Bug Summary

File:llvm/lib/Transforms/Scalar/Reassociate.cpp
Warning:line 172, column 8
Dereference of null pointer (loaded from variable '__begin1')

Annotated Source Code

Press '?' to see keyboard shortcuts

clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name Reassociate.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 -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/build-llvm -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I lib/Transforms/Scalar -I /build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar -I include -I /build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/include -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-command-line-argument -Wno-unknown-warning-option -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/build-llvm -ferror-limit 19 -fvisibility-inlines-hidden -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-10-17-004846-21170-1 -x c++ /build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp
1//===- Reassociate.cpp - Reassociate binary expressions -------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This pass reassociates commutative expressions in an order that is designed
10// to promote better constant propagation, GCSE, LICM, PRE, etc.
11//
12// For example: 4 + (x + 5) -> x + (4 + 5)
13//
14// In the implementation of this algorithm, constants are assigned rank = 0,
15// function arguments are rank = 1, and other values are assigned ranks
16// corresponding to the reverse post order traversal of current function
17// (starting at 2), which effectively gives values in deep loops higher rank
18// than values not in loops.
19//
20//===----------------------------------------------------------------------===//
21
22#include "llvm/Transforms/Scalar/Reassociate.h"
23#include "llvm/ADT/APFloat.h"
24#include "llvm/ADT/APInt.h"
25#include "llvm/ADT/DenseMap.h"
26#include "llvm/ADT/PostOrderIterator.h"
27#include "llvm/ADT/SetVector.h"
28#include "llvm/ADT/SmallPtrSet.h"
29#include "llvm/ADT/SmallSet.h"
30#include "llvm/ADT/SmallVector.h"
31#include "llvm/ADT/Statistic.h"
32#include "llvm/Analysis/BasicAliasAnalysis.h"
33#include "llvm/Analysis/GlobalsModRef.h"
34#include "llvm/Analysis/ValueTracking.h"
35#include "llvm/IR/Argument.h"
36#include "llvm/IR/BasicBlock.h"
37#include "llvm/IR/CFG.h"
38#include "llvm/IR/Constant.h"
39#include "llvm/IR/Constants.h"
40#include "llvm/IR/Function.h"
41#include "llvm/IR/IRBuilder.h"
42#include "llvm/IR/InstrTypes.h"
43#include "llvm/IR/Instruction.h"
44#include "llvm/IR/Instructions.h"
45#include "llvm/IR/IntrinsicInst.h"
46#include "llvm/IR/Operator.h"
47#include "llvm/IR/PassManager.h"
48#include "llvm/IR/PatternMatch.h"
49#include "llvm/IR/Type.h"
50#include "llvm/IR/User.h"
51#include "llvm/IR/Value.h"
52#include "llvm/IR/ValueHandle.h"
53#include "llvm/InitializePasses.h"
54#include "llvm/Pass.h"
55#include "llvm/Support/Casting.h"
56#include "llvm/Support/Debug.h"
57#include "llvm/Support/ErrorHandling.h"
58#include "llvm/Support/raw_ostream.h"
59#include "llvm/Transforms/Scalar.h"
60#include "llvm/Transforms/Utils/Local.h"
61#include <algorithm>
62#include <cassert>
63#include <utility>
64
65using namespace llvm;
66using namespace reassociate;
67using namespace PatternMatch;
68
69#define DEBUG_TYPE"reassociate" "reassociate"
70
71STATISTIC(NumChanged, "Number of insts reassociated")static llvm::Statistic NumChanged = {"reassociate", "NumChanged"
, "Number of insts reassociated"}
;
72STATISTIC(NumAnnihil, "Number of expr tree annihilated")static llvm::Statistic NumAnnihil = {"reassociate", "NumAnnihil"
, "Number of expr tree annihilated"}
;
73STATISTIC(NumFactor , "Number of multiplies factored")static llvm::Statistic NumFactor = {"reassociate", "NumFactor"
, "Number of multiplies factored"}
;
74
75#ifndef NDEBUG
76/// Print out the expression identified in the Ops list.
77static void PrintOps(Instruction *I, const SmallVectorImpl<ValueEntry> &Ops) {
78 Module *M = I->getModule();
79 dbgs() << Instruction::getOpcodeName(I->getOpcode()) << " "
80 << *Ops[0].Op->getType() << '\t';
81 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
82 dbgs() << "[ ";
83 Ops[i].Op->printAsOperand(dbgs(), false, M);
84 dbgs() << ", #" << Ops[i].Rank << "] ";
85 }
86}
87#endif
88
89/// Utility class representing a non-constant Xor-operand. We classify
90/// non-constant Xor-Operands into two categories:
91/// C1) The operand is in the form "X & C", where C is a constant and C != ~0
92/// C2)
93/// C2.1) The operand is in the form of "X | C", where C is a non-zero
94/// constant.
95/// C2.2) Any operand E which doesn't fall into C1 and C2.1, we view this
96/// operand as "E | 0"
97class llvm::reassociate::XorOpnd {
98public:
99 XorOpnd(Value *V);
100
101 bool isInvalid() const { return SymbolicPart == nullptr; }
102 bool isOrExpr() const { return isOr; }
103 Value *getValue() const { return OrigVal; }
104 Value *getSymbolicPart() const { return SymbolicPart; }
105 unsigned getSymbolicRank() const { return SymbolicRank; }
106 const APInt &getConstPart() const { return ConstPart; }
107
108 void Invalidate() { SymbolicPart = OrigVal = nullptr; }
109 void setSymbolicRank(unsigned R) { SymbolicRank = R; }
110
111private:
112 Value *OrigVal;
113 Value *SymbolicPart;
114 APInt ConstPart;
115 unsigned SymbolicRank;
116 bool isOr;
117};
118
119XorOpnd::XorOpnd(Value *V) {
120 assert(!isa<ConstantInt>(V) && "No ConstantInt")(static_cast <bool> (!isa<ConstantInt>(V) &&
"No ConstantInt") ? void (0) : __assert_fail ("!isa<ConstantInt>(V) && \"No ConstantInt\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 120, __extension__ __PRETTY_FUNCTION__))
;
121 OrigVal = V;
122 Instruction *I = dyn_cast<Instruction>(V);
123 SymbolicRank = 0;
124
125 if (I && (I->getOpcode() == Instruction::Or ||
126 I->getOpcode() == Instruction::And)) {
127 Value *V0 = I->getOperand(0);
128 Value *V1 = I->getOperand(1);
129 const APInt *C;
130 if (match(V0, m_APInt(C)))
131 std::swap(V0, V1);
132
133 if (match(V1, m_APInt(C))) {
134 ConstPart = *C;
135 SymbolicPart = V0;
136 isOr = (I->getOpcode() == Instruction::Or);
137 return;
138 }
139 }
140
141 // view the operand as "V | 0"
142 SymbolicPart = V;
143 ConstPart = APInt::getZero(V->getType()->getScalarSizeInBits());
144 isOr = true;
145}
146
147/// Return true if V is an instruction of the specified opcode and if it
148/// only has one use.
149static BinaryOperator *isReassociableOp(Value *V, unsigned Opcode) {
150 auto *I = dyn_cast<Instruction>(V);
151 if (I && I->hasOneUse() && I->getOpcode() == Opcode)
152 if (!isa<FPMathOperator>(I) || I->isFast())
153 return cast<BinaryOperator>(I);
154 return nullptr;
155}
156
157static BinaryOperator *isReassociableOp(Value *V, unsigned Opcode1,
158 unsigned Opcode2) {
159 auto *I = dyn_cast<Instruction>(V);
160 if (I && I->hasOneUse() &&
161 (I->getOpcode() == Opcode1 || I->getOpcode() == Opcode2))
162 if (!isa<FPMathOperator>(I) || I->isFast())
163 return cast<BinaryOperator>(I);
164 return nullptr;
165}
166
167void ReassociatePass::BuildRankMap(Function &F,
168 ReversePostOrderTraversal<Function*> &RPOT) {
169 unsigned Rank = 2;
170
171 // Assign distinct ranks to function arguments.
172 for (auto &Arg :
8.1
'__begin1' is not equal to '__end1'
F.args()) {
5
Assuming '__begin1' is not equal to '__end1'
8
Null pointer value stored to '__begin1'
9
Dereference of null pointer (loaded from variable '__begin1')
173 ValueRankMap[&Arg] = ++Rank;
174 LLVM_DEBUG(dbgs() << "Calculated Rank[" << Arg.getName() << "] = " << Rankdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "Calculated Rank[" <<
Arg.getName() << "] = " << Rank << "\n"; }
} while (false)
6
Assuming 'DebugFlag' is false
7
Loop condition is false. Exiting loop
175 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "Calculated Rank[" <<
Arg.getName() << "] = " << Rank << "\n"; }
} while (false)
;
176 }
177
178 // Traverse basic blocks in ReversePostOrder.
179 for (BasicBlock *BB : RPOT) {
180 unsigned BBRank = RankMap[BB] = ++Rank << 16;
181
182 // Walk the basic block, adding precomputed ranks for any instructions that
183 // we cannot move. This ensures that the ranks for these instructions are
184 // all different in the block.
185 for (Instruction &I : *BB)
186 if (mayBeMemoryDependent(I))
187 ValueRankMap[&I] = ++BBRank;
188 }
189}
190
191unsigned ReassociatePass::getRank(Value *V) {
192 Instruction *I = dyn_cast<Instruction>(V);
193 if (!I) {
194 if (isa<Argument>(V)) return ValueRankMap[V]; // Function argument.
195 return 0; // Otherwise it's a global or constant, rank 0.
196 }
197
198 if (unsigned Rank = ValueRankMap[I])
199 return Rank; // Rank already known?
200
201 // If this is an expression, return the 1+MAX(rank(LHS), rank(RHS)) so that
202 // we can reassociate expressions for code motion! Since we do not recurse
203 // for PHI nodes, we cannot have infinite recursion here, because there
204 // cannot be loops in the value graph that do not go through PHI nodes.
205 unsigned Rank = 0, MaxRank = RankMap[I->getParent()];
206 for (unsigned i = 0, e = I->getNumOperands(); i != e && Rank != MaxRank; ++i)
207 Rank = std::max(Rank, getRank(I->getOperand(i)));
208
209 // If this is a 'not' or 'neg' instruction, do not count it for rank. This
210 // assures us that X and ~X will have the same rank.
211 if (!match(I, m_Not(m_Value())) && !match(I, m_Neg(m_Value())) &&
212 !match(I, m_FNeg(m_Value())))
213 ++Rank;
214
215 LLVM_DEBUG(dbgs() << "Calculated Rank[" << V->getName() << "] = " << Rankdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "Calculated Rank[" <<
V->getName() << "] = " << Rank << "\n";
} } while (false)
216 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "Calculated Rank[" <<
V->getName() << "] = " << Rank << "\n";
} } while (false)
;
217
218 return ValueRankMap[I] = Rank;
219}
220
221// Canonicalize constants to RHS. Otherwise, sort the operands by rank.
222void ReassociatePass::canonicalizeOperands(Instruction *I) {
223 assert(isa<BinaryOperator>(I) && "Expected binary operator.")(static_cast <bool> (isa<BinaryOperator>(I) &&
"Expected binary operator.") ? void (0) : __assert_fail ("isa<BinaryOperator>(I) && \"Expected binary operator.\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 223, __extension__ __PRETTY_FUNCTION__))
;
224 assert(I->isCommutative() && "Expected commutative operator.")(static_cast <bool> (I->isCommutative() && "Expected commutative operator."
) ? void (0) : __assert_fail ("I->isCommutative() && \"Expected commutative operator.\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 224, __extension__ __PRETTY_FUNCTION__))
;
225
226 Value *LHS = I->getOperand(0);
227 Value *RHS = I->getOperand(1);
228 if (LHS == RHS || isa<Constant>(RHS))
229 return;
230 if (isa<Constant>(LHS) || getRank(RHS) < getRank(LHS))
231 cast<BinaryOperator>(I)->swapOperands();
232}
233
234static BinaryOperator *CreateAdd(Value *S1, Value *S2, const Twine &Name,
235 Instruction *InsertBefore, Value *FlagsOp) {
236 if (S1->getType()->isIntOrIntVectorTy())
237 return BinaryOperator::CreateAdd(S1, S2, Name, InsertBefore);
238 else {
239 BinaryOperator *Res =
240 BinaryOperator::CreateFAdd(S1, S2, Name, InsertBefore);
241 Res->setFastMathFlags(cast<FPMathOperator>(FlagsOp)->getFastMathFlags());
242 return Res;
243 }
244}
245
246static BinaryOperator *CreateMul(Value *S1, Value *S2, const Twine &Name,
247 Instruction *InsertBefore, Value *FlagsOp) {
248 if (S1->getType()->isIntOrIntVectorTy())
249 return BinaryOperator::CreateMul(S1, S2, Name, InsertBefore);
250 else {
251 BinaryOperator *Res =
252 BinaryOperator::CreateFMul(S1, S2, Name, InsertBefore);
253 Res->setFastMathFlags(cast<FPMathOperator>(FlagsOp)->getFastMathFlags());
254 return Res;
255 }
256}
257
258static Instruction *CreateNeg(Value *S1, const Twine &Name,
259 Instruction *InsertBefore, Value *FlagsOp) {
260 if (S1->getType()->isIntOrIntVectorTy())
261 return BinaryOperator::CreateNeg(S1, Name, InsertBefore);
262
263 if (auto *FMFSource = dyn_cast<Instruction>(FlagsOp))
264 return UnaryOperator::CreateFNegFMF(S1, FMFSource, Name, InsertBefore);
265
266 return UnaryOperator::CreateFNeg(S1, Name, InsertBefore);
267}
268
269/// Replace 0-X with X*-1.
270static BinaryOperator *LowerNegateToMultiply(Instruction *Neg) {
271 assert((isa<UnaryOperator>(Neg) || isa<BinaryOperator>(Neg)) &&(static_cast <bool> ((isa<UnaryOperator>(Neg) || isa
<BinaryOperator>(Neg)) && "Expected a Negate!")
? void (0) : __assert_fail ("(isa<UnaryOperator>(Neg) || isa<BinaryOperator>(Neg)) && \"Expected a Negate!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 272, __extension__ __PRETTY_FUNCTION__))
272 "Expected a Negate!")(static_cast <bool> ((isa<UnaryOperator>(Neg) || isa
<BinaryOperator>(Neg)) && "Expected a Negate!")
? void (0) : __assert_fail ("(isa<UnaryOperator>(Neg) || isa<BinaryOperator>(Neg)) && \"Expected a Negate!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 272, __extension__ __PRETTY_FUNCTION__))
;
273 // FIXME: It's not safe to lower a unary FNeg into a FMul by -1.0.
274 unsigned OpNo = isa<BinaryOperator>(Neg) ? 1 : 0;
275 Type *Ty = Neg->getType();
276 Constant *NegOne = Ty->isIntOrIntVectorTy() ?
277 ConstantInt::getAllOnesValue(Ty) : ConstantFP::get(Ty, -1.0);
278
279 BinaryOperator *Res = CreateMul(Neg->getOperand(OpNo), NegOne, "", Neg, Neg);
280 Neg->setOperand(OpNo, Constant::getNullValue(Ty)); // Drop use of op.
281 Res->takeName(Neg);
282 Neg->replaceAllUsesWith(Res);
283 Res->setDebugLoc(Neg->getDebugLoc());
284 return Res;
285}
286
287/// Returns k such that lambda(2^Bitwidth) = 2^k, where lambda is the Carmichael
288/// function. This means that x^(2^k) === 1 mod 2^Bitwidth for
289/// every odd x, i.e. x^(2^k) = 1 for every odd x in Bitwidth-bit arithmetic.
290/// Note that 0 <= k < Bitwidth, and if Bitwidth > 3 then x^(2^k) = 0 for every
291/// even x in Bitwidth-bit arithmetic.
292static unsigned CarmichaelShift(unsigned Bitwidth) {
293 if (Bitwidth < 3)
294 return Bitwidth - 1;
295 return Bitwidth - 2;
296}
297
298/// Add the extra weight 'RHS' to the existing weight 'LHS',
299/// reducing the combined weight using any special properties of the operation.
300/// The existing weight LHS represents the computation X op X op ... op X where
301/// X occurs LHS times. The combined weight represents X op X op ... op X with
302/// X occurring LHS + RHS times. If op is "Xor" for example then the combined
303/// operation is equivalent to X if LHS + RHS is odd, or 0 if LHS + RHS is even;
304/// the routine returns 1 in LHS in the first case, and 0 in LHS in the second.
305static void IncorporateWeight(APInt &LHS, const APInt &RHS, unsigned Opcode) {
306 // If we were working with infinite precision arithmetic then the combined
307 // weight would be LHS + RHS. But we are using finite precision arithmetic,
308 // and the APInt sum LHS + RHS may not be correct if it wraps (it is correct
309 // for nilpotent operations and addition, but not for idempotent operations
310 // and multiplication), so it is important to correctly reduce the combined
311 // weight back into range if wrapping would be wrong.
312
313 // If RHS is zero then the weight didn't change.
314 if (RHS.isMinValue())
315 return;
316 // If LHS is zero then the combined weight is RHS.
317 if (LHS.isMinValue()) {
318 LHS = RHS;
319 return;
320 }
321 // From this point on we know that neither LHS nor RHS is zero.
322
323 if (Instruction::isIdempotent(Opcode)) {
324 // Idempotent means X op X === X, so any non-zero weight is equivalent to a
325 // weight of 1. Keeping weights at zero or one also means that wrapping is
326 // not a problem.
