Bug Summary

File:src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Transforms/IPO/IROutliner.cpp
Warning:line 1037, column 7
Value stored to 'WrongSize' is never read

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name IROutliner.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 -setup-static-analyzer -mrelocation-model static -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/clang/libLLVM/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Analysis -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ASMParser -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/BinaryFormat -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitcode -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitcode -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitstream -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /include/llvm/CodeGen -I /include/llvm/CodeGen/PBQP -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/IR -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/IR -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Coroutines -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ProfileData/Coverage -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/CodeView -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/DWARF -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/MSF -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/PDB -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Demangle -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine/JITLink -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine/Orc -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend/OpenACC -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend/OpenMP -I /include/llvm/CodeGen/GlobalISel -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/IRReader -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/InstCombine -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/Transforms/InstCombine -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/LTO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Linker -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/MC -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/MC/MCParser -I /include/llvm/CodeGen/MIRParser -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Object -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Option -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Passes -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ProfileData -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Scalar -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ADT -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Support -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/Symbolize -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Target -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Utils -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Vectorize -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/IPO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/libLLVM/../include -I /usr/src/gnu/usr.bin/clang/libLLVM/obj -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include -D NDEBUG -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D LLVM_PREFIX="/usr" -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/usr/src/gnu/usr.bin/clang/libLLVM/obj -ferror-limit 19 -fvisibility-inlines-hidden -fwrapv -stack-protector 2 -fno-rtti -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c++ /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Transforms/IPO/IROutliner.cpp
1//===- IROutliner.cpp -- Outline Similar Regions ----------------*- 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/// \file
10// Implementation for the IROutliner which is used by the IROutliner Pass.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Transforms/IPO/IROutliner.h"
15#include "llvm/Analysis/IRSimilarityIdentifier.h"
16#include "llvm/Analysis/OptimizationRemarkEmitter.h"
17#include "llvm/Analysis/TargetTransformInfo.h"
18#include "llvm/IR/Attributes.h"
19#include "llvm/IR/DebugInfoMetadata.h"
20#include "llvm/IR/DIBuilder.h"
21#include "llvm/IR/Mangler.h"
22#include "llvm/IR/PassManager.h"
23#include "llvm/InitializePasses.h"
24#include "llvm/Pass.h"
25#include "llvm/Support/CommandLine.h"
26#include "llvm/Transforms/IPO.h"
27#include <map>
28#include <set>
29#include <vector>
30
31#define DEBUG_TYPE"iroutliner" "iroutliner"
32
33using namespace llvm;
34using namespace IRSimilarity;
35
36// Set to true if the user wants the ir outliner to run on linkonceodr linkage
37// functions. This is false by default because the linker can dedupe linkonceodr
38// functions. Since the outliner is confined to a single module (modulo LTO),
39// this is off by default. It should, however, be the default behavior in
40// LTO.
41static cl::opt<bool> EnableLinkOnceODRIROutlining(
42 "enable-linkonceodr-ir-outlining", cl::Hidden,
43 cl::desc("Enable the IR outliner on linkonceodr functions"),
44 cl::init(false));
45
46// This is a debug option to test small pieces of code to ensure that outlining
47// works correctly.
48static cl::opt<bool> NoCostModel(
49 "ir-outlining-no-cost", cl::init(false), cl::ReallyHidden,
50 cl::desc("Debug option to outline greedily, without restriction that "
51 "calculated benefit outweighs cost"));
52
53/// The OutlinableGroup holds all the overarching information for outlining
54/// a set of regions that are structurally similar to one another, such as the
55/// types of the overall function, the output blocks, the sets of stores needed
56/// and a list of the different regions. This information is used in the
57/// deduplication of extracted regions with the same structure.
58struct OutlinableGroup {
59 /// The sections that could be outlined
60 std::vector<OutlinableRegion *> Regions;
61
62 /// The argument types for the function created as the overall function to
63 /// replace the extracted function for each region.
64 std::vector<Type *> ArgumentTypes;
65 /// The FunctionType for the overall function.
66 FunctionType *OutlinedFunctionType = nullptr;
67 /// The Function for the collective overall function.
68 Function *OutlinedFunction = nullptr;
69
70 /// Flag for whether we should not consider this group of OutlinableRegions
71 /// for extraction.
72 bool IgnoreGroup = false;
73
74 /// The return block for the overall function.
75 BasicBlock *EndBB = nullptr;
76
77 /// A set containing the different GVN store sets needed. Each array contains
78 /// a sorted list of the different values that need to be stored into output
79 /// registers.
80 DenseSet<ArrayRef<unsigned>> OutputGVNCombinations;
81
82 /// Flag for whether the \ref ArgumentTypes have been defined after the
83 /// extraction of the first region.
84 bool InputTypesSet = false;
85
86 /// The number of input values in \ref ArgumentTypes. Anything after this
87 /// index in ArgumentTypes is an output argument.
88 unsigned NumAggregateInputs = 0;
89
90 /// The number of instructions that will be outlined by extracting \ref
91 /// Regions.
92 InstructionCost Benefit = 0;
93 /// The number of added instructions needed for the outlining of the \ref
94 /// Regions.
95 InstructionCost Cost = 0;
96
97 /// The argument that needs to be marked with the swifterr attribute. If not
98 /// needed, there is no value.
99 Optional<unsigned> SwiftErrorArgument;
100
101 /// For the \ref Regions, we look at every Value. If it is a constant,
102 /// we check whether it is the same in Region.
103 ///
104 /// \param [in,out] NotSame contains the global value numbers where the
105 /// constant is not always the same, and must be passed in as an argument.
106 void findSameConstants(DenseSet<unsigned> &NotSame);
107
108 /// For the regions, look at each set of GVN stores needed and account for
109 /// each combination. Add an argument to the argument types if there is
110 /// more than one combination.
111 ///
112 /// \param [in] M - The module we are outlining from.
113 void collectGVNStoreSets(Module &M);
114};
115
116/// Move the contents of \p SourceBB to before the last instruction of \p
117/// TargetBB.
118/// \param SourceBB - the BasicBlock to pull Instructions from.
119/// \param TargetBB - the BasicBlock to put Instruction into.
120static void moveBBContents(BasicBlock &SourceBB, BasicBlock &TargetBB) {
121 BasicBlock::iterator BBCurr, BBEnd, BBNext;
122 for (BBCurr = SourceBB.begin(), BBEnd = SourceBB.end(); BBCurr != BBEnd;
123 BBCurr = BBNext) {
124 BBNext = std::next(BBCurr);
125 BBCurr->moveBefore(TargetBB, TargetBB.end());
126 }
127}
128
129void OutlinableRegion::splitCandidate() {
130 assert(!CandidateSplit && "Candidate already split!")((void)0);
131
132 Instruction *StartInst = (*Candidate->begin()).Inst;
133 Instruction *EndInst = (*Candidate->end()).Inst;
134 assert(StartInst && EndInst && "Expected a start and end instruction?")((void)0);
135 StartBB = StartInst->getParent();
136 PrevBB = StartBB;
137
138 // The basic block gets split like so:
139 // block: block:
140 // inst1 inst1
141 // inst2 inst2
142 // region1 br block_to_outline
143 // region2 block_to_outline:
144 // region3 -> region1
145 // region4 region2
146 // inst3 region3
147 // inst4 region4
148 // br block_after_outline
149 // block_after_outline:
150 // inst3
151 // inst4
152
153 std::string OriginalName = PrevBB->getName().str();
154
155 StartBB = PrevBB->splitBasicBlock(StartInst, OriginalName + "_to_outline");
156
157 // This is the case for the inner block since we do not have to include
158 // multiple blocks.
159 EndBB = StartBB;
160 FollowBB = EndBB->splitBasicBlock(EndInst, OriginalName + "_after_outline");
161
162 CandidateSplit = true;
163}
164
165void OutlinableRegion::reattachCandidate() {
166 assert(CandidateSplit && "Candidate is not split!")((void)0);
167
168 // The basic block gets reattached like so:
169 // block: block:
170 // inst1 inst1
171 // inst2 inst2
172 // br block_to_outline region1
173 // block_to_outline: -> region2
174 // region1 region3
175 // region2 region4
176 // region3 inst3
177 // region4 inst4
178 // br block_after_outline
179 // block_after_outline:
180 // inst3
181 // inst4
182 assert(StartBB != nullptr && "StartBB for Candidate is not defined!")((void)0);
183 assert(FollowBB != nullptr && "StartBB for Candidate is not defined!")((void)0);
184
185 // StartBB should only have one predecessor since we put an unconditional
186 // branch at the end of PrevBB when we split the BasicBlock.
187 PrevBB = StartBB->getSinglePredecessor();
188 assert(PrevBB != nullptr &&((void)0)
189 "No Predecessor for the region start basic block!")((void)0);
190
191 assert(PrevBB->getTerminator() && "Terminator removed from PrevBB!")((void)0);
192 assert(EndBB->getTerminator() && "Terminator removed from EndBB!")((void)0);
193 PrevBB->getTerminator()->eraseFromParent();
194 EndBB->getTerminator()->eraseFromParent();
195
196 moveBBContents(*StartBB, *PrevBB);
197
198 BasicBlock *PlacementBB = PrevBB;
199 if (StartBB != EndBB)
200 PlacementBB = EndBB;
201 moveBBContents(*FollowBB, *PlacementBB);
202
203 PrevBB->replaceSuccessorsPhiUsesWith(StartBB, PrevBB);
204 PrevBB->replaceSuccessorsPhiUsesWith(FollowBB, PlacementBB);
205 StartBB->eraseFromParent();
206 FollowBB->eraseFromParent();
207
208 // Make sure to save changes back to the StartBB.
209 StartBB = PrevBB;
210 EndBB = nullptr;
211 PrevBB = nullptr;
212 FollowBB = nullptr;
213
214 CandidateSplit = false;
215}
216
217/// Find whether \p V matches the Constants previously found for the \p GVN.
218///
219/// \param V - The value to check for consistency.
220/// \param GVN - The global value number assigned to \p V.
221/// \param GVNToConstant - The mapping of global value number to Constants.
222/// \returns true if the Value matches the Constant mapped to by V and false if
223/// it \p V is a Constant but does not match.
224/// \returns None if \p V is not a Constant.
225static Optional<bool>
226constantMatches(Value *V, unsigned GVN,
227 DenseMap<unsigned, Constant *> &GVNToConstant) {
228 // See if we have a constants
229 Constant *CST = dyn_cast<Constant>(V);
230 if (!CST)
231 return None;
232
233 // Holds a mapping from a global value number to a Constant.
234 DenseMap<unsigned, Constant *>::iterator GVNToConstantIt;
235 bool Inserted;
236
237
238 // If we have a constant, try to make a new entry in the GVNToConstant.
