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llvm-project/llvm/unittests/IR/DomTreeUpdaterTest.cpp

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//==- llvm/unittests/IR/DomTreeUpdaterTest.cpp - DomTreeUpdater unit tests ===//
//
// 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 "llvm/IR/DomTreeUpdater.h"
#include "llvm/Analysis/PostDominators.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"
#include <algorithm>
using namespace llvm;
static std::unique_ptr<Module> makeLLVMModule(LLVMContext &Context,
StringRef ModuleStr) {
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(ModuleStr, Err, Context);
assert(M && "Bad LLVM IR?");
return M;
}
TEST(DomTreeUpdater, EagerUpdateBasicOperations) {
StringRef FuncName = "f";
StringRef ModuleString = R"(
define i32 @f(i32 %i, i32 *%p) {
bb0:
store i32 %i, i32 *%p
switch i32 %i, label %bb1 [
i32 1, label %bb2
i32 2, label %bb3
]
bb1:
ret i32 1
bb2:
ret i32 2
bb3:
ret i32 3
})";
// Make the module.
LLVMContext Context;
std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
Function *F = M->getFunction(FuncName);
// Make the DomTreeUpdater.
DominatorTree DT(*F);
PostDominatorTree PDT(*F);
DomTreeUpdater DTU(DT, PDT, DomTreeUpdater::UpdateStrategy::Eager);
ASSERT_TRUE(DTU.hasDomTree());
ASSERT_TRUE(DTU.hasPostDomTree());
ASSERT_TRUE(DTU.isEager());
ASSERT_FALSE(DTU.isLazy());
ASSERT_TRUE(DTU.getDomTree().verify());
ASSERT_TRUE(DTU.getPostDomTree().verify());
ASSERT_FALSE(DTU.hasPendingUpdates());
Function::iterator FI = F->begin();
BasicBlock *BB0 = &*FI++;
BasicBlock *BB1 = &*FI++;
BasicBlock *BB2 = &*FI++;
BasicBlock *BB3 = &*FI++;
SwitchInst *SI = dyn_cast<SwitchInst>(BB0->getTerminator());
ASSERT_NE(SI, nullptr) << "Couldn't get SwitchInst.";
DTU.insertEdgeRelaxed(BB0, BB0);
DTU.deleteEdgeRelaxed(BB0, BB0);
// Delete edge bb0 -> bb3 and push the update twice to verify duplicate
// entries are discarded.
std::vector<DominatorTree::UpdateType> Updates;
Updates.reserve(4);
Updates.push_back({DominatorTree::Delete, BB0, BB3});
Updates.push_back({DominatorTree::Delete, BB0, BB3});
// Invalid Insert: no edge bb1 -> bb2 after change to bb0.
Updates.push_back({DominatorTree::Insert, BB1, BB2});
// Invalid Delete: edge exists bb0 -> bb1 after change to bb0.
Updates.push_back({DominatorTree::Delete, BB0, BB1});
// CFG Change: remove edge bb0 -> bb3.
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 3u);
BB3->removePredecessor(BB0);
for (auto i = SI->case_begin(), e = SI->case_end(); i != e; ++i) {
if (i->getCaseSuccessor() == BB3) {
SI->removeCase(i);
break;
}
}
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 2u);
// Deletion of a BasicBlock is an immediate event. We remove all uses to the
// contained Instructions and change the Terminator to "unreachable" when
// queued for deletion.
ASSERT_FALSE(isa<UnreachableInst>(BB3->getTerminator()));
EXPECT_FALSE(DTU.isBBPendingDeletion(BB3));
DTU.applyUpdates(Updates, /*ForceRemoveDuplicates*/ true);
ASSERT_FALSE(DTU.hasPendingUpdates());
// Invalid Insert: no edge bb1 -> bb2 after change to bb0.
DTU.insertEdgeRelaxed(BB1, BB2);
// Invalid Delete: edge exists bb0 -> bb1 after change to bb0.
DTU.deleteEdgeRelaxed(BB0, BB1);
// DTU working with Eager UpdateStrategy does not need to flush.
ASSERT_TRUE(DT.verify());
ASSERT_TRUE(PDT.verify());
// Test callback utils.