327 assert(LHS == 1 && RHS == 1 && "Weights not reduced!")(static_cast <bool> (LHS == 1 && RHS == 1 &&
"Weights not reduced!") ? void (0) : __assert_fail ("LHS == 1 && RHS == 1 && \"Weights not reduced!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 327, __extension__ __PRETTY_FUNCTION__))
;
328 return; // Return a weight of 1.
329 }
330 if (Instruction::isNilpotent(Opcode)) {
331 // Nilpotent means X op X === 0, so reduce weights modulo 2.
332 assert(LHS == 1 && RHS == 1 && "Weights not reduced!")(static_cast <bool> (LHS == 1 && RHS == 1 &&
"Weights not reduced!") ? void (0) : __assert_fail ("LHS == 1 && RHS == 1 && \"Weights not reduced!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 332, __extension__ __PRETTY_FUNCTION__))
;
333 LHS = 0; // 1 + 1 === 0 modulo 2.
334 return;
335 }
336 if (Opcode == Instruction::Add || Opcode == Instruction::FAdd) {
337 // TODO: Reduce the weight by exploiting nsw/nuw?
338 LHS += RHS;
339 return;
340 }
341
342 assert((Opcode == Instruction::Mul || Opcode == Instruction::FMul) &&(static_cast <bool> ((Opcode == Instruction::Mul || Opcode
== Instruction::FMul) && "Unknown associative operation!"
) ? void (0) : __assert_fail ("(Opcode == Instruction::Mul || Opcode == Instruction::FMul) && \"Unknown associative operation!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 343, __extension__ __PRETTY_FUNCTION__))
343 "Unknown associative operation!")(static_cast <bool> ((Opcode == Instruction::Mul || Opcode
== Instruction::FMul) && "Unknown associative operation!"
) ? void (0) : __assert_fail ("(Opcode == Instruction::Mul || Opcode == Instruction::FMul) && \"Unknown associative operation!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 343, __extension__ __PRETTY_FUNCTION__))
;
344 unsigned Bitwidth = LHS.getBitWidth();
345 // If CM is the Carmichael number then a weight W satisfying W >= CM+Bitwidth
346 // can be replaced with W-CM. That's because x^W=x^(W-CM) for every Bitwidth
347 // bit number x, since either x is odd in which case x^CM = 1, or x is even in
348 // which case both x^W and x^(W - CM) are zero. By subtracting off multiples
349 // of CM like this weights can always be reduced to the range [0, CM+Bitwidth)
350 // which by a happy accident means that they can always be represented using
351 // Bitwidth bits.
352 // TODO: Reduce the weight by exploiting nsw/nuw? (Could do much better than
353 // the Carmichael number).
354 if (Bitwidth > 3) {
355 /// CM - The value of Carmichael's lambda function.
356 APInt CM = APInt::getOneBitSet(Bitwidth, CarmichaelShift(Bitwidth));
357 // Any weight W >= Threshold can be replaced with W - CM.
358 APInt Threshold = CM + Bitwidth;
359 assert(LHS.ult(Threshold) && RHS.ult(Threshold) && "Weights not reduced!")(static_cast <bool> (LHS.ult(Threshold) && RHS.
ult(Threshold) && "Weights not reduced!") ? void (0) :
__assert_fail ("LHS.ult(Threshold) && RHS.ult(Threshold) && \"Weights not reduced!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 359, __extension__ __PRETTY_FUNCTION__))
;
360 // For Bitwidth 4 or more the following sum does not overflow.
361 LHS += RHS;
362 while (LHS.uge(Threshold))
363 LHS -= CM;
364 } else {
365 // To avoid problems with overflow do everything the same as above but using
366 // a larger type.
367 unsigned CM = 1U << CarmichaelShift(Bitwidth);
368 unsigned Threshold = CM + Bitwidth;
369 assert(LHS.getZExtValue() < Threshold && RHS.getZExtValue() < Threshold &&(static_cast <bool> (LHS.getZExtValue() < Threshold &&
RHS.getZExtValue() < Threshold && "Weights not reduced!"
) ? void (0) : __assert_fail ("LHS.getZExtValue() < Threshold && RHS.getZExtValue() < Threshold && \"Weights not reduced!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 370, __extension__ __PRETTY_FUNCTION__))
370 "Weights not reduced!")(static_cast <bool> (LHS.getZExtValue() < Threshold &&
RHS.getZExtValue() < Threshold && "Weights not reduced!"
) ? void (0) : __assert_fail ("LHS.getZExtValue() < Threshold && RHS.getZExtValue() < Threshold && \"Weights not reduced!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 370, __extension__ __PRETTY_FUNCTION__))
;
371 unsigned Total = LHS.getZExtValue() + RHS.getZExtValue();
372 while (Total >= Threshold)
373 Total -= CM;
374 LHS = Total;
375 }
376}
377
378using RepeatedValue = std::pair<Value*, APInt>;
379
380/// Given an associative binary expression, return the leaf
381/// nodes in Ops along with their weights (how many times the leaf occurs). The
382/// original expression is the same as
383/// (Ops[0].first op Ops[0].first op ... Ops[0].first) <- Ops[0].second times
384/// op
385/// (Ops[1].first op Ops[1].first op ... Ops[1].first) <- Ops[1].second times
386/// op
387/// ...
388/// op
389/// (Ops[N].first op Ops[N].first op ... Ops[N].first) <- Ops[N].second times
390///
391/// Note that the values Ops[0].first, ..., Ops[N].first are all distinct.
392///
393/// This routine may modify the function, in which case it returns 'true'. The
394/// changes it makes may well be destructive, changing the value computed by 'I'
395/// to something completely different. Thus if the routine returns 'true' then
396/// you MUST either replace I with a new expression computed from the Ops array,
397/// or use RewriteExprTree to put the values back in.
398///
399/// A leaf node is either not a binary operation of the same kind as the root
400/// node 'I' (i.e. is not a binary operator at all, or is, but with a different
401/// opcode), or is the same kind of binary operator but has a use which either
402/// does not belong to the expression, or does belong to the expression but is
403/// a leaf node. Every leaf node has at least one use that is a non-leaf node
404/// of the expression, while for non-leaf nodes (except for the root 'I') every
405/// use is a non-leaf node of the expression.
406///
407/// For example:
408/// expression graph node names
409///
410/// + | I
411/// / \ |
412/// + + | A, B
413/// / \ / \ |
414/// * + * | C, D, E
415/// / \ / \ / \ |
416/// + * | F, G
417///
418/// The leaf nodes are C, E, F and G. The Ops array will contain (maybe not in
419/// that order) (C, 1), (E, 1), (F, 2), (G, 2).
420///
421/// The expression is maximal: if some instruction is a binary operator of the
422/// same kind as 'I', and all of its uses are non-leaf nodes of the expression,
423/// then the instruction also belongs to the expression, is not a leaf node of
424/// it, and its operands also belong to the expression (but may be leaf nodes).
425///
426/// NOTE: This routine will set operands of non-leaf non-root nodes to undef in
427/// order to ensure that every non-root node in the expression has *exactly one*
428/// use by a non-leaf node of the expression. This destruction means that the
429/// caller MUST either replace 'I' with a new expression or use something like
430/// RewriteExprTree to put the values back in if the routine indicates that it
431/// made a change by returning 'true'.
432///
433/// In the above example either the right operand of A or the left operand of B
434/// will be replaced by undef. If it is B's operand then this gives:
435///
436/// + | I
437/// / \ |
438/// + + | A, B - operand of B replaced with undef
439/// / \ \ |
440/// * + * | C, D, E
441/// / \ / \ / \ |
442/// + * | F, G
443///
444/// Note that such undef operands can only be reached by passing through 'I'.
445/// For example, if you visit operands recursively starting from a leaf node
446/// then you will never see such an undef operand unless you get back to 'I',
447/// which requires passing through a phi node.
448///
449/// Note that this routine may also mutate binary operators of the wrong type
450/// that have all uses inside the expression (i.e. only used by non-leaf nodes
451/// of the expression) if it can turn them into binary operators of the right
452/// type and thus make the expression bigger.
453static bool LinearizeExprTree(Instruction *I,
454 SmallVectorImpl<RepeatedValue> &Ops) {
455 assert((isa<UnaryOperator>(I) || isa<BinaryOperator>(I)) &&(static_cast <bool> ((isa<UnaryOperator>(I) || isa
<BinaryOperator>(I)) && "Expected a UnaryOperator or BinaryOperator!"
) ? void (0) : __assert_fail ("(isa<UnaryOperator>(I) || isa<BinaryOperator>(I)) && \"Expected a UnaryOperator or BinaryOperator!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 456, __extension__ __PRETTY_FUNCTION__))
456 "Expected a UnaryOperator or BinaryOperator!")(static_cast <bool> ((isa<UnaryOperator>(I) || isa
<BinaryOperator>(I)) && "Expected a UnaryOperator or BinaryOperator!"
) ? void (0) : __assert_fail ("(isa<UnaryOperator>(I) || isa<BinaryOperator>(I)) && \"Expected a UnaryOperator or BinaryOperator!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 456, __extension__ __PRETTY_FUNCTION__))
;
457 LLVM_DEBUG(dbgs() << "LINEARIZE: " << *I << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "LINEARIZE: " << *I <<
'\n'; } } while (false)
;
458 unsigned Bitwidth = I->getType()->getScalarType()->getPrimitiveSizeInBits();
459 unsigned Opcode = I->getOpcode();
460 assert(I->isAssociative() && I->isCommutative() &&(static_cast <bool> (I->isAssociative() && I
->isCommutative() && "Expected an associative and commutative operation!"
) ? void (0) : __assert_fail ("I->isAssociative() && I->isCommutative() && \"Expected an associative and commutative operation!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 461, __extension__ __PRETTY_FUNCTION__))
461 "Expected an associative and commutative operation!")(static_cast <bool> (I->isAssociative() && I
->isCommutative() && "Expected an associative and commutative operation!"
) ? void (0) : __assert_fail ("I->isAssociative() && I->isCommutative() && \"Expected an associative and commutative operation!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 461, __extension__ __PRETTY_FUNCTION__))
;
462
463 // Visit all operands of the expression, keeping track of their weight (the
464 // number of paths from the expression root to the operand, or if you like
465 // the number of times that operand occurs in the linearized expression).
466 // For example, if I = X + A, where X = A + B, then I, X and B have weight 1
467 // while A has weight two.
468
469 // Worklist of non-leaf nodes (their operands are in the expression too) along
470 // with their weights, representing a certain number of paths to the operator.
471 // If an operator occurs in the worklist multiple times then we found multiple
472 // ways to get to it.
473 SmallVector<std::pair<Instruction*, APInt>, 8> Worklist; // (Op, Weight)
474 Worklist.push_back(std::make_pair(I, APInt(Bitwidth, 1)));
475 bool Changed = false;
476
477 // Leaves of the expression are values that either aren't the right kind of
478 // operation (eg: a constant, or a multiply in an add tree), or are, but have
479 // some uses that are not inside the expression. For example, in I = X + X,
480 // X = A + B, the value X has two uses (by I) that are in the expression. If
481 // X has any other uses, for example in a return instruction, then we consider
482 // X to be a leaf, and won't analyze it further. When we first visit a value,
483 // if it has more than one use then at first we conservatively consider it to
484 // be a leaf. Later, as the expression is explored, we may discover some more
485 // uses of the value from inside the expression. If all uses turn out to be
486 // from within the expression (and the value is a binary operator of the right
487 // kind) then the value is no longer considered to be a leaf, and its operands
488 // are explored.
489
490 // Leaves - Keeps track of the set of putative leaves as well as the number of
491 // paths to each leaf seen so far.
492 using LeafMap = DenseMap<Value *, APInt>;
493 LeafMap Leaves; // Leaf -> Total weight so far.
494 SmallVector<Value *, 8> LeafOrder; // Ensure deterministic leaf output order.
495
496#ifndef NDEBUG
497 SmallPtrSet<Value *, 8> Visited; // For sanity checking the iteration scheme.
498#endif
499 while (!Worklist.empty()) {
500 std::pair<Instruction*, APInt> P = Worklist.pop_back_val();
501 I = P.first; // We examine the operands of this binary operator.
502
503 for (unsigned OpIdx = 0; OpIdx < I->getNumOperands(); ++OpIdx) { // Visit operands.
504 Value *Op = I->getOperand(OpIdx);
505 APInt Weight = P.second; // Number of paths to this operand.
506 LLVM_DEBUG(dbgs() << "OPERAND: " << *Op << " (" << Weight << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "OPERAND: " << *Op <<
" (" << Weight << ")\n"; } } while (false)
;
507 assert(!Op->use_empty() && "No uses, so how did we get to it?!")(static_cast <bool> (!Op->use_empty() && "No uses, so how did we get to it?!"
) ? void (0) : __assert_fail ("!Op->use_empty() && \"No uses, so how did we get to it?!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 507, __extension__ __PRETTY_FUNCTION__))
;
508
509 // If this is a binary operation of the right kind with only one use then
510 // add its operands to the expression.
511 if (BinaryOperator *BO = isReassociableOp(Op, Opcode)) {
512 assert(Visited.insert(Op).second && "Not first visit!")(static_cast <bool> (Visited.insert(Op).second &&
"Not first visit!") ? void (0) : __assert_fail ("Visited.insert(Op).second && \"Not first visit!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 512, __extension__ __PRETTY_FUNCTION__))
;
513 LLVM_DEBUG(dbgs() << "DIRECT ADD: " << *Op << " (" << Weight << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "DIRECT ADD: " << *Op
<< " (" << Weight << ")\n"; } } while (false
)
;
514 Worklist.push_back(std::make_pair(BO, Weight));
515 continue;
516 }
517
518 // Appears to be a leaf. Is the operand already in the set of leaves?
519 LeafMap::iterator It = Leaves.find(Op);
520 if (It == Leaves.end()) {
521 // Not in the leaf map. Must be the first time we saw this operand.
522 assert(Visited.insert(Op).second && "Not first visit!")(static_cast <bool> (Visited.insert(Op).second &&
"Not first visit!") ? void (0) : __assert_fail ("Visited.insert(Op).second && \"Not first visit!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 522, __extension__ __PRETTY_FUNCTION__))
;
523 if (!Op->hasOneUse()) {
524 // This value has uses not accounted for by the expression, so it is
525 // not safe to modify. Mark it as being a leaf.
526 LLVM_DEBUG(dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "ADD USES LEAF: " <<
*Op << " (" << Weight << ")\n"; } } while (
false)
527 << "ADD USES LEAF: " << *Op << " (" << Weight << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "ADD USES LEAF: " <<
*Op << " (" << Weight << ")\n"; } } while (
false)
;
528 LeafOrder.push_back(Op);
529 Leaves[Op] = Weight;
530 continue;
531 }
532 // No uses outside the expression, try morphing it.
533 } else {
534 // Already in the leaf map.
535 assert(It != Leaves.end() && Visited.count(Op) &&(static_cast <bool> (It != Leaves.end() && Visited
.count(Op) && "In leaf map but not visited!") ? void (
0) : __assert_fail ("It != Leaves.end() && Visited.count(Op) && \"In leaf map but not visited!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 536, __extension__ __PRETTY_FUNCTION__))
536 "In leaf map but not visited!")(static_cast <bool> (It != Leaves.end() && Visited
.count(Op) && "In leaf map but not visited!") ? void (
0) : __assert_fail ("It != Leaves.end() && Visited.count(Op) && \"In leaf map but not visited!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 536, __extension__ __PRETTY_FUNCTION__))
;
537
538 // Update the number of paths to the leaf.
539 IncorporateWeight(It->second, Weight, Opcode);
540
541#if 0 // TODO: Re-enable once PR13021 is fixed.
542 // The leaf already has one use from inside the expression. As we want
543 // exactly one such use, drop this new use of the leaf.
544 assert(!Op->hasOneUse() && "Only one use, but we got here twice!")(static_cast <bool> (!Op->hasOneUse() && "Only one use, but we got here twice!"
) ? void (0) : __assert_fail ("!Op->hasOneUse() && \"Only one use, but we got here twice!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 544, __extension__ __PRETTY_FUNCTION__))
;
545 I->setOperand(OpIdx, UndefValue::get(I->getType()));
546 Changed = true;
547
548 // If the leaf is a binary operation of the right kind and we now see
549 // that its multiple original uses were in fact all by nodes belonging
550 // to the expression, then no longer consider it to be a leaf and add
551 // its operands to the expression.
552 if (BinaryOperator *BO = isReassociableOp(Op, Opcode)) {
553 LLVM_DEBUG(dbgs() << "UNLEAF: " << *Op << " (" << It->second << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "UNLEAF: " << *Op <<
" (" << It->second << ")\n"; } } while (false
)
;
554 Worklist.push_back(std::make_pair(BO, It->second));
555 Leaves.erase(It);
556 continue;
557 }
558#endif
559
560 // If we still have uses that are not accounted for by the expression
561 // then it is not safe to modify the value.
562 if (!Op->hasOneUse())
563 continue;
564
565 // No uses outside the expression, try morphing it.
566 Weight = It->second;
567 Leaves.erase(It); // Since the value may be morphed below.
568 }
569
570 // At this point we have a value which, first of all, is not a binary
571 // expression of the right kind, and secondly, is only used inside the
572 // expression. This means that it can safely be modified. See if we
573 // can usefully morph it into an expression of the right kind.
