FnTree. This must be updated carefully whenever the FnTree is
284 // modified, i.e. in insert(), remove(), and replaceFunctionInTree(), to avoid
285 // dangling iterators into FnTree. The invariant that preserves this is that
286 // there is exactly one mapping F -> FN for each FunctionNode FN in FnTree.
287 ValueMap<Function*, FnTreeType::iterator> FNodesInTree;
288};
289
290} // end anonymous namespace
291
292char MergeFunctions::ID = 0;
293
294INITIALIZE_PASS(MergeFunctions, "mergefunc", "Merge Functions", false, false)static void *initializeMergeFunctionsPassOnce(PassRegistry &
Registry) { PassInfo *PI = new PassInfo( "Merge Functions", "mergefunc"
, &MergeFunctions::ID, PassInfo::NormalCtor_t(callDefaultCtor
<MergeFunctions>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeMergeFunctionsPassFlag
; void llvm::initializeMergeFunctionsPass(PassRegistry &Registry
) { llvm::call_once(InitializeMergeFunctionsPassFlag, initializeMergeFunctionsPassOnce
, std::ref(Registry)); }
295
296ModulePass *llvm::createMergeFunctionsPass() {
297 return new MergeFunctions();
298}
299
300#ifndef NDEBUG
301bool MergeFunctions::doSanityCheck(std::vector<WeakTrackingVH> &Worklist) {
302 if (const unsigned Max = NumFunctionsForSanityCheck) {
303 unsigned TripleNumber = 0;
304 bool Valid = true;
305
306 dbgs() << "MERGEFUNC-SANITY: Started for first " << Max << " functions.\n";
307
308 unsigned i = 0;
309 for (std::vector<WeakTrackingVH>::iterator I = Worklist.begin(),
310 E = Worklist.end();
311 I != E && i < Max; ++I, ++i) {
312 unsigned j = i;
313 for (std::vector<WeakTrackingVH>::iterator J = I; J != E && j < Max;
314 ++J, ++j) {
315 Function *F1 = cast<Function>(*I);
316 Function *F2 = cast<Function>(*J);
317 int Res1 = FunctionComparator(F1, F2, &GlobalNumbers).compare();
318 int Res2 = FunctionComparator(F2, F1, &GlobalNumbers).compare();
319
320 // If F1 <= F2, then F2 >= F1, otherwise report failure.
321 if (Res1 != -Res2) {
322 dbgs() << "MERGEFUNC-SANITY: Non-symmetric; triple: " << TripleNumber
323 << "\n";
324 dbgs() << *F1 << '\n' << *F2 << '\n';
325 Valid = false;
326 }
327
328 if (Res1 == 0)
329 continue;
330
331 unsigned k = j;
332 for (std::vector<WeakTrackingVH>::iterator K = J; K != E && k < Max;
333 ++k, ++K, ++TripleNumber) {
334 if (K == J)
335 continue;
336
337 Function *F3 = cast<Function>(*K);
338 int Res3 = FunctionComparator(F1, F3, &GlobalNumbers).compare();
339 int Res4 = FunctionComparator(F2, F3, &GlobalNumbers).compare();
340
341 bool Transitive = true;
342
343 if (Res1 != 0 && Res1 == Res4) {
344 // F1 > F2, F2 > F3 => F1 > F3
345 Transitive = Res3 == Res1;
346 } else if (Res3 != 0 && Res3 == -Res4) {
347 // F1 > F3, F3 > F2 => F1 > F2
348 Transitive = Res3 == Res1;
349 } else if (Res4 != 0 && -Res3 == Res4) {
350 // F2 > F3, F3 > F1 => F2 > F1
351 Transitive = Res4 == -Res1;
352 }
353
354 if (!Transitive) {
355 dbgs() << "MERGEFUNC-SANITY: Non-transitive; triple: "
356 << TripleNumber << "\n";
357 dbgs() << "Res1, Res3, Res4: " << Res1 << ", " << Res3 << ", "
358 << Res4 << "\n";
359 dbgs() << *F1 << '\n' << *F2 << '\n' << *F3 << '\n';
360 Valid = false;
361 }
362 }
363 }
364 }
365
366 dbgs() << "MERGEFUNC-SANITY: " << (Valid ? "Passed." : "Failed.") << "\n";
367 return Valid;
368 }
369 return true;
370}
371#endif
372
373bool MergeFunctions::runOnModule(Module &M) {
374 if (skipModule(M))
1
Assuming the condition is false
2
Taking false branch
375 return false;
376
377 bool Changed = false;
378
379 // All functions in the module, ordered by hash. Functions with a unique
380 // hash value are easily eliminated.
