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//===- llvm/Testing/Support/CFGBuilder.cpp --------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "CFGBuilder.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "gtest/gtest.h"
#define DEBUG_TYPE "cfg-builder"
using namespace llvm;
CFGHolder::CFGHolder(StringRef ModuleName, StringRef FunctionName)
: Context(std::make_unique<LLVMContext>()),
M(std::make_unique<Module>(ModuleName, *Context)) {
FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Context), {}, false);
F = Function::Create(FTy, Function::ExternalLinkage, FunctionName, M.get());
}
CFGHolder::~CFGHolder() = default;
CFGBuilder::CFGBuilder(Function *F, const std::vector<Arc> &InitialArcs,
std::vector<Update> Updates)
: F(F), Updates(std::move(Updates)) {
assert(F);
buildCFG(InitialArcs);
}
static void ConnectBlocks(BasicBlock *From, BasicBlock *To) {
LLVM_DEBUG(dbgs() << "Creating BB arc " << From->getName() << " -> "
<< To->getName() << "\n";
dbgs().flush());
auto *IntTy = IntegerType::get(From->getContext(), 32);
if (isa<UnreachableInst>(From->getTerminator()))
From->getTerminator()->eraseFromParent();
if (!From->getTerminator()) {
IRBuilder<> IRB(From);
IRB.CreateSwitch(ConstantInt::get(IntTy, 0), To);
return;
}
SwitchInst *SI = cast<SwitchInst>(From->getTerminator());
const auto Last = SI->getNumCases();
auto *IntVal = ConstantInt::get(IntTy, Last);
SI->addCase(IntVal, To);
}
static void DisconnectBlocks(BasicBlock *From, BasicBlock *To) {
LLVM_DEBUG(dbgs() << "Deleting BB arc " << From->getName() << " -> "
<< To->getName() << "\n";
dbgs().flush());
SwitchInst *SI = cast<SwitchInst>(From->getTerminator());
if (SI->getNumCases() == 0) {
SI->eraseFromParent();
IRBuilder<> IRB(From);
IRB.CreateUnreachable();
return;
}
if (SI->getDefaultDest() == To) {
auto FirstC = SI->case_begin();
SI->setDefaultDest(FirstC->getCaseSuccessor());
SI->removeCase(FirstC);
return;
}
for (auto CIt = SI->case_begin(); CIt != SI->case_end(); ++CIt)
if (CIt->getCaseSuccessor() == To) {
SI->removeCase(CIt);
return;
}
}
BasicBlock *CFGBuilder::getOrAddBlock(StringRef BlockName) {
auto BIt = NameToBlock.find(BlockName);
if (BIt != NameToBlock.end())
return BIt->second;
auto *BB = BasicBlock::Create(F->getParent()->getContext(), BlockName, F);
IRBuilder<> IRB(BB);
IRB.CreateUnreachable();
NameToBlock[BlockName] = BB;
return BB;
}
bool CFGBuilder::connect(const Arc &A) {
BasicBlock *From = getOrAddBlock(A.From);
BasicBlock *To = getOrAddBlock(A.To);
if (Arcs.count(A) != 0)
return false;
Arcs.insert(A);
ConnectBlocks(From, To);
return true;
}
bool CFGBuilder::disconnect(const Arc &A) {
assert(NameToBlock.count(A.From) != 0 && "No block to disconnect (From)");
assert(NameToBlock.count(A.To) != 0 && "No block to disconnect (To)");
if (Arcs.count(A) == 0)
return false;
BasicBlock *From = getOrAddBlock(A.From);
BasicBlock *To = getOrAddBlock(A.To);
Arcs.erase(A);
DisconnectBlocks(From, To);
return true;
}
void CFGBuilder::buildCFG(const std::vector<Arc> &NewArcs) {
for (const auto &A : NewArcs) {
const bool Connected = connect(A);
(void)Connected;
assert(Connected);
}
}
Optional<CFGBuilder::Update> CFGBuilder::getNextUpdate() const {
if (UpdateIdx == Updates.size())
return None;
return Updates[UpdateIdx];
}
Optional<CFGBuilder::Update> CFGBuilder::applyUpdate() {
if (UpdateIdx == Updates.size())
return None;
Update NextUpdate = Updates[UpdateIdx++];
if (NextUpdate.Action == ActionKind::Insert)
connect(NextUpdate.Edge);
else
disconnect(NextUpdate.Edge);
return NextUpdate;
}
void CFGBuilder::dump(raw_ostream &OS) const {
OS << "Arcs:\n";
size_t i = 0;
for (const auto &A : Arcs)
OS << " " << i++ << ":\t" << A.From << " -> " << A.To << "\n";
OS << "Updates:\n";
i = 0;
for (const auto &U : Updates) {
OS << (i + 1 == UpdateIdx ? "->" : " ") << i
<< ((U.Action == ActionKind::Insert) ? "\tIns " : "\tDel ")
<< U.Edge.From << " -> " << U.Edge.To << "\n";
++i;
}
}
//---- CFGBuilder tests ---------------------------------------------------===//
TEST(CFGBuilder, Construction) {
CFGHolder Holder;
std::vector<CFGBuilder::Arc> Arcs = {{"entry", "a"}, {"a", "b"}, {"a", "c"},
{"c", "d"}, {"d", "b"}, {"d", "e"},
{"d", "f"}, {"e", "f"}};
CFGBuilder B(Holder.F, Arcs, {});
EXPECT_TRUE(B.getOrAddBlock("entry") == &Holder.F->getEntryBlock());
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("entry")->getTerminator()));
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("a")->getTerminator()));
EXPECT_TRUE(isa<UnreachableInst>(B.getOrAddBlock("b")->getTerminator()));
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("d")->getTerminator()));
auto *DSwitch = cast<SwitchInst>(B.getOrAddBlock("d")->getTerminator());
// d has 3 successors, but one of them if going to be a default case
EXPECT_EQ(DSwitch->getNumCases(), 2U);
EXPECT_FALSE(B.getNextUpdate()); // No updates to apply.