ASSERT_EQ(BB3->getParent(), F);
DTU.callbackDeleteBB(BB3,
[&F](BasicBlock *BB) { ASSERT_NE(BB->getParent(), F); });
ASSERT_TRUE(DT.verify());
ASSERT_TRUE(PDT.verify());
ASSERT_FALSE(DTU.hasPendingUpdates());
// Unnecessary flush() test
DTU.flush();
EXPECT_TRUE(DT.verify());
EXPECT_TRUE(PDT.verify());
// Remove all case branch to BB2 to test Eager recalculation.
// Code section from llvm::ConstantFoldTerminator
for (auto i = SI->case_begin(), e = SI->case_end(); i != e;) {
if (i->getCaseSuccessor() == BB2) {
// Remove this entry.
BB2->removePredecessor(BB0);
i = SI->removeCase(i);
e = SI->case_end();
} else
++i;
}
ASSERT_FALSE(DT.verify());
ASSERT_FALSE(PDT.verify());
DTU.recalculate(*F);
ASSERT_TRUE(DT.verify());
ASSERT_TRUE(PDT.verify());
}
TEST(DomTreeUpdater, EagerUpdateReplaceEntryBB) {
StringRef FuncName = "f";
StringRef ModuleString = R"(
define i32 @f() {
bb0:
br label %bb1
bb1:
ret i32 1
}
)";
// Make the module.
LLVMContext Context;
std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
Function *F = M->getFunction(FuncName);
// Make the DTU.
DominatorTree DT(*F);
PostDominatorTree PDT(*F);
DomTreeUpdater DTU(DT, PDT, DomTreeUpdater::UpdateStrategy::Eager);
ASSERT_TRUE(DTU.hasDomTree());
ASSERT_TRUE(DTU.hasPostDomTree());
ASSERT_TRUE(DTU.isEager());
ASSERT_FALSE(DTU.isLazy());
ASSERT_TRUE(DT.verify());
ASSERT_TRUE(PDT.verify());
Function::iterator FI = F->begin();
BasicBlock *BB0 = &*FI++;
BasicBlock *BB1 = &*FI++;
// Add a block as the new function entry BB. We also link it to BB0.
BasicBlock *NewEntry =
BasicBlock::Create(F->getContext(), "new_entry", F, BB0);
BranchInst::Create(BB0, NewEntry);
EXPECT_EQ(F->begin()->getName(), NewEntry->getName());
EXPECT_TRUE(&F->getEntryBlock() == NewEntry);
DTU.insertEdgeRelaxed(NewEntry, BB0);
// Changing the Entry BB requires a full recalculation of DomTree.
DTU.recalculate(*F);
ASSERT_TRUE(DT.verify());
ASSERT_TRUE(PDT.verify());
// CFG Change: remove new_edge -> bb0 and redirect to new_edge -> bb1.
EXPECT_EQ(NewEntry->getTerminator()->getNumSuccessors(), 1u);
NewEntry->getTerminator()->eraseFromParent();
BranchInst::Create(BB1, NewEntry);
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 1u);
// Update the DTU. At this point bb0 now has no predecessors but is still a
// Child of F.
DTU.applyUpdates({{DominatorTree::Delete, NewEntry, BB0},
{DominatorTree::Insert, NewEntry, BB1}});
ASSERT_TRUE(DT.verify());
ASSERT_TRUE(PDT.verify());
// Now remove bb0 from F.
ASSERT_FALSE(isa<UnreachableInst>(BB0->getTerminator()));
EXPECT_FALSE(DTU.isBBPendingDeletion(BB0));
DTU.deleteBB(BB0);
ASSERT_TRUE(DT.verify());
ASSERT_TRUE(PDT.verify());
}
TEST(DomTreeUpdater, LazyUpdateDTBasicOperations) {
StringRef FuncName = "f";
StringRef ModuleString = R"(
define i32 @f(i32 %i, i32 *%p) {
bb0:
store i32 %i, i32 *%p
switch i32 %i, label %bb1 [
i32 0, label %bb2
i32 1, label %bb2
i32 2, label %bb3
]
bb1:
ret i32 1
bb2:
ret i32 2
bb3:
ret i32 3
}
)";
// Make the module.