381 std::vector<std::pair<FunctionComparator::FunctionHash, Function *>>
382 HashedFuncs;
383 for (Function &Func : M) {
384 if (!Func.isDeclaration() && !Func.hasAvailableExternallyLinkage()) {
385 HashedFuncs.push_back({FunctionComparator::functionHash(Func), &Func});
386 }
387 }
388
389 std::stable_sort(
390 HashedFuncs.begin(), HashedFuncs.end(),
391 [](const std::pair<FunctionComparator::FunctionHash, Function *> &a,
392 const std::pair<FunctionComparator::FunctionHash, Function *> &b) {
393 return a.first < b.first;
394 });
395
396 auto S = HashedFuncs.begin();
397 for (auto I = HashedFuncs.begin(), IE = HashedFuncs.end(); I != IE; ++I) {
3
Loop condition is false. Execution continues on line 407
398 // If the hash value matches the previous value or the next one, we must
399 // consider merging it. Otherwise it is dropped and never considered again.
400 if ((I != S && std::prev(I)->first == I->first) ||
401 (std::next(I) != IE && std::next(I)->first == I->first) ) {
402 Deferred.push_back(WeakTrackingVH(I->second));
403 }
404 }
405
406 do {
407 std::vector<WeakTrackingVH> Worklist;
408 Deferred.swap(Worklist);
409
410 LLVM_DEBUG(doSanityCheck(Worklist))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { doSanityCheck(Worklist); } } while (false)
;
411
412 LLVM_DEBUG(dbgs() << "size of module: " << M.size() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "size of module: " << M
.size() << '\n'; } } while (false)
;
413 LLVM_DEBUG(dbgs() << "size of worklist: " << Worklist.size() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "size of worklist: " <<
Worklist.size() << '\n'; } } while (false)
;
414
415 // Insert functions and merge them.
416 for (WeakTrackingVH &I : Worklist) {
417 if (!I)
4
Assuming the condition is false
5
Taking false branch
418 continue;
419 Function *F = cast<Function>(I);
420 if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage()) {
6
Assuming the condition is true
7
Taking true branch
421 Changed |= insert(F);
8
Calling 'MergeFunctions::insert'
422 }
423 }
424 LLVM_DEBUG(dbgs() << "size of FnTree: " << FnTree.size() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "size of FnTree: " << FnTree
.size() << '\n'; } } while (false)
;
425 } while (!Deferred.empty());
426
427 FnTree.clear();
428 GlobalNumbers.clear();
429
430 return Changed;
431}
432
433// Replace direct callers of Old with New.
434void MergeFunctions::replaceDirectCallers(Function *Old, Function *New) {
435 Constant *BitcastNew = ConstantExpr::getBitCast(New, Old->getType());
436 for (auto UI = Old->use_begin(), UE = Old->use_end(); UI != UE;) {
437 Use *U = &*UI;
438 ++UI;
439 CallSite CS(U->getUser());
440 if (CS && CS.isCallee(U)) {
441 // Transfer the called function's attributes to the call site. Due to the
442 // bitcast we will 'lose' ABI changing attributes because the 'called
443 // function' is no longer a Function* but the bitcast. Code that looks up
444 // the attributes from the called function will fail.
445
446 // FIXME: This is not actually true, at least not anymore. The callsite
447 // will always have the same ABI affecting attributes as the callee,
448 // because otherwise the original input has UB. Note that Old and New
449 // always have matching ABI, so no attributes need to be changed.
450 // Transferring other attributes may help other optimizations, but that
451 // should be done uniformly and not in this ad-hoc way.
452 auto &Context = New->getContext();
453 auto NewPAL = New->getAttributes();
454 SmallVector<AttributeSet, 4> NewArgAttrs;
455 for (unsigned argIdx = 0; argIdx < CS.arg_size(); argIdx++)
456 NewArgAttrs.push_back(NewPAL.getParamAttributes(argIdx));
457 // Don't transfer attributes from the function to the callee. Function
458 // attributes typically aren't relevant to the calling convention or ABI.