574 assert((!isa<Instruction>(Op) ||(static_cast <bool> ((!isa<Instruction>(Op) || cast
<Instruction>(Op)->getOpcode() != Opcode || (isa<
FPMathOperator>(Op) && !cast<Instruction>(Op
)->isFast())) && "Should have been handled above!"
) ? void (0) : __assert_fail ("(!isa<Instruction>(Op) || cast<Instruction>(Op)->getOpcode() != Opcode || (isa<FPMathOperator>(Op) && !cast<Instruction>(Op)->isFast())) && \"Should have been handled above!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 578, __extension__ __PRETTY_FUNCTION__))
575 cast<Instruction>(Op)->getOpcode() != Opcode(static_cast <bool> ((!isa<Instruction>(Op) || cast
<Instruction>(Op)->getOpcode() != Opcode || (isa<
FPMathOperator>(Op) && !cast<Instruction>(Op
)->isFast())) && "Should have been handled above!"
) ? void (0) : __assert_fail ("(!isa<Instruction>(Op) || cast<Instruction>(Op)->getOpcode() != Opcode || (isa<FPMathOperator>(Op) && !cast<Instruction>(Op)->isFast())) && \"Should have been handled above!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 578, __extension__ __PRETTY_FUNCTION__))
576 || (isa<FPMathOperator>(Op) &&(static_cast <bool> ((!isa<Instruction>(Op) || cast
<Instruction>(Op)->getOpcode() != Opcode || (isa<
FPMathOperator>(Op) && !cast<Instruction>(Op
)->isFast())) && "Should have been handled above!"
) ? void (0) : __assert_fail ("(!isa<Instruction>(Op) || cast<Instruction>(Op)->getOpcode() != Opcode || (isa<FPMathOperator>(Op) && !cast<Instruction>(Op)->isFast())) && \"Should have been handled above!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 578, __extension__ __PRETTY_FUNCTION__))
577 !cast<Instruction>(Op)->isFast())) &&(static_cast <bool> ((!isa<Instruction>(Op) || cast
<Instruction>(Op)->getOpcode() != Opcode || (isa<
FPMathOperator>(Op) && !cast<Instruction>(Op
)->isFast())) && "Should have been handled above!"
) ? void (0) : __assert_fail ("(!isa<Instruction>(Op) || cast<Instruction>(Op)->getOpcode() != Opcode || (isa<FPMathOperator>(Op) && !cast<Instruction>(Op)->isFast())) && \"Should have been handled above!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 578, __extension__ __PRETTY_FUNCTION__))
578 "Should have been handled above!")(static_cast <bool> ((!isa<Instruction>(Op) || cast
<Instruction>(Op)->getOpcode() != Opcode || (isa<
FPMathOperator>(Op) && !cast<Instruction>(Op
)->isFast())) && "Should have been handled above!"
) ? void (0) : __assert_fail ("(!isa<Instruction>(Op) || cast<Instruction>(Op)->getOpcode() != Opcode || (isa<FPMathOperator>(Op) && !cast<Instruction>(Op)->isFast())) && \"Should have been handled above!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 578, __extension__ __PRETTY_FUNCTION__))
;
579 assert(Op->hasOneUse() && "Has uses outside the expression tree!")(static_cast <bool> (Op->hasOneUse() && "Has uses outside the expression tree!"
) ? void (0) : __assert_fail ("Op->hasOneUse() && \"Has uses outside the expression tree!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 579, __extension__ __PRETTY_FUNCTION__))
;
580
581 // If this is a multiply expression, turn any internal negations into
582 // multiplies by -1 so they can be reassociated.
583 if (Instruction *Tmp = dyn_cast<Instruction>(Op))
584 if ((Opcode == Instruction::Mul && match(Tmp, m_Neg(m_Value()))) ||
585 (Opcode == Instruction::FMul && match(Tmp, m_FNeg(m_Value())))) {
586 LLVM_DEBUG(dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "MORPH LEAF: " << *Op
<< " (" << Weight << ") TO "; } } while (false
)
587 << "MORPH LEAF: " << *Op << " (" << Weight << ") TO ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "MORPH LEAF: " << *Op
<< " (" << Weight << ") TO "; } } while (false
)
;
588 Tmp = LowerNegateToMultiply(Tmp);
589 LLVM_DEBUG(dbgs() << *Tmp << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << *Tmp << '\n'; } } while
(false)
;
590 Worklist.push_back(std::make_pair(Tmp, Weight));
591 Changed = true;
592 continue;
593 }
594
595 // Failed to morph into an expression of the right type. This really is
596 // a leaf.
597 LLVM_DEBUG(dbgs() << "ADD LEAF: " << *Op << " (" << Weight << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "ADD LEAF: " << *Op <<
" (" << Weight << ")\n"; } } while (false)
;
598 assert(!isReassociableOp(Op, Opcode) && "Value was morphed?")(static_cast <bool> (!isReassociableOp(Op, Opcode) &&
"Value was morphed?") ? void (0) : __assert_fail ("!isReassociableOp(Op, Opcode) && \"Value was morphed?\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 598, __extension__ __PRETTY_FUNCTION__))
;
599 LeafOrder.push_back(Op);
600 Leaves[Op] = Weight;
601 }
602 }
603
604 // The leaves, repeated according to their weights, represent the linearized
605 // form of the expression.
606 for (unsigned i = 0, e = LeafOrder.size(); i != e; ++i) {
607 Value *V = LeafOrder[i];
608 LeafMap::iterator It = Leaves.find(V);
609 if (It == Leaves.end())
610 // Node initially thought to be a leaf wasn't.
611 continue;
612 assert(!isReassociableOp(V, Opcode) && "Shouldn't be a leaf!")(static_cast <bool> (!isReassociableOp(V, Opcode) &&
"Shouldn't be a leaf!") ? void (0) : __assert_fail ("!isReassociableOp(V, Opcode) && \"Shouldn't be a leaf!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 612, __extension__ __PRETTY_FUNCTION__))
;
613 APInt Weight = It->second;
614 if (Weight.isMinValue())
615 // Leaf already output or weight reduction eliminated it.
616 continue;
617 // Ensure the leaf is only output once.
618 It->second = 0;
619 Ops.push_back(std::make_pair(V, Weight));
620 }
621
622 // For nilpotent operations or addition there may be no operands, for example
623 // because the expression was "X xor X" or consisted of 2^Bitwidth additions:
624 // in both cases the weight reduces to 0 causing the value to be skipped.
625 if (Ops.empty()) {
626 Constant *Identity = ConstantExpr::getBinOpIdentity(Opcode, I->getType());
627 assert(Identity && "Associative operation without identity!")(static_cast <bool> (Identity && "Associative operation without identity!"
) ? void (0) : __assert_fail ("Identity && \"Associative operation without identity!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 627, __extension__ __PRETTY_FUNCTION__))
;
628 Ops.emplace_back(Identity, APInt(Bitwidth, 1));
629 }
630
631 return Changed;
632}
633
634/// Now that the operands for this expression tree are
635/// linearized and optimized, emit them in-order.
636void ReassociatePass::RewriteExprTree(BinaryOperator *I,
637 SmallVectorImpl<ValueEntry> &Ops) {
638 assert(Ops.size() > 1 && "Single values should be used directly!")(static_cast <bool> (Ops.size() > 1 && "Single values should be used directly!"
) ? void (0) : __assert_fail ("Ops.size() > 1 && \"Single values should be used directly!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 638, __extension__ __PRETTY_FUNCTION__))
;
639
640 // Since our optimizations should never increase the number of operations, the
641 // new expression can usually be written reusing the existing binary operators
642 // from the original expression tree, without creating any new instructions,
643 // though the rewritten expression may have a completely different topology.
644 // We take care to not change anything if the new expression will be the same
645 // as the original. If more than trivial changes (like commuting operands)
646 // were made then we are obliged to clear out any optional subclass data like
647 // nsw flags.
648
649 /// NodesToRewrite - Nodes from the original expression available for writing
650 /// the new expression into.
651 SmallVector<BinaryOperator*, 8> NodesToRewrite;
652 unsigned Opcode = I->getOpcode();
653 BinaryOperator *Op = I;
654
655 /// NotRewritable - The operands being written will be the leaves of the new
656 /// expression and must not be used as inner nodes (via NodesToRewrite) by
657 /// mistake. Inner nodes are always reassociable, and usually leaves are not
658 /// (if they were they would have been incorporated into the expression and so
659 /// would not be leaves), so most of the time there is no danger of this. But
660 /// in rare cases a leaf may become reassociable if an optimization kills uses
661 /// of it, or it may momentarily become reassociable during rewriting (below)
662 /// due it being removed as an operand of one of its uses. Ensure that misuse
663 /// of leaf nodes as inner nodes cannot occur by remembering all of the future
664 /// leaves and refusing to reuse any of them as inner nodes.
665 SmallPtrSet<Value*, 8> NotRewritable;
666 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
667 NotRewritable.insert(Ops[i].Op);
668
669 // ExpressionChanged - Non-null if the rewritten expression differs from the
670 // original in some non-trivial way, requiring the clearing of optional flags.
671 // Flags are cleared from the operator in ExpressionChanged up to I inclusive.
672 BinaryOperator *ExpressionChanged = nullptr;
673 for (unsigned i = 0; ; ++i) {
674 // The last operation (which comes earliest in the IR) is special as both
675 // operands will come from Ops, rather than just one with the other being
676 // a subexpression.
677 if (i+2 == Ops.size()) {
678 Value *NewLHS = Ops[i].Op;
679 Value *NewRHS = Ops[i+1].Op;
680 Value *OldLHS = Op->getOperand(0);
681 Value *OldRHS = Op->getOperand(1);
682
683 if (NewLHS == OldLHS && NewRHS == OldRHS)
684 // Nothing changed, leave it alone.
685 break;
686
687 if (NewLHS == OldRHS && NewRHS == OldLHS) {
688 // The order of the operands was reversed. Swap them.
689 LLVM_DEBUG(dbgs() << "RA: " << *Op << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "RA: " << *Op <<
'\n'; } } while (false)
;
690 Op->swapOperands();
691 LLVM_DEBUG(dbgs() << "TO: " << *Op << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "TO: " << *Op <<
'\n'; } } while (false)
;
692 MadeChange = true;
693 ++NumChanged;
694 break;
695 }
696
697 // The new operation differs non-trivially from the original. Overwrite
698 // the old operands with the new ones.
699 LLVM_DEBUG(dbgs() << "RA: " << *Op << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "RA: " << *Op <<
'\n'; } } while (false)
;
700 if (NewLHS != OldLHS) {
701 BinaryOperator *BO = isReassociableOp(OldLHS, Opcode);
702 if (BO && !NotRewritable.count(BO))
703 NodesToRewrite.push_back(BO);
704 Op->setOperand(0, NewLHS);
705 }
706 if (NewRHS != OldRHS) {
707 BinaryOperator *BO = isReassociableOp(OldRHS, Opcode);
708 if (BO && !NotRewritable.count(BO))
709 NodesToRewrite.push_back(BO);
710 Op->setOperand(1, NewRHS);
711 }
712 LLVM_DEBUG(dbgs() << "TO: " << *Op << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "TO: " << *Op <<
'\n'; } } while (false)
;
713
714 ExpressionChanged = Op;
715 MadeChange = true;
716 ++NumChanged;
717
718 break;
719 }
720
721 // Not the last operation. The left-hand side will be a sub-expression
722 // while the right-hand side will be the current element of Ops.
723 Value *NewRHS = Ops[i].Op;
724 if (NewRHS != Op->getOperand(1)) {
725 LLVM_DEBUG(dbgs() << "RA: " << *Op << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "RA: " << *Op <<
'\n'; } } while (false)
;
726 if (NewRHS == Op->getOperand(0)) {
727 // The new right-hand side was already present as the left operand. If
728 // we are lucky then swapping the operands will sort out both of them.
729 Op->swapOperands();
730 } else {
731 // Overwrite with the new right-hand side.
732 BinaryOperator *BO = isReassociableOp(Op->getOperand(1), Opcode);
733 if (BO && !NotRewritable.count(BO))
734 NodesToRewrite.push_back(BO);
735 Op->setOperand(1, NewRHS);
736 ExpressionChanged = Op;
737 }
738 LLVM_DEBUG(dbgs() << "TO: " << *Op << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "TO: " << *Op <<
'\n'; } } while (false)
;
739 MadeChange = true;
740 ++NumChanged;
741 }
742
743 // Now deal with the left-hand side. If this is already an operation node
744 // from the original expression then just rewrite the rest of the expression
745 // into it.
746 BinaryOperator *BO = isReassociableOp(Op->getOperand(0), Opcode);
747 if (BO && !NotRewritable.count(BO)) {
748 Op = BO;
749 continue;
750 }
751
752 // Otherwise, grab a spare node from the original expression and use that as
753 // the left-hand side. If there are no nodes left then the optimizers made
754 // an expression with more nodes than the original! This usually means that
755 // they did something stupid but it might mean that the problem was just too
756 // hard (finding the mimimal number of multiplications needed to realize a
757 // multiplication expression is NP-complete). Whatever the reason, smart or
758 // stupid, create a new node if there are none left.
759 BinaryOperator *NewOp;
760 if (NodesToRewrite.empty()) {
761 Constant *Undef = UndefValue::get(I->getType());
762 NewOp = BinaryOperator::Create(Instruction::BinaryOps(Opcode),
763 Undef, Undef, "", I);
764 if (NewOp->getType()->isFPOrFPVectorTy())
765 NewOp->setFastMathFlags(I->getFastMathFlags());
766 } else {
767 NewOp = NodesToRewrite.pop_back_val();
768 }
769
770 LLVM_DEBUG(dbgs() << "RA: " << *Op << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "RA: " << *Op <<
'\n'; } } while (false)
;
771 Op->setOperand(0, NewOp);
772 LLVM_DEBUG(dbgs() << "TO: " << *Op << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "TO: " << *Op <<
'\n'; } } while (false)
;
773 ExpressionChanged = Op;
774 MadeChange = true;
775 ++NumChanged;
776 Op = NewOp;
777 }
778
779 // If the expression changed non-trivially then clear out all subclass data
780 // starting from the operator specified in ExpressionChanged, and compactify
781 // the operators to just before the expression root to guarantee that the
782 // expression tree is dominated by all of Ops.
783 if (ExpressionChanged)
784 do {
785 // Preserve FastMathFlags.
786 if (isa<FPMathOperator>(I)) {
787 FastMathFlags Flags = I->getFastMathFlags();
788 ExpressionChanged->clearSubclassOptionalData();
789 ExpressionChanged->setFastMathFlags(Flags);
790 } else
791 ExpressionChanged->clearSubclassOptionalData();
792
793 if (ExpressionChanged == I)
794 break;
795
796 // Discard any debug info related to the expressions that has changed (we
797 // can leave debug infor related to the root, since the result of the
798 // expression tree should be the same even after reassociation).
799 replaceDbgUsesWithUndef(ExpressionChanged);
800
801 ExpressionChanged->moveBefore(I);
802 ExpressionChanged = cast<BinaryOperator>(*ExpressionChanged->user_begin());
803 } while (true);
804
805 // Throw away any left over nodes from the original expression.
806 for (unsigned i = 0, e = NodesToRewrite.size(); i != e; ++i)
807 RedoInsts.insert(NodesToRewrite[i]);
808}
809
810/// Insert instructions before the instruction pointed to by BI,
811/// that computes the negative version of the value specified. The negative
812/// version of the value is returned, and BI is left pointing at the instruction
813/// that should be processed next by the reassociation pass.
814/// Also add intermediate instructions to the redo list that are modified while
815/// pushing the negates through adds. These will be revisited to see if
816/// additional opportunities have been exposed.
817static Value *NegateValue(Value *V, Instruction *BI,
818 ReassociatePass::OrderedSet &ToRedo) {
819 if (auto *C = dyn_cast<Constant>(V))
820 return C->getType()->isFPOrFPVectorTy() ? ConstantExpr::getFNeg(C) :
821 ConstantExpr::getNeg(C);
822
823 // We are trying to expose opportunity for reassociation. One of the things
824 // that we want to do to achieve this is to push a negation as deep into an
825 // expression chain as possible, to expose the add instructions. In practice,
826 // this means that we turn this:
827 // X = -(A+12+C+D) into X = -A + -12 + -C + -D = -12 + -A + -C + -D
828 // so that later, a: Y = 12+X could get reassociated with the -12 to eliminate
829 // the constants. We assume that instcombine will clean up the mess later if
830 // we introduce tons of unnecessary negation instructions.
831 //
832 if (BinaryOperator *I =
833 isReassociableOp(V, Instruction::Add, Instruction::FAdd)) {
834 // Push the negates through the add.
835 I->setOperand(0, NegateValue(I->getOperand(0), BI, ToRedo));
836 I->setOperand(1, NegateValue(I->getOperand(1), BI, ToRedo));
837 if (I->getOpcode() == Instruction::Add) {
838 I->setHasNoUnsignedWrap(false);
839 I->setHasNoSignedWrap(false);
840 }
841
842 // We must move the add instruction here, because the neg instructions do
843 // not dominate the old add instruction in general. By moving it, we are
844 // assured that the neg instructions we just inserted dominate the
845 // instruction we are about to insert after them.
846 //
847 I->moveBefore(BI);
848 I->setName(I->getName()+".neg");
849
850 // Add the intermediate negates to the redo list as processing them later
851 // could expose more reassociating opportunities.