LLVMContext Context;
std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
Function *F = M->getFunction(FuncName);
// Make the DTU.
DominatorTree DT(*F);
PostDominatorTree *PDT = nullptr;
DomTreeUpdater DTU(&DT, PDT, DomTreeUpdater::UpdateStrategy::Lazy);
ASSERT_TRUE(DTU.hasDomTree());
ASSERT_FALSE(DTU.hasPostDomTree());
ASSERT_FALSE(DTU.isEager());
ASSERT_TRUE(DTU.isLazy());
ASSERT_TRUE(DTU.getDomTree().verify());
Function::iterator FI = F->begin();
BasicBlock *BB0 = &*FI++;
BasicBlock *BB1 = &*FI++;
BasicBlock *BB2 = &*FI++;
BasicBlock *BB3 = &*FI++;
// Test discards of self-domination update.
DTU.deleteEdge(BB0, BB0);
ASSERT_FALSE(DTU.hasPendingDomTreeUpdates());
// Delete edge bb0 -> bb3 and push the update twice to verify duplicate
// entries are discarded.
std::vector<DominatorTree::UpdateType> Updates;
Updates.reserve(4);
Updates.push_back({DominatorTree::Delete, BB0, BB3});
Updates.push_back({DominatorTree::Delete, BB0, BB3});
// Invalid Insert: no edge bb1 -> bb2 after change to bb0.
Updates.push_back({DominatorTree::Insert, BB1, BB2});
// Invalid Delete: edge exists bb0 -> bb1 after change to bb0.
Updates.push_back({DominatorTree::Delete, BB0, BB1});
// CFG Change: remove edge bb0 -> bb3 and one duplicate edge bb0 -> bb2.
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 4u);
BB0->getTerminator()->eraseFromParent();
BranchInst::Create(BB1, BB2, ConstantInt::getTrue(F->getContext()), BB0);
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 2u);
// Verify. Updates to DTU must be applied *after* all changes to the CFG
// (including block deletion).
DTU.applyUpdates(Updates);
ASSERT_TRUE(DTU.getDomTree().verify());
// Deletion of a BasicBlock is an immediate event. We remove all uses to the
// contained Instructions and change the Terminator to "unreachable" when
// queued for deletion. Its parent is still F until all the pending updates
// are applied to all trees held by the DomTreeUpdater (DomTree/PostDomTree).
// We don't defer this action because it can cause problems for other
// transforms or analysis as it's part of the actual CFG. We only defer
// updates to the DominatorTrees. This code will crash if it is placed before
// the BranchInst::Create() call above. After a deletion of a BasicBlock. Only
// an explicit flush event can trigger the flushing of deleteBBs. Because some
// passes using Lazy UpdateStrategy rely on this behavior.
ASSERT_FALSE(isa<UnreachableInst>(BB3->getTerminator()));
EXPECT_FALSE(DTU.isBBPendingDeletion(BB3));
EXPECT_FALSE(DTU.hasPendingDeletedBB());
DTU.deleteBB(BB3);
EXPECT_TRUE(DTU.isBBPendingDeletion(BB3));
EXPECT_TRUE(DTU.hasPendingDeletedBB());
ASSERT_TRUE(isa<UnreachableInst>(BB3->getTerminator()));
EXPECT_EQ(BB3->getParent(), F);
DTU.recalculate(*F);
EXPECT_FALSE(DTU.hasPendingDeletedBB());
}
TEST(DomTreeUpdater, LazyUpdateDTInheritedPreds) {
StringRef FuncName = "f";
StringRef ModuleString = R"(
define i32 @f(i32 %i, i32 *%p) {
bb0:
store i32 %i, i32 *%p
switch i32 %i, label %bb1 [
i32 2, label %bb2
i32 3, label %bb3
]
bb1:
br label %bb3
bb2:
br label %bb3
bb3:
ret i32 3
}
)";
// Make the module.
LLVMContext Context;
std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
Function *F = M->getFunction(FuncName);
// Make the DTU.