459 CS.setAttributes(AttributeList::get(Context, /*FnAttrs=*/AttributeSet(),
460 NewPAL.getRetAttributes(),
461 NewArgAttrs));
462
463 remove(CS.getInstruction()->getParent()->getParent());
464 U->set(BitcastNew);
465 }
466 }
467}
468
469// Helper for writeThunk,
470// Selects proper bitcast operation,
471// but a bit simpler then CastInst::getCastOpcode.
472static Value *createCast(IRBuilder<> &Builder, Value *V, Type *DestTy) {
473 Type *SrcTy = V->getType();
474 if (SrcTy->isStructTy()) {
475 assert(DestTy->isStructTy())(static_cast <bool> (DestTy->isStructTy()) ? void (0
) : __assert_fail ("DestTy->isStructTy()", "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO/MergeFunctions.cpp"
, 475, __extension__ __PRETTY_FUNCTION__))
;
476 assert(SrcTy->getStructNumElements() == DestTy->getStructNumElements())(static_cast <bool> (SrcTy->getStructNumElements() ==
DestTy->getStructNumElements()) ? void (0) : __assert_fail
("SrcTy->getStructNumElements() == DestTy->getStructNumElements()"
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO/MergeFunctions.cpp"
, 476, __extension__ __PRETTY_FUNCTION__))
;
477 Value *Result = UndefValue::get(DestTy);
478 for (unsigned int I = 0, E = SrcTy->getStructNumElements(); I < E; ++I) {
479 Value *Element = createCast(
480 Builder, Builder.CreateExtractValue(V, makeArrayRef(I)),
481 DestTy->getStructElementType(I));
482
483 Result =
484 Builder.CreateInsertValue(Result, Element, makeArrayRef(I));
485 }
486 return Result;
487 }
488 assert(!DestTy->isStructTy())(static_cast <bool> (!DestTy->isStructTy()) ? void (
0) : __assert_fail ("!DestTy->isStructTy()", "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO/MergeFunctions.cpp"
, 488, __extension__ __PRETTY_FUNCTION__))
;
489 if (SrcTy->isIntegerTy() && DestTy->isPointerTy())
490 return Builder.CreateIntToPtr(V, DestTy);
491 else if (SrcTy->isPointerTy() && DestTy->isIntegerTy())
492 return Builder.CreatePtrToInt(V, DestTy);
493 else
494 return Builder.CreateBitCast(V, DestTy);
495}
496
497// Erase the instructions in PDIUnrelatedWL as they are unrelated to the
498// parameter debug info, from the entry block.
499void MergeFunctions::eraseInstsUnrelatedToPDI(
500 std::vector<Instruction *> &PDIUnrelatedWL) {
501 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Erasing instructions (in reverse order of appearance in "
"entry block) unrelated to parameter debug info from entry "
"block: {\n"; } } while (false)
502 dbgs() << " Erasing instructions (in reverse order of appearance in "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Erasing instructions (in reverse order of appearance in "
"entry block) unrelated to parameter debug info from entry "
"block: {\n"; } } while (false)
503 "entry block) unrelated to parameter debug info from entry "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Erasing instructions (in reverse order of appearance in "
"entry block) unrelated to parameter debug info from entry "
"block: {\n"; } } while (false)
504 "block: {\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Erasing instructions (in reverse order of appearance in "
"entry block) unrelated to parameter debug info from entry "
"block: {\n"; } } while (false)
;
505 while (!PDIUnrelatedWL.empty()) {
506 Instruction *I = PDIUnrelatedWL.back();
507 LLVM_DEBUG(dbgs() << " Deleting Instruction: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Deleting Instruction: "; }
} while (false)
;
508 LLVM_DEBUG(I->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { I->print(dbgs()); } } while (false)
;
509 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
510 I->eraseFromParent();
511 PDIUnrelatedWL.pop_back();
512 }
513 LLVM_DEBUG(dbgs() << " } // Done erasing instructions unrelated to parameter "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " } // Done erasing instructions unrelated to parameter "
"debug info from entry block. \n"; } } while (false)
514 "debug info from entry block. \n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " } // Done erasing instructions unrelated to parameter "
"debug info from entry block. \n"; } } while (false)
;
515}
516
517// Reduce G to its entry block.