239 std::tie(GVNToConstantIt, Inserted) =
240 GVNToConstant.insert(std::make_pair(GVN, CST));
241 // If it was found and is not equal, it is not the same. We do not
242 // handle this case yet, and exit early.
243 if (Inserted || (GVNToConstantIt->second == CST))
244 return true;
245
246 return false;
247}
248
249InstructionCost OutlinableRegion::getBenefit(TargetTransformInfo &TTI) {
250 InstructionCost Benefit = 0;
251
252 // Estimate the benefit of outlining a specific sections of the program. We
253 // delegate mostly this task to the TargetTransformInfo so that if the target
254 // has specific changes, we can have a more accurate estimate.
255
256 // However, getInstructionCost delegates the code size calculation for
257 // arithmetic instructions to getArithmeticInstrCost in
258 // include/Analysis/TargetTransformImpl.h, where it always estimates that the
259 // code size for a division and remainder instruction to be equal to 4, and
260 // everything else to 1. This is not an accurate representation of the
261 // division instruction for targets that have a native division instruction.
262 // To be overly conservative, we only add 1 to the number of instructions for
263 // each division instruction.
264 for (Instruction &I : *StartBB) {
265 switch (I.getOpcode()) {
266 case Instruction::FDiv:
267 case Instruction::FRem:
268 case Instruction::SDiv:
269 case Instruction::SRem:
270 case Instruction::UDiv:
271 case Instruction::URem:
272 Benefit += 1;
273 break;
274 default:
275 Benefit += TTI.getInstructionCost(&I, TargetTransformInfo::TCK_CodeSize);
276 break;
277 }
278 }
279
280 return Benefit;
281}
282
283/// Find whether \p Region matches the global value numbering to Constant
284/// mapping found so far.
285///
286/// \param Region - The OutlinableRegion we are checking for constants
287/// \param GVNToConstant - The mapping of global value number to Constants.
288/// \param NotSame - The set of global value numbers that do not have the same
289/// constant in each region.
290/// \returns true if all Constants are the same in every use of a Constant in \p
291/// Region and false if not
292static bool
293collectRegionsConstants(OutlinableRegion &Region,
294 DenseMap<unsigned, Constant *> &GVNToConstant,
295 DenseSet<unsigned> &NotSame) {
296 bool ConstantsTheSame = true;
297
298 IRSimilarityCandidate &C = *Region.Candidate;
299 for (IRInstructionData &ID : C) {
300
301 // Iterate over the operands in an instruction. If the global value number,
302 // assigned by the IRSimilarityCandidate, has been seen before, we check if
303 // the the number has been found to be not the same value in each instance.
304 for (Value *V : ID.OperVals) {
305 Optional<unsigned> GVNOpt = C.getGVN(V);
306 assert(GVNOpt.hasValue() && "Expected a GVN for operand?")((void)0);
307 unsigned GVN = GVNOpt.getValue();
308
309 // Check if this global value has been found to not be the same already.
310 if (NotSame.contains(GVN)) {
311 if (isa<Constant>(V))
312 ConstantsTheSame = false;
313 continue;
314 }
315
316 // If it has been the same so far, we check the value for if the
317 // associated Constant value match the previous instances of the same
318 // global value number. If the global value does not map to a Constant,
319 // it is considered to not be the same value.
320 Optional<bool> ConstantMatches = constantMatches(V, GVN, GVNToConstant);
321 if (ConstantMatches.hasValue()) {
322 if (ConstantMatches.getValue())
323 continue;
324 else
325 ConstantsTheSame = false;
326 }
327
328 // While this value is a register, it might not have been previously,
329 // make sure we don't already have a constant mapped to this global value
330 // number.
331 if (GVNToConstant.find(GVN) != GVNToConstant.end())
332 ConstantsTheSame = false;
333
334 NotSame.insert(GVN);
335 }
336 }
337
338 return ConstantsTheSame;
339}
340
341void OutlinableGroup::findSameConstants(DenseSet<unsigned> &NotSame) {
342 DenseMap<unsigned, Constant *> GVNToConstant;
343
344 for (OutlinableRegion *Region : Regions)
345 collectRegionsConstants(*Region, GVNToConstant, NotSame);
346}
347
348void OutlinableGroup::collectGVNStoreSets(Module &M) {
349 for (OutlinableRegion *OS : Regions)
350 OutputGVNCombinations.insert(OS->GVNStores);
351
352 // We are adding an extracted argument to decide between which output path
353 // to use in the basic block. It is used in a switch statement and only
354 // needs to be an integer.
355 if (OutputGVNCombinations.size() > 1)
356 ArgumentTypes.push_back(Type::getInt32Ty(M.getContext()));
357}
358
359/// Get the subprogram if it exists for one of the outlined regions.
360///
361/// \param [in] Group - The set of regions to find a subprogram for.
362/// \returns the subprogram if it exists, or nullptr.
363static DISubprogram *getSubprogramOrNull(OutlinableGroup &Group) {
364 for (OutlinableRegion *OS : Group.Regions)
365 if (Function *F = OS->Call->getFunction())
366 if (DISubprogram *SP = F->getSubprogram())
367 return SP;
368
369 return nullptr;
370}
371
372Function *IROutliner::createFunction(Module &M, OutlinableGroup &Group,
373 unsigned FunctionNameSuffix) {
374 assert(!Group.OutlinedFunction && "Function is already defined!")((void)0);
375
376 Group.OutlinedFunctionType = FunctionType::get(
377 Type::getVoidTy(M.getContext()), Group.ArgumentTypes, false);
378
379 // These functions will only be called from within the same module, so
380 // we can set an internal linkage.
381 Group.OutlinedFunction = Function::Create(
382 Group.OutlinedFunctionType, GlobalValue::InternalLinkage,
383 "outlined_ir_func_" + std::to_string(FunctionNameSuffix), M);
384
385 // Transfer the swifterr attribute to the correct function parameter.
386 if (Group.SwiftErrorArgument.hasValue())
387 Group.OutlinedFunction->addParamAttr(Group.SwiftErrorArgument.getValue(),
388 Attribute::SwiftError);
389
390 Group.OutlinedFunction->addFnAttr(Attribute::OptimizeForSize);
391 Group.OutlinedFunction->addFnAttr(Attribute::MinSize);
392
393 // If there's a DISubprogram associated with this outlined function, then
394 // emit debug info for the outlined function.
395 if (DISubprogram *SP = getSubprogramOrNull(Group)) {
396 Function *F = Group.OutlinedFunction;
397 // We have a DISubprogram. Get its DICompileUnit.
398 DICompileUnit *CU = SP->getUnit();
399 DIBuilder DB(M, true, CU);
400 DIFile *Unit = SP->getFile();
401 Mangler Mg;
402 // Get the mangled name of the function for the linkage name.
403 std::string Dummy;
404 llvm::raw_string_ostream MangledNameStream(Dummy);
405 Mg.getNameWithPrefix(MangledNameStream, F, false);
406
407 DISubprogram *OutlinedSP = DB.createFunction(
408 Unit /* Context */, F->getName(), MangledNameStream.str(),
409 Unit /* File */,
410 0 /* Line 0 is reserved for compiler-generated code. */,
411 DB.createSubroutineType(DB.getOrCreateTypeArray(None)), /* void type */
412 0, /* Line 0 is reserved for compiler-generated code. */
413 DINode::DIFlags::FlagArtificial /* Compiler-generated code. */,
414 /* Outlined code is optimized code by definition. */
415 DISubprogram::SPFlagDefinition | DISubprogram::SPFlagOptimized);
416
417 // Don't add any new variables to the subprogram.
418 DB.finalizeSubprogram(OutlinedSP);
419
420 // Attach subprogram to the function.
421 F->setSubprogram(OutlinedSP);
422 // We're done with the DIBuilder.
423 DB.finalize();
424 }
425
426 return Group.OutlinedFunction;
427}
428
429/// Move each BasicBlock in \p Old to \p New.
430///
431/// \param [in] Old - The function to move the basic blocks from.
432/// \param [in] New - The function to move the basic blocks to.
433/// \returns the first return block for the function in New.
434static BasicBlock *moveFunctionData(Function &Old, Function &New) {
435 Function::iterator CurrBB, NextBB, FinalBB;
436 BasicBlock *NewEnd = nullptr;
437 std::vector<Instruction *> DebugInsts;
438 for (CurrBB = Old.begin(), FinalBB = Old.end(); CurrBB != FinalBB;
439 CurrBB = NextBB) {
440 NextBB = std::next(CurrBB);
441 CurrBB->removeFromParent();
442 CurrBB->insertInto(&New);
443 Instruction *I = CurrBB->getTerminator();
444 if (isa<ReturnInst>(I))
445 NewEnd = &(*CurrBB);
446
447 for (Instruction &Val : *CurrBB) {
448 // We must handle the scoping of called functions differently than
449 // other outlined instructions.
450 if (!isa<CallInst>(&Val)) {
451 // Remove the debug information for outlined functions.
452 Val.setDebugLoc(DebugLoc());
453 continue;
454 }
455
456 // From this point we are only handling call instructions.
457 CallInst *CI = cast<CallInst>(&Val);
458
459 // We add any debug statements here, to be removed after. Since the
460 // instructions originate from many different locations in the program,
461 // it will cause incorrect reporting from a debugger if we keep the
462 // same debug instructions.
463 if (isa<DbgInfoIntrinsic>(CI)) {
464 DebugInsts.push_back(&Val);
465 continue;
466 }
467
468 // Edit the scope of called functions inside of outlined functions.
469 if (DISubprogram *SP = New.getSubprogram()) {
470 DILocation *DI = DILocation::get(New.getContext(), 0, 0, SP);
471 Val.setDebugLoc(DI);
472 }
473 }
474
475 for (Instruction *I : DebugInsts)
476 I->eraseFromParent();
477 }
478
479 assert(NewEnd && "No return instruction for new function?")((void)0);
480 return NewEnd;
481}
482
483/// Find the the constants that will need to be lifted into arguments
484/// as they are not the same in each instance of the region.
485///
486/// \param [in] C - The IRSimilarityCandidate containing the region we are
487/// analyzing.
488/// \param [in] NotSame - The set of global value numbers that do not have a
489/// single Constant across all OutlinableRegions similar to \p C.
490/// \param [out] Inputs - The list containing the global value numbers of the
491/// arguments needed for the region of code.
492static void findConstants(IRSimilarityCandidate &C, DenseSet<unsigned> &NotSame,
493 std::vector<unsigned> &Inputs) {
494 DenseSet<unsigned> Seen;
495 // Iterate over the instructions, and find what constants will need to be
496 // extracted into arguments.
497 for (IRInstructionDataList::iterator IDIt = C.begin(), EndIDIt = C.end();
498 IDIt != EndIDIt; IDIt++) {
499 for (Value *V : (*IDIt).OperVals) {
500 // Since these are stored before any outlining, they will be in the
501 // global value numbering.
