[llvm-readobj] - Simplify stack-sizes.test test case.
[llvm-complete.git] / lib / Analysis / AssumptionCache.cpp
blob7d6429a0fec1c0938300521ce792f11a999e9f7e
1 //===- AssumptionCache.cpp - Cache finding @llvm.assume calls -------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains a pass that keeps track of @llvm.assume intrinsics in
10 // the functions of a module.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Analysis/AssumptionCache.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/ADT/SmallPtrSet.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/IR/BasicBlock.h"
19 #include "llvm/IR/Function.h"
20 #include "llvm/IR/InstrTypes.h"
21 #include "llvm/IR/Instruction.h"
22 #include "llvm/IR/Instructions.h"
23 #include "llvm/IR/Intrinsics.h"
24 #include "llvm/IR/PassManager.h"
25 #include "llvm/IR/PatternMatch.h"
26 #include "llvm/Pass.h"
27 #include "llvm/Support/Casting.h"
28 #include "llvm/Support/CommandLine.h"
29 #include "llvm/Support/ErrorHandling.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include <algorithm>
32 #include <cassert>
33 #include <utility>
35 using namespace llvm;
36 using namespace llvm::PatternMatch;
38 static cl::opt<bool>
39 VerifyAssumptionCache("verify-assumption-cache", cl::Hidden,
40 cl::desc("Enable verification of assumption cache"),
41 cl::init(false));
43 SmallVector<WeakTrackingVH, 1> &
44 AssumptionCache::getOrInsertAffectedValues(Value *V) {
45 // Try using find_as first to avoid creating extra value handles just for the
46 // purpose of doing the lookup.
47 auto AVI = AffectedValues.find_as(V);
48 if (AVI != AffectedValues.end())
49 return AVI->second;
51 auto AVIP = AffectedValues.insert(
52 {AffectedValueCallbackVH(V, this), SmallVector<WeakTrackingVH, 1>()});
53 return AVIP.first->second;
56 static void findAffectedValues(CallInst *CI,
57 SmallVectorImpl<Value *> &Affected) {
58 // Note: This code must be kept in-sync with the code in
59 // computeKnownBitsFromAssume in ValueTracking.
61 auto AddAffected = [&Affected](Value *V) {
62 if (isa<Argument>(V)) {
63 Affected.push_back(V);
64 } else if (auto *I = dyn_cast<Instruction>(V)) {
65 Affected.push_back(I);
67 // Peek through unary operators to find the source of the condition.
68 Value *Op;
69 if (match(I, m_BitCast(m_Value(Op))) ||
70 match(I, m_PtrToInt(m_Value(Op))) ||
71 match(I, m_Not(m_Value(Op)))) {
72 if (isa<Instruction>(Op) || isa<Argument>(Op))
73 Affected.push_back(Op);
78 Value *Cond = CI->getArgOperand(0), *A, *B;
79 AddAffected(Cond);
81 CmpInst::Predicate Pred;
82 if (match(Cond, m_ICmp(Pred, m_Value(A), m_Value(B)))) {
83 AddAffected(A);
84 AddAffected(B);
86 if (Pred == ICmpInst::ICMP_EQ) {
87 // For equality comparisons, we handle the case of bit inversion.
88 auto AddAffectedFromEq = [&AddAffected](Value *V) {
89 Value *A;
90 if (match(V, m_Not(m_Value(A)))) {
91 AddAffected(A);
92 V = A;
95 Value *B;
96 ConstantInt *C;
97 // (A & B) or (A | B) or (A ^ B).
98 if (match(V, m_BitwiseLogic(m_Value(A), m_Value(B)))) {
99 AddAffected(A);
100 AddAffected(B);
101 // (A << C) or (A >>_s C) or (A >>_u C) where C is some constant.
102 } else if (match(V, m_Shift(m_Value(A), m_ConstantInt(C)))) {
103 AddAffected(A);
107 AddAffectedFromEq(A);
108 AddAffectedFromEq(B);
113 void AssumptionCache::updateAffectedValues(CallInst *CI) {
114 SmallVector<Value *, 16> Affected;
115 findAffectedValues(CI, Affected);
117 for (auto &AV : Affected) {
118 auto &AVV = getOrInsertAffectedValues(AV);
119 if (std::find(AVV.begin(), AVV.end(), CI) == AVV.end())
120 AVV.push_back(CI);
124 void AssumptionCache::unregisterAssumption(CallInst *CI) {
125 SmallVector<Value *, 16> Affected;
126 findAffectedValues(CI, Affected);
128 for (auto &AV : Affected) {
129 auto AVI = AffectedValues.find_as(AV);
130 if (AVI != AffectedValues.end())
131 AffectedValues.erase(AVI);
133 remove_if(AssumeHandles, [CI](WeakTrackingVH &VH) { return CI == VH; });
136 void AssumptionCache::AffectedValueCallbackVH::deleted() {
137 auto AVI = AC->AffectedValues.find(getValPtr());
138 if (AVI != AC->AffectedValues.end())
139 AC->AffectedValues.erase(AVI);
140 // 'this' now dangles!
143 void AssumptionCache::transferAffectedValuesInCache(Value *OV, Value *NV) {
144 auto &NAVV = getOrInsertAffectedValues(NV);
145 auto AVI = AffectedValues.find(OV);
146 if (AVI == AffectedValues.end())
147 return;
149 for (auto &A : AVI->second)
150 if (std::find(NAVV.begin(), NAVV.end(), A) == NAVV.end())
151 NAVV.push_back(A);
152 AffectedValues.erase(OV);
155 void AssumptionCache::AffectedValueCallbackVH::allUsesReplacedWith(Value *NV) {
156 if (!isa<Instruction>(NV) && !isa<Argument>(NV))
157 return;
159 // Any assumptions that affected this value now affect the new value.