518void MergeFunctions::eraseTail(Function *G) {
519 std::vector<BasicBlock *> WorklistBB;
520 for (Function::iterator BBI = std::next(G->begin()), BBE = G->end();
521 BBI != BBE; ++BBI) {
522 BBI->dropAllReferences();
523 WorklistBB.push_back(&*BBI);
524 }
525 while (!WorklistBB.empty()) {
526 BasicBlock *BB = WorklistBB.back();
527 BB->eraseFromParent();
528 WorklistBB.pop_back();
529 }
530}
531
532// We are interested in the following instructions from the entry block as being
533// related to parameter debug info:
534// - @llvm.dbg.declare
535// - stores from the incoming parameters to locations on the stack-frame
536// - allocas that create these locations on the stack-frame
537// - @llvm.dbg.value
538// - the entry block's terminator
539// The rest are unrelated to debug info for the parameters; fill up
540// PDIUnrelatedWL with such instructions.
541void MergeFunctions::filterInstsUnrelatedToPDI(
542 BasicBlock *GEntryBlock, std::vector<Instruction *> &PDIUnrelatedWL) {
543 std::set<Instruction *> PDIRelated;
544 for (BasicBlock::iterator BI = GEntryBlock->begin(), BIE = GEntryBlock->end();
545 BI != BIE; ++BI) {
546 if (auto *DVI = dyn_cast<DbgValueInst>(&*BI)) {
547 LLVM_DEBUG(dbgs() << " Deciding: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Deciding: "; } } while (false
)
;
548 LLVM_DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
549 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
550 DILocalVariable *DILocVar = DVI->getVariable();
551 if (DILocVar->isParameter()) {
552 LLVM_DEBUG(dbgs() << " Include (parameter): ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Include (parameter): "; }
} while (false)
;
553 LLVM_DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
554 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
555 PDIRelated.insert(&*BI);
556 } else {
557 LLVM_DEBUG(dbgs() << " Delete (!parameter): ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Delete (!parameter): "; }
} while (false)
;
558 LLVM_DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
559 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
560 }
561 } else if (auto *DDI = dyn_cast<DbgDeclareInst>(&*BI)) {
562 LLVM_DEBUG(dbgs() << " Deciding: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Deciding: "; } } while (false
)
;
563 LLVM_DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
564 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
565 DILocalVariable *DILocVar = DDI->getVariable();
566 if (DILocVar->isParameter()) {
567 LLVM_DEBUG(dbgs() << " Parameter: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Parameter: "; } } while (
false)
;
568 LLVM_DEBUG(DILocVar->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { DILocVar->print(dbgs()); } } while (false
)
;
569 AllocaInst *AI = dyn_cast_or_null<AllocaInst>(DDI->getAddress());
570 if (AI) {
571 LLVM_DEBUG(dbgs() << " Processing alloca users: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Processing alloca users: "
; } } while (false)
;
572 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
573 for (User *U : AI->users()) {
574 if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
575 if (Value *Arg = SI->getValueOperand()) {
576 if (dyn_cast<Argument>(Arg)) {
577 LLVM_DEBUG(dbgs() << " Include: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Include: "; } } while (false
)
;
578 LLVM_DEBUG(AI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { AI->print(dbgs()); } } while (false)
;
579 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
580 PDIRelated.insert(AI);
581 LLVM_DEBUG(dbgs() << " Include (parameter): ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Include (parameter): "; }
} while (false)
;
582 LLVM_DEBUG(SI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { SI->print(dbgs()); } } while (false)
;
583 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
584 PDIRelated.insert(SI);
585 LLVM_DEBUG(dbgs() << " Include: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Include: "; } } while (false
)
;
586 LLVM_DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
587 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
588 PDIRelated.insert(&*BI);
589 } else {
590 LLVM_DEBUG(dbgs() << " Delete (!parameter): ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Delete (!parameter): "; }
} while (false)
;
591 LLVM_DEBUG(SI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { SI->print(dbgs()); } } while (false)
;
592 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
593 }
594 }
595 } else {
596 LLVM_DEBUG(dbgs() << " Defer: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Defer: "; } } while (false
)
;
597 LLVM_DEBUG(U->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { U->print(dbgs()); } } while (false)
;
598 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
599 }
600 }
601 } else {