502 unsigned GVN = C.getGVN(V).getValue();
503 if (isa<Constant>(V))
504 if (NotSame.contains(GVN) && !Seen.contains(GVN)) {
505 Inputs.push_back(GVN);
506 Seen.insert(GVN);
507 }
508 }
509 }
510}
511
512/// Find the GVN for the inputs that have been found by the CodeExtractor.
513///
514/// \param [in] C - The IRSimilarityCandidate containing the region we are
515/// analyzing.
516/// \param [in] CurrentInputs - The set of inputs found by the
517/// CodeExtractor.
518/// \param [in] OutputMappings - The mapping of values that have been replaced
519/// by a new output value.
520/// \param [out] EndInputNumbers - The global value numbers for the extracted
521/// arguments.
522static void mapInputsToGVNs(IRSimilarityCandidate &C,
523 SetVector<Value *> &CurrentInputs,
524 const DenseMap<Value *, Value *> &OutputMappings,
525 std::vector<unsigned> &EndInputNumbers) {
526 // Get the Global Value Number for each input. We check if the Value has been
527 // replaced by a different value at output, and use the original value before
528 // replacement.
529 for (Value *Input : CurrentInputs) {
530 assert(Input && "Have a nullptr as an input")((void)0);
531 if (OutputMappings.find(Input) != OutputMappings.end())
532 Input = OutputMappings.find(Input)->second;
533 assert(C.getGVN(Input).hasValue() &&((void)0)
534 "Could not find a numbering for the given input")((void)0);
535 EndInputNumbers.push_back(C.getGVN(Input).getValue());
536 }
537}
538
539/// Find the original value for the \p ArgInput values if any one of them was
540/// replaced during a previous extraction.
541///
542/// \param [in] ArgInputs - The inputs to be extracted by the code extractor.
543/// \param [in] OutputMappings - The mapping of values that have been replaced
544/// by a new output value.
545/// \param [out] RemappedArgInputs - The remapped values according to
546/// \p OutputMappings that will be extracted.
547static void
548remapExtractedInputs(const ArrayRef<Value *> ArgInputs,
549 const DenseMap<Value *, Value *> &OutputMappings,
550 SetVector<Value *> &RemappedArgInputs) {
551 // Get the global value number for each input that will be extracted as an
552 // argument by the code extractor, remapping if needed for reloaded values.
553 for (Value *Input : ArgInputs) {
554 if (OutputMappings.find(Input) != OutputMappings.end())
555 Input = OutputMappings.find(Input)->second;
556 RemappedArgInputs.insert(Input);
557 }
558}
559
560/// Find the input GVNs and the output values for a region of Instructions.
561/// Using the code extractor, we collect the inputs to the extracted function.
562///
563/// The \p Region can be identified as needing to be ignored in this function.
564/// It should be checked whether it should be ignored after a call to this
565/// function.
566///
567/// \param [in,out] Region - The region of code to be analyzed.
568/// \param [out] InputGVNs - The global value numbers for the extracted
569/// arguments.
570/// \param [in] NotSame - The global value numbers in the region that do not
571/// have the same constant value in the regions structurally similar to
572/// \p Region.
573/// \param [in] OutputMappings - The mapping of values that have been replaced
574/// by a new output value after extraction.
575/// \param [out] ArgInputs - The values of the inputs to the extracted function.
576/// \param [out] Outputs - The set of values extracted by the CodeExtractor
577/// as outputs.
578static void getCodeExtractorArguments(
579 OutlinableRegion &Region, std::vector<unsigned> &InputGVNs,
580 DenseSet<unsigned> &NotSame, DenseMap<Value *, Value *> &OutputMappings,
581 SetVector<Value *> &ArgInputs, SetVector<Value *> &Outputs) {
582 IRSimilarityCandidate &C = *Region.Candidate;
583
584 // OverallInputs are the inputs to the region found by the CodeExtractor,
585 // SinkCands and HoistCands are used by the CodeExtractor to find sunken
586 // allocas of values whose lifetimes are contained completely within the
587 // outlined region. PremappedInputs are the arguments found by the
588 // CodeExtractor, removing conditions such as sunken allocas, but that
589 // may need to be remapped due to the extracted output values replacing
590 // the original values. We use DummyOutputs for this first run of finding
591 // inputs and outputs since the outputs could change during findAllocas,
592 // the correct set of extracted outputs will be in the final Outputs ValueSet.
593 SetVector<Value *> OverallInputs, PremappedInputs, SinkCands, HoistCands,
594 DummyOutputs;
595
596 // Use the code extractor to get the inputs and outputs, without sunken
597 // allocas or removing llvm.assumes.
598 CodeExtractor *CE = Region.CE;
599 CE->findInputsOutputs(OverallInputs, DummyOutputs, SinkCands);
600 assert(Region.StartBB && "Region must have a start BasicBlock!")((void)0);
601 Function *OrigF = Region.StartBB->getParent();
602 CodeExtractorAnalysisCache CEAC(*OrigF);
603 BasicBlock *Dummy = nullptr;
604
605 // The region may be ineligible due to VarArgs in the parent function. In this
606 // case we ignore the region.
607 if (!CE->isEligible()) {
608 Region.IgnoreRegion = true;
609 return;
610 }
611
612 // Find if any values are going to be sunk into the function when extracted
613 CE->findAllocas(CEAC, SinkCands, HoistCands, Dummy);
614 CE->findInputsOutputs(PremappedInputs, Outputs, SinkCands);
615
616 // TODO: Support regions with sunken allocas: values whose lifetimes are
617 // contained completely within the outlined region. These are not guaranteed
618 // to be the same in every region, so we must elevate them all to arguments
619 // when they appear. If these values are not equal, it means there is some
620 // Input in OverallInputs that was removed for ArgInputs.
621 if (OverallInputs.size() != PremappedInputs.size()) {
622 Region.IgnoreRegion = true;
623 return;
624 }
625
626 findConstants(C, NotSame, InputGVNs);
627
628 mapInputsToGVNs(C, OverallInputs, OutputMappings, InputGVNs);
629
630 remapExtractedInputs(PremappedInputs.getArrayRef(), OutputMappings,
631 ArgInputs);
632
633 // Sort the GVNs, since we now have constants included in the \ref InputGVNs
634 // we need to make sure they are in a deterministic order.
635 stable_sort(InputGVNs);
636}
637
638/// Look over the inputs and map each input argument to an argument in the
639/// overall function for the OutlinableRegions. This creates a way to replace
640/// the arguments of the extracted function with the arguments of the new
641/// overall function.
642///
643/// \param [in,out] Region - The region of code to be analyzed.
644/// \param [in] InputGVNs - The global value numbering of the input values
645/// collected.
646/// \param [in] ArgInputs - The values of the arguments to the extracted
647/// function.
648static void
649findExtractedInputToOverallInputMapping(OutlinableRegion &Region,
650 std::vector<unsigned> &InputGVNs,
651 SetVector<Value *> &ArgInputs) {
652
653 IRSimilarityCandidate &C = *Region.Candidate;
654 OutlinableGroup &Group = *Region.Parent;
655
656 // This counts the argument number in the overall function.
657 unsigned TypeIndex = 0;
658
659 // This counts the argument number in the extracted function.
660 unsigned OriginalIndex = 0;
661
662 // Find the mapping of the extracted arguments to the arguments for the
663 // overall function. Since there may be extra arguments in the overall
664 // function to account for the extracted constants, we have two different
665 // counters as we find extracted arguments, and as we come across overall
666 // arguments.
667 for (unsigned InputVal : InputGVNs) {
668 Optional<Value *> InputOpt = C.fromGVN(InputVal);
669 assert(InputOpt.hasValue() && "Global value number not found?")((void)0);
670 Value *Input = InputOpt.getValue();
671
672 if (!Group.InputTypesSet) {
673 Group.ArgumentTypes.push_back(Input->getType());
674 // If the input value has a swifterr attribute, make sure to mark the
675 // argument in the overall function.
676 if (Input->isSwiftError()) {
677 assert(((void)0)
678 !Group.SwiftErrorArgument.hasValue() &&((void)0)
679 "Argument already marked with swifterr for this OutlinableGroup!")((void)0);
680 Group.SwiftErrorArgument = TypeIndex;
681 }
682 }
683
684 // Check if we have a constant. If we do add it to the overall argument
685 // number to Constant map for the region, and continue to the next input.
686 if (Constant *CST = dyn_cast<Constant>(Input)) {
687 Region.AggArgToConstant.insert(std::make_pair(TypeIndex, CST));
688 TypeIndex++;
689 continue;
690 }
691
692 // It is not a constant, we create the mapping from extracted argument list
693 // to the overall argument list.
694 assert(ArgInputs.count(Input) && "Input cannot be found!")((void)0);
695
696 Region.ExtractedArgToAgg.insert(std::make_pair(OriginalIndex, TypeIndex));
697 Region.AggArgToExtracted.insert(std::make_pair(TypeIndex, OriginalIndex));
698 OriginalIndex++;
699 TypeIndex++;
700 }
701
702 // If the function type definitions for the OutlinableGroup holding the region
703 // have not been set, set the length of the inputs here. We should have the
704 // same inputs for all of the different regions contained in the
705 // OutlinableGroup since they are all structurally similar to one another.
706 if (!Group.InputTypesSet) {
707 Group.NumAggregateInputs = TypeIndex;
708 Group.InputTypesSet = true;
709 }
710
711 Region.NumExtractedInputs = OriginalIndex;
712}
713
714/// Create a mapping of the output arguments for the \p Region to the output
715/// arguments of the overall outlined function.
716///
717/// \param [in,out] Region - The region of code to be analyzed.
718/// \param [in] Outputs - The values found by the code extractor.
719static void
720findExtractedOutputToOverallOutputMapping(OutlinableRegion &Region,
721 ArrayRef<Value *> Outputs) {
722 OutlinableGroup &Group = *Region.Parent;
723 IRSimilarityCandidate &C = *Region.Candidate;
724
725 // This counts the argument number in the extracted function.
726 unsigned OriginalIndex = Region.NumExtractedInputs;
727
728 // This counts the argument number in the overall function.
729 unsigned TypeIndex = Group.NumAggregateInputs;
730 bool TypeFound;
731 DenseSet<unsigned> AggArgsUsed;
732
733 // Iterate over the output types and identify if there is an aggregate pointer
734 // type whose base type matches the current output type. If there is, we mark
735 // that we will use this output register for this value. If not we add another
736 // type to the overall argument type list. We also store the GVNs used for
737 // stores to identify which values will need to be moved into an special
738 // block that holds the stores to the output registers.
739 for (Value *Output : Outputs) {
740 TypeFound = false;
741 // We can do this since it is a result value, and will have a number
742 // that is necessarily the same. BUT if in the future, the instructions
743 // do not have to be in same order, but are functionally the same, we will
744 // have to use a different scheme, as one-to-one correspondence is not
745 // guaranteed.