161 AC->transferAffectedValuesInCache(getValPtr(), NV);
162 // 'this' now might dangle! If the AffectedValues map was resized to add an
163 // entry for NV then this object might have been destroyed in favor of some
164 // copy in the grown map.
167 void AssumptionCache::scanFunction() {
168 assert(!Scanned && "Tried to scan the function twice!");
169 assert(AssumeHandles.empty() && "Already have assumes when scanning!");
171 // Go through all instructions in all blocks, add all calls to @llvm.assume
172 // to this cache.
173 for (BasicBlock &B : F)
174 for (Instruction &II : B)
175 if (match(&II, m_Intrinsic<Intrinsic::assume>()))
176 AssumeHandles.push_back(&II);
178 // Mark the scan as complete.
179 Scanned = true;
181 // Update affected values.
182 for (auto &A : AssumeHandles)
183 updateAffectedValues(cast<CallInst>(A));
186 void AssumptionCache::registerAssumption(CallInst *CI) {
187 assert(match(CI, m_Intrinsic<Intrinsic::assume>()) &&
188 "Registered call does not call @llvm.assume");
190 // If we haven't scanned the function yet, just drop this assumption. It will
191 // be found when we scan later.
192 if (!Scanned)
193 return;
195 AssumeHandles.push_back(CI);
197 #ifndef NDEBUG
198 assert(CI->getParent() &&
199 "Cannot register @llvm.assume call not in a basic block");
200 assert(&F == CI->getParent()->getParent() &&
201 "Cannot register @llvm.assume call not in this function");
203 // We expect the number of assumptions to be small, so in an asserts build
204 // check that we don't accumulate duplicates and that all assumptions point
205 // to the same function.
206 SmallPtrSet<Value *, 16> AssumptionSet;
207 for (auto &VH : AssumeHandles) {
208 if (!VH)
209 continue;
211 assert(&F == cast<Instruction>(VH)->getParent()->getParent() &&
212 "Cached assumption not inside this function!");
213 assert(match(cast<CallInst>(VH), m_Intrinsic<Intrinsic::assume>()) &&
214 "Cached something other than a call to @llvm.assume!");
215 assert(AssumptionSet.insert(VH).second &&
216 "Cache contains multiple copies of a call!");
218 #endif
220 updateAffectedValues(CI);
223 AnalysisKey AssumptionAnalysis::Key;
225 PreservedAnalyses AssumptionPrinterPass::run(Function &F,
226 FunctionAnalysisManager &AM) {
227 AssumptionCache &AC = AM.getResult<AssumptionAnalysis>(F);
229 OS << "Cached assumptions for function: " << F.getName() << "\n";
230 for (auto &VH : AC.assumptions())
231 if (VH)
232 OS << " " << *cast<CallInst>(VH)->getArgOperand(0) << "\n";
234 return PreservedAnalyses::all();
237 void AssumptionCacheTracker::FunctionCallbackVH::deleted() {
238 auto I = ACT->AssumptionCaches.find_as(cast<Function>(getValPtr()));
239 if (I != ACT->AssumptionCaches.end())
240 ACT->AssumptionCaches.erase(I);
241 // 'this' now dangles!
244 AssumptionCache &AssumptionCacheTracker::getAssumptionCache(Function &F) {
245 // We probe the function map twice to try and avoid creating a value handle
246 // around the function in common cases. This makes insertion a bit slower,
247 // but if we have to insert we're going to scan the whole function so that
248 // shouldn't matter.
249 auto I = AssumptionCaches.find_as(&F);
250 if (I != AssumptionCaches.end())
251 return *I->second;
253 // Ok, build a new cache by scanning the function, insert it and the value
254 // handle into our map, and return the newly populated cache.
255 auto IP = AssumptionCaches.insert(std::make_pair(
256 FunctionCallbackVH(&F, this), std::make_unique<AssumptionCache>(F)));
257 assert(IP.second && "Scanning function already in the map?");
258 return *IP.first->second;
261 AssumptionCache *AssumptionCacheTracker::lookupAssumptionCache(Function &F) {
262 auto I = AssumptionCaches.find_as(&F);
263 if (I != AssumptionCaches.end())
264 return I->second.get();
265 return nullptr;
268 void AssumptionCacheTracker::verifyAnalysis() const {
269 // FIXME: In the long term the verifier should not be controllable with a
270 // flag. We should either fix all passes to correctly update the assumption
271 // cache and enable the verifier unconditionally or somehow arrange for the
272 // assumption list to be updated automatically by passes.
273 if (!VerifyAssumptionCache)
274 return;
276 SmallPtrSet<const CallInst *, 4> AssumptionSet;
277 for (const auto &I : AssumptionCaches) {
278 for (auto &VH : I.second->assumptions())
279 if (VH)
280 AssumptionSet.insert(cast<CallInst>(VH));
282 for (const BasicBlock &B : cast<Function>(*I.first))
283 for (const Instruction &II : B)
284 if (match(&II, m_Intrinsic<Intrinsic::assume>()) &&
285 !AssumptionSet.count(cast<CallInst>(&II)))
286 report_fatal_error("Assumption in scanned function not in cache");
290 AssumptionCacheTracker::AssumptionCacheTracker() : ImmutablePass(ID) {
291 initializeAssumptionCacheTrackerPass(*PassRegistry::getPassRegistry());
294 AssumptionCacheTracker::~AssumptionCacheTracker() = default;
296 char AssumptionCacheTracker::ID = 0;
298 INITIALIZE_PASS(AssumptionCacheTracker, "assumption-cache-tracker",
299 "Assumption Cache Tracker", false, true)