}
TEST(CFGBuilder, Insertions) {
CFGHolder Holder;
const auto Insert = CFGBuilder::ActionKind::Insert;
std::vector<CFGBuilder::Update> Updates = {
{Insert, {"entry", "a"}}, {Insert, {"a", "b"}}, {Insert, {"a", "c"}},
{Insert, {"c", "d"}}, {Insert, {"d", "b"}}, {Insert, {"d", "e"}},
{Insert, {"d", "f"}}, {Insert, {"e", "f"}}};
const size_t NumUpdates = Updates.size();
CFGBuilder B(Holder.F, {}, Updates);
size_t i = 0;
while (B.applyUpdate())
++i;
EXPECT_EQ(i, NumUpdates);
EXPECT_TRUE(B.getOrAddBlock("entry") == &Holder.F->getEntryBlock());
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("entry")->getTerminator()));
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("a")->getTerminator()));
EXPECT_TRUE(isa<UnreachableInst>(B.getOrAddBlock("b")->getTerminator()));
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("d")->getTerminator()));
auto *DSwitch = cast<SwitchInst>(B.getOrAddBlock("d")->getTerminator());
// d has 3 successors, but one of them if going to be a default case
EXPECT_EQ(DSwitch->getNumCases(), 2U);
EXPECT_FALSE(B.getNextUpdate()); // No updates to apply.
}
TEST(CFGBuilder, Deletions) {
CFGHolder Holder;
std::vector<CFGBuilder::Arc> Arcs = {
{"entry", "a"}, {"a", "b"}, {"a", "c"}, {"c", "d"}, {"d", "b"}};
const auto Delete = CFGBuilder::ActionKind::Delete;
std::vector<CFGBuilder::Update> Updates = {
{Delete, {"c", "d"}}, {Delete, {"a", "c"}}, {Delete, {"entry", "a"}},
};
const size_t NumUpdates = Updates.size();
CFGBuilder B(Holder.F, Arcs, Updates);
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("entry")->getTerminator()));
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("a")->getTerminator()));
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("c")->getTerminator()));
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("d")->getTerminator()));
auto UpdateC = B.applyUpdate();
EXPECT_TRUE(UpdateC);
EXPECT_EQ(UpdateC->Action, CFGBuilder::ActionKind::Delete);
EXPECT_EQ(UpdateC->Edge.From, "c");
EXPECT_EQ(UpdateC->Edge.To, "d");
EXPECT_TRUE(isa<UnreachableInst>(B.getOrAddBlock("c")->getTerminator()));
size_t i = 1;
while (B.applyUpdate())
++i;
EXPECT_EQ(i, NumUpdates);
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("a")->getTerminator()));
EXPECT_TRUE(isa<UnreachableInst>(B.getOrAddBlock("entry")->getTerminator()));
}
TEST(CFGBuilder, Rebuild) {
CFGHolder Holder;
std::vector<CFGBuilder::Arc> Arcs = {
{"entry", "a"}, {"a", "b"}, {"a", "c"}, {"c", "d"}, {"d", "b"}};
const auto Insert = CFGBuilder::ActionKind::Insert;
const auto Delete = CFGBuilder::ActionKind::Delete;
std::vector<CFGBuilder::Update> Updates = {
{Delete, {"c", "d"}}, {Delete, {"a", "c"}}, {Delete, {"entry", "a"}},
{Insert, {"c", "d"}}, {Insert, {"a", "c"}}, {Insert, {"entry", "a"}},
};
const size_t NumUpdates = Updates.size();
CFGBuilder B(Holder.F, Arcs, Updates);
size_t i = 0;
while (B.applyUpdate())
++i;
EXPECT_EQ(i, NumUpdates);
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("entry")->getTerminator()));
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("a")->getTerminator()));
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("c")->getTerminator()));
EXPECT_TRUE(isa<SwitchInst>(B.getOrAddBlock("d")->getTerminator()));
}
static_assert(std::is_trivially_copyable<succ_iterator>::value,
"trivially copyable");
static_assert(std::is_trivially_copyable<const_succ_iterator>::value,
"trivially copyable");
static_assert(std::is_trivially_copyable<succ_range>::value,
"trivially copyable");
static_assert(std::is_trivially_copyable<const_succ_range>::value,
"trivially copyable");
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