602 LLVM_DEBUG(dbgs() << " Delete (alloca NULL): ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Delete (alloca NULL): "; }
} while (false)
;
603 LLVM_DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
604 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
605 }
606 } else {
607 LLVM_DEBUG(dbgs() << " Delete (!parameter): ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Delete (!parameter): "; }
} while (false)
;
608 LLVM_DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
609 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
610 }
611 } else if (dyn_cast<TerminatorInst>(BI) == GEntryBlock->getTerminator()) {
612 LLVM_DEBUG(dbgs() << " Will Include Terminator: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Will Include Terminator: "
; } } while (false)
;
613 LLVM_DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
614 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
615 PDIRelated.insert(&*BI);
616 } else {
617 LLVM_DEBUG(dbgs() << " Defer: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Defer: "; } } while (false
)
;
618 LLVM_DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
619 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
620 }
621 }
622 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Report parameter debug info related/related instructions: {\n"
; } } while (false)
623 dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Report parameter debug info related/related instructions: {\n"
; } } while (false)
624 << " Report parameter debug info related/related instructions: {\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Report parameter debug info related/related instructions: {\n"
; } } while (false)
;
625 for (BasicBlock::iterator BI = GEntryBlock->begin(), BE = GEntryBlock->end();
626 BI != BE; ++BI) {
627
628 Instruction *I = &*BI;
629 if (PDIRelated.find(I) == PDIRelated.end()) {
630 LLVM_DEBUG(dbgs() << " !PDIRelated: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " !PDIRelated: "; } } while
(false)
;
631 LLVM_DEBUG(I->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { I->print(dbgs()); } } while (false)
;
632 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
633 PDIUnrelatedWL.push_back(I);
634 } else {
635 LLVM_DEBUG(dbgs() << " PDIRelated: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " PDIRelated: "; } } while
(false)
;
636 LLVM_DEBUG(I->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { I->print(dbgs()); } } while (false)
;
637 LLVM_DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
638 }
639 }
640 LLVM_DEBUG(dbgs() << " }\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " }\n"; } } while (false)
;
641}
642
643// Don't merge tiny functions using a thunk, since it can just end up
644// making the function larger.
645static bool isThunkProfitable(Function * F) {
646 if (F->size() == 1) {
647 if (F->front().size() <= 2) {
648 LLVM_DEBUG(dbgs() << "isThunkProfitable: " << F->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "isThunkProfitable: " <<
F->getName() << " is too small to bother creating a thunk for\n"
; } } while (false)
649 << " is too small to bother creating a thunk for\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "isThunkProfitable: " <<
F->getName() << " is too small to bother creating a thunk for\n"
; } } while (false)
;
650 return false;
651 }
652 }
653 return true;
654}
655
656// Replace G with a simple tail call to bitcast(F). Also (unless
657// MergeFunctionsPDI holds) replace direct uses of G with bitcast(F),
658// delete G. Under MergeFunctionsPDI, we use G itself for creating
659// the thunk as we preserve the debug info (and associated instructions)
660// from G's entry block pertaining to G's incoming arguments which are
661// passed on as corresponding arguments in the call that G makes to F.
662// For better debugability, under MergeFunctionsPDI, we do not modify G's
663// call sites to point to F even when within the same translation unit.
664void MergeFunctions::writeThunk(Function *F, Function *G) {
665 BasicBlock *GEntryBlock = nullptr;
666 std::vector<Instruction *> PDIUnrelatedWL;
667 BasicBlock *BB = nullptr;
668 Function *NewG = nullptr;
16
'NewG' initialized to a null pointer value
669 if (MergeFunctionsPDI) {
17
Assuming the condition is true
18
Taking true branch
670 LLVM_DEBUG(dbgs() << "writeThunk: (MergeFunctionsPDI) Do not create a new "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) Do not create a new "
"function as thunk; retain original: " << G->getName
() << "()\n"; } } while (false)
671 "function as thunk; retain original: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) Do not create a new "
"function as thunk; retain original: " << G->getName
() << "()\n"; } } while (false)
672 << G->getName() << "()\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) Do not create a new "
"function as thunk; retain original: " << G->getName