DominatorTree DT(*F);
PostDominatorTree *PDT = nullptr;
DomTreeUpdater DTU(&DT, PDT, DomTreeUpdater::UpdateStrategy::Lazy);
ASSERT_TRUE(DTU.hasDomTree());
ASSERT_FALSE(DTU.hasPostDomTree());
ASSERT_FALSE(DTU.isEager());
ASSERT_TRUE(DTU.isLazy());
ASSERT_TRUE(DTU.getDomTree().verify());
Function::iterator FI = F->begin();
BasicBlock *BB0 = &*FI++;
BasicBlock *BB1 = &*FI++;
BasicBlock *BB2 = &*FI++;
BasicBlock *BB3 = &*FI++;
// There are several CFG locations where we have:
//
// pred1..predN
// | |
// +> curr <+ converted into: pred1..predN curr
// | | |
// v +> succ <+
// succ
//
// There is a specific shape of this we have to be careful of:
//
// pred1..predN
// || |
// |+> curr <+ converted into: pred1..predN curr
// | | | |
// | v +> succ <+
// +-> succ
//
// While the final CFG form is functionally identical the updates to
// DTU are not. In the first case we must have DTU.insertEdge(Pred1, Succ)
// while in the latter case we must *NOT* have DTU.insertEdge(Pred1, Succ).
// CFG Change: bb0 now only has bb0 -> bb1 and bb0 -> bb3. We are preparing to
// remove bb2.
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 3u);
BB0->getTerminator()->eraseFromParent();
BranchInst::Create(BB1, BB3, ConstantInt::getTrue(F->getContext()), BB0);
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 2u);
// Test callback utils.
std::vector<BasicBlock *> BasicBlocks;
BasicBlocks.push_back(BB1);
BasicBlocks.push_back(BB2);
auto Eraser = [&](BasicBlock *BB) {
BasicBlocks.erase(
std::remove_if(BasicBlocks.begin(), BasicBlocks.end(),
[&](const BasicBlock *i) { return i == BB; }),
BasicBlocks.end());
};
ASSERT_EQ(BasicBlocks.size(), static_cast<size_t>(2));
// Remove bb2 from F. This has to happen before the call to applyUpdates() for
// DTU to detect there is no longer an edge between bb2 -> bb3. The deleteBB()
// method converts bb2's TI into "unreachable".
ASSERT_FALSE(isa<UnreachableInst>(BB2->getTerminator()));
EXPECT_FALSE(DTU.isBBPendingDeletion(BB2));
DTU.callbackDeleteBB(BB2, Eraser);
EXPECT_TRUE(DTU.isBBPendingDeletion(BB2));
ASSERT_TRUE(isa<UnreachableInst>(BB2->getTerminator()));
EXPECT_EQ(BB2->getParent(), F);
// Queue up the DTU updates.
std::vector<DominatorTree::UpdateType> Updates;
Updates.reserve(4);
Updates.push_back({DominatorTree::Delete, BB0, BB2});
Updates.push_back({DominatorTree::Delete, BB2, BB3});
// Handle the specific shape case next.
// CFG Change: bb0 now only branches to bb3. We are preparing to remove bb1.
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 2u);
BB0->getTerminator()->eraseFromParent();
BranchInst::Create(BB3, BB0);
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 1u);
// Remove bb1 from F. This has to happen before the call to applyUpdates() for
// DTU to detect there is no longer an edge between bb1 -> bb3. The deleteBB()
// method converts bb1's TI into "unreachable".
ASSERT_FALSE(isa<UnreachableInst>(BB1->getTerminator()));
EXPECT_FALSE(DTU.isBBPendingDeletion(BB1));
DTU.callbackDeleteBB(BB1, Eraser);
EXPECT_TRUE(DTU.isBBPendingDeletion(BB1));
ASSERT_TRUE(isa<UnreachableInst>(BB1->getTerminator()));
EXPECT_EQ(BB1->getParent(), F);
// Update the DTU. In this case we don't call DTU.insertEdge(BB0, BB3) because
// the edge previously existed at the start of this test when DT was first
// created.
Updates.push_back({DominatorTree::Delete, BB0, BB1});
Updates.push_back({DominatorTree::Delete, BB1, BB3});
// Verify everything.
