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-rw-r--r--contrib/llvm/lib/Transforms/Utils/SplitModule.cpp284
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diff --git a/contrib/llvm/lib/Transforms/Utils/SplitModule.cpp b/contrib/llvm/lib/Transforms/Utils/SplitModule.cpp
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-//===- SplitModule.cpp - Split a module into partitions -------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This file defines the function llvm::SplitModule, which splits a module
-// into multiple linkable partitions. It can be used to implement parallel code
-// generation for link-time optimization.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Transforms/Utils/SplitModule.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/EquivalenceClasses.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/StringRef.h"
-#include "llvm/IR/Comdat.h"
-#include "llvm/IR/Constant.h"
-#include "llvm/IR/Constants.h"
-#include "llvm/IR/Function.h"
-#include "llvm/IR/GlobalAlias.h"
-#include "llvm/IR/GlobalObject.h"
-#include "llvm/IR/GlobalIndirectSymbol.h"
-#include "llvm/IR/GlobalValue.h"
-#include "llvm/IR/GlobalVariable.h"
-#include "llvm/IR/Instruction.h"
-#include "llvm/IR/Module.h"
-#include "llvm/IR/User.h"
-#include "llvm/IR/Value.h"
-#include "llvm/Support/Casting.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/MD5.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Transforms/Utils/Cloning.h"
-#include "llvm/Transforms/Utils/ValueMapper.h"
-#include <algorithm>
-#include <cassert>
-#include <iterator>
-#include <memory>
-#include <queue>
-#include <utility>
-#include <vector>
-
-using namespace llvm;
-
-#define DEBUG_TYPE "split-module"
-
-namespace {
-
-using ClusterMapType = EquivalenceClasses<const GlobalValue *>;
-using ComdatMembersType = DenseMap<const Comdat *, const GlobalValue *>;
-using ClusterIDMapType = DenseMap<const GlobalValue *, unsigned>;
-
-} // end anonymous namespace
-
-static void addNonConstUser(ClusterMapType &GVtoClusterMap,
- const GlobalValue *GV, const User *U) {
- assert((!isa<Constant>(U) || isa<GlobalValue>(U)) && "Bad user");
-
- if (const Instruction *I = dyn_cast<Instruction>(U)) {
- const GlobalValue *F = I->getParent()->getParent();
- GVtoClusterMap.unionSets(GV, F);
- } else if (isa<GlobalIndirectSymbol>(U) || isa<Function>(U) ||
- isa<GlobalVariable>(U)) {
- GVtoClusterMap.unionSets(GV, cast<GlobalValue>(U));
- } else {
- llvm_unreachable("Underimplemented use case");
- }
-}
-
-// Adds all GlobalValue users of V to the same cluster as GV.
-static void addAllGlobalValueUsers(ClusterMapType &GVtoClusterMap,
- const GlobalValue *GV, const Value *V) {
- for (auto *U : V->users()) {
- SmallVector<const User *, 4> Worklist;
- Worklist.push_back(U);
- while (!Worklist.empty()) {
- const User *UU = Worklist.pop_back_val();
- // For each constant that is not a GV (a pure const) recurse.
- if (isa<Constant>(UU) && !isa<GlobalValue>(UU)) {
- Worklist.append(UU->user_begin(), UU->user_end());
- continue;
- }
- addNonConstUser(GVtoClusterMap, GV, UU);
- }
- }
-}
-
-// Find partitions for module in the way that no locals need to be
-// globalized.
-// Try to balance pack those partitions into N files since this roughly equals
-// thread balancing for the backend codegen step.
-static void findPartitions(Module *M, ClusterIDMapType &ClusterIDMap,
- unsigned N) {
- // At this point module should have the proper mix of globals and locals.
- // As we attempt to partition this module, we must not change any
- // locals to globals.
- LLVM_DEBUG(dbgs() << "Partition module with (" << M->size()
- << ")functions\n");
- ClusterMapType GVtoClusterMap;
- ComdatMembersType ComdatMembers;
-
- auto recordGVSet = [&GVtoClusterMap, &ComdatMembers](GlobalValue &GV) {
- if (GV.isDeclaration())
- return;
-
- if (!GV.hasName())
- GV.setName("__llvmsplit_unnamed");
-
- // Comdat groups must not be partitioned. For comdat groups that contain
- // locals, record all their members here so we can keep them together.
- // Comdat groups that only contain external globals are already handled by
- // the MD5-based partitioning.
- if (const Comdat *C = GV.getComdat()) {
- auto &Member = ComdatMembers[C];
- if (Member)
- GVtoClusterMap.unionSets(Member, &GV);
- else
- Member = &GV;
- }
-
- // For aliases we should not separate them from their aliasees regardless
- // of linkage.
- if (auto *GIS = dyn_cast<GlobalIndirectSymbol>(&GV)) {
- if (const GlobalObject *Base = GIS->getBaseObject())
- GVtoClusterMap.unionSets(&GV, Base);
- }
-
- if (const Function *F = dyn_cast<Function>(&GV)) {
- for (const BasicBlock &BB : *F) {
- BlockAddress *BA = BlockAddress::lookup(&BB);
- if (!BA || !BA->isConstantUsed())
- continue;
- addAllGlobalValueUsers(GVtoClusterMap, F, BA);
- }
- }
-
- if (GV.hasLocalLinkage())
- addAllGlobalValueUsers(GVtoClusterMap, &GV, &GV);
- };
-
- llvm::for_each(M->functions(), recordGVSet);
- llvm::for_each(M->globals(), recordGVSet);
- llvm::for_each(M->aliases(), recordGVSet);
-
- // Assigned all GVs to merged clusters while balancing number of objects in
- // each.