852 ToRedo.insert(I);
853 return I;
854 }
855
856 // Okay, we need to materialize a negated version of V with an instruction.
857 // Scan the use lists of V to see if we have one already.
858 for (User *U : V->users()) {
859 if (!match(U, m_Neg(m_Value())) && !match(U, m_FNeg(m_Value())))
860 continue;
861
862 // We found one! Now we have to make sure that the definition dominates
863 // this use. We do this by moving it to the entry block (if it is a
864 // non-instruction value) or right after the definition. These negates will
865 // be zapped by reassociate later, so we don't need much finesse here.
866 Instruction *TheNeg = cast<Instruction>(U);
867
868 // Verify that the negate is in this function, V might be a constant expr.
869 if (TheNeg->getParent()->getParent() != BI->getParent()->getParent())
870 continue;
871
872 bool FoundCatchSwitch = false;
873
874 BasicBlock::iterator InsertPt;
875 if (Instruction *InstInput = dyn_cast<Instruction>(V)) {
876 if (InvokeInst *II = dyn_cast<InvokeInst>(InstInput)) {
877 InsertPt = II->getNormalDest()->begin();
878 } else {
879 InsertPt = ++InstInput->getIterator();
880 }
881
882 const BasicBlock *BB = InsertPt->getParent();
883
884 // Make sure we don't move anything before PHIs or exception
885 // handling pads.
886 while (InsertPt != BB->end() && (isa<PHINode>(InsertPt) ||
887 InsertPt->isEHPad())) {
888 if (isa<CatchSwitchInst>(InsertPt))
889 // A catchswitch cannot have anything in the block except
890 // itself and PHIs. We'll bail out below.
891 FoundCatchSwitch = true;
892 ++InsertPt;
893 }
894 } else {
895 InsertPt = TheNeg->getParent()->getParent()->getEntryBlock().begin();
896 }
897
898 // We found a catchswitch in the block where we want to move the
899 // neg. We cannot move anything into that block. Bail and just
900 // create the neg before BI, as if we hadn't found an existing
901 // neg.
902 if (FoundCatchSwitch)
903 break;
904
905 TheNeg->moveBefore(&*InsertPt);
906 if (TheNeg->getOpcode() == Instruction::Sub) {
907 TheNeg->setHasNoUnsignedWrap(false);
908 TheNeg->setHasNoSignedWrap(false);
909 } else {
910 TheNeg->andIRFlags(BI);
911 }
912 ToRedo.insert(TheNeg);
913 return TheNeg;
914 }
915
916 // Insert a 'neg' instruction that subtracts the value from zero to get the
917 // negation.
918 Instruction *NewNeg = CreateNeg(V, V->getName() + ".neg", BI, BI);
919 ToRedo.insert(NewNeg);
920 return NewNeg;
921}
922
923// See if this `or` looks like an load widening reduction, i.e. that it
924// consists of an `or`/`shl`/`zext`/`load` nodes only. Note that we don't
925// ensure that the pattern is *really* a load widening reduction,
926// we do not ensure that it can really be replaced with a widened load,
927// only that it mostly looks like one.
928static bool isLoadCombineCandidate(Instruction *Or) {
929 SmallVector<Instruction *, 8> Worklist;
930 SmallSet<Instruction *, 8> Visited;
931
932 auto Enqueue = [&](Value *V) {
933 auto *I = dyn_cast<Instruction>(V);
934 // Each node of an `or` reduction must be an instruction,
935 if (!I)
936 return false; // Node is certainly not part of an `or` load reduction.
937 // Only process instructions we have never processed before.
938 if (Visited.insert(I).second)
939 Worklist.emplace_back(I);
940 return true; // Will need to look at parent nodes.
941 };
942
943 if (!Enqueue(Or))
944 return false; // Not an `or` reduction pattern.
945
946 while (!Worklist.empty()) {
947 auto *I = Worklist.pop_back_val();
948
949 // Okay, which instruction is this node?
950 switch (I->getOpcode()) {
951 case Instruction::Or:
952 // Got an `or` node. That's fine, just recurse into it's operands.
953 for (Value *Op : I->operands())
954 if (!Enqueue(Op))
955 return false; // Not an `or` reduction pattern.
956 continue;
957
958 case Instruction::Shl:
959 case Instruction::ZExt:
960 // `shl`/`zext` nodes are fine, just recurse into their base operand.
961 if (!Enqueue(I->getOperand(0)))
962 return false; // Not an `or` reduction pattern.
963 continue;
964
965 case Instruction::Load:
966 // Perfect, `load` node means we've reached an edge of the graph.
967 continue;
968
969 default: // Unknown node.
970 return false; // Not an `or` reduction pattern.
971 }
972 }
973
974 return true;
975}
976
977/// Return true if it may be profitable to convert this (X|Y) into (X+Y).
978static bool shouldConvertOrWithNoCommonBitsToAdd(Instruction *Or) {
979 // Don't bother to convert this up unless either the LHS is an associable add
980 // or subtract or mul or if this is only used by one of the above.
981 // This is only a compile-time improvement, it is not needed for correctness!
982 auto isInteresting = [](Value *V) {
983 for (auto Op : {Instruction::Add, Instruction::Sub, Instruction::Mul,
984 Instruction::Shl})
985 if (isReassociableOp(V, Op))
986 return true;
987 return false;
988 };
989
990 if (any_of(Or->operands(), isInteresting))
991 return true;
992
993 Value *VB = Or->user_back();
994 if (Or->hasOneUse() && isInteresting(VB))
995 return true;
996
997 return false;
998}
999
1000/// If we have (X|Y), and iff X and Y have no common bits set,
1001/// transform this into (X+Y) to allow arithmetics reassociation.
1002static BinaryOperator *convertOrWithNoCommonBitsToAdd(Instruction *Or) {
1003 // Convert an or into an add.
1004 BinaryOperator *New =
1005 CreateAdd(Or->getOperand(0), Or->getOperand(1), "", Or, Or);
1006 New->setHasNoSignedWrap();
1007 New->setHasNoUnsignedWrap();
1008 New->takeName(Or);
1009
1010 // Everyone now refers to the add instruction.
1011 Or->replaceAllUsesWith(New);
1012 New->setDebugLoc(Or->getDebugLoc());
1013
1014 LLVM_DEBUG(dbgs() << "Converted or into an add: " << *New << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "Converted or into an add: "
<< *New << '\n'; } } while (false)
;
1015 return New;
1016}
1017
1018/// Return true if we should break up this subtract of X-Y into (X + -Y).
1019static bool ShouldBreakUpSubtract(Instruction *Sub) {
1020 // If this is a negation, we can't split it up!
1021 if (match(Sub, m_Neg(m_Value())) || match(Sub, m_FNeg(m_Value())))
1022 return false;
1023
1024 // Don't breakup X - undef.
1025 if (isa<UndefValue>(Sub->getOperand(1)))
1026 return false;
1027
1028 // Don't bother to break this up unless either the LHS is an associable add or
1029 // subtract or if this is only used by one.
1030 Value *V0 = Sub->getOperand(0);
1031 if (isReassociableOp(V0, Instruction::Add, Instruction::FAdd) ||
1032 isReassociableOp(V0, Instruction::Sub, Instruction::FSub))
1033 return true;
1034 Value *V1 = Sub->getOperand(1);
1035 if (isReassociableOp(V1, Instruction::Add, Instruction::FAdd) ||
1036 isReassociableOp(V1, Instruction::Sub, Instruction::FSub))
1037 return true;
1038 Value *VB = Sub->user_back();
1039 if (Sub->hasOneUse() &&
1040 (isReassociableOp(VB, Instruction::Add, Instruction::FAdd) ||
1041 isReassociableOp(VB, Instruction::Sub, Instruction::FSub)))
1042 return true;
1043
1044 return false;
1045}
1046
1047/// If we have (X-Y), and if either X is an add, or if this is only used by an
1048/// add, transform this into (X+(0-Y)) to promote better reassociation.
1049static BinaryOperator *BreakUpSubtract(Instruction *Sub,
1050 ReassociatePass::OrderedSet &ToRedo) {
1051 // Convert a subtract into an add and a neg instruction. This allows sub
1052 // instructions to be commuted with other add instructions.
1053 //
1054 // Calculate the negative value of Operand 1 of the sub instruction,
1055 // and set it as the RHS of the add instruction we just made.
1056 Value *NegVal = NegateValue(Sub->getOperand(1), Sub, ToRedo);
1057 BinaryOperator *New = CreateAdd(Sub->getOperand(0), NegVal, "", Sub, Sub);
1058 Sub->setOperand(0, Constant::getNullValue(Sub->getType())); // Drop use of op.
1059 Sub->setOperand(1, Constant::getNullValue(Sub->getType())); // Drop use of op.
1060 New->takeName(Sub);
1061
1062 // Everyone now refers to the add instruction.
1063 Sub->replaceAllUsesWith(New);
1064 New->setDebugLoc(Sub->getDebugLoc());
1065
1066 LLVM_DEBUG(dbgs() << "Negated: " << *New << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "Negated: " << *New <<
'\n'; } } while (false)
;
1067 return New;
1068}
1069
1070/// If this is a shift of a reassociable multiply or is used by one, change
1071/// this into a multiply by a constant to assist with further reassociation.
1072static BinaryOperator *ConvertShiftToMul(Instruction *Shl) {
1073 Constant *MulCst = ConstantInt::get(Shl->getType(), 1);
1074 auto *SA = cast<ConstantInt>(Shl->getOperand(1));
1075 MulCst = ConstantExpr::getShl(MulCst, SA);
1076
1077 BinaryOperator *Mul =
1078 BinaryOperator::CreateMul(Shl->getOperand(0), MulCst, "", Shl);
1079 Shl->setOperand(0, UndefValue::get(Shl->getType())); // Drop use of op.
1080 Mul->takeName(Shl);
1081
1082 // Everyone now refers to the mul instruction.
1083 Shl->replaceAllUsesWith(Mul);
1084 Mul->setDebugLoc(Shl->getDebugLoc());
1085
1086 // We can safely preserve the nuw flag in all cases. It's also safe to turn a
1087 // nuw nsw shl into a nuw nsw mul. However, nsw in isolation requires special
1088 // handling. It can be preserved as long as we're not left shifting by
1089 // bitwidth - 1.
1090 bool NSW = cast<BinaryOperator>(Shl)->hasNoSignedWrap();
1091 bool NUW = cast<BinaryOperator>(Shl)->hasNoUnsignedWrap();
1092 unsigned BitWidth = Shl->getType()->getIntegerBitWidth();
1093 if (NSW && (NUW || SA->getValue().ult(BitWidth - 1)))
1094 Mul->setHasNoSignedWrap(true);
1095 Mul->setHasNoUnsignedWrap(NUW);
1096 return Mul;
1097}
1098
1099/// Scan backwards and forwards among values with the same rank as element i
1100/// to see if X exists. If X does not exist, return i. This is useful when
1101/// scanning for 'x' when we see '-x' because they both get the same rank.
1102static unsigned FindInOperandList(const SmallVectorImpl<ValueEntry> &Ops,
1103 unsigned i, Value *X) {
1104 unsigned XRank = Ops[i].Rank;
1105 unsigned e = Ops.size();
1106 for (unsigned j = i+1; j != e && Ops[j].Rank == XRank; ++j) {
1107 if (Ops[j].Op == X)
1108 return j;
1109 if (Instruction *I1 = dyn_cast<Instruction>(Ops[j].Op))
1110 if (Instruction *I2 = dyn_cast<Instruction>(X))
1111 if (I1->isIdenticalTo(I2))
1112 return j;
1113 }
1114 // Scan backwards.
1115 for (unsigned j = i-1; j != ~0U && Ops[j].Rank == XRank; --j) {
1116 if (Ops[j].Op == X)
1117 return j;
1118 if (Instruction *I1 = dyn_cast<Instruction>(Ops[j].Op))
1119 if (Instruction *I2 = dyn_cast<Instruction>(X))
1120 if (I1->isIdenticalTo(I2))
1121 return j;
1122 }
1123 return i;
1124}
1125
1126/// Emit a tree of add instructions, summing Ops together
1127/// and returning the result. Insert the tree before I.
1128static Value *EmitAddTreeOfValues(Instruction *I,
1129 SmallVectorImpl<WeakTrackingVH> &Ops) {
1130 if (Ops.size() == 1) return Ops.back();
1131
1132 Value *V1 = Ops.pop_back_val();
1133 Value *V2 = EmitAddTreeOfValues(I, Ops);
1134 return CreateAdd(V2, V1, "reass.add", I, I);
1135}
1136
1137/// If V is an expression tree that is a multiplication sequence,
1138/// and if this sequence contains a multiply by Factor,
1139/// remove Factor from the tree and return the new tree.
1140Value *ReassociatePass::RemoveFactorFromExpression(Value *V, Value *Factor) {
1141 BinaryOperator *BO = isReassociableOp(V, Instruction::Mul, Instruction::FMul);
1142 if (!BO)
1143 return nullptr;
1144
1145 SmallVector<RepeatedValue, 8> Tree;
1146 MadeChange |= LinearizeExprTree(BO, Tree);
1147 SmallVector<ValueEntry, 8> Factors;
1148 Factors.reserve(Tree.size());
1149 for (unsigned i = 0, e = Tree.size(); i != e; ++i) {
1150 RepeatedValue E = Tree[i];
1151 Factors.append(E.second.getZExtValue(),
1152 ValueEntry(getRank(E.first), E.first));
1153 }
1154
1155 bool FoundFactor = false;
1156 bool NeedsNegate = false;
1157 for (unsigned i = 0, e = Factors.size(); i != e; ++i) {
1158 if (Factors[i].Op == Factor) {
1159 FoundFactor = true;
1160 Factors.erase(Factors.begin()+i);
1161 break;
1162 }
1163
1164 // If this is a negative version of this factor, remove it.
1165 if (ConstantInt *FC1 = dyn_cast<ConstantInt>(Factor)) {
1166 if (ConstantInt *FC2 = dyn_cast<ConstantInt>(Factors[i].Op))
1167 if (FC1->getValue() == -FC2->getValue()) {
1168 FoundFactor = NeedsNegate = true;
1169 Factors.erase(Factors.begin()+i);
1170 break;
1171 }
1172 } else if (ConstantFP *FC1 = dyn_cast<ConstantFP>(Factor)) {
1173 if (ConstantFP *FC2 = dyn_cast<ConstantFP>(Factors[i].Op)) {
1174 const APFloat &F1 = FC1->getValueAPF();
1175 APFloat F2(FC2->getValueAPF());
1176 F2.changeSign();
1177 if (F1 == F2) {
1178 FoundFactor = NeedsNegate = true;
1179 Factors.erase(Factors.begin() + i);
1180 break;
1181 }
1182 }
1183 }
1184 }
1185
1186 if (!FoundFactor) {
1187 // Make sure to restore the operands to the expression tree.
1188 RewriteExprTree(BO, Factors);
1189 return nullptr;
1190 }
1191
1192 BasicBlock::iterator InsertPt = ++BO->getIterator();
1193
1194 // If this was just a single multiply, remove the multiply and return the only
1195 // remaining operand.
1196 if (Factors.size() == 1) {
1197 RedoInsts.insert(BO);
1198 V = Factors[0].Op;
1199 } else {
1200 RewriteExprTree(BO, Factors);
1201 V = BO;
1202 }
1203
1204 if (NeedsNegate)
1205 V = CreateNeg(V, "neg", &*InsertPt, BO);
1206
1207 return V;
1208}
1209
1210/// If V is a single-use multiply, recursively add its operands as factors,
1211/// otherwise add V to the list of factors.
1212///
1213/// Ops is the top-level list of add operands we're trying to factor.
1214static void FindSingleUseMultiplyFactors(Value *V,
1215 SmallVectorImpl<Value*> &Factors) {
1216 BinaryOperator *BO = isReassociableOp(V, Instruction::Mul, Instruction::FMul);
1217 if (!BO) {
1218 Factors.push_back(V);
1219 return;
1220 }
1221
1222 // Otherwise, add the LHS and RHS to the list of factors.
1223 FindSingleUseMultiplyFactors(BO->getOperand(1), Factors);
1224 FindSingleUseMultiplyFactors(BO->getOperand(0), Factors);
1225}
1226
1227/// Optimize a series of operands to an 'and', 'or', or 'xor' instruction.
1228/// This optimizes based on identities. If it can be reduced to a single Value,
1229/// it is returned, otherwise the Ops list is mutated as necessary.
1230static Value *OptimizeAndOrXor(unsigned Opcode,
1231 SmallVectorImpl<ValueEntry> &Ops) {
1232 // Scan the operand lists looking for X and ~X pairs, along with X,X pairs.
1233 // If we find any, we can simplify the expression. X&~X == 0, X|~X == -1.
1234 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
1235 // First, check for X and ~X in the operand list.
1236 assert(i < Ops.size())(static_cast <bool> (i < Ops.size()) ? void (0) : __assert_fail
("i < Ops.size()", "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 1236, __extension__ __PRETTY_FUNCTION__))
;
1237 Value *X;
1238 if (match(Ops[i].Op, m_Not(m_Value(X)))) { // Cannot occur for ^.
1239 unsigned FoundX = FindInOperandList(Ops, i, X);
1240 if (FoundX != i) {
1241 if (Opcode == Instruction::And) // ...&X&~X = 0
1242 return Constant::getNullValue(X->getType());
1243
1244 if (Opcode == Instruction::Or) // ...|X|~X = -1
1245 return Constant::getAllOnesValue(X->getType());
1246 }
1247 }
1248
1249 // Next, check for duplicate pairs of values, which we assume are next to
1250 // each other, due to our sorting criteria.