DTU.applyUpdates(Updates);
ASSERT_EQ(BasicBlocks.size(), static_cast<size_t>(2));
DTU.flush();
ASSERT_EQ(BasicBlocks.size(), static_cast<size_t>(0));
ASSERT_TRUE(DT.verify());
}
TEST(DomTreeUpdater, LazyUpdateBasicOperations) {
StringRef FuncName = "f";
StringRef ModuleString = R"(
define i32 @f(i32 %i, i32 *%p) {
bb0:
store i32 %i, i32 *%p
switch i32 %i, label %bb1 [
i32 0, label %bb2
i32 1, label %bb2
i32 2, label %bb3
]
bb1:
ret i32 1
bb2:
ret i32 2
bb3:
ret i32 3
}
)";
// Make the module.
LLVMContext Context;
std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
Function *F = M->getFunction(FuncName);
// Make the DTU.
DominatorTree DT(*F);
PostDominatorTree PDT(*F);
DomTreeUpdater DTU(&DT, &PDT, DomTreeUpdater::UpdateStrategy::Lazy);
ASSERT_TRUE(DTU.hasDomTree());
ASSERT_TRUE(DTU.hasPostDomTree());
ASSERT_FALSE(DTU.isEager());
ASSERT_TRUE(DTU.isLazy());
ASSERT_TRUE(DTU.getDomTree().verify());
ASSERT_TRUE(DTU.getPostDomTree().verify());
Function::iterator FI = F->begin();
BasicBlock *BB0 = &*FI++;
BasicBlock *BB1 = &*FI++;
BasicBlock *BB2 = &*FI++;
BasicBlock *BB3 = &*FI++;
// Test discards of self-domination update.
DTU.deleteEdge(BB0, BB0);
// Delete edge bb0 -> bb3 and push the update twice to verify duplicate
// entries are discarded.
std::vector<DominatorTree::UpdateType> Updates;
Updates.reserve(4);
Updates.push_back({DominatorTree::Delete, BB0, BB3});
Updates.push_back({DominatorTree::Delete, BB0, BB3});
// Unnecessary Insert: no edge bb1 -> bb2 after change to bb0.
Updates.push_back({DominatorTree::Insert, BB1, BB2});
// Unnecessary Delete: edge exists bb0 -> bb1 after change to bb0.
Updates.push_back({DominatorTree::Delete, BB0, BB1});
// CFG Change: remove edge bb0 -> bb3 and one duplicate edge bb0 -> bb2.
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 4u);
BB0->getTerminator()->eraseFromParent();
BranchInst::Create(BB1, BB2, ConstantInt::getTrue(F->getContext()), BB0);
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 2u);
// Deletion of a BasicBlock is an immediate event. We remove all uses to the
// contained Instructions and change the Terminator to "unreachable" when
// queued for deletion. Its parent is still F until DTU.flushDomTree is
// called. We don't defer this action because it can cause problems for other
// transforms or analysis as it's part of the actual CFG. We only defer
// updates to the DominatorTree. This code will crash if it is placed before
// the BranchInst::Create() call above.
bool CallbackFlag = false;
ASSERT_FALSE(isa<UnreachableInst>(BB3->getTerminator()));
EXPECT_FALSE(DTU.isBBPendingDeletion(BB3));
DTU.callbackDeleteBB(BB3, [&](BasicBlock *) { CallbackFlag = true; });
EXPECT_TRUE(DTU.isBBPendingDeletion(BB3));
ASSERT_TRUE(isa<UnreachableInst>(BB3->getTerminator()));
EXPECT_EQ(BB3->getParent(), F);
// Verify. Updates to DTU must be applied *after* all changes to the CFG
// (including block deletion).