746 unsigned GlobalValue = C.getGVN(Output).getValue();
747 unsigned ArgumentSize = Group.ArgumentTypes.size();
748
749 for (unsigned Jdx = TypeIndex; Jdx < ArgumentSize; Jdx++) {
750 if (Group.ArgumentTypes[Jdx] != PointerType::getUnqual(Output->getType()))
751 continue;
752
753 if (AggArgsUsed.contains(Jdx))
754 continue;
755
756 TypeFound = true;
757 AggArgsUsed.insert(Jdx);
758 Region.ExtractedArgToAgg.insert(std::make_pair(OriginalIndex, Jdx));
759 Region.AggArgToExtracted.insert(std::make_pair(Jdx, OriginalIndex));
760 Region.GVNStores.push_back(GlobalValue);
761 break;
762 }
763
764 // We were unable to find an unused type in the output type set that matches
765 // the output, so we add a pointer type to the argument types of the overall
766 // function to handle this output and create a mapping to it.
767 if (!TypeFound) {
768 Group.ArgumentTypes.push_back(PointerType::getUnqual(Output->getType()));
769 AggArgsUsed.insert(Group.ArgumentTypes.size() - 1);
770 Region.ExtractedArgToAgg.insert(
771 std::make_pair(OriginalIndex, Group.ArgumentTypes.size() - 1));
772 Region.AggArgToExtracted.insert(
773 std::make_pair(Group.ArgumentTypes.size() - 1, OriginalIndex));
774 Region.GVNStores.push_back(GlobalValue);
775 }
776
777 stable_sort(Region.GVNStores);
778 OriginalIndex++;
779 TypeIndex++;
780 }
781}
782
783void IROutliner::findAddInputsOutputs(Module &M, OutlinableRegion &Region,
784 DenseSet<unsigned> &NotSame) {
785 std::vector<unsigned> Inputs;
786 SetVector<Value *> ArgInputs, Outputs;
787
788 getCodeExtractorArguments(Region, Inputs, NotSame, OutputMappings, ArgInputs,
789 Outputs);
790
791 if (Region.IgnoreRegion)
792 return;
793
794 // Map the inputs found by the CodeExtractor to the arguments found for
795 // the overall function.
796 findExtractedInputToOverallInputMapping(Region, Inputs, ArgInputs);
797
798 // Map the outputs found by the CodeExtractor to the arguments found for
799 // the overall function.
800 findExtractedOutputToOverallOutputMapping(Region, Outputs.getArrayRef());
801}
802
803/// Replace the extracted function in the Region with a call to the overall
804/// function constructed from the deduplicated similar regions, replacing and
805/// remapping the values passed to the extracted function as arguments to the
806/// new arguments of the overall function.
807///
808/// \param [in] M - The module to outline from.
809/// \param [in] Region - The regions of extracted code to be replaced with a new
810/// function.
811/// \returns a call instruction with the replaced function.
812CallInst *replaceCalledFunction(Module &M, OutlinableRegion &Region) {
813 std::vector<Value *> NewCallArgs;
814 DenseMap<unsigned, unsigned>::iterator ArgPair;
815
816 OutlinableGroup &Group = *Region.Parent;
817 CallInst *Call = Region.Call;
818 assert(Call && "Call to replace is nullptr?")((void)0);
819 Function *AggFunc = Group.OutlinedFunction;
820 assert(AggFunc && "Function to replace with is nullptr?")((void)0);
821
822 // If the arguments are the same size, there are not values that need to be
823 // made argument, or different output registers to handle. We can simply
824 // replace the called function in this case.
825 if (AggFunc->arg_size() == Call->arg_size()) {
826 LLVM_DEBUG(dbgs() << "Replace call to " << *Call << " with call to "do { } while (false)
827 << *AggFunc << " with same number of arguments\n")do { } while (false);
828 Call->setCalledFunction(AggFunc);
829 return Call;
830 }
831
832 // We have a different number of arguments than the new function, so
833 // we need to use our previously mappings off extracted argument to overall
834 // function argument, and constants to overall function argument to create the
835 // new argument list.
836 for (unsigned AggArgIdx = 0; AggArgIdx < AggFunc->arg_size(); AggArgIdx++) {
837
838 if (AggArgIdx == AggFunc->arg_size() - 1 &&
839 Group.OutputGVNCombinations.size() > 1) {
840 // If we are on the last argument, and we need to differentiate between
841 // output blocks, add an integer to the argument list to determine
842 // what block to take
843 LLVM_DEBUG(dbgs() << "Set switch block argument to "do { } while (false)
844 << Region.OutputBlockNum << "\n")do { } while (false);
845 NewCallArgs.push_back(ConstantInt::get(Type::getInt32Ty(M.getContext()),
846 Region.OutputBlockNum));
847 continue;
848 }
849
850 ArgPair = Region.AggArgToExtracted.find(AggArgIdx);
851 if (ArgPair != Region.AggArgToExtracted.end()) {
852 Value *ArgumentValue = Call->getArgOperand(ArgPair->second);
853 // If we found the mapping from the extracted function to the overall
854 // function, we simply add it to the argument list. We use the same
855 // value, it just needs to honor the new order of arguments.
856 LLVM_DEBUG(dbgs() << "Setting argument " << AggArgIdx << " to value "do { } while (false)
857 << *ArgumentValue << "\n")do { } while (false);
858 NewCallArgs.push_back(ArgumentValue);
859 continue;
860 }
861
862 // If it is a constant, we simply add it to the argument list as a value.
863 if (Region.AggArgToConstant.find(AggArgIdx) !=
864 Region.AggArgToConstant.end()) {
865 Constant *CST = Region.AggArgToConstant.find(AggArgIdx)->second;
866 LLVM_DEBUG(dbgs() << "Setting argument " << AggArgIdx << " to value "do { } while (false)
867 << *CST << "\n")do { } while (false);
868 NewCallArgs.push_back(CST);
869 continue;
870 }
871
872 // Add a nullptr value if the argument is not found in the extracted
873 // function. If we cannot find a value, it means it is not in use
874 // for the region, so we should not pass anything to it.
875 LLVM_DEBUG(dbgs() << "Setting argument " << AggArgIdx << " to nullptr\n")do { } while (false);
876 NewCallArgs.push_back(ConstantPointerNull::get(
877 static_cast<PointerType *>(AggFunc->getArg(AggArgIdx)->getType())));
878 }
879
880 LLVM_DEBUG(dbgs() << "Replace call to " << *Call << " with call to "do { } while (false)
881 << *AggFunc << " with new set of arguments\n")do { } while (false);
882 // Create the new call instruction and erase the old one.
883 Call = CallInst::Create(AggFunc->getFunctionType(), AggFunc, NewCallArgs, "",
884 Call);
885
886 // It is possible that the call to the outlined function is either the first
887 // instruction is in the new block, the last instruction, or both. If either
888 // of these is the case, we need to make sure that we replace the instruction
889 // in the IRInstructionData struct with the new call.
890 CallInst *OldCall = Region.Call;
891 if (Region.NewFront->Inst == OldCall)
892 Region.NewFront->Inst = Call;
893 if (Region.NewBack->Inst == OldCall)
894 Region.NewBack->Inst = Call;
895
896 // Transfer any debug information.
897 Call->setDebugLoc(Region.Call->getDebugLoc());
898
899 // Remove the old instruction.
900 OldCall->eraseFromParent();
901 Region.Call = Call;
902
903 // Make sure that the argument in the new function has the SwiftError
904 // argument.
905 if (Group.SwiftErrorArgument.hasValue())
906 Call->addParamAttr(Group.SwiftErrorArgument.getValue(),
907 Attribute::SwiftError);
908
909 return Call;
910}
911
912// Within an extracted function, replace the argument uses of the extracted
913// region with the arguments of the function for an OutlinableGroup.
914//
915/// \param [in] Region - The region of extracted code to be changed.
916/// \param [in,out] OutputBB - The BasicBlock for the output stores for this
917/// region.
918static void replaceArgumentUses(OutlinableRegion &Region,
919 BasicBlock *OutputBB) {
920 OutlinableGroup &Group = *Region.Parent;
921 assert(Region.ExtractedFunction && "Region has no extracted function?")((void)0);
922
923 for (unsigned ArgIdx = 0; ArgIdx < Region.ExtractedFunction->arg_size();
924 ArgIdx++) {
925 assert(Region.ExtractedArgToAgg.find(ArgIdx) !=((void)0)
926 Region.ExtractedArgToAgg.end() &&((void)0)
927 "No mapping from extracted to outlined?")((void)0);
928 unsigned AggArgIdx = Region.ExtractedArgToAgg.find(ArgIdx)->second;
929 Argument *AggArg = Group.OutlinedFunction->getArg(AggArgIdx);
930 Argument *Arg = Region.ExtractedFunction->getArg(ArgIdx);
931 // The argument is an input, so we can simply replace it with the overall
932 // argument value
933 if (ArgIdx < Region.NumExtractedInputs) {
934 LLVM_DEBUG(dbgs() << "Replacing uses of input " << *Arg << " in function "do { } while (false)
935 << *Region.ExtractedFunction << " with " << *AggArgdo { } while (false)
936 << " in function " << *Group.OutlinedFunction << "\n")do { } while (false);
937 Arg->replaceAllUsesWith(AggArg);
938 continue;
939 }
940
941 // If we are replacing an output, we place the store value in its own
942 // block inside the overall function before replacing the use of the output
943 // in the function.
944 assert(Arg->hasOneUse() && "Output argument can only have one use")((void)0);
945 User *InstAsUser = Arg->user_back();
946 assert(InstAsUser && "User is nullptr!")((void)0);
947
948 Instruction *I = cast<Instruction>(InstAsUser);
949 I->setDebugLoc(DebugLoc());
950 LLVM_DEBUG(dbgs() << "Move store for instruction " << *I << " to "do { } while (false)
951 << *OutputBB << "\n")do { } while (false);
952
953 I->moveBefore(*OutputBB, OutputBB->end());
954
955 LLVM_DEBUG(dbgs() << "Replacing uses of output " << *Arg << " in function "do { } while (false)
956 << *Region.ExtractedFunction << " with " << *AggArgdo { } while (false)
957 << " in function " << *Group.OutlinedFunction << "\n")do { } while (false);
958 Arg->replaceAllUsesWith(AggArg);
959 }
960}
961
962/// Within an extracted function, replace the constants that need to be lifted
963/// into arguments with the actual argument.
964///
965/// \param Region [in] - The region of extracted code to be changed.
966void replaceConstants(OutlinableRegion &Region) {
967 OutlinableGroup &Group = *Region.Parent;
968 // Iterate over the constants that need to be elevated into arguments
969 for (std::pair<unsigned, Constant *> &Const : Region.AggArgToConstant) {
970 unsigned AggArgIdx = Const.first;
971 Function *OutlinedFunction = Group.OutlinedFunction;
972 assert(OutlinedFunction && "Overall Function is not defined?")((void)0);
973 Constant *CST = Const.second;
974 Argument *Arg = Group.OutlinedFunction->getArg(AggArgIdx);
975 // Identify the argument it will be elevated to, and replace instances of
976 // that constant in the function.