1251 assert(i < Ops.size())(static_cast <bool> (i < Ops.size()) ? void (0) : __assert_fail
("i < Ops.size()", "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 1251, __extension__ __PRETTY_FUNCTION__))
;
1252 if (i+1 != Ops.size() && Ops[i+1].Op == Ops[i].Op) {
1253 if (Opcode == Instruction::And || Opcode == Instruction::Or) {
1254 // Drop duplicate values for And and Or.
1255 Ops.erase(Ops.begin()+i);
1256 --i; --e;
1257 ++NumAnnihil;
1258 continue;
1259 }
1260
1261 // Drop pairs of values for Xor.
1262 assert(Opcode == Instruction::Xor)(static_cast <bool> (Opcode == Instruction::Xor) ? void
(0) : __assert_fail ("Opcode == Instruction::Xor", "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 1262, __extension__ __PRETTY_FUNCTION__))
;
1263 if (e == 2)
1264 return Constant::getNullValue(Ops[0].Op->getType());
1265
1266 // Y ^ X^X -> Y
1267 Ops.erase(Ops.begin()+i, Ops.begin()+i+2);
1268 i -= 1; e -= 2;
1269 ++NumAnnihil;
1270 }
1271 }
1272 return nullptr;
1273}
1274
1275/// Helper function of CombineXorOpnd(). It creates a bitwise-and
1276/// instruction with the given two operands, and return the resulting
1277/// instruction. There are two special cases: 1) if the constant operand is 0,
1278/// it will return NULL. 2) if the constant is ~0, the symbolic operand will
1279/// be returned.
1280static Value *createAndInstr(Instruction *InsertBefore, Value *Opnd,
1281 const APInt &ConstOpnd) {
1282 if (ConstOpnd.isZero())
1283 return nullptr;
1284
1285 if (ConstOpnd.isAllOnes())
1286 return Opnd;
1287
1288 Instruction *I = BinaryOperator::CreateAnd(
1289 Opnd, ConstantInt::get(Opnd->getType(), ConstOpnd), "and.ra",
1290 InsertBefore);
1291 I->setDebugLoc(InsertBefore->getDebugLoc());
1292 return I;
1293}
1294
1295// Helper function of OptimizeXor(). It tries to simplify "Opnd1 ^ ConstOpnd"
1296// into "R ^ C", where C would be 0, and R is a symbolic value.
1297//
1298// If it was successful, true is returned, and the "R" and "C" is returned
1299// via "Res" and "ConstOpnd", respectively; otherwise, false is returned,
1300// and both "Res" and "ConstOpnd" remain unchanged.
1301bool ReassociatePass::CombineXorOpnd(Instruction *I, XorOpnd *Opnd1,
1302 APInt &ConstOpnd, Value *&Res) {
1303 // Xor-Rule 1: (x | c1) ^ c2 = (x | c1) ^ (c1 ^ c1) ^ c2
1304 // = ((x | c1) ^ c1) ^ (c1 ^ c2)
1305 // = (x & ~c1) ^ (c1 ^ c2)
1306 // It is useful only when c1 == c2.
1307 if (!Opnd1->isOrExpr() || Opnd1->getConstPart().isZero())
1308 return false;
1309
1310 if (!Opnd1->getValue()->hasOneUse())
1311 return false;
1312
1313 const APInt &C1 = Opnd1->getConstPart();
1314 if (C1 != ConstOpnd)
1315 return false;
1316
1317 Value *X = Opnd1->getSymbolicPart();
1318 Res = createAndInstr(I, X, ~C1);
1319 // ConstOpnd was C2, now C1 ^ C2.
1320 ConstOpnd ^= C1;
1321
1322 if (Instruction *T = dyn_cast<Instruction>(Opnd1->getValue()))
1323 RedoInsts.insert(T);
1324 return true;
1325}
1326
1327// Helper function of OptimizeXor(). It tries to simplify
1328// "Opnd1 ^ Opnd2 ^ ConstOpnd" into "R ^ C", where C would be 0, and R is a
1329// symbolic value.
1330//
1331// If it was successful, true is returned, and the "R" and "C" is returned
1332// via "Res" and "ConstOpnd", respectively (If the entire expression is
1333// evaluated to a constant, the Res is set to NULL); otherwise, false is
1334// returned, and both "Res" and "ConstOpnd" remain unchanged.
1335bool ReassociatePass::CombineXorOpnd(Instruction *I, XorOpnd *Opnd1,
1336 XorOpnd *Opnd2, APInt &ConstOpnd,
1337 Value *&Res) {
1338 Value *X = Opnd1->getSymbolicPart();
1339 if (X != Opnd2->getSymbolicPart())
1340 return false;
1341
1342 // This many instruction become dead.(At least "Opnd1 ^ Opnd2" will die.)
1343 int DeadInstNum = 1;
1344 if (Opnd1->getValue()->hasOneUse())
1345 DeadInstNum++;
1346 if (Opnd2->getValue()->hasOneUse())
1347 DeadInstNum++;
1348
1349 // Xor-Rule 2:
1350 // (x | c1) ^ (x & c2)
1351 // = (x|c1) ^ (x&c2) ^ (c1 ^ c1) = ((x|c1) ^ c1) ^ (x & c2) ^ c1
1352 // = (x & ~c1) ^ (x & c2) ^ c1 // Xor-Rule 1
1353 // = (x & c3) ^ c1, where c3 = ~c1 ^ c2 // Xor-rule 3
1354 //
1355 if (Opnd1->isOrExpr() != Opnd2->isOrExpr()) {
1356 if (Opnd2->isOrExpr())
1357 std::swap(Opnd1, Opnd2);
1358
1359 const APInt &C1 = Opnd1->getConstPart();
1360 const APInt &C2 = Opnd2->getConstPart();
1361 APInt C3((~C1) ^ C2);
1362
1363 // Do not increase code size!
1364 if (!C3.isZero() && !C3.isAllOnes()) {
1365 int NewInstNum = ConstOpnd.getBoolValue() ? 1 : 2;
1366 if (NewInstNum > DeadInstNum)
1367 return false;
1368 }
1369
1370 Res = createAndInstr(I, X, C3);
1371 ConstOpnd ^= C1;
1372 } else if (Opnd1->isOrExpr()) {
1373 // Xor-Rule 3: (x | c1) ^ (x | c2) = (x & c3) ^ c3 where c3 = c1 ^ c2
1374 //
1375 const APInt &C1 = Opnd1->getConstPart();
1376 const APInt &C2 = Opnd2->getConstPart();
1377 APInt C3 = C1 ^ C2;
1378
1379 // Do not increase code size
1380 if (!C3.isZero() && !C3.isAllOnes()) {
1381 int NewInstNum = ConstOpnd.getBoolValue() ? 1 : 2;
1382 if (NewInstNum > DeadInstNum)
1383 return false;
1384 }
1385
1386 Res = createAndInstr(I, X, C3);
1387 ConstOpnd ^= C3;
1388 } else {
1389 // Xor-Rule 4: (x & c1) ^ (x & c2) = (x & (c1^c2))
1390 //
1391 const APInt &C1 = Opnd1->getConstPart();
1392 const APInt &C2 = Opnd2->getConstPart();
1393 APInt C3 = C1 ^ C2;
1394 Res = createAndInstr(I, X, C3);
1395 }
1396
1397 // Put the original operands in the Redo list; hope they will be deleted
1398 // as dead code.
1399 if (Instruction *T = dyn_cast<Instruction>(Opnd1->getValue()))
1400 RedoInsts.insert(T);
1401 if (Instruction *T = dyn_cast<Instruction>(Opnd2->getValue()))
1402 RedoInsts.insert(T);
1403
1404 return true;
1405}
1406
1407/// Optimize a series of operands to an 'xor' instruction. If it can be reduced
1408/// to a single Value, it is returned, otherwise the Ops list is mutated as
1409/// necessary.
1410Value *ReassociatePass::OptimizeXor(Instruction *I,
1411 SmallVectorImpl<ValueEntry> &Ops) {
1412 if (Value *V = OptimizeAndOrXor(Instruction::Xor, Ops))
1413 return V;
1414
1415 if (Ops.size() == 1)
1416 return nullptr;
1417
1418 SmallVector<XorOpnd, 8> Opnds;
1419 SmallVector<XorOpnd*, 8> OpndPtrs;
1420 Type *Ty = Ops[0].Op->getType();
1421 APInt ConstOpnd(Ty->getScalarSizeInBits(), 0);
1422
1423 // Step 1: Convert ValueEntry to XorOpnd
1424 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
1425 Value *V = Ops[i].Op;
1426 const APInt *C;
1427 // TODO: Support non-splat vectors.
1428 if (match(V, m_APInt(C))) {
1429 ConstOpnd ^= *C;
1430 } else {
1431 XorOpnd O(V);
1432 O.setSymbolicRank(getRank(O.getSymbolicPart()));
1433 Opnds.push_back(O);
1434 }
1435 }
1436
1437 // NOTE: From this point on, do *NOT* add/delete element to/from "Opnds".
1438 // It would otherwise invalidate the "Opnds"'s iterator, and hence invalidate
1439 // the "OpndPtrs" as well. For the similar reason, do not fuse this loop
1440 // with the previous loop --- the iterator of the "Opnds" may be invalidated
1441 // when new elements are added to the vector.
1442 for (unsigned i = 0, e = Opnds.size(); i != e; ++i)
1443 OpndPtrs.push_back(&Opnds[i]);
1444
1445 // Step 2: Sort the Xor-Operands in a way such that the operands containing
1446 // the same symbolic value cluster together. For instance, the input operand
1447 // sequence ("x | 123", "y & 456", "x & 789") will be sorted into:
1448 // ("x | 123", "x & 789", "y & 456").
1449 //
1450 // The purpose is twofold:
1451 // 1) Cluster together the operands sharing the same symbolic-value.
1452 // 2) Operand having smaller symbolic-value-rank is permuted earlier, which
1453 // could potentially shorten crital path, and expose more loop-invariants.
1454 // Note that values' rank are basically defined in RPO order (FIXME).
1455 // So, if Rank(X) < Rank(Y) < Rank(Z), it means X is defined earlier
1456 // than Y which is defined earlier than Z. Permute "x | 1", "Y & 2",
1457 // "z" in the order of X-Y-Z is better than any other orders.
1458 llvm::stable_sort(OpndPtrs, [](XorOpnd *LHS, XorOpnd *RHS) {
1459 return LHS->getSymbolicRank() < RHS->getSymbolicRank();
1460 });
1461
1462 // Step 3: Combine adjacent operands
1463 XorOpnd *PrevOpnd = nullptr;
1464 bool Changed = false;
1465 for (unsigned i = 0, e = Opnds.size(); i < e; i++) {
1466 XorOpnd *CurrOpnd = OpndPtrs[i];
1467 // The combined value
1468 Value *CV;
1469
1470 // Step 3.1: Try simplifying "CurrOpnd ^ ConstOpnd"
1471 if (!ConstOpnd.isZero() && CombineXorOpnd(I, CurrOpnd, ConstOpnd, CV)) {
1472 Changed = true;
1473 if (CV)
1474 *CurrOpnd = XorOpnd(CV);
1475 else {
1476 CurrOpnd->Invalidate();
1477 continue;
1478 }
1479 }
1480
1481 if (!PrevOpnd || CurrOpnd->getSymbolicPart() != PrevOpnd->getSymbolicPart()) {
1482 PrevOpnd = CurrOpnd;
1483 continue;
1484 }
1485
1486 // step 3.2: When previous and current operands share the same symbolic
1487 // value, try to simplify "PrevOpnd ^ CurrOpnd ^ ConstOpnd"
1488 if (CombineXorOpnd(I, CurrOpnd, PrevOpnd, ConstOpnd, CV)) {
1489 // Remove previous operand
1490 PrevOpnd->Invalidate();
1491 if (CV) {
1492 *CurrOpnd = XorOpnd(CV);
1493 PrevOpnd = CurrOpnd;
1494 } else {
1495 CurrOpnd->Invalidate();
1496 PrevOpnd = nullptr;
1497 }
1498 Changed = true;
1499 }
1500 }
1501
1502 // Step 4: Reassemble the Ops
1503 if (Changed) {
1504 Ops.clear();
1505 for (unsigned int i = 0, e = Opnds.size(); i < e; i++) {
1506 XorOpnd &O = Opnds[i];
1507 if (O.isInvalid())
1508 continue;
1509 ValueEntry VE(getRank(O.getValue()), O.getValue());
1510 Ops.push_back(VE);
1511 }
1512 if (!ConstOpnd.isZero()) {
1513 Value *C = ConstantInt::get(Ty, ConstOpnd);
1514 ValueEntry VE(getRank(C), C);
1515 Ops.push_back(VE);
1516 }
1517 unsigned Sz = Ops.size();
1518 if (Sz == 1)
1519 return Ops.back().Op;
1520 if (Sz == 0) {
1521 assert(ConstOpnd.isZero())(static_cast <bool> (ConstOpnd.isZero()) ? void (0) : __assert_fail
("ConstOpnd.isZero()", "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 1521, __extension__ __PRETTY_FUNCTION__))
;
1522 return ConstantInt::get(Ty, ConstOpnd);
1523 }
1524 }
1525
1526 return nullptr;
1527}
1528
1529/// Optimize a series of operands to an 'add' instruction. This
1530/// optimizes based on identities. If it can be reduced to a single Value, it
1531/// is returned, otherwise the Ops list is mutated as necessary.
1532Value *ReassociatePass::OptimizeAdd(Instruction *I,
1533 SmallVectorImpl<ValueEntry> &Ops) {
1534 // Scan the operand lists looking for X and -X pairs. If we find any, we
1535 // can simplify expressions like X+-X == 0 and X+~X ==-1. While we're at it,
1536 // scan for any
1537 // duplicates. We want to canonicalize Y+Y+Y+Z -> 3*Y+Z.
1538
1539 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
1540 Value *TheOp = Ops[i].Op;
1541 // Check to see if we've seen this operand before. If so, we factor all
1542 // instances of the operand together. Due to our sorting criteria, we know
1543 // that these need to be next to each other in the vector.
1544 if (i+1 != Ops.size() && Ops[i+1].Op == TheOp) {
1545 // Rescan the list, remove all instances of this operand from the expr.
1546 unsigned NumFound = 0;
1547 do {
1548 Ops.erase(Ops.begin()+i);
1549 ++NumFound;
1550 } while (i != Ops.size() && Ops[i].Op == TheOp);
1551
1552 LLVM_DEBUG(dbgs() << "\nFACTORING [" << NumFound << "]: " << *TheOpdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "\nFACTORING [" << NumFound
<< "]: " << *TheOp << '\n'; } } while (false
)
1553 << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "\nFACTORING [" << NumFound
<< "]: " << *TheOp << '\n'; } } while (false
)
;
1554 ++NumFactor;
1555
1556 // Insert a new multiply.
1557 Type *Ty = TheOp->getType();
1558 Constant *C = Ty->isIntOrIntVectorTy() ?
1559 ConstantInt::get(Ty, NumFound) : ConstantFP::get(Ty, NumFound);
1560 Instruction *Mul = CreateMul(TheOp, C, "factor", I, I);
1561
1562 // Now that we have inserted a multiply, optimize it. This allows us to
1563 // handle cases that require multiple factoring steps, such as this:
1564 // (X*2) + (X*2) + (X*2) -> (X*2)*3 -> X*6
1565 RedoInsts.insert(Mul);
1566
1567 // If every add operand was a duplicate, return the multiply.
1568 if (Ops.empty())
1569 return Mul;
1570
1571 // Otherwise, we had some input that didn't have the dupe, such as
1572 // "A + A + B" -> "A*2 + B". Add the new multiply to the list of
1573 // things being added by this operation.
1574 Ops.insert(Ops.begin(), ValueEntry(getRank(Mul), Mul));
1575
1576 --i;
1577 e = Ops.size();
1578 continue;
1579 }
1580
1581 // Check for X and -X or X and ~X in the operand list.
1582 Value *X;
1583 if (!match(TheOp, m_Neg(m_Value(X))) && !match(TheOp, m_Not(m_Value(X))) &&
1584 !match(TheOp, m_FNeg(m_Value(X))))
1585 continue;
1586
1587 unsigned FoundX = FindInOperandList(Ops, i, X);
1588 if (FoundX == i)
1589 continue;
1590
1591 // Remove X and -X from the operand list.
1592 if (Ops.size() == 2 &&
1593 (match(TheOp, m_Neg(m_Value())) || match(TheOp, m_FNeg(m_Value()))))
1594 return Constant::getNullValue(X->getType());
1595
1596 // Remove X and ~X from the operand list.
1597 if (Ops.size() == 2 && match(TheOp, m_Not(m_Value())))
1598 return Constant::getAllOnesValue(X->getType());
1599
1600 Ops.erase(Ops.begin()+i);
1601 if (i < FoundX)
1602 --FoundX;
1603 else
1604 --i; // Need to back up an extra one.
1605 Ops.erase(Ops.begin()+FoundX);
1606 ++NumAnnihil;
1607 --i; // Revisit element.
1608 e -= 2; // Removed two elements.
1609
1610 // if X and ~X we append -1 to the operand list.