() << "()\n"; } } while (false)
;
673 GEntryBlock = &G->getEntryBlock();
674 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) filter parameter related "
"debug info for " << G->getName() << "() {\n"
; } } while (false)
675 dbgs() << "writeThunk: (MergeFunctionsPDI) filter parameter related "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) filter parameter related "
"debug info for " << G->getName() << "() {\n"
; } } while (false)
676 "debug info for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) filter parameter related "
"debug info for " << G->getName() << "() {\n"
; } } while (false)
677 << G->getName() << "() {\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) filter parameter related "
"debug info for " << G->getName() << "() {\n"
; } } while (false)
;
678 filterInstsUnrelatedToPDI(GEntryBlock, PDIUnrelatedWL);
679 GEntryBlock->getTerminator()->eraseFromParent();
680 BB = GEntryBlock;
681 } else {
682 NewG = Function::Create(G->getFunctionType(), G->getLinkage(), "",
683 G->getParent());
684 BB = BasicBlock::Create(F->getContext(), "", NewG);
685 }
686
687 IRBuilder<> Builder(BB);
688 Function *H = MergeFunctionsPDI ? G : NewG;
19
Assuming the condition is false
20
'?' condition is false
21
'H' initialized to a null pointer value
689 SmallVector<Value *, 16> Args;
690 unsigned i = 0;
691 FunctionType *FFTy = F->getFunctionType();
692 for (Argument &AI : H->args()) {
22
Called C++ object pointer is null
693 Args.push_back(createCast(Builder, &AI, FFTy->getParamType(i)));
694 ++i;
695 }
696
697 CallInst *CI = Builder.CreateCall(F, Args);
698 ReturnInst *RI = nullptr;
699 CI->setTailCall();
700 CI->setCallingConv(F->getCallingConv());
701 CI->setAttributes(F->getAttributes());
702 if (H->getReturnType()->isVoidTy()) {
703 RI = Builder.CreateRetVoid();
704 } else {
705 RI = Builder.CreateRet(createCast(Builder, CI, H->getReturnType()));
706 }
707
708 if (MergeFunctionsPDI) {
709 DISubprogram *DIS = G->getSubprogram();
710 if (DIS) {
711 DebugLoc CIDbgLoc = DebugLoc::get(DIS->getScopeLine(), 0, DIS);
712 DebugLoc RIDbgLoc = DebugLoc::get(DIS->getScopeLine(), 0, DIS);
713 CI->setDebugLoc(CIDbgLoc);
714 RI->setDebugLoc(RIDbgLoc);
715 } else {
716 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) No DISubprogram for "
<< G->getName() << "()\n"; } } while (false)
717 dbgs() << "writeThunk: (MergeFunctionsPDI) No DISubprogram for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) No DISubprogram for "
<< G->getName() << "()\n"; } } while (false)
718 << G->getName() << "()\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) No DISubprogram for "
<< G->getName() << "()\n"; } } while (false)
;
719 }
720 eraseTail(G);
721 eraseInstsUnrelatedToPDI(PDIUnrelatedWL);
722 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "} // End of parameter related debug info filtering for: "
<< G->getName() << "()\n"; } } while (false)
723 dbgs() << "} // End of parameter related debug info filtering for: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "} // End of parameter related debug info filtering for: "
<< G->getName() << "()\n"; } } while (false)
724 << G->getName() << "()\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "} // End of parameter related debug info filtering for: "
<< G->getName() << "()\n"; } } while (false)
;
725 } else {
726 NewG->copyAttributesFrom(G);
727 NewG->takeName(G);
728 removeUsers(G);
729 G->replaceAllUsesWith(NewG);
730 G->eraseFromParent();
731 }
732
733 LLVM_DEBUG(dbgs() << "writeThunk: " << H->getName() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: " << H->
getName() << '\n'; } } while (false)
;
734 ++NumThunksWritten;
735}
736
737// Merge two equivalent functions. Upon completion, Function G is deleted.
738void MergeFunctions::mergeTwoFunctions(Function *F, Function *G) {
739 if (F->isInterposable()) {
13
Taking false branch
740 assert(G->isInterposable())(static_cast <bool> (G->isInterposable()) ? void (0)
: __assert_fail ("G->isInterposable()", "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO/MergeFunctions.cpp"
, 740, __extension__ __PRETTY_FUNCTION__))
;
741
742 if (!isThunkProfitable(F)) {
743 return;
744 }
745
746 // Make them both thunks to the same internal function.
747 Function *H = Function::Create(F->getFunctionType(), F->getLinkage(), "",
748 F->getParent());
749 H->copyAttributesFrom(F);
750 H->takeName(F);
751 removeUsers(F);
752 F->replaceAllUsesWith(H);
753
754 unsigned MaxAlignment = std::max(G->getAlignment(), H->getAlignment());
755
756 writeThunk(F, G);
757 writeThunk(F, H);
758
759 F->setAlignment(MaxAlignment);
760 F->setLinkage(GlobalValue::PrivateLinkage);
761 ++NumDoubleWeak;
762 ++NumFunctionsMerged;
763 } else {
764 // For better debugability, under MergeFunctionsPDI, we do not modify G's
765 // call sites to point to F even when within the same translation unit.