977
978 // TODO: If in the future constants do not have one global value number,
979 // i.e. a constant 1 could be mapped to several values, this check will
980 // have to be more strict. It cannot be using only replaceUsesWithIf.
981
982 LLVM_DEBUG(dbgs() << "Replacing uses of constant " << *CSTdo { } while (false)
983 << " in function " << *OutlinedFunction << " with "do { } while (false)
984 << *Arg << "\n")do { } while (false);
985 CST->replaceUsesWithIf(Arg, [OutlinedFunction](Use &U) {
986 if (Instruction *I = dyn_cast<Instruction>(U.getUser()))
987 return I->getFunction() == OutlinedFunction;
988 return false;
989 });
990 }
991}
992
993/// For the given function, find all the nondebug or lifetime instructions,
994/// and return them as a vector. Exclude any blocks in \p ExludeBlocks.
995///
996/// \param [in] F - The function we collect the instructions from.
997/// \param [in] ExcludeBlocks - BasicBlocks to ignore.
998/// \returns the list of instructions extracted.
999static std::vector<Instruction *>
1000collectRelevantInstructions(Function &F,
1001 DenseSet<BasicBlock *> &ExcludeBlocks) {
1002 std::vector<Instruction *> RelevantInstructions;
1003
1004 for (BasicBlock &BB : F) {
1005 if (ExcludeBlocks.contains(&BB))
1006 continue;
1007
1008 for (Instruction &Inst : BB) {
1009 if (Inst.isLifetimeStartOrEnd())
1010 continue;
1011 if (isa<DbgInfoIntrinsic>(Inst))
1012 continue;
1013
1014 RelevantInstructions.push_back(&Inst);
1015 }
1016 }
1017
1018 return RelevantInstructions;
1019}
1020
1021/// It is possible that there is a basic block that already performs the same
1022/// stores. This returns a duplicate block, if it exists
1023///
1024/// \param OutputBB [in] the block we are looking for a duplicate of.
1025/// \param OutputStoreBBs [in] The existing output blocks.
1026/// \returns an optional value with the number output block if there is a match.
1027Optional<unsigned>
1028findDuplicateOutputBlock(BasicBlock *OutputBB,
1029 ArrayRef<BasicBlock *> OutputStoreBBs) {
1030
1031 bool WrongInst = false;
1032 bool WrongSize = false;
1033 unsigned MatchingNum = 0;
1034 for (BasicBlock *CompBB : OutputStoreBBs) {
1035 WrongInst = false;
1036 if (CompBB->size() - 1 != OutputBB->size()) {
1037 WrongSize = true;
Value stored to 'WrongSize' is never read
1038 MatchingNum++;
1039 continue;
1040 }
1041
1042 WrongSize = false;
1043 BasicBlock::iterator NIt = OutputBB->begin();
1044 for (Instruction &I : *CompBB) {
1045 if (isa<BranchInst>(&I))
1046 continue;
1047
1048 if (!I.isIdenticalTo(&(*NIt))) {
1049 WrongInst = true;
1050 break;
1051 }
1052
1053 NIt++;
1054 }
1055 if (!WrongInst && !WrongSize)
1056 return MatchingNum;
1057
1058 MatchingNum++;
1059 }
1060
1061 return None;
1062}
1063
1064/// For the outlined section, move needed the StoreInsts for the output
1065/// registers into their own block. Then, determine if there is a duplicate
1066/// output block already created.
1067///
1068/// \param [in] OG - The OutlinableGroup of regions to be outlined.
1069/// \param [in] Region - The OutlinableRegion that is being analyzed.
1070/// \param [in,out] OutputBB - the block that stores for this region will be
1071/// placed in.
1072/// \param [in] EndBB - the final block of the extracted function.
1073/// \param [in] OutputMappings - OutputMappings the mapping of values that have
1074/// been replaced by a new output value.
1075/// \param [in,out] OutputStoreBBs - The existing output blocks.
1076static void
1077alignOutputBlockWithAggFunc(OutlinableGroup &OG, OutlinableRegion &Region,
1078 BasicBlock *OutputBB, BasicBlock *EndBB,
1079 const DenseMap<Value *, Value *> &OutputMappings,
1080 std::vector<BasicBlock *> &OutputStoreBBs) {
1081 DenseSet<unsigned> ValuesToFind(Region.GVNStores.begin(),
1082 Region.GVNStores.end());
1083
1084 // We iterate over the instructions in the extracted function, and find the
1085 // global value number of the instructions. If we find a value that should
1086 // be contained in a store, we replace the uses of the value with the value
1087 // from the overall function, so that the store is storing the correct
1088 // value from the overall function.
1089 DenseSet<BasicBlock *> ExcludeBBs(OutputStoreBBs.begin(),
1090 OutputStoreBBs.end());
1091 ExcludeBBs.insert(OutputBB);
1092 std::vector<Instruction *> ExtractedFunctionInsts =
1093 collectRelevantInstructions(*(Region.ExtractedFunction), ExcludeBBs);
1094 std::vector<Instruction *> OverallFunctionInsts =
1095 collectRelevantInstructions(*OG.OutlinedFunction, ExcludeBBs);
1096
1097 assert(ExtractedFunctionInsts.size() == OverallFunctionInsts.size() &&((void)0)
1098 "Number of relevant instructions not equal!")((void)0);
1099
1100 unsigned NumInstructions = ExtractedFunctionInsts.size();
1101 for (unsigned Idx = 0; Idx < NumInstructions; Idx++) {
1102 Value *V = ExtractedFunctionInsts[Idx];
1103
1104 if (OutputMappings.find(V) != OutputMappings.end())
1105 V = OutputMappings.find(V)->second;
1106 Optional<unsigned> GVN = Region.Candidate->getGVN(V);
1107
1108 // If we have found one of the stored values for output, replace the value
1109 // with the corresponding one from the overall function.
1110 if (GVN.hasValue() && ValuesToFind.erase(GVN.getValue())) {
1111 V->replaceAllUsesWith(OverallFunctionInsts[Idx]);
1112 if (ValuesToFind.size() == 0)
1113 break;
1114 }
1115
1116 if (ValuesToFind.size() == 0)
1117 break;
1118 }
1119
1120 assert(ValuesToFind.size() == 0 && "Not all store values were handled!")((void)0);
1121
1122 // If the size of the block is 0, then there are no stores, and we do not
1123 // need to save this block.
1124 if (OutputBB->size() == 0) {
1125 Region.OutputBlockNum = -1;
1126 OutputBB->eraseFromParent();
1127 return;
1128 }
1129
1130 // Determine is there is a duplicate block.
1131 Optional<unsigned> MatchingBB =
1132 findDuplicateOutputBlock(OutputBB, OutputStoreBBs);
1133
1134 // If there is, we remove the new output block. If it does not,
1135 // we add it to our list of output blocks.
1136 if (MatchingBB.hasValue()) {
1137 LLVM_DEBUG(dbgs() << "Set output block for region in function"do { } while (false)
1138 << Region.ExtractedFunction << " to "do { } while (false)
1139 << MatchingBB.getValue())do { } while (false);
1140
1141 Region.OutputBlockNum = MatchingBB.getValue();
1142 OutputBB->eraseFromParent();
1143 return;
1144 }
1145
1146 Region.OutputBlockNum = OutputStoreBBs.size();
1147
1148 LLVM_DEBUG(dbgs() << "Create output block for region in"do { } while (false)
1149 << Region.ExtractedFunction << " to "do { } while (false)
1150 << *OutputBB)do { } while (false);
1151 OutputStoreBBs.push_back(OutputBB);
1152 BranchInst::Create(EndBB, OutputBB);
1153}
1154
1155/// Create the switch statement for outlined function to differentiate between
1156/// all the output blocks.
1157///
1158/// For the outlined section, determine if an outlined block already exists that
1159/// matches the needed stores for the extracted section.
1160/// \param [in] M - The module we are outlining from.
1161/// \param [in] OG - The group of regions to be outlined.
1162/// \param [in] EndBB - The final block of the extracted function.
1163/// \param [in,out] OutputStoreBBs - The existing output blocks.
1164void createSwitchStatement(Module &M, OutlinableGroup &OG, BasicBlock *EndBB,
1165 ArrayRef<BasicBlock *> OutputStoreBBs) {
1166 // We only need the switch statement if there is more than one store
1167 // combination.
1168 if (OG.OutputGVNCombinations.size() > 1) {
1169 Function *AggFunc = OG.OutlinedFunction;
1170 // Create a final block
1171 BasicBlock *ReturnBlock =
1172 BasicBlock::Create(M.getContext(), "final_block", AggFunc);
1173 Instruction *Term = EndBB->getTerminator();
1174 Term->moveBefore(*ReturnBlock, ReturnBlock->end());
1175 // Put the switch statement in the old end basic block for the function with
1176 // a fall through to the new return block
1177 LLVM_DEBUG(dbgs() << "Create switch statement in " << *AggFunc << " for "do { } while (false)
1178 << OutputStoreBBs.size() << "\n")do { } while (false);
1179 SwitchInst *SwitchI =
1180 SwitchInst::Create(AggFunc->getArg(AggFunc->arg_size() - 1),
1181 ReturnBlock, OutputStoreBBs.size(), EndBB);
1182
1183 unsigned Idx = 0;
1184 for (BasicBlock *BB : OutputStoreBBs) {
1185 SwitchI->addCase(ConstantInt::get(Type::getInt32Ty(M.getContext()), Idx),
1186 BB);
1187 Term = BB->getTerminator();
1188 Term->setSuccessor(0, ReturnBlock);
1189 Idx++;
1190 }
1191 return;
1192 }
1193
1194 // If there needs to be stores, move them from the output block to the end
1195 // block to save on branching instructions.
1196 if (OutputStoreBBs.size() == 1) {
1197 LLVM_DEBUG(dbgs() << "Move store instructions to the end block in "do { } while (false)
1198 << *OG.OutlinedFunction << "\n")do { } while (false);
1199 BasicBlock *OutputBlock = OutputStoreBBs[0];
1200 Instruction *Term = OutputBlock->getTerminator();
1201 Term->eraseFromParent();
1202 Term = EndBB->getTerminator();
1203 moveBBContents(*OutputBlock, *EndBB);
1204 Term->moveBefore(*EndBB, EndBB->end());
1205 OutputBlock->eraseFromParent();
1206 }
1207}
1208
1209/// Fill the new function that will serve as the replacement function for all of
1210/// the extracted regions of a certain structure from the first region in the
1211/// list of regions. Replace this first region's extracted function with the
1212/// new overall function.