1611 if (match(TheOp, m_Not(m_Value()))) {
1612 Value *V = Constant::getAllOnesValue(X->getType());
1613 Ops.insert(Ops.end(), ValueEntry(getRank(V), V));
1614 e += 1;
1615 }
1616 }
1617
1618 // Scan the operand list, checking to see if there are any common factors
1619 // between operands. Consider something like A*A+A*B*C+D. We would like to
1620 // reassociate this to A*(A+B*C)+D, which reduces the number of multiplies.
1621 // To efficiently find this, we count the number of times a factor occurs
1622 // for any ADD operands that are MULs.
1623 DenseMap<Value*, unsigned> FactorOccurrences;
1624
1625 // Keep track of each multiply we see, to avoid triggering on (X*4)+(X*4)
1626 // where they are actually the same multiply.
1627 unsigned MaxOcc = 0;
1628 Value *MaxOccVal = nullptr;
1629 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
1630 BinaryOperator *BOp =
1631 isReassociableOp(Ops[i].Op, Instruction::Mul, Instruction::FMul);
1632 if (!BOp)
1633 continue;
1634
1635 // Compute all of the factors of this added value.
1636 SmallVector<Value*, 8> Factors;
1637 FindSingleUseMultiplyFactors(BOp, Factors);
1638 assert(Factors.size() > 1 && "Bad linearize!")(static_cast <bool> (Factors.size() > 1 && "Bad linearize!"
) ? void (0) : __assert_fail ("Factors.size() > 1 && \"Bad linearize!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 1638, __extension__ __PRETTY_FUNCTION__))
;
1639
1640 // Add one to FactorOccurrences for each unique factor in this op.
1641 SmallPtrSet<Value*, 8> Duplicates;
1642 for (unsigned i = 0, e = Factors.size(); i != e; ++i) {
1643 Value *Factor = Factors[i];
1644 if (!Duplicates.insert(Factor).second)
1645 continue;
1646
1647 unsigned Occ = ++FactorOccurrences[Factor];
1648 if (Occ > MaxOcc) {
1649 MaxOcc = Occ;
1650 MaxOccVal = Factor;
1651 }
1652
1653 // If Factor is a negative constant, add the negated value as a factor
1654 // because we can percolate the negate out. Watch for minint, which
1655 // cannot be positivified.
1656 if (ConstantInt *CI = dyn_cast<ConstantInt>(Factor)) {
1657 if (CI->isNegative() && !CI->isMinValue(true)) {
1658 Factor = ConstantInt::get(CI->getContext(), -CI->getValue());
1659 if (!Duplicates.insert(Factor).second)
1660 continue;
1661 unsigned Occ = ++FactorOccurrences[Factor];
1662 if (Occ > MaxOcc) {
1663 MaxOcc = Occ;
1664 MaxOccVal = Factor;
1665 }
1666 }
1667 } else if (ConstantFP *CF = dyn_cast<ConstantFP>(Factor)) {
1668 if (CF->isNegative()) {
1669 APFloat F(CF->getValueAPF());
1670 F.changeSign();
1671 Factor = ConstantFP::get(CF->getContext(), F);
1672 if (!Duplicates.insert(Factor).second)
1673 continue;
1674 unsigned Occ = ++FactorOccurrences[Factor];
1675 if (Occ > MaxOcc) {
1676 MaxOcc = Occ;
1677 MaxOccVal = Factor;
1678 }
1679 }
1680 }
1681 }
1682 }
1683
1684 // If any factor occurred more than one time, we can pull it out.
1685 if (MaxOcc > 1) {
1686 LLVM_DEBUG(dbgs() << "\nFACTORING [" << MaxOcc << "]: " << *MaxOccValdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "\nFACTORING [" << MaxOcc
<< "]: " << *MaxOccVal << '\n'; } } while (
false)
1687 << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "\nFACTORING [" << MaxOcc
<< "]: " << *MaxOccVal << '\n'; } } while (
false)
;
1688 ++NumFactor;
1689
1690 // Create a new instruction that uses the MaxOccVal twice. If we don't do
1691 // this, we could otherwise run into situations where removing a factor
1692 // from an expression will drop a use of maxocc, and this can cause
1693 // RemoveFactorFromExpression on successive values to behave differently.
1694 Instruction *DummyInst =
1695 I->getType()->isIntOrIntVectorTy()
1696 ? BinaryOperator::CreateAdd(MaxOccVal, MaxOccVal)
1697 : BinaryOperator::CreateFAdd(MaxOccVal, MaxOccVal);
1698
1699 SmallVector<WeakTrackingVH, 4> NewMulOps;
1700 for (unsigned i = 0; i != Ops.size(); ++i) {
1701 // Only try to remove factors from expressions we're allowed to.
1702 BinaryOperator *BOp =
1703 isReassociableOp(Ops[i].Op, Instruction::Mul, Instruction::FMul);
1704 if (!BOp)
1705 continue;
1706
1707 if (Value *V = RemoveFactorFromExpression(Ops[i].Op, MaxOccVal)) {
1708 // The factorized operand may occur several times. Convert them all in
1709 // one fell swoop.
1710 for (unsigned j = Ops.size(); j != i;) {
1711 --j;
1712 if (Ops[j].Op == Ops[i].Op) {
1713 NewMulOps.push_back(V);
1714 Ops.erase(Ops.begin()+j);
1715 }
1716 }
1717 --i;
1718 }
1719 }
1720
1721 // No need for extra uses anymore.
1722 DummyInst->deleteValue();
1723
1724 unsigned NumAddedValues = NewMulOps.size();
1725 Value *V = EmitAddTreeOfValues(I, NewMulOps);
1726
1727 // Now that we have inserted the add tree, optimize it. This allows us to
1728 // handle cases that require multiple factoring steps, such as this:
1729 // A*A*B + A*A*C --> A*(A*B+A*C) --> A*(A*(B+C))
1730 assert(NumAddedValues > 1 && "Each occurrence should contribute a value")(static_cast <bool> (NumAddedValues > 1 && "Each occurrence should contribute a value"
) ? void (0) : __assert_fail ("NumAddedValues > 1 && \"Each occurrence should contribute a value\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 1730, __extension__ __PRETTY_FUNCTION__))
;
1731 (void)NumAddedValues;
1732 if (Instruction *VI = dyn_cast<Instruction>(V))
1733 RedoInsts.insert(VI);
1734
1735 // Create the multiply.
1736 Instruction *V2 = CreateMul(V, MaxOccVal, "reass.mul", I, I);
1737
1738 // Rerun associate on the multiply in case the inner expression turned into
1739 // a multiply. We want to make sure that we keep things in canonical form.
1740 RedoInsts.insert(V2);
1741
1742 // If every add operand included the factor (e.g. "A*B + A*C"), then the
1743 // entire result expression is just the multiply "A*(B+C)".
1744 if (Ops.empty())
1745 return V2;
1746
1747 // Otherwise, we had some input that didn't have the factor, such as
1748 // "A*B + A*C + D" -> "A*(B+C) + D". Add the new multiply to the list of
1749 // things being added by this operation.
1750 Ops.insert(Ops.begin(), ValueEntry(getRank(V2), V2));
1751 }
1752
1753 return nullptr;
1754}
1755
1756/// Build up a vector of value/power pairs factoring a product.
1757///
1758/// Given a series of multiplication operands, build a vector of factors and
1759/// the powers each is raised to when forming the final product. Sort them in
1760/// the order of descending power.
1761///
1762/// (x*x) -> [(x, 2)]
1763/// ((x*x)*x) -> [(x, 3)]
1764/// ((((x*y)*x)*y)*x) -> [(x, 3), (y, 2)]
1765///
1766/// \returns Whether any factors have a power greater than one.
1767static bool collectMultiplyFactors(SmallVectorImpl<ValueEntry> &Ops,
1768 SmallVectorImpl<Factor> &Factors) {
1769 // FIXME: Have Ops be (ValueEntry, Multiplicity) pairs, simplifying this.
1770 // Compute the sum of powers of simplifiable factors.
1771 unsigned FactorPowerSum = 0;
1772 for (unsigned Idx = 1, Size = Ops.size(); Idx < Size; ++Idx) {
1773 Value *Op = Ops[Idx-1].Op;
1774
1775 // Count the number of occurrences of this value.
1776 unsigned Count = 1;
1777 for (; Idx < Size && Ops[Idx].Op == Op; ++Idx)
1778 ++Count;
1779 // Track for simplification all factors which occur 2 or more times.
1780 if (Count > 1)
1781 FactorPowerSum += Count;
1782 }
1783
1784 // We can only simplify factors if the sum of the powers of our simplifiable
1785 // factors is 4 or higher. When that is the case, we will *always* have
1786 // a simplification. This is an important invariant to prevent cyclicly
1787 // trying to simplify already minimal formations.
1788 if (FactorPowerSum < 4)
1789 return false;
1790
1791 // Now gather the simplifiable factors, removing them from Ops.
1792 FactorPowerSum = 0;
1793 for (unsigned Idx = 1; Idx < Ops.size(); ++Idx) {
1794 Value *Op = Ops[Idx-1].Op;
1795
1796 // Count the number of occurrences of this value.
1797 unsigned Count = 1;
1798 for (; Idx < Ops.size() && Ops[Idx].Op == Op; ++Idx)
1799 ++Count;
1800 if (Count == 1)
1801 continue;
1802 // Move an even number of occurrences to Factors.
1803 Count &= ~1U;
1804 Idx -= Count;
1805 FactorPowerSum += Count;
1806 Factors.push_back(Factor(Op, Count));
1807 Ops.erase(Ops.begin()+Idx, Ops.begin()+Idx+Count);
1808 }
1809
1810 // None of the adjustments above should have reduced the sum of factor powers
1811 // below our mininum of '4'.
1812 assert(FactorPowerSum >= 4)(static_cast <bool> (FactorPowerSum >= 4) ? void (0)
: __assert_fail ("FactorPowerSum >= 4", "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 1812, __extension__ __PRETTY_FUNCTION__))
;
1813
1814 llvm::stable_sort(Factors, [](const Factor &LHS, const Factor &RHS) {
1815 return LHS.Power > RHS.Power;
1816 });
1817 return true;
1818}
1819
1820/// Build a tree of multiplies, computing the product of Ops.
1821static Value *buildMultiplyTree(IRBuilderBase &Builder,
1822 SmallVectorImpl<Value*> &Ops) {
1823 if (Ops.size() == 1)
1824 return Ops.back();
1825
1826 Value *LHS = Ops.pop_back_val();
1827 do {
1828 if (LHS->getType()->isIntOrIntVectorTy())
1829 LHS = Builder.CreateMul(LHS, Ops.pop_back_val());
1830 else
1831 LHS = Builder.CreateFMul(LHS, Ops.pop_back_val());
1832 } while (!Ops.empty());
1833
1834 return LHS;
1835}
1836
1837/// Build a minimal multiplication DAG for (a^x)*(b^y)*(c^z)*...
1838///
1839/// Given a vector of values raised to various powers, where no two values are
1840/// equal and the powers are sorted in decreasing order, compute the minimal
1841/// DAG of multiplies to compute the final product, and return that product
1842/// value.
1843Value *
1844ReassociatePass::buildMinimalMultiplyDAG(IRBuilderBase &Builder,
1845 SmallVectorImpl<Factor> &Factors) {
1846 assert(Factors[0].Power)(static_cast <bool> (Factors[0].Power) ? void (0) : __assert_fail
("Factors[0].Power", "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 1846, __extension__ __PRETTY_FUNCTION__))
;
1847 SmallVector<Value *, 4> OuterProduct;
1848 for (unsigned LastIdx = 0, Idx = 1, Size = Factors.size();
1849 Idx < Size && Factors[Idx].Power > 0; ++Idx) {
1850 if (Factors[Idx].Power != Factors[LastIdx].Power) {
1851 LastIdx = Idx;
1852 continue;
1853 }
1854
1855 // We want to multiply across all the factors with the same power so that
1856 // we can raise them to that power as a single entity. Build a mini tree
1857 // for that.
1858 SmallVector<Value *, 4> InnerProduct;
1859 InnerProduct.push_back(Factors[LastIdx].Base);
1860 do {
1861 InnerProduct.push_back(Factors[Idx].Base);
1862 ++Idx;
1863 } while (Idx < Size && Factors[Idx].Power == Factors[LastIdx].Power);
1864
1865 // Reset the base value of the first factor to the new expression tree.
1866 // We'll remove all the factors with the same power in a second pass.
1867 Value *M = Factors[LastIdx].Base = buildMultiplyTree(Builder, InnerProduct);
1868 if (Instruction *MI = dyn_cast<Instruction>(M))
1869 RedoInsts.insert(MI);
1870
1871 LastIdx = Idx;
1872 }
1873 // Unique factors with equal powers -- we've folded them into the first one's
1874 // base.
1875 Factors.erase(std::unique(Factors.begin(), Factors.end(),
1876 [](const Factor &LHS, const Factor &RHS) {
1877 return LHS.Power == RHS.Power;
1878 }),
1879 Factors.end());
1880
1881 // Iteratively collect the base of each factor with an add power into the
1882 // outer product, and halve each power in preparation for squaring the
1883 // expression.
1884 for (unsigned Idx = 0, Size = Factors.size(); Idx != Size; ++Idx) {
1885 if (Factors[Idx].Power & 1)
1886 OuterProduct.push_back(Factors[Idx].Base);
1887 Factors[Idx].Power >>= 1;
1888 }
1889 if (Factors[0].Power) {
1890 Value *SquareRoot = buildMinimalMultiplyDAG(Builder, Factors);
1891 OuterProduct.push_back(SquareRoot);
1892 OuterProduct.push_back(SquareRoot);
1893 }
1894 if (OuterProduct.size() == 1)
1895 return OuterProduct.front();
1896
1897 Value *V = buildMultiplyTree(Builder, OuterProduct);
1898 return V;
1899}
1900
1901Value *ReassociatePass::OptimizeMul(BinaryOperator *I,
1902 SmallVectorImpl<ValueEntry> &Ops) {
1903 // We can only optimize the multiplies when there is a chain of more than
1904 // three, such that a balanced tree might require fewer total multiplies.
1905 if (Ops.size() < 4)
1906 return nullptr;
1907
1908 // Try to turn linear trees of multiplies without other uses of the
1909 // intermediate stages into minimal multiply DAGs with perfect sub-expression
1910 // re-use.
1911 SmallVector<Factor, 4> Factors;
1912 if (!collectMultiplyFactors(Ops, Factors))
1913 return nullptr; // All distinct factors, so nothing left for us to do.
1914
1915 IRBuilder<> Builder(I);
1916 // The reassociate transformation for FP operations is performed only
1917 // if unsafe algebra is permitted by FastMathFlags. Propagate those flags
1918 // to the newly generated operations.
1919 if (auto FPI = dyn_cast<FPMathOperator>(I))
1920 Builder.setFastMathFlags(FPI->getFastMathFlags());
1921
1922 Value *V = buildMinimalMultiplyDAG(Builder, Factors);
1923 if (Ops.empty())
1924 return V;
1925
1926 ValueEntry NewEntry = ValueEntry(getRank(V), V);
1927 Ops.insert(llvm::lower_bound(Ops, NewEntry), NewEntry);
1928 return nullptr;
1929}
1930
1931Value *ReassociatePass::OptimizeExpression(BinaryOperator *I,
1932 SmallVectorImpl<ValueEntry> &Ops) {
1933 // Now that we have the linearized expression tree, try to optimize it.
1934 // Start by folding any constants that we found.
1935 Constant *Cst = nullptr;
1936 unsigned Opcode = I->getOpcode();
1937 while (!Ops.empty() && isa<Constant>(Ops.back().Op)) {
1938 Constant *C = cast<Constant>(Ops.pop_back_val().Op);
1939 Cst = Cst ? ConstantExpr::get(Opcode, C, Cst) : C;
1940 }
1941 // If there was nothing but constants then we are done.
1942 if (Ops.empty())
1943 return Cst;
1944
1945 // Put the combined constant back at the end of the operand list, except if
1946 // there is no point. For example, an add of 0 gets dropped here, while a
1947 // multiplication by zero turns the whole expression into zero.
1948 if (Cst && Cst != ConstantExpr::getBinOpIdentity(Opcode, I->getType())) {
1949 if (Cst == ConstantExpr::getBinOpAbsorber(Opcode, I->getType()))
1950 return Cst;
1951 Ops.push_back(ValueEntry(0, Cst));
1952 }
1953
1954 if (Ops.size() == 1) return Ops[0].Op;
1955
1956 // Handle destructive annihilation due to identities between elements in the
1957 // argument list here.
1958 unsigned NumOps = Ops.size();
1959 switch (Opcode) {
1960 default: break;
1961 case Instruction::And:
1962 case Instruction::Or:
1963 if (Value *Result = OptimizeAndOrXor(Opcode, Ops))
1964 return Result;
1965 break;
1966
1967 case Instruction::Xor:
1968 if (Value *Result = OptimizeXor(I, Ops))
1969 return Result;
1970 break;
1971
1972 case Instruction::Add:
1973 case Instruction::FAdd:
1974 if (Value *Result = OptimizeAdd(I, Ops))
1975 return Result;
1976 break;
1977
1978 case Instruction::Mul:
1979 case Instruction::FMul:
1980 if (Value *Result = OptimizeMul(I, Ops))
1981 return Result;
1982 break;
1983 }
1984
1985 if (Ops.size() != NumOps)
1986 return OptimizeExpression(I, Ops);
1987 return nullptr;
1988}
1989
1990// Remove dead instructions and if any operands are trivially dead add them to
1991// Insts so they will be removed as well.