766 if (!G->isInterposable() && !MergeFunctionsPDI) {
767 if (G->hasGlobalUnnamedAddr()) {
768 // G might have been a key in our GlobalNumberState, and it's illegal
769 // to replace a key in ValueMap<GlobalValue *> with a non-global.
770 GlobalNumbers.erase(G);
771 // If G's address is not significant, replace it entirely.
772 Constant *BitcastF = ConstantExpr::getBitCast(F, G->getType());
773 G->replaceAllUsesWith(BitcastF);
774 } else {
775 // Redirect direct callers of G to F. (See note on MergeFunctionsPDI
776 // above).
777 replaceDirectCallers(G, F);
778 }
779 }
780
781 // If G was internal then we may have replaced all uses of G with F. If so,
782 // stop here and delete G. There's no need for a thunk. (See note on
783 // MergeFunctionsPDI above).
784 if (G->hasLocalLinkage() && G->use_empty() && !MergeFunctionsPDI) {
785 G->eraseFromParent();
786 ++NumFunctionsMerged;
787 return;
788 }
789
790 if (!isThunkProfitable(F)) {
14
Taking false branch
791 return;
792 }
793
794 writeThunk(F, G);
15
Calling 'MergeFunctions::writeThunk'
795 ++NumFunctionsMerged;
796 }
797}
798
799/// Replace function F by function G.
800void MergeFunctions::replaceFunctionInTree(const FunctionNode &FN,
801 Function *G) {
802 Function *F = FN.getFunc();
803 assert(FunctionComparator(F, G, &GlobalNumbers).compare() == 0 &&(static_cast <bool> (FunctionComparator(F, G, &GlobalNumbers
).compare() == 0 && "The two functions must be equal"
) ? void (0) : __assert_fail ("FunctionComparator(F, G, &GlobalNumbers).compare() == 0 && \"The two functions must be equal\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO/MergeFunctions.cpp"
, 804, __extension__ __PRETTY_FUNCTION__))
804 "The two functions must be equal")(static_cast <bool> (FunctionComparator(F, G, &GlobalNumbers
).compare() == 0 && "The two functions must be equal"
) ? void (0) : __assert_fail ("FunctionComparator(F, G, &GlobalNumbers).compare() == 0 && \"The two functions must be equal\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO/MergeFunctions.cpp"
, 804, __extension__ __PRETTY_FUNCTION__))
;
805
806 auto I = FNodesInTree.find(F);
807 assert(I != FNodesInTree.end() && "F should be in FNodesInTree")(static_cast <bool> (I != FNodesInTree.end() &&
"F should be in FNodesInTree") ? void (0) : __assert_fail ("I != FNodesInTree.end() && \"F should be in FNodesInTree\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO/MergeFunctions.cpp"
, 807, __extension__ __PRETTY_FUNCTION__))
;
808 assert(FNodesInTree.count(G) == 0 && "FNodesInTree should not contain G")(static_cast <bool> (FNodesInTree.count(G) == 0 &&
"FNodesInTree should not contain G") ? void (0) : __assert_fail
("FNodesInTree.count(G) == 0 && \"FNodesInTree should not contain G\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO/MergeFunctions.cpp"
, 808, __extension__ __PRETTY_FUNCTION__))
;
809
810 FnTreeType::iterator IterToFNInFnTree = I->second;
811 assert(&(*IterToFNInFnTree) == &FN && "F should map to FN in FNodesInTree.")(static_cast <bool> (&(*IterToFNInFnTree) == &FN
&& "F should map to FN in FNodesInTree.") ? void (0)
: __assert_fail ("&(*IterToFNInFnTree) == &FN && \"F should map to FN in FNodesInTree.\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO/MergeFunctions.cpp"
, 811, __extension__ __PRETTY_FUNCTION__))
;
812 // Remove F -> FN and insert G -> FN
813 FNodesInTree.erase(I);
814 FNodesInTree.insert({G, IterToFNInFnTree});
815 // Replace F with G in FN, which is stored inside the FnTree.