- auto CompareClusters = [](const std::pair<unsigned, unsigned> &a,
- const std::pair<unsigned, unsigned> &b) {
- if (a.second || b.second)
- return a.second > b.second;
- else
- return a.first > b.first;
- };
-
- std::priority_queue<std::pair<unsigned, unsigned>,
- std::vector<std::pair<unsigned, unsigned>>,
- decltype(CompareClusters)>
- BalancinQueue(CompareClusters);
- // Pre-populate priority queue with N slot blanks.
- for (unsigned i = 0; i < N; ++i)
- BalancinQueue.push(std::make_pair(i, 0));
-
- using SortType = std::pair<unsigned, ClusterMapType::iterator>;
-
- SmallVector<SortType, 64> Sets;
- SmallPtrSet<const GlobalValue *, 32> Visited;
-
- // To guarantee determinism, we have to sort SCC according to size.
- // When size is the same, use leader's name.
- for (ClusterMapType::iterator I = GVtoClusterMap.begin(),
- E = GVtoClusterMap.end(); I != E; ++I)
- if (I->isLeader())
- Sets.push_back(
- std::make_pair(std::distance(GVtoClusterMap.member_begin(I),
- GVtoClusterMap.member_end()), I));
-
- llvm::sort(Sets, [](const SortType &a, const SortType &b) {
- if (a.first == b.first)
- return a.second->getData()->getName() > b.second->getData()->getName();
- else
- return a.first > b.first;
- });
-
- for (auto &I : Sets) {
- unsigned CurrentClusterID = BalancinQueue.top().first;
- unsigned CurrentClusterSize = BalancinQueue.top().second;
- BalancinQueue.pop();
-
- LLVM_DEBUG(dbgs() << "Root[" << CurrentClusterID << "] cluster_size("
- << I.first << ") ----> " << I.second->getData()->getName()
- << "\n");
-
- for (ClusterMapType::member_iterator MI =
- GVtoClusterMap.findLeader(I.second);
- MI != GVtoClusterMap.member_end(); ++MI) {
- if (!Visited.insert(*MI).second)
- continue;
- LLVM_DEBUG(dbgs() << "----> " << (*MI)->getName()
- << ((*MI)->hasLocalLinkage() ? " l " : " e ") << "\n");
- Visited.insert(*MI);
- ClusterIDMap[*MI] = CurrentClusterID;
- CurrentClusterSize++;
- }
- // Add this set size to the number of entries in this cluster.
- BalancinQueue.push(std::make_pair(CurrentClusterID, CurrentClusterSize));
- }
-}
-
-static void externalize(GlobalValue *GV) {
- if (GV->hasLocalLinkage()) {
- GV->setLinkage(GlobalValue::ExternalLinkage);
- GV->setVisibility(GlobalValue::HiddenVisibility);
- }
-
- // Unnamed entities must be named consistently between modules. setName will
- // give a distinct name to each such entity.
- if (!GV->hasName())
- GV->setName("__llvmsplit_unnamed");
-}
-
-// Returns whether GV should be in partition (0-based) I of N.
-static bool isInPartition(const GlobalValue *GV, unsigned I, unsigned N) {
- if (auto *GIS = dyn_cast<GlobalIndirectSymbol>(GV))
- if (const GlobalObject *Base = GIS->getBaseObject())
- GV = Base;
-
- StringRef Name;
- if (const Comdat *C = GV->getComdat())
- Name = C->getName();
- else
- Name = GV->getName();
-
- // Partition by MD5 hash. We only need a few bits for evenness as the number
- // of partitions will generally be in the 1-2 figure range; the low 16 bits
- // are enough.
- MD5 H;
- MD5::MD5Result R;
- H.update(Name);
- H.final(R);
- return (R[0] | (R[1] << 8)) % N == I;
-}
-
-void llvm::SplitModule(
- std::unique_ptr<Module> M, unsigned N,
- function_ref<void(std::unique_ptr<Module> MPart)> ModuleCallback,
- bool PreserveLocals) {
- if (!PreserveLocals) {
- for (Function &F : *M)
- externalize(&F);
- for (GlobalVariable &GV : M->globals())
- externalize(&GV);
- for (GlobalAlias &GA : M->aliases())
- externalize(&GA);
- for (GlobalIFunc &GIF : M->ifuncs())
- externalize(&GIF);
- }
-
- // This performs splitting without a need for externalization, which might not
- // always be possible.
- ClusterIDMapType ClusterIDMap;
- findPartitions(M.get(), ClusterIDMap, N);
-
- // FIXME: We should be able to reuse M as the last partition instead of
- // cloning it.
- for (unsigned I = 0; I < N; ++I) {
- ValueToValueMapTy VMap;
- std::unique_ptr<Module> MPart(
- CloneModule(*M, VMap, [&](const GlobalValue *GV) {
- if (ClusterIDMap.count(GV))
- return (ClusterIDMap[GV] == I);
- else
- return isInPartition(GV, I, N);
- }));
- if (I != 0)
- MPart->setModuleInlineAsm("");
- ModuleCallback(std::move(MPart));
- }
-}
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