DTU.applyUpdates(Updates);
ASSERT_TRUE(DTU.getDomTree().verify());
ASSERT_TRUE(DTU.hasPendingUpdates());
ASSERT_TRUE(DTU.hasPendingPostDomTreeUpdates());
ASSERT_FALSE(DTU.hasPendingDomTreeUpdates());
ASSERT_TRUE(DTU.hasPendingDeletedBB());
ASSERT_TRUE(DTU.getPostDomTree().verify());
ASSERT_FALSE(DTU.hasPendingUpdates());
ASSERT_FALSE(DTU.hasPendingPostDomTreeUpdates());
ASSERT_FALSE(DTU.hasPendingDomTreeUpdates());
ASSERT_FALSE(DTU.hasPendingDeletedBB());
ASSERT_EQ(CallbackFlag, true);
}
TEST(DomTreeUpdater, LazyUpdateReplaceEntryBB) {
StringRef FuncName = "f";
StringRef ModuleString = R"(
define i32 @f() {
bb0:
br label %bb1
bb1:
ret i32 1
}
)";
// Make the module.
LLVMContext Context;
std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
Function *F = M->getFunction(FuncName);
// Make the DTU.
DominatorTree DT(*F);
PostDominatorTree PDT(*F);
DomTreeUpdater DTU(DT, PDT, DomTreeUpdater::UpdateStrategy::Lazy);
ASSERT_TRUE(DTU.hasDomTree());
ASSERT_TRUE(DTU.hasPostDomTree());
ASSERT_FALSE(DTU.isEager());
ASSERT_TRUE(DTU.isLazy());
ASSERT_TRUE(DTU.getDomTree().verify());
ASSERT_TRUE(DTU.getPostDomTree().verify());
Function::iterator FI = F->begin();
BasicBlock *BB0 = &*FI++;
BasicBlock *BB1 = &*FI++;
// Add a block as the new function entry BB. We also link it to BB0.
BasicBlock *NewEntry =
BasicBlock::Create(F->getContext(), "new_entry", F, BB0);
BranchInst::Create(BB0, NewEntry);
EXPECT_EQ(F->begin()->getName(), NewEntry->getName());
EXPECT_TRUE(&F->getEntryBlock() == NewEntry);
// Insert the new edge between new_entry -> bb0. Without this the
// recalculate() call below will not actually recalculate the DT as there
// are no changes pending and no blocks deleted.
DTU.insertEdge(NewEntry, BB0);
// Changing the Entry BB requires a full recalculation.
DTU.recalculate(*F);
ASSERT_TRUE(DTU.getDomTree().verify());
ASSERT_TRUE(DTU.getPostDomTree().verify());
// CFG Change: remove new_edge -> bb0 and redirect to new_edge -> bb1.
EXPECT_EQ(NewEntry->getTerminator()->getNumSuccessors(), 1u);
NewEntry->getTerminator()->eraseFromParent();
BranchInst::Create(BB1, NewEntry);
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 1u);
// Update the DTU. At this point bb0 now has no predecessors but is still a
// Child of F.
DTU.applyUpdates({{DominatorTree::Delete, NewEntry, BB0},
{DominatorTree::Insert, NewEntry, BB1}});
DTU.flush();
ASSERT_TRUE(DT.verify());
ASSERT_TRUE(PDT.verify());
// Now remove bb0 from F.
ASSERT_FALSE(isa<UnreachableInst>(BB0->getTerminator()));
EXPECT_FALSE(DTU.isBBPendingDeletion(BB0));
DTU.deleteBB(BB0);
EXPECT_TRUE(DTU.isBBPendingDeletion(BB0));
ASSERT_TRUE(isa<UnreachableInst>(BB0->getTerminator()));
EXPECT_EQ(BB0->getParent(), F);
// Perform a full recalculation of the DTU. It is not necessary here but we
// do this to test the case when there are no pending DT updates but there are
// pending deleted BBs.
ASSERT_TRUE(DTU.hasPendingDeletedBB());
DTU.recalculate(*F);
ASSERT_FALSE(DTU.hasPendingDeletedBB());
}
TEST(DomTreeUpdater, LazyUpdateStepTest) {
// This test focus on testing a DTU holding both trees applying multiple
// updates and DT/PDT not flushed together.
StringRef FuncName = "f";
StringRef ModuleString = R"(
define i32 @f(i32 %i, i32 *%p) {
bb0:
store i32 %i, i32 *%p
switch i32 %i, label %bb1 [
i32 0, label %bb1
i32 1, label %bb2
i32 2, label %bb3
i32 3, label %bb1
]
bb1:
ret i32 1
bb2:
ret i32 2
bb3:
ret i32 3
}
)";
// Make the module.