816 FN.replaceBy(G);
817}
818
819// Insert a ComparableFunction into the FnTree, or merge it away if equal to one
820// that was already inserted.
821bool MergeFunctions::insert(Function *NewFunction) {
822 std::pair<FnTreeType::iterator, bool> Result =
823 FnTree.insert(FunctionNode(NewFunction));
824
825 if (Result.second) {
9
Assuming the condition is false
10
Taking false branch
826 assert(FNodesInTree.count(NewFunction) == 0)(static_cast <bool> (FNodesInTree.count(NewFunction) ==
0) ? void (0) : __assert_fail ("FNodesInTree.count(NewFunction) == 0"
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO/MergeFunctions.cpp"
, 826, __extension__ __PRETTY_FUNCTION__))
;
827 FNodesInTree.insert({NewFunction, Result.first});
828 LLVM_DEBUG(dbgs() << "Inserting as unique: " << NewFunction->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "Inserting as unique: " <<
NewFunction->getName() << '\n'; } } while (false)
829 << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "Inserting as unique: " <<
NewFunction->getName() << '\n'; } } while (false)
;
830 return false;
831 }
832
833 const FunctionNode &OldF = *Result.first;
834
835 // Impose a total order (by name) on the replacement of functions. This is
836 // important when operating on more than one module independently to prevent
837 // cycles of thunks calling each other when the modules are linked together.
838 //
839 // First of all, we process strong functions before weak functions.
840 if ((OldF.getFunc()->isInterposable() && !NewFunction->isInterposable()) ||
11
Taking false branch
841 (OldF.getFunc()->isInterposable() == NewFunction->isInterposable() &&
842 OldF.getFunc()->getName() > NewFunction->getName())) {
843 // Swap the two functions.
844 Function *F = OldF.getFunc();
845 replaceFunctionInTree(*Result.first, NewFunction);
846 NewFunction = F;
847 assert(OldF.getFunc() != F && "Must have swapped the functions.")(static_cast <bool> (OldF.getFunc() != F && "Must have swapped the functions."
) ? void (0) : __assert_fail ("OldF.getFunc() != F && \"Must have swapped the functions.\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/IPO/MergeFunctions.cpp"
, 847, __extension__ __PRETTY_FUNCTION__))
;
848 }
849
850 LLVM_DEBUG(dbgs() << " " << OldF.getFunc()->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " " << OldF.getFunc()
->getName() << " == " << NewFunction->getName
() << '\n'; } } while (false)
851 << " == " << NewFunction->getName() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " " << OldF.getFunc()
->getName() << " == " << NewFunction->getName
() << '\n'; } } while (false)
;
852
853 Function *DeleteF = NewFunction;
854 mergeTwoFunctions(OldF.getFunc(), DeleteF);
12
Calling 'MergeFunctions::mergeTwoFunctions'
855 return true;
856}
857
858// Remove a function from FnTree. If it was already in FnTree, add
859// it to Deferred so that we'll look at it in the next round.
860void MergeFunctions::remove(Function *F) {
861 auto I = FNodesInTree.find(F);
862 if (I != FNodesInTree.end()) {
863 LLVM_DEBUG(dbgs() << "Deferred " << F->getName() << ".\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "Deferred " << F->getName
() << ".\n"; } } while (false)
;
864 FnTree.erase(I->second);
865 // I->second has been invalidated, remove it from the FNodesInTree map to
866 // preserve the invariant.
867 FNodesInTree.erase(I);
868 Deferred.emplace_back(F);
869 }
870}
871
872// For each instruction used by the value, remove() the function that contains
873// the instruction. This should happen right before a call to RAUW.
874void MergeFunctions::removeUsers(Value *V) {
875 std::vector<Value *> Worklist;
876 Worklist.push_back(V);
877 SmallPtrSet<Value*, 8> Visited;
878 Visited.insert(V);
879 while (!Worklist.empty()) {
880 Value *V = Worklist.back();
881 Worklist.pop_back();
882
883 for (User *U : V->users()) {
884 if (Instruction *I = dyn_cast<Instruction>(U)) {
885 remove(I->getParent()->getParent());
886 } else if (isa<GlobalValue>(U)) {
887 // do nothing
888 } else if (Constant *C = dyn_cast<Constant>(U)) {
889 for (User *UU : C->users()) {
890 if (!Visited.insert(UU).second)
891 Worklist.push_back(UU);
892 }
893 }
894 }
895 }
896}