1992void ReassociatePass::RecursivelyEraseDeadInsts(Instruction *I,
1993 OrderedSet &Insts) {
1994 assert(isInstructionTriviallyDead(I) && "Trivially dead instructions only!")(static_cast <bool> (isInstructionTriviallyDead(I) &&
"Trivially dead instructions only!") ? void (0) : __assert_fail
("isInstructionTriviallyDead(I) && \"Trivially dead instructions only!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 1994, __extension__ __PRETTY_FUNCTION__))
;
1995 SmallVector<Value *, 4> Ops(I->operands());
1996 ValueRankMap.erase(I);
1997 Insts.remove(I);
1998 RedoInsts.remove(I);
1999 llvm::salvageDebugInfo(*I);
2000 I->eraseFromParent();
2001 for (auto Op : Ops)
2002 if (Instruction *OpInst = dyn_cast<Instruction>(Op))
2003 if (OpInst->use_empty())
2004 Insts.insert(OpInst);
2005}
2006
2007/// Zap the given instruction, adding interesting operands to the work list.
2008void ReassociatePass::EraseInst(Instruction *I) {
2009 assert(isInstructionTriviallyDead(I) && "Trivially dead instructions only!")(static_cast <bool> (isInstructionTriviallyDead(I) &&
"Trivially dead instructions only!") ? void (0) : __assert_fail
("isInstructionTriviallyDead(I) && \"Trivially dead instructions only!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2009, __extension__ __PRETTY_FUNCTION__))
;
2010 LLVM_DEBUG(dbgs() << "Erasing dead inst: "; I->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "Erasing dead inst: "; I->
dump(); } } while (false)
;
2011
2012 SmallVector<Value *, 8> Ops(I->operands());
2013 // Erase the dead instruction.
2014 ValueRankMap.erase(I);
2015 RedoInsts.remove(I);
2016 llvm::salvageDebugInfo(*I);
2017 I->eraseFromParent();
2018 // Optimize its operands.
2019 SmallPtrSet<Instruction *, 8> Visited; // Detect self-referential nodes.
2020 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2021 if (Instruction *Op = dyn_cast<Instruction>(Ops[i])) {
2022 // If this is a node in an expression tree, climb to the expression root
2023 // and add that since that's where optimization actually happens.
2024 unsigned Opcode = Op->getOpcode();
2025 while (Op->hasOneUse() && Op->user_back()->getOpcode() == Opcode &&
2026 Visited.insert(Op).second)
2027 Op = Op->user_back();
2028
2029 // The instruction we're going to push may be coming from a
2030 // dead block, and Reassociate skips the processing of unreachable
2031 // blocks because it's a waste of time and also because it can
2032 // lead to infinite loop due to LLVM's non-standard definition
2033 // of dominance.
2034 if (ValueRankMap.find(Op) != ValueRankMap.end())
2035 RedoInsts.insert(Op);
2036 }
2037
2038 MadeChange = true;
2039}
2040
2041/// Recursively analyze an expression to build a list of instructions that have
2042/// negative floating-point constant operands. The caller can then transform
2043/// the list to create positive constants for better reassociation and CSE.
2044static void getNegatibleInsts(Value *V,
2045 SmallVectorImpl<Instruction *> &Candidates) {
2046 // Handle only one-use instructions. Combining negations does not justify
2047 // replicating instructions.
2048 Instruction *I;
2049 if (!match(V, m_OneUse(m_Instruction(I))))
2050 return;
2051
2052 // Handle expressions of multiplications and divisions.
2053 // TODO: This could look through floating-point casts.
2054 const APFloat *C;
2055 switch (I->getOpcode()) {
2056 case Instruction::FMul:
2057 // Not expecting non-canonical code here. Bail out and wait.
2058 if (match(I->getOperand(0), m_Constant()))
2059 break;
2060
2061 if (match(I->getOperand(1), m_APFloat(C)) && C->isNegative()) {
2062 Candidates.push_back(I);
2063 LLVM_DEBUG(dbgs() << "FMul with negative constant: " << *I << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "FMul with negative constant: "
<< *I << '\n'; } } while (false)
;
2064 }
2065 getNegatibleInsts(I->getOperand(0), Candidates);
2066 getNegatibleInsts(I->getOperand(1), Candidates);
2067 break;
2068 case Instruction::FDiv:
2069 // Not expecting non-canonical code here. Bail out and wait.
2070 if (match(I->getOperand(0), m_Constant()) &&
2071 match(I->getOperand(1), m_Constant()))
2072 break;
2073
2074 if ((match(I->getOperand(0), m_APFloat(C)) && C->isNegative()) ||
2075 (match(I->getOperand(1), m_APFloat(C)) && C->isNegative())) {
2076 Candidates.push_back(I);
2077 LLVM_DEBUG(dbgs() << "FDiv with negative constant: " << *I << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "FDiv with negative constant: "
<< *I << '\n'; } } while (false)
;
2078 }
2079 getNegatibleInsts(I->getOperand(0), Candidates);
2080 getNegatibleInsts(I->getOperand(1), Candidates);
2081 break;
2082 default:
2083 break;
2084 }
2085}
2086
2087/// Given an fadd/fsub with an operand that is a one-use instruction
2088/// (the fadd/fsub), try to change negative floating-point constants into
2089/// positive constants to increase potential for reassociation and CSE.
2090Instruction *ReassociatePass::canonicalizeNegFPConstantsForOp(Instruction *I,
2091 Instruction *Op,
2092 Value *OtherOp) {
2093 assert((I->getOpcode() == Instruction::FAdd ||(static_cast <bool> ((I->getOpcode() == Instruction::
FAdd || I->getOpcode() == Instruction::FSub) && "Expected fadd/fsub"
) ? void (0) : __assert_fail ("(I->getOpcode() == Instruction::FAdd || I->getOpcode() == Instruction::FSub) && \"Expected fadd/fsub\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2094, __extension__ __PRETTY_FUNCTION__))
2094 I->getOpcode() == Instruction::FSub) && "Expected fadd/fsub")(static_cast <bool> ((I->getOpcode() == Instruction::
FAdd || I->getOpcode() == Instruction::FSub) && "Expected fadd/fsub"
) ? void (0) : __assert_fail ("(I->getOpcode() == Instruction::FAdd || I->getOpcode() == Instruction::FSub) && \"Expected fadd/fsub\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2094, __extension__ __PRETTY_FUNCTION__))
;
2095
2096 // Collect instructions with negative FP constants from the subtree that ends
2097 // in Op.
2098 SmallVector<Instruction *, 4> Candidates;
2099 getNegatibleInsts(Op, Candidates);
2100 if (Candidates.empty())
2101 return nullptr;
2102
2103 // Don't canonicalize x + (-Constant * y) -> x - (Constant * y), if the
2104 // resulting subtract will be broken up later. This can get us into an
2105 // infinite loop during reassociation.
2106 bool IsFSub = I->getOpcode() == Instruction::FSub;
2107 bool NeedsSubtract = !IsFSub && Candidates.size() % 2 == 1;
2108 if (NeedsSubtract && ShouldBreakUpSubtract(I))
2109 return nullptr;
2110
2111 for (Instruction *Negatible : Candidates) {
2112 const APFloat *C;
2113 if (match(Negatible->getOperand(0), m_APFloat(C))) {
2114 assert(!match(Negatible->getOperand(1), m_Constant()) &&(static_cast <bool> (!match(Negatible->getOperand(1)
, m_Constant()) && "Expecting only 1 constant operand"
) ? void (0) : __assert_fail ("!match(Negatible->getOperand(1), m_Constant()) && \"Expecting only 1 constant operand\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2115, __extension__ __PRETTY_FUNCTION__))
2115 "Expecting only 1 constant operand")(static_cast <bool> (!match(Negatible->getOperand(1)
, m_Constant()) && "Expecting only 1 constant operand"
) ? void (0) : __assert_fail ("!match(Negatible->getOperand(1), m_Constant()) && \"Expecting only 1 constant operand\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2115, __extension__ __PRETTY_FUNCTION__))
;
2116 assert(C->isNegative() && "Expected negative FP constant")(static_cast <bool> (C->isNegative() && "Expected negative FP constant"
) ? void (0) : __assert_fail ("C->isNegative() && \"Expected negative FP constant\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2116, __extension__ __PRETTY_FUNCTION__))
;
2117 Negatible->setOperand(0, ConstantFP::get(Negatible->getType(), abs(*C)));
2118 MadeChange = true;
2119 }
2120 if (match(Negatible->getOperand(1), m_APFloat(C))) {
2121 assert(!match(Negatible->getOperand(0), m_Constant()) &&(static_cast <bool> (!match(Negatible->getOperand(0)
, m_Constant()) && "Expecting only 1 constant operand"
) ? void (0) : __assert_fail ("!match(Negatible->getOperand(0), m_Constant()) && \"Expecting only 1 constant operand\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2122, __extension__ __PRETTY_FUNCTION__))
2122 "Expecting only 1 constant operand")(static_cast <bool> (!match(Negatible->getOperand(0)
, m_Constant()) && "Expecting only 1 constant operand"
) ? void (0) : __assert_fail ("!match(Negatible->getOperand(0), m_Constant()) && \"Expecting only 1 constant operand\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2122, __extension__ __PRETTY_FUNCTION__))
;
2123 assert(C->isNegative() && "Expected negative FP constant")(static_cast <bool> (C->isNegative() && "Expected negative FP constant"
) ? void (0) : __assert_fail ("C->isNegative() && \"Expected negative FP constant\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2123, __extension__ __PRETTY_FUNCTION__))
;
2124 Negatible->setOperand(1, ConstantFP::get(Negatible->getType(), abs(*C)));
2125 MadeChange = true;
2126 }
2127 }
2128 assert(MadeChange == true && "Negative constant candidate was not changed")(static_cast <bool> (MadeChange == true && "Negative constant candidate was not changed"
) ? void (0) : __assert_fail ("MadeChange == true && \"Negative constant candidate was not changed\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2128, __extension__ __PRETTY_FUNCTION__))
;
2129
2130 // Negations cancelled out.
2131 if (Candidates.size() % 2 == 0)
2132 return I;
2133
2134 // Negate the final operand in the expression by flipping the opcode of this
2135 // fadd/fsub.
2136 assert(Candidates.size() % 2 == 1 && "Expected odd number")(static_cast <bool> (Candidates.size() % 2 == 1 &&
"Expected odd number") ? void (0) : __assert_fail ("Candidates.size() % 2 == 1 && \"Expected odd number\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2136, __extension__ __PRETTY_FUNCTION__))
;
2137 IRBuilder<> Builder(I);
2138 Value *NewInst = IsFSub ? Builder.CreateFAddFMF(OtherOp, Op, I)
2139 : Builder.CreateFSubFMF(OtherOp, Op, I);
2140 I->replaceAllUsesWith(NewInst);
2141 RedoInsts.insert(I);
2142 return dyn_cast<Instruction>(NewInst);
2143}
2144
2145/// Canonicalize expressions that contain a negative floating-point constant
2146/// of the following form:
2147/// OtherOp + (subtree) -> OtherOp {+/-} (canonical subtree)
2148/// (subtree) + OtherOp -> OtherOp {+/-} (canonical subtree)
2149/// OtherOp - (subtree) -> OtherOp {+/-} (canonical subtree)
2150///
2151/// The fadd/fsub opcode may be switched to allow folding a negation into the
2152/// input instruction.
2153Instruction *ReassociatePass::canonicalizeNegFPConstants(Instruction *I) {
2154 LLVM_DEBUG(dbgs() << "Combine negations for: " << *I << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "Combine negations for: " <<
*I << '\n'; } } while (false)
;
2155 Value *X;
2156 Instruction *Op;
2157 if (match(I, m_FAdd(m_Value(X), m_OneUse(m_Instruction(Op)))))
2158 if (Instruction *R = canonicalizeNegFPConstantsForOp(I, Op, X))
2159 I = R;
2160 if (match(I, m_FAdd(m_OneUse(m_Instruction(Op)), m_Value(X))))
2161 if (Instruction *R = canonicalizeNegFPConstantsForOp(I, Op, X))
2162 I = R;
2163 if (match(I, m_FSub(m_Value(X), m_OneUse(m_Instruction(Op)))))
2164 if (Instruction *R = canonicalizeNegFPConstantsForOp(I, Op, X))
2165 I = R;
2166 return I;
2167}
2168
2169/// Inspect and optimize the given instruction. Note that erasing
2170/// instructions is not allowed.
2171void ReassociatePass::OptimizeInst(Instruction *I) {
2172 // Only consider operations that we understand.
2173 if (!isa<UnaryOperator>(I) && !isa<BinaryOperator>(I))
2174 return;
2175
2176 if (I->getOpcode() == Instruction::Shl && isa<ConstantInt>(I->getOperand(1)))
2177 // If an operand of this shift is a reassociable multiply, or if the shift
2178 // is used by a reassociable multiply or add, turn into a multiply.
2179 if (isReassociableOp(I->getOperand(0), Instruction::Mul) ||
2180 (I->hasOneUse() &&
2181 (isReassociableOp(I->user_back(), Instruction::Mul) ||
2182 isReassociableOp(I->user_back(), Instruction::Add)))) {
2183 Instruction *NI = ConvertShiftToMul(I);
2184 RedoInsts.insert(I);
2185 MadeChange = true;
2186 I = NI;
2187 }
2188
2189 // Commute binary operators, to canonicalize the order of their operands.
2190 // This can potentially expose more CSE opportunities, and makes writing other
2191 // transformations simpler.
2192 if (I->isCommutative())
2193 canonicalizeOperands(I);
2194
2195 // Canonicalize negative constants out of expressions.
2196 if (Instruction *Res = canonicalizeNegFPConstants(I))
2197 I = Res;
2198
2199 // Don't optimize floating-point instructions unless they are 'fast'.
2200 if (I->getType()->isFPOrFPVectorTy() && !I->isFast())
2201 return;
2202
2203 // Do not reassociate boolean (i1) expressions. We want to preserve the
2204 // original order of evaluation for short-circuited comparisons that
2205 // SimplifyCFG has folded to AND/OR expressions. If the expression
2206 // is not further optimized, it is likely to be transformed back to a
2207 // short-circuited form for code gen, and the source order may have been
2208 // optimized for the most likely conditions.
2209 if (I->getType()->isIntegerTy(1))
2210 return;
2211
2212 // If this is a bitwise or instruction of operands
2213 // with no common bits set, convert it to X+Y.
2214 if (I->getOpcode() == Instruction::Or &&
2215 shouldConvertOrWithNoCommonBitsToAdd(I) && !isLoadCombineCandidate(I) &&
2216 haveNoCommonBitsSet(I->getOperand(0), I->getOperand(1),
2217 I->getModule()->getDataLayout(), /*AC=*/nullptr, I,
2218 /*DT=*/nullptr)) {
2219 Instruction *NI = convertOrWithNoCommonBitsToAdd(I);
2220 RedoInsts.insert(I);
2221 MadeChange = true;
2222 I = NI;
2223 }
2224
2225 // If this is a subtract instruction which is not already in negate form,
2226 // see if we can convert it to X+-Y.
2227 if (I->getOpcode() == Instruction::Sub) {
2228 if (ShouldBreakUpSubtract(I)) {
2229 Instruction *NI = BreakUpSubtract(I, RedoInsts);
2230 RedoInsts.insert(I);
2231 MadeChange = true;
2232 I = NI;
2233 } else if (match(I, m_Neg(m_Value()))) {
2234 // Otherwise, this is a negation. See if the operand is a multiply tree
2235 // and if this is not an inner node of a multiply tree.
2236 if (isReassociableOp(I->getOperand(1), Instruction::Mul) &&
2237 (!I->hasOneUse() ||
2238 !isReassociableOp(I->user_back(), Instruction::Mul))) {
2239 Instruction *NI = LowerNegateToMultiply(I);
2240 // If the negate was simplified, revisit the users to see if we can
2241 // reassociate further.
2242 for (User *U : NI->users()) {
2243 if (BinaryOperator *Tmp = dyn_cast<BinaryOperator>(U))
2244 RedoInsts.insert(Tmp);
2245 }
2246 RedoInsts.insert(I);
2247 MadeChange = true;
2248 I = NI;
2249 }
2250 }
2251 } else if (I->getOpcode() == Instruction::FNeg ||
2252 I->getOpcode() == Instruction::FSub) {
2253 if (ShouldBreakUpSubtract(I)) {
2254 Instruction *NI = BreakUpSubtract(I, RedoInsts);
2255 RedoInsts.insert(I);
2256 MadeChange = true;
2257 I = NI;
2258 } else if (match(I, m_FNeg(m_Value()))) {
2259 // Otherwise, this is a negation. See if the operand is a multiply tree
2260 // and if this is not an inner node of a multiply tree.
2261 Value *Op = isa<BinaryOperator>(I) ? I->getOperand(1) :
2262 I->getOperand(0);
2263 if (isReassociableOp(Op, Instruction::FMul) &&
2264 (!I->hasOneUse() ||
2265 !isReassociableOp(I->user_back(), Instruction::FMul))) {
2266 // If the negate was simplified, revisit the users to see if we can
2267 // reassociate further.
2268 Instruction *NI = LowerNegateToMultiply(I);
2269 for (User *U : NI->users()) {
2270 if (BinaryOperator *Tmp = dyn_cast<BinaryOperator>(U))
2271 RedoInsts.insert(Tmp);
2272 }
2273 RedoInsts.insert(I);
2274 MadeChange = true;
2275 I = NI;
2276 }
2277 }
2278 }
2279
2280 // If this instruction is an associative binary operator, process it.