LLVMContext Context;
std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
Function *F = M->getFunction(FuncName);
// Make the DomTreeUpdater.
DominatorTree DT(*F);
PostDominatorTree PDT(*F);
DomTreeUpdater DTU(DT, PDT, DomTreeUpdater::UpdateStrategy::Lazy);
ASSERT_TRUE(DTU.hasDomTree());
ASSERT_TRUE(DTU.hasPostDomTree());
ASSERT_FALSE(DTU.isEager());
ASSERT_TRUE(DTU.isLazy());
ASSERT_TRUE(DTU.getDomTree().verify());
ASSERT_TRUE(DTU.getPostDomTree().verify());
ASSERT_FALSE(DTU.hasPendingUpdates());
Function::iterator FI = F->begin();
BasicBlock *BB0 = &*FI++;
FI++;
BasicBlock *BB2 = &*FI++;
BasicBlock *BB3 = &*FI++;
SwitchInst *SI = dyn_cast<SwitchInst>(BB0->getTerminator());
ASSERT_NE(SI, nullptr) << "Couldn't get SwitchInst.";
// Delete edge bb0 -> bb3 and push the update twice to verify duplicate
// entries are discarded.
std::vector<DominatorTree::UpdateType> Updates;
Updates.reserve(1);
Updates.push_back({DominatorTree::Delete, BB0, BB3});
// CFG Change: remove edge bb0 -> bb3.
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 5u);
BB3->removePredecessor(BB0);
for (auto i = SI->case_begin(), e = SI->case_end(); i != e; ++i) {
if (i->getCaseIndex() == 2) {
SI->removeCase(i);
break;
}
}
EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 4u);
// Deletion of a BasicBlock is an immediate event. We remove all uses to the
// contained Instructions and change the Terminator to "unreachable" when
// queued for deletion.
ASSERT_FALSE(isa<UnreachableInst>(BB3->getTerminator()));
EXPECT_FALSE(DTU.isBBPendingDeletion(BB3));
DTU.applyUpdates(Updates);
// Only flush DomTree.
ASSERT_TRUE(DTU.getDomTree().verify());
ASSERT_TRUE(DTU.hasPendingPostDomTreeUpdates());
ASSERT_FALSE(DTU.hasPendingDomTreeUpdates());
ASSERT_EQ(BB3->getParent(), F);
DTU.deleteBB(BB3);
Updates.clear();
// Remove all case branch to BB2 to test Eager recalculation.
// Code section from llvm::ConstantFoldTerminator
for (auto i = SI->case_begin(), e = SI->case_end(); i != e;) {
if (i->getCaseSuccessor() == BB2) {
// Remove this entry.
BB2->removePredecessor(BB0);
i = SI->removeCase(i);
e = SI->case_end();
Updates.push_back({DominatorTree::Delete, BB0, BB2});
} else
++i;
}
DTU.applyUpdates(Updates);
// flush PostDomTree
ASSERT_TRUE(DTU.getPostDomTree().verify());
ASSERT_FALSE(DTU.hasPendingPostDomTreeUpdates());
ASSERT_TRUE(DTU.hasPendingDomTreeUpdates());
// flush both trees
DTU.flush();
ASSERT_TRUE(DT.verify());
}
TEST(DomTreeUpdater, NoTreeTest) {
StringRef FuncName = "f";
StringRef ModuleString = R"(
define i32 @f() {
bb0:
ret i32 0
}
)";
// Make the module.
LLVMContext Context;
std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
Function *F = M->getFunction(FuncName);
// Make the DTU.
DomTreeUpdater DTU(nullptr, nullptr, DomTreeUpdater::UpdateStrategy::Lazy);
ASSERT_FALSE(DTU.hasDomTree());
ASSERT_FALSE(DTU.hasPostDomTree());
Function::iterator FI = F->begin();
BasicBlock *BB0 = &*FI++;
// Test whether PendingDeletedBB is flushed after the recalculation.
DTU.deleteBB(BB0);
ASSERT_TRUE(DTU.hasPendingDeletedBB());
DTU.recalculate(*F);
ASSERT_FALSE(DTU.hasPendingDeletedBB());
}
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