1213///
1214/// \param [in] M - The module we are outlining from.
1215/// \param [in] CurrentGroup - The group of regions to be outlined.
1216/// \param [in,out] OutputStoreBBs - The output blocks for each different
1217/// set of stores needed for the different functions.
1218/// \param [in,out] FuncsToRemove - Extracted functions to erase from module
1219/// once outlining is complete.
1220static void fillOverallFunction(Module &M, OutlinableGroup &CurrentGroup,
1221 std::vector<BasicBlock *> &OutputStoreBBs,
1222 std::vector<Function *> &FuncsToRemove) {
1223 OutlinableRegion *CurrentOS = CurrentGroup.Regions[0];
1224
1225 // Move first extracted function's instructions into new function.
1226 LLVM_DEBUG(dbgs() << "Move instructions from "do { } while (false)
1227 << *CurrentOS->ExtractedFunction << " to instruction "do { } while (false)
1228 << *CurrentGroup.OutlinedFunction << "\n")do { } while (false);
1229
1230 CurrentGroup.EndBB = moveFunctionData(*CurrentOS->ExtractedFunction,
1231 *CurrentGroup.OutlinedFunction);
1232
1233 // Transfer the attributes from the function to the new function.
1234 for (Attribute A :
1235 CurrentOS->ExtractedFunction->getAttributes().getFnAttributes())
1236 CurrentGroup.OutlinedFunction->addFnAttr(A);
1237
1238 // Create an output block for the first extracted function.
1239 BasicBlock *NewBB = BasicBlock::Create(
1240 M.getContext(), Twine("output_block_") + Twine(static_cast<unsigned>(0)),
1241 CurrentGroup.OutlinedFunction);
1242 CurrentOS->OutputBlockNum = 0;
1243
1244 replaceArgumentUses(*CurrentOS, NewBB);
1245 replaceConstants(*CurrentOS);
1246
1247 // If the new basic block has no new stores, we can erase it from the module.
1248 // It it does, we create a branch instruction to the last basic block from the
1249 // new one.
1250 if (NewBB->size() == 0) {
1251 CurrentOS->OutputBlockNum = -1;
1252 NewBB->eraseFromParent();
1253 } else {
1254 BranchInst::Create(CurrentGroup.EndBB, NewBB);
1255 OutputStoreBBs.push_back(NewBB);
1256 }
1257
1258 // Replace the call to the extracted function with the outlined function.
1259 CurrentOS->Call = replaceCalledFunction(M, *CurrentOS);
1260
1261 // We only delete the extracted functions at the end since we may need to
1262 // reference instructions contained in them for mapping purposes.
1263 FuncsToRemove.push_back(CurrentOS->ExtractedFunction);
1264}
1265
1266void IROutliner::deduplicateExtractedSections(
1267 Module &M, OutlinableGroup &CurrentGroup,
1268 std::vector<Function *> &FuncsToRemove, unsigned &OutlinedFunctionNum) {
1269 createFunction(M, CurrentGroup, OutlinedFunctionNum);
1270
1271 std::vector<BasicBlock *> OutputStoreBBs;
1272
1273 OutlinableRegion *CurrentOS;
1274
1275 fillOverallFunction(M, CurrentGroup, OutputStoreBBs, FuncsToRemove);
1276
1277 for (unsigned Idx = 1; Idx < CurrentGroup.Regions.size(); Idx++) {
1278 CurrentOS = CurrentGroup.Regions[Idx];
1279 AttributeFuncs::mergeAttributesForOutlining(*CurrentGroup.OutlinedFunction,
1280 *CurrentOS->ExtractedFunction);
1281
1282 // Create a new BasicBlock to hold the needed store instructions.
1283 BasicBlock *NewBB = BasicBlock::Create(
1284 M.getContext(), "output_block_" + std::to_string(Idx),
1285 CurrentGroup.OutlinedFunction);
1286 replaceArgumentUses(*CurrentOS, NewBB);
1287
1288 alignOutputBlockWithAggFunc(CurrentGroup, *CurrentOS, NewBB,
1289 CurrentGroup.EndBB, OutputMappings,
1290 OutputStoreBBs);
1291
1292 CurrentOS->Call = replaceCalledFunction(M, *CurrentOS);
1293 FuncsToRemove.push_back(CurrentOS->ExtractedFunction);
1294 }
1295
1296 // Create a switch statement to handle the different output schemes.
1297 createSwitchStatement(M, CurrentGroup, CurrentGroup.EndBB, OutputStoreBBs);
1298
1299 OutlinedFunctionNum++;
1300}
1301
1302void IROutliner::pruneIncompatibleRegions(
1303 std::vector<IRSimilarityCandidate> &CandidateVec,
1304 OutlinableGroup &CurrentGroup) {
1305 bool PreviouslyOutlined;
1306
1307 // Sort from beginning to end, so the IRSimilarityCandidates are in order.
1308 stable_sort(CandidateVec, [](const IRSimilarityCandidate &LHS,
1309 const IRSimilarityCandidate &RHS) {
1310 return LHS.getStartIdx() < RHS.getStartIdx();
1311 });
1312
1313 unsigned CurrentEndIdx = 0;
1314 for (IRSimilarityCandidate &IRSC : CandidateVec) {
1315 PreviouslyOutlined = false;
1316 unsigned StartIdx = IRSC.getStartIdx();
1317 unsigned EndIdx = IRSC.getEndIdx();
1318
1319 for (unsigned Idx = StartIdx; Idx <= EndIdx; Idx++)
1320 if (Outlined.contains(Idx)) {
1321 PreviouslyOutlined = true;
1322 break;
1323 }
1324
1325 if (PreviouslyOutlined)
1326 continue;
1327
1328 // TODO: If in the future we can outline across BasicBlocks, we will need to
1329 // check all BasicBlocks contained in the region.
1330 if (IRSC.getStartBB()->hasAddressTaken())
1331 continue;
1332
1333 if (IRSC.front()->Inst->getFunction()->hasLinkOnceODRLinkage() &&
1334 !OutlineFromLinkODRs)
1335 continue;
1336
1337 // Greedily prune out any regions that will overlap with already chosen
1338 // regions.
1339 if (CurrentEndIdx != 0 && StartIdx <= CurrentEndIdx)
1340 continue;
1341
1342 bool BadInst = any_of(IRSC, [this](IRInstructionData &ID) {
1343 // We check if there is a discrepancy between the InstructionDataList
1344 // and the actual next instruction in the module. If there is, it means
1345 // that an extra instruction was added, likely by the CodeExtractor.
1346
1347 // Since we do not have any similarity data about this particular
1348 // instruction, we cannot confidently outline it, and must discard this
1349 // candidate.
1350 if (std::next(ID.getIterator())->Inst !=
1351 ID.Inst->getNextNonDebugInstruction())
1352 return true;
1353 return !this->InstructionClassifier.visit(ID.Inst);
1354 });
1355
1356 if (BadInst)
1357 continue;
1358
1359 OutlinableRegion *OS = new (RegionAllocator.Allocate())
1360 OutlinableRegion(IRSC, CurrentGroup);
1361 CurrentGroup.Regions.push_back(OS);
1362
1363 CurrentEndIdx = EndIdx;
1364 }
1365}
1366
1367InstructionCost
1368IROutliner::findBenefitFromAllRegions(OutlinableGroup &CurrentGroup) {
1369 InstructionCost RegionBenefit = 0;
1370 for (OutlinableRegion *Region : CurrentGroup.Regions) {
1371 TargetTransformInfo &TTI = getTTI(*Region->StartBB->getParent());
1372 // We add the number of instructions in the region to the benefit as an
1373 // estimate as to how much will be removed.
1374 RegionBenefit += Region->getBenefit(TTI);
1375 LLVM_DEBUG(dbgs() << "Adding: " << RegionBenefitdo { } while (false)
1376 << " saved instructions to overfall benefit.\n")do { } while (false);
1377 }
1378
1379 return RegionBenefit;
1380}
1381
1382InstructionCost
1383IROutliner::findCostOutputReloads(OutlinableGroup &CurrentGroup) {
1384 InstructionCost OverallCost = 0;
1385 for (OutlinableRegion *Region : CurrentGroup.Regions) {
1386 TargetTransformInfo &TTI = getTTI(*Region->StartBB->getParent());
1387
1388 // Each output incurs a load after the call, so we add that to the cost.
1389 for (unsigned OutputGVN : Region->GVNStores) {
1390 Optional<Value *> OV = Region->Candidate->fromGVN(OutputGVN);
1391 assert(OV.hasValue() && "Could not find value for GVN?")((void)0);
1392 Value *V = OV.getValue();
1393 InstructionCost LoadCost =
1394 TTI.getMemoryOpCost(Instruction::Load, V->getType(), Align(1), 0,
1395 TargetTransformInfo::TCK_CodeSize);
1396
1397 LLVM_DEBUG(dbgs() << "Adding: " << LoadCostdo { } while (false)
1398 << " instructions to cost for output of type "do { } while (false)
1399 << *V->getType() << "\n")do { } while (false);
1400 OverallCost += LoadCost;
1401 }
1402 }
1403
1404 return OverallCost;
1405}
1406
1407/// Find the extra instructions needed to handle any output values for the
1408/// region.
1409///
1410/// \param [in] M - The Module to outline from.
1411/// \param [in] CurrentGroup - The collection of OutlinableRegions to analyze.
1412/// \param [in] TTI - The TargetTransformInfo used to collect information for
1413/// new instruction costs.
1414/// \returns the additional cost to handle the outputs.
1415static InstructionCost findCostForOutputBlocks(Module &M,
1416 OutlinableGroup &CurrentGroup,
1417 TargetTransformInfo &TTI) {
1418 InstructionCost OutputCost = 0;
1419
1420 for (const ArrayRef<unsigned> &OutputUse :
1421 CurrentGroup.OutputGVNCombinations) {
1422 IRSimilarityCandidate &Candidate = *CurrentGroup.Regions[0]->Candidate;
1423 for (unsigned GVN : OutputUse) {
1424 Optional<Value *> OV = Candidate.fromGVN(GVN);
1425 assert(OV.hasValue() && "Could not find value for GVN?")((void)0);
1426 Value *V = OV.getValue();
1427 InstructionCost StoreCost =
1428 TTI.getMemoryOpCost(Instruction::Load, V->getType(), Align(1), 0,
1429 TargetTransformInfo::TCK_CodeSize);
1430
1431 // An instruction cost is added for each store set that needs to occur for
1432 // various output combinations inside the function, plus a branch to
1433 // return to the exit block.