2281 if (!I->isAssociative()) return;
2282 BinaryOperator *BO = cast<BinaryOperator>(I);
2283
2284 // If this is an interior node of a reassociable tree, ignore it until we
2285 // get to the root of the tree, to avoid N^2 analysis.
2286 unsigned Opcode = BO->getOpcode();
2287 if (BO->hasOneUse() && BO->user_back()->getOpcode() == Opcode) {
2288 // During the initial run we will get to the root of the tree.
2289 // But if we get here while we are redoing instructions, there is no
2290 // guarantee that the root will be visited. So Redo later
2291 if (BO->user_back() != BO &&
2292 BO->getParent() == BO->user_back()->getParent())
2293 RedoInsts.insert(BO->user_back());
2294 return;
2295 }
2296
2297 // If this is an add tree that is used by a sub instruction, ignore it
2298 // until we process the subtract.
2299 if (BO->hasOneUse() && BO->getOpcode() == Instruction::Add &&
2300 cast<Instruction>(BO->user_back())->getOpcode() == Instruction::Sub)
2301 return;
2302 if (BO->hasOneUse() && BO->getOpcode() == Instruction::FAdd &&
2303 cast<Instruction>(BO->user_back())->getOpcode() == Instruction::FSub)
2304 return;
2305
2306 ReassociateExpression(BO);
2307}
2308
2309void ReassociatePass::ReassociateExpression(BinaryOperator *I) {
2310 // First, walk the expression tree, linearizing the tree, collecting the
2311 // operand information.
2312 SmallVector<RepeatedValue, 8> Tree;
2313 MadeChange |= LinearizeExprTree(I, Tree);
2314 SmallVector<ValueEntry, 8> Ops;
2315 Ops.reserve(Tree.size());
2316 for (unsigned i = 0, e = Tree.size(); i != e; ++i) {
2317 RepeatedValue E = Tree[i];
2318 Ops.append(E.second.getZExtValue(),
2319 ValueEntry(getRank(E.first), E.first));
2320 }
2321
2322 LLVM_DEBUG(dbgs() << "RAIn:\t"; PrintOps(I, Ops); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "RAIn:\t"; PrintOps(I, Ops
); dbgs() << '\n'; } } while (false)
;
2323
2324 // Now that we have linearized the tree to a list and have gathered all of
2325 // the operands and their ranks, sort the operands by their rank. Use a
2326 // stable_sort so that values with equal ranks will have their relative
2327 // positions maintained (and so the compiler is deterministic). Note that
2328 // this sorts so that the highest ranking values end up at the beginning of
2329 // the vector.
2330 llvm::stable_sort(Ops);
2331
2332 // Now that we have the expression tree in a convenient
2333 // sorted form, optimize it globally if possible.
2334 if (Value *V = OptimizeExpression(I, Ops)) {
2335 if (V == I)
2336 // Self-referential expression in unreachable code.
2337 return;
2338 // This expression tree simplified to something that isn't a tree,
2339 // eliminate it.
2340 LLVM_DEBUG(dbgs() << "Reassoc to scalar: " << *V << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "Reassoc to scalar: " <<
*V << '\n'; } } while (false)
;
2341 I->replaceAllUsesWith(V);
2342 if (Instruction *VI = dyn_cast<Instruction>(V))
2343 if (I->getDebugLoc())
2344 VI->setDebugLoc(I->getDebugLoc());
2345 RedoInsts.insert(I);
2346 ++NumAnnihil;
2347 return;
2348 }
2349
2350 // We want to sink immediates as deeply as possible except in the case where
2351 // this is a multiply tree used only by an add, and the immediate is a -1.
2352 // In this case we reassociate to put the negation on the outside so that we
2353 // can fold the negation into the add: (-X)*Y + Z -> Z-X*Y
2354 if (I->hasOneUse()) {
2355 if (I->getOpcode() == Instruction::Mul &&
2356 cast<Instruction>(I->user_back())->getOpcode() == Instruction::Add &&
2357 isa<ConstantInt>(Ops.back().Op) &&
2358 cast<ConstantInt>(Ops.back().Op)->isMinusOne()) {
2359 ValueEntry Tmp = Ops.pop_back_val();
2360 Ops.insert(Ops.begin(), Tmp);
2361 } else if (I->getOpcode() == Instruction::FMul &&
2362 cast<Instruction>(I->user_back())->getOpcode() ==
2363 Instruction::FAdd &&
2364 isa<ConstantFP>(Ops.back().Op) &&
2365 cast<ConstantFP>(Ops.back().Op)->isExactlyValue(-1.0)) {
2366 ValueEntry Tmp = Ops.pop_back_val();
2367 Ops.insert(Ops.begin(), Tmp);
2368 }
2369 }
2370
2371 LLVM_DEBUG(dbgs() << "RAOut:\t"; PrintOps(I, Ops); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("reassociate")) { dbgs() << "RAOut:\t"; PrintOps(I, Ops
); dbgs() << '\n'; } } while (false)
;
2372
2373 if (Ops.size() == 1) {
2374 if (Ops[0].Op == I)
2375 // Self-referential expression in unreachable code.
2376 return;
2377
2378 // This expression tree simplified to something that isn't a tree,
2379 // eliminate it.
2380 I->replaceAllUsesWith(Ops[0].Op);
2381 if (Instruction *OI = dyn_cast<Instruction>(Ops[0].Op))
2382 OI->setDebugLoc(I->getDebugLoc());
2383 RedoInsts.insert(I);
2384 return;
2385 }
2386
2387 if (Ops.size() > 2 && Ops.size() <= GlobalReassociateLimit) {
2388 // Find the pair with the highest count in the pairmap and move it to the
2389 // back of the list so that it can later be CSE'd.
2390 // example:
2391 // a*b*c*d*e
2392 // if c*e is the most "popular" pair, we can express this as
2393 // (((c*e)*d)*b)*a
2394 unsigned Max = 1;
2395 unsigned BestRank = 0;
2396 std::pair<unsigned, unsigned> BestPair;
2397 unsigned Idx = I->getOpcode() - Instruction::BinaryOpsBegin;
2398 for (unsigned i = 0; i < Ops.size() - 1; ++i)
2399 for (unsigned j = i + 1; j < Ops.size(); ++j) {
2400 unsigned Score = 0;
2401 Value *Op0 = Ops[i].Op;
2402 Value *Op1 = Ops[j].Op;
2403 if (std::less<Value *>()(Op1, Op0))
2404 std::swap(Op0, Op1);
2405 auto it = PairMap[Idx].find({Op0, Op1});
2406 if (it != PairMap[Idx].end()) {
2407 // Functions like BreakUpSubtract() can erase the Values we're using
2408 // as keys and create new Values after we built the PairMap. There's a
2409 // small chance that the new nodes can have the same address as
2410 // something already in the table. We shouldn't accumulate the stored
2411 // score in that case as it refers to the wrong Value.
2412 if (it->second.isValid())
2413 Score += it->second.Score;
2414 }
2415
2416 unsigned MaxRank = std::max(Ops[i].Rank, Ops[j].Rank);
2417 if (Score > Max || (Score == Max && MaxRank < BestRank)) {
2418 BestPair = {i, j};
2419 Max = Score;
2420 BestRank = MaxRank;
2421 }
2422 }
2423 if (Max > 1) {
2424 auto Op0 = Ops[BestPair.first];
2425 auto Op1 = Ops[BestPair.second];
2426 Ops.erase(&Ops[BestPair.second]);
2427 Ops.erase(&Ops[BestPair.first]);
2428 Ops.push_back(Op0);
2429 Ops.push_back(Op1);
2430 }
2431 }
2432 // Now that we ordered and optimized the expressions, splat them back into
2433 // the expression tree, removing any unneeded nodes.
2434 RewriteExprTree(I, Ops);
2435}
2436
2437void
2438ReassociatePass::BuildPairMap(ReversePostOrderTraversal<Function *> &RPOT) {
2439 // Make a "pairmap" of how often each operand pair occurs.
2440 for (BasicBlock *BI : RPOT) {
2441 for (Instruction &I : *BI) {
2442 if (!I.isAssociative())
2443 continue;
2444
2445 // Ignore nodes that aren't at the root of trees.
2446 if (I.hasOneUse() && I.user_back()->getOpcode() == I.getOpcode())
2447 continue;
2448
2449 // Collect all operands in a single reassociable expression.
2450 // Since Reassociate has already been run once, we can assume things
2451 // are already canonical according to Reassociation's regime.
2452 SmallVector<Value *, 8> Worklist = { I.getOperand(0), I.getOperand(1) };
2453 SmallVector<Value *, 8> Ops;
2454 while (!Worklist.empty() && Ops.size() <= GlobalReassociateLimit) {
2455 Value *Op = Worklist.pop_back_val();
2456 Instruction *OpI = dyn_cast<Instruction>(Op);
2457 if (!OpI || OpI->getOpcode() != I.getOpcode() || !OpI->hasOneUse()) {
2458 Ops.push_back(Op);
2459 continue;
2460 }
2461 // Be paranoid about self-referencing expressions in unreachable code.
2462 if (OpI->getOperand(0) != OpI)
2463 Worklist.push_back(OpI->getOperand(0));
2464 if (OpI->getOperand(1) != OpI)
2465 Worklist.push_back(OpI->getOperand(1));
2466 }
2467 // Skip extremely long expressions.
2468 if (Ops.size() > GlobalReassociateLimit)
2469 continue;
2470
2471 // Add all pairwise combinations of operands to the pair map.
2472 unsigned BinaryIdx = I.getOpcode() - Instruction::BinaryOpsBegin;
2473 SmallSet<std::pair<Value *, Value*>, 32> Visited;
2474 for (unsigned i = 0; i < Ops.size() - 1; ++i) {
2475 for (unsigned j = i + 1; j < Ops.size(); ++j) {
2476 // Canonicalize operand orderings.
2477 Value *Op0 = Ops[i];
2478 Value *Op1 = Ops[j];
2479 if (std::less<Value *>()(Op1, Op0))
2480 std::swap(Op0, Op1);
2481 if (!Visited.insert({Op0, Op1}).second)
2482 continue;
2483 auto res = PairMap[BinaryIdx].insert({{Op0, Op1}, {Op0, Op1, 1}});
2484 if (!res.second) {
2485 // If either key value has been erased then we've got the same
2486 // address by coincidence. That can't happen here because nothing is
2487 // erasing values but it can happen by the time we're querying the
2488 // map.
2489 assert(res.first->second.isValid() && "WeakVH invalidated")(static_cast <bool> (res.first->second.isValid() &&
"WeakVH invalidated") ? void (0) : __assert_fail ("res.first->second.isValid() && \"WeakVH invalidated\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2489, __extension__ __PRETTY_FUNCTION__))
;
2490 ++res.first->second.Score;
2491 }
2492 }
2493 }
2494 }
2495 }
2496}
2497
2498PreservedAnalyses ReassociatePass::run(Function &F, FunctionAnalysisManager &) {
2499 // Get the functions basic blocks in Reverse Post Order. This order is used by
2500 // BuildRankMap to pre calculate ranks correctly. It also excludes dead basic
2501 // blocks (it has been seen that the analysis in this pass could hang when
2502 // analysing dead basic blocks).
2503 ReversePostOrderTraversal<Function *> RPOT(&F);
2504
2505 // Calculate the rank map for F.
2506 BuildRankMap(F, RPOT);
4
Calling 'ReassociatePass::BuildRankMap'
2507
2508 // Build the pair map before running reassociate.
2509 // Technically this would be more accurate if we did it after one round
2510 // of reassociation, but in practice it doesn't seem to help much on
2511 // real-world code, so don't waste the compile time running reassociate
2512 // twice.
2513 // If a user wants, they could expicitly run reassociate twice in their
2514 // pass pipeline for further potential gains.
2515 // It might also be possible to update the pair map during runtime, but the
2516 // overhead of that may be large if there's many reassociable chains.
2517 BuildPairMap(RPOT);
2518
2519 MadeChange = false;
2520
2521 // Traverse the same blocks that were analysed by BuildRankMap.
2522 for (BasicBlock *BI : RPOT) {
2523 assert(RankMap.count(&*BI) && "BB should be ranked.")(static_cast <bool> (RankMap.count(&*BI) &&
"BB should be ranked.") ? void (0) : __assert_fail ("RankMap.count(&*BI) && \"BB should be ranked.\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2523, __extension__ __PRETTY_FUNCTION__))
;
2524 // Optimize every instruction in the basic block.
2525 for (BasicBlock::iterator II = BI->begin(), IE = BI->end(); II != IE;)
2526 if (isInstructionTriviallyDead(&*II)) {
2527 EraseInst(&*II++);
2528 } else {
2529 OptimizeInst(&*II);
2530 assert(II->getParent() == &*BI && "Moved to a different block!")(static_cast <bool> (II->getParent() == &*BI &&
"Moved to a different block!") ? void (0) : __assert_fail ("II->getParent() == &*BI && \"Moved to a different block!\""
, "/build/llvm-toolchain-snapshot-14~++20211016100712+8e1d532707fd/llvm/lib/Transforms/Scalar/Reassociate.cpp"
, 2530, __extension__ __PRETTY_FUNCTION__))
;
2531 ++II;
2532 }
2533
2534 // Make a copy of all the instructions to be redone so we can remove dead
2535 // instructions.
2536 OrderedSet ToRedo(RedoInsts);
2537 // Iterate over all instructions to be reevaluated and remove trivially dead
2538 // instructions. If any operand of the trivially dead instruction becomes
2539 // dead mark it for deletion as well. Continue this process until all
2540 // trivially dead instructions have been removed.
2541 while (!ToRedo.empty()) {
2542 Instruction *I = ToRedo.pop_back_val();
2543 if (isInstructionTriviallyDead(I)) {
2544 RecursivelyEraseDeadInsts(I, ToRedo);
2545 MadeChange = true;
2546 }
2547 }
2548
2549 // Now that we have removed dead instructions, we can reoptimize the
2550 // remaining instructions.
2551 while (!RedoInsts.empty()) {
2552 Instruction *I = RedoInsts.front();
2553 RedoInsts.erase(RedoInsts.begin());
2554 if (isInstructionTriviallyDead(I))
2555 EraseInst(I);
2556 else
2557 OptimizeInst(I);
2558 }
2559 }
2560
2561 // We are done with the rank map and pair map.
2562 RankMap.clear();
2563 ValueRankMap.clear();
2564 for (auto &Entry : PairMap)
2565 Entry.clear();
2566
2567 if (MadeChange) {
2568 PreservedAnalyses PA;
2569 PA.preserveSet<CFGAnalyses>();
2570 return PA;
2571 }
2572
2573 return PreservedAnalyses::all();
2574}
2575
2576namespace {
2577
2578 class ReassociateLegacyPass : public FunctionPass {
2579 ReassociatePass Impl;
2580
2581 public:
2582 static char ID; // Pass identification, replacement for typeid
2583
2584 ReassociateLegacyPass() : FunctionPass(ID) {
2585 initializeReassociateLegacyPassPass(*PassRegistry::getPassRegistry());
2586 }
2587
2588 bool runOnFunction(Function &F) override {
2589 if (skipFunction(F))
1
Assuming the condition is false
2
Taking false branch
2590 return false;
2591
2592 FunctionAnalysisManager DummyFAM;
2593 auto PA = Impl.run(F, DummyFAM);
3
Calling 'ReassociatePass::run'
2594 return !PA.areAllPreserved();
2595 }
2596
2597 void getAnalysisUsage(AnalysisUsage &AU) const override {
2598 AU.setPreservesCFG();
2599 AU.addPreserved<AAResultsWrapperPass>();
2600 AU.addPreserved<BasicAAWrapperPass>();
2601 AU.addPreserved<GlobalsAAWrapperPass>();
2602 }
2603 };
2604
2605} // end anonymous namespace
2606
2607char ReassociateLegacyPass::ID = 0;
2608
2609INITIALIZE_PASS(ReassociateLegacyPass, "reassociate",static void *initializeReassociateLegacyPassPassOnce(PassRegistry
&Registry) { PassInfo *PI = new PassInfo( "Reassociate expressions"
, "reassociate", &ReassociateLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<ReassociateLegacyPass>), false, false)
; Registry.registerPass(*PI, true); return PI; } static llvm::
once_flag InitializeReassociateLegacyPassPassFlag; void llvm::
initializeReassociateLegacyPassPass(PassRegistry &Registry
) { llvm::call_once(InitializeReassociateLegacyPassPassFlag, initializeReassociateLegacyPassPassOnce
, std::ref(Registry)); }
2610 "Reassociate expressions", false, false)static void *initializeReassociateLegacyPassPassOnce(PassRegistry
&Registry) { PassInfo *PI = new PassInfo( "Reassociate expressions"
, "reassociate", &ReassociateLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<ReassociateLegacyPass>), false, false)
; Registry.registerPass(*PI, true); return PI; } static llvm::
once_flag InitializeReassociateLegacyPassPassFlag; void llvm::
initializeReassociateLegacyPassPass(PassRegistry &Registry
) { llvm::call_once(InitializeReassociateLegacyPassPassFlag, initializeReassociateLegacyPassPassOnce
, std::ref(Registry)); }
2611
2612// Public interface to the Reassociate pass
2613FunctionPass *llvm::createReassociatePass() {
2614 return new ReassociateLegacyPass();
2615}