1434 LLVM_DEBUG(dbgs() << "Adding: " << StoreCostdo { } while (false)
1435 << " instructions to cost for output of type "do { } while (false)
1436 << *V->getType() << "\n")do { } while (false);
1437 OutputCost += StoreCost;
1438 }
1439
1440 InstructionCost BranchCost =
1441 TTI.getCFInstrCost(Instruction::Br, TargetTransformInfo::TCK_CodeSize);
1442 LLVM_DEBUG(dbgs() << "Adding " << BranchCost << " to the current cost for"do { } while (false)
1443 << " a branch instruction\n")do { } while (false);
1444 OutputCost += BranchCost;
1445 }
1446
1447 // If there is more than one output scheme, we must have a comparison and
1448 // branch for each different item in the switch statement.
1449 if (CurrentGroup.OutputGVNCombinations.size() > 1) {
1450 InstructionCost ComparisonCost = TTI.getCmpSelInstrCost(
1451 Instruction::ICmp, Type::getInt32Ty(M.getContext()),
1452 Type::getInt32Ty(M.getContext()), CmpInst::BAD_ICMP_PREDICATE,
1453 TargetTransformInfo::TCK_CodeSize);
1454 InstructionCost BranchCost =
1455 TTI.getCFInstrCost(Instruction::Br, TargetTransformInfo::TCK_CodeSize);
1456
1457 unsigned DifferentBlocks = CurrentGroup.OutputGVNCombinations.size();
1458 InstructionCost TotalCost = ComparisonCost * BranchCost * DifferentBlocks;
1459
1460 LLVM_DEBUG(dbgs() << "Adding: " << TotalCostdo { } while (false)
1461 << " instructions for each switch case for each different"do { } while (false)
1462 << " output path in a function\n")do { } while (false);
1463 OutputCost += TotalCost;
1464 }
1465
1466 return OutputCost;
1467}
1468
1469void IROutliner::findCostBenefit(Module &M, OutlinableGroup &CurrentGroup) {
1470 InstructionCost RegionBenefit = findBenefitFromAllRegions(CurrentGroup);
1471 CurrentGroup.Benefit += RegionBenefit;
1472 LLVM_DEBUG(dbgs() << "Current Benefit: " << CurrentGroup.Benefit << "\n")do { } while (false);
1473
1474 InstructionCost OutputReloadCost = findCostOutputReloads(CurrentGroup);
1475 CurrentGroup.Cost += OutputReloadCost;
1476 LLVM_DEBUG(dbgs() << "Current Cost: " << CurrentGroup.Cost << "\n")do { } while (false);
1477
1478 InstructionCost AverageRegionBenefit =
1479 RegionBenefit / CurrentGroup.Regions.size();
1480 unsigned OverallArgumentNum = CurrentGroup.ArgumentTypes.size();
1481 unsigned NumRegions = CurrentGroup.Regions.size();
1482 TargetTransformInfo &TTI =
1483 getTTI(*CurrentGroup.Regions[0]->Candidate->getFunction());
1484
1485 // We add one region to the cost once, to account for the instructions added
1486 // inside of the newly created function.
1487 LLVM_DEBUG(dbgs() << "Adding: " << AverageRegionBenefitdo { } while (false)
1488 << " instructions to cost for body of new function.\n")do { } while (false);
1489 CurrentGroup.Cost += AverageRegionBenefit;
1490 LLVM_DEBUG(dbgs() << "Current Cost: " << CurrentGroup.Cost << "\n")do { } while (false);
1491
1492 // For each argument, we must add an instruction for loading the argument
1493 // out of the register and into a value inside of the newly outlined function.
1494 LLVM_DEBUG(dbgs() << "Adding: " << OverallArgumentNumdo { } while (false)
1495 << " instructions to cost for each argument in the new"do { } while (false)
1496 << " function.\n")do { } while (false);
1497 CurrentGroup.Cost +=
1498 OverallArgumentNum * TargetTransformInfo::TCC_Basic;
1499 LLVM_DEBUG(dbgs() << "Current Cost: " << CurrentGroup.Cost << "\n")do { } while (false);
1500
1501 // Each argument needs to either be loaded into a register or onto the stack.
1502 // Some arguments will only be loaded into the stack once the argument
1503 // registers are filled.
1504 LLVM_DEBUG(dbgs() << "Adding: " << OverallArgumentNumdo { } while (false)
1505 << " instructions to cost for each argument in the new"do { } while (false)
1506 << " function " << NumRegions << " times for the "do { } while (false)
1507 << "needed argument handling at the call site.\n")do { } while (false);
1508 CurrentGroup.Cost +=
1509 2 * OverallArgumentNum * TargetTransformInfo::TCC_Basic * NumRegions;
1510 LLVM_DEBUG(dbgs() << "Current Cost: " << CurrentGroup.Cost << "\n")do { } while (false);
1511
1512 CurrentGroup.Cost += findCostForOutputBlocks(M, CurrentGroup, TTI);
1513 LLVM_DEBUG(dbgs() << "Current Cost: " << CurrentGroup.Cost << "\n")do { } while (false);
1514}
1515
1516void IROutliner::updateOutputMapping(OutlinableRegion &Region,
1517 ArrayRef<Value *> Outputs,
1518 LoadInst *LI) {
1519 // For and load instructions following the call
1520 Value *Operand = LI->getPointerOperand();
1521 Optional<unsigned> OutputIdx = None;
1522 // Find if the operand it is an output register.
1523 for (unsigned ArgIdx = Region.NumExtractedInputs;
1524 ArgIdx < Region.Call->arg_size(); ArgIdx++) {
1525 if (Operand == Region.Call->getArgOperand(ArgIdx)) {
1526 OutputIdx = ArgIdx - Region.NumExtractedInputs;
1527 break;
1528 }
1529 }
1530
1531 // If we found an output register, place a mapping of the new value
1532 // to the original in the mapping.
1533 if (!OutputIdx.hasValue())
1534 return;
1535
1536 if (OutputMappings.find(Outputs[OutputIdx.getValue()]) ==
1537 OutputMappings.end()) {
1538 LLVM_DEBUG(dbgs() << "Mapping extracted output " << *LI << " to "do { } while (false)
1539 << *Outputs[OutputIdx.getValue()] << "\n")do { } while (false);
1540 OutputMappings.insert(std::make_pair(LI, Outputs[OutputIdx.getValue()]));
1541 } else {
1542 Value *Orig = OutputMappings.find(Outputs[OutputIdx.getValue()])->second;
1543 LLVM_DEBUG(dbgs() << "Mapping extracted output " << *Orig << " to "do { } while (false)
1544 << *Outputs[OutputIdx.getValue()] << "\n")do { } while (false);
1545 OutputMappings.insert(std::make_pair(LI, Orig));
1546 }
1547}
1548
1549bool IROutliner::extractSection(OutlinableRegion &Region) {
1550 SetVector<Value *> ArgInputs, Outputs, SinkCands;
1551 Region.CE->findInputsOutputs(ArgInputs, Outputs, SinkCands);
1552
1553 assert(Region.StartBB && "StartBB for the OutlinableRegion is nullptr!")((void)0);
1554 assert(Region.FollowBB && "FollowBB for the OutlinableRegion is nullptr!")((void)0);
1555 Function *OrigF = Region.StartBB->getParent();
1556 CodeExtractorAnalysisCache CEAC(*OrigF);
1557 Region.ExtractedFunction = Region.CE->extractCodeRegion(CEAC);
1558
1559 // If the extraction was successful, find the BasicBlock, and reassign the
1560 // OutlinableRegion blocks
1561 if (!Region.ExtractedFunction) {
1562 LLVM_DEBUG(dbgs() << "CodeExtractor failed to outline " << Region.StartBBdo { } while (false)
1563 << "\n")do { } while (false);
1564 Region.reattachCandidate();
1565 return false;
1566 }
1567
1568 BasicBlock *RewrittenBB = Region.FollowBB->getSinglePredecessor();
1569 Region.StartBB = RewrittenBB;
1570 Region.EndBB = RewrittenBB;
1571
1572 // The sequences of outlinable regions has now changed. We must fix the
1573 // IRInstructionDataList for consistency. Although they may not be illegal
1574 // instructions, they should not be compared with anything else as they
1575 // should not be outlined in this round. So marking these as illegal is
1576 // allowed.
1577 IRInstructionDataList *IDL = Region.Candidate->front()->IDL;
1578 Instruction *BeginRewritten = &*RewrittenBB->begin();
1579 Instruction *EndRewritten = &*RewrittenBB->begin();
1580 Region.NewFront = new (InstDataAllocator.Allocate()) IRInstructionData(
1581 *BeginRewritten, InstructionClassifier.visit(*BeginRewritten), *IDL);
1582 Region.NewBack = new (InstDataAllocator.Allocate()) IRInstructionData(
1583 *EndRewritten, InstructionClassifier.visit(*EndRewritten), *IDL);
1584
1585 // Insert the first IRInstructionData of the new region in front of the
1586 // first IRInstructionData of the IRSimilarityCandidate.
1587 IDL->insert(Region.Candidate->begin(), *Region.NewFront);
1588 // Insert the first IRInstructionData of the new region after the
1589 // last IRInstructionData of the IRSimilarityCandidate.
1590 IDL->insert(Region.Candidate->end(), *Region.NewBack);
1591 // Remove the IRInstructionData from the IRSimilarityCandidate.
1592 IDL->erase(Region.Candidate->begin(), std::prev(Region.Candidate->end()));
1593
1594 assert(RewrittenBB != nullptr &&((void)0)
1595 "Could not find a predecessor after extraction!")((void)0);
1596
1597 // Iterate over the new set of instructions to find the new call
1598 // instruction.
1599 for (Instruction &I : *RewrittenBB)
1600 if (CallInst *CI = dyn_cast<CallInst>(&I)) {
1601 if (Region.ExtractedFunction == CI->getCalledFunction())
1602 Region.Call = CI;
1603 } else if (LoadInst *LI = dyn_cast<LoadInst>(&I))
1604 updateOutputMapping(Region, Outputs.getArrayRef(), LI);
1605 Region.reattachCandidate();
1606 return true;
1607}
1608
1609unsigned IROutliner::doOutline(Module &M) {
1610 // Find the possible similarity sections.
1611 IRSimilarityIdentifier &Identifier = getIRSI(M);
1612 SimilarityGroupList &SimilarityCandidates = *Identifier.getSimilarity();
1613
1614 // Sort them by size of extracted sections
1615 unsigned OutlinedFunctionNum = 0;
1616 // If we only have one SimilarityGroup in SimilarityCandidates, we do not have
1617 // to sort them by the potential number of instructions to be outlined
1618 if (SimilarityCandidates.size() > 1)
1619 llvm::stable_sort(SimilarityCandidates,
1620 [](const std::vector<IRSimilarityCandidate> &LHS,
1621 const std::vector<IRSimilarityCandidate> &RHS) {
1622 return LHS[0].getLength() * LHS.size() >
1623 RHS[0].getLength() * RHS.size();
1624 });
1625
1626 DenseSet<unsigned> NotSame;
1627 std::vector<Function *> FuncsToRemove;
1628 // Iterate over the possible sets of similarity.
1629 for (SimilarityGroup &CandidateVec : SimilarityCandidates) {
1630 OutlinableGroup CurrentGroup;
1631
1632 // Remove entries that were previously outlined
1633 pruneIncompatibleRegions(CandidateVec, CurrentGroup);
1634
1635 // We pruned the number of regions to 0 to 1, meaning that it's not worth
1636 // trying to outlined since there is no compatible similar instance of this
1637 // code.
1638 if (CurrentGroup.Regions.size() < 2)
1639 continue;
1640
1641 // Determine if there are any values that are the same constant throughout
1642 // each section in the set.
1643 NotSame.clear();
1644 CurrentGroup.findSameConstants(NotSame);
1645
1646 if (CurrentGroup.IgnoreGroup)
1647 continue;
1648
1649 // Create a CodeExtractor for each outlinable region. Identify inputs and
1650 // outputs for each section using the code extractor and create the argument
1651 // types for the Aggregate Outlining Function.
1652 std::vector<OutlinableRegion *> OutlinedRegions;
1653 for (OutlinableRegion *OS : CurrentGroup.Regions) {
1654 // Break the outlinable region out of its parent BasicBlock into its own
1655 // BasicBlocks (see function implementation).
1656 OS->splitCandidate();
1657 std::vector<BasicBlock *> BE = {OS->StartBB};
1658 OS->CE = new (ExtractorAllocator.Allocate())
1659 CodeExtractor(BE, nullptr, false, nullptr, nullptr, nullptr, false,
1660 false, "outlined");
1661 findAddInputsOutputs(M, *OS, NotSame);
1662 if (!OS->IgnoreRegion)
1663 OutlinedRegions.push_back(OS);
1664 else
1665 OS->reattachCandidate();
1666 }
1667
1668 CurrentGroup.Regions = std::move(OutlinedRegions);
1669
1670 if (CurrentGroup.Regions.empty())
1671 continue;
1672
1673 CurrentGroup.collectGVNStoreSets(M);
1674
1675 if (CostModel)
1676 findCostBenefit(M, CurrentGroup);
1677
1678 // If we are adhering to the cost model, reattach all the candidates
1679 if (CurrentGroup.Cost >= CurrentGroup.Benefit && CostModel) {
1680 for (OutlinableRegion *OS : CurrentGroup.Regions)
1681 OS->reattachCandidate();
1682 OptimizationRemarkEmitter &ORE = getORE(
1683 *CurrentGroup.Regions[0]->Candidate->getFunction());
1684 ORE.emit([&]() {
1685 IRSimilarityCandidate *C = CurrentGroup.Regions[0]->Candidate;
1686 OptimizationRemarkMissed R(DEBUG_TYPE"iroutliner", "WouldNotDecreaseSize",
1687 C->frontInstruction());
1688 R << "did not outline "
1689 << ore::NV(std::to_string(CurrentGroup.Regions.size()))
1690 << " regions due to estimated increase of "
1691 << ore::NV("InstructionIncrease",
1692 CurrentGroup.Cost - CurrentGroup.Benefit)
1693 << " instructions at locations ";
1694 interleave(
1695 CurrentGroup.Regions.begin(), CurrentGroup.Regions.end(),
1696 [&R](OutlinableRegion *Region) {
1697 R << ore::NV(
1698 "DebugLoc",
1699 Region->Candidate->frontInstruction()->getDebugLoc());
1700 },
1701 [&R]() { R << " "; });
1702 return R;
1703 });
1704 continue;
1705 }
1706
1707 LLVM_DEBUG(dbgs() << "Outlining regions with cost " << CurrentGroup.Costdo { } while (false)
1708 << " and benefit " << CurrentGroup.Benefit << "\n")do { } while (false);
1709
1710 // Create functions out of all the sections, and mark them as outlined.
1711 OutlinedRegions.clear();
1712 for (OutlinableRegion *OS : CurrentGroup.Regions) {
1713 bool FunctionOutlined = extractSection(*OS);
1714 if (FunctionOutlined) {
1715 unsigned StartIdx = OS->Candidate->getStartIdx();
1716 unsigned EndIdx = OS->Candidate->getEndIdx();
1717 for (unsigned Idx = StartIdx; Idx <= EndIdx; Idx++)
1718 Outlined.insert(Idx);
1719
1720 OutlinedRegions.push_back(OS);
1721 }
1722 }
1723
1724 LLVM_DEBUG(dbgs() << "Outlined " << OutlinedRegions.size()do { } while (false)
1725 << " with benefit " << CurrentGroup.Benefitdo { } while (false)
1726 << " and cost " << CurrentGroup.Cost << "\n")do { } while (false);
1727
1728 CurrentGroup.Regions = std::move(OutlinedRegions);
1729
1730 if (CurrentGroup.Regions.empty())
1731 continue;
1732
1733 OptimizationRemarkEmitter &ORE =
1734 getORE(*CurrentGroup.Regions[0]->Call->getFunction());
1735 ORE.emit([&]() {
1736 IRSimilarityCandidate *C = CurrentGroup.Regions[0]->Candidate;
1737 OptimizationRemark R(DEBUG_TYPE"iroutliner", "Outlined", C->front()->Inst);
1738 R << "outlined " << ore::NV(std::to_string(CurrentGroup.Regions.size()))
1739 << " regions with decrease of "
1740 << ore::NV("Benefit", CurrentGroup.Benefit - CurrentGroup.Cost)
1741 << " instructions at locations ";
1742 interleave(
1743 CurrentGroup.Regions.begin(), CurrentGroup.Regions.end(),
1744 [&R](OutlinableRegion *Region) {
1745 R << ore::NV("DebugLoc",
1746 Region->Candidate->frontInstruction()->getDebugLoc());
1747 },
1748 [&R]() { R << " "; });
1749 return R;
1750 });
1751
1752 deduplicateExtractedSections(M, CurrentGroup, FuncsToRemove,
1753 OutlinedFunctionNum);
1754 }
1755
1756 for (Function *F : FuncsToRemove)
1757 F->eraseFromParent();
1758
1759 return OutlinedFunctionNum;
1760}
1761
1762bool IROutliner::run(Module &M) {
1763 CostModel = !NoCostModel;
1764 OutlineFromLinkODRs = EnableLinkOnceODRIROutlining;
1765
1766 return doOutline(M) > 0;
1767}
1768
1769// Pass Manager Boilerplate
1770class IROutlinerLegacyPass : public ModulePass {
1771public:
1772 static char ID;
1773 IROutlinerLegacyPass() : ModulePass(ID) {
1774 initializeIROutlinerLegacyPassPass(*PassRegistry::getPassRegistry());
1775 }
1776
1777 void getAnalysisUsage(AnalysisUsage &AU) const override {
1778 AU.addRequired<OptimizationRemarkEmitterWrapperPass>();
1779 AU.addRequired<TargetTransformInfoWrapperPass>();
1780 AU.addRequired<IRSimilarityIdentifierWrapperPass>();
1781 }
1782
1783 bool runOnModule(Module &M) override;
1784};
1785
1786bool IROutlinerLegacyPass::runOnModule(Module &M) {
1787 if (skipModule(M))
1788 return false;
1789
1790 std::unique_ptr<OptimizationRemarkEmitter> ORE;
1791 auto GORE = [&ORE](Function &F) -> OptimizationRemarkEmitter & {
1792 ORE.reset(new OptimizationRemarkEmitter(&F));
1793 return *ORE.get();
1794 };
1795
1796 auto GTTI = [this](Function &F) -> TargetTransformInfo & {
1797 return this->getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
1798 };
1799
1800 auto GIRSI = [this](Module &) -> IRSimilarityIdentifier & {
1801 return this->getAnalysis<IRSimilarityIdentifierWrapperPass>().getIRSI();
1802 };
1803
1804 return IROutliner(GTTI, GIRSI, GORE).run(M);
1805}
1806
1807PreservedAnalyses IROutlinerPass::run(Module &M, ModuleAnalysisManager &AM) {
1808 auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
1809
1810 std::function<TargetTransformInfo &(Function &)> GTTI =
1811 [&FAM](Function &F) -> TargetTransformInfo & {
1812 return FAM.getResult<TargetIRAnalysis>(F);
1813 };
1814
1815 std::function<IRSimilarityIdentifier &(Module &)> GIRSI =
1816 [&AM](Module &M) -> IRSimilarityIdentifier & {
1817 return AM.getResult<IRSimilarityAnalysis>(M);
1818 };
1819
1820 std::unique_ptr<OptimizationRemarkEmitter> ORE;
1821 std::function<OptimizationRemarkEmitter &(Function &)> GORE =
1822 [&ORE](Function &F) -> OptimizationRemarkEmitter & {
1823 ORE.reset(new OptimizationRemarkEmitter(&F));
1824 return *ORE.get();
1825 };
1826
1827 if (IROutliner(GTTI, GIRSI, GORE).run(M))
1828 return PreservedAnalyses::none();
1829 return PreservedAnalyses::all();
1830}
1831
1832char IROutlinerLegacyPass::ID = 0;
1833INITIALIZE_PASS_BEGIN(IROutlinerLegacyPass, "iroutliner", "IR Outliner", false,static void *initializeIROutlinerLegacyPassPassOnce(PassRegistry
&Registry) {
1834 false)static void *initializeIROutlinerLegacyPassPassOnce(PassRegistry
&Registry) {
1835INITIALIZE_PASS_DEPENDENCY(IRSimilarityIdentifierWrapperPass)initializeIRSimilarityIdentifierWrapperPassPass(Registry);
1836INITIALIZE_PASS_DEPENDENCY(OptimizationRemarkEmitterWrapperPass)initializeOptimizationRemarkEmitterWrapperPassPass(Registry);
1837INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)initializeTargetTransformInfoWrapperPassPass(Registry);
1838INITIALIZE_PASS_END(IROutlinerLegacyPass, "iroutliner", "IR Outliner", false,PassInfo *PI = new PassInfo( "IR Outliner", "iroutliner", &
IROutlinerLegacyPass::ID, PassInfo::NormalCtor_t(callDefaultCtor
<IROutlinerLegacyPass>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeIROutlinerLegacyPassPassFlag
; void llvm::initializeIROutlinerLegacyPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeIROutlinerLegacyPassPassFlag
, initializeIROutlinerLegacyPassPassOnce, std::ref(Registry))
; }
1839 false)PassInfo *PI = new PassInfo( "IR Outliner", "iroutliner", &
IROutlinerLegacyPass::ID, PassInfo::NormalCtor_t(callDefaultCtor
<IROutlinerLegacyPass>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeIROutlinerLegacyPassPassFlag
; void llvm::initializeIROutlinerLegacyPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeIROutlinerLegacyPassPassFlag
, initializeIROutlinerLegacyPassPassOnce, std::ref(Registry))
; }
1840
1841ModulePass *llvm::createIROutlinerPass() { return new IROutlinerLegacyPass(); }