[DTU] Refine the interface and logic of applyUpdates
Summary:
This patch separates two semantics of `applyUpdates`:
1. User provides an accurate CFG diff and the dominator tree is updated according to the difference of `the number of edge insertions` and `the number of edge deletions` to infer the status of an edge before and after the update.
2. User provides a sequence of hints. Updates mentioned in this sequence might never happened and even duplicated.
Logic changes:
Previously, removing invalid updates is considered a side-effect of deduplication and is not guaranteed to be reliable. To handle the second semantic, `applyUpdates` does validity checking before deduplication, which can cause updates that have already been applied to be submitted again. Then, different calls to `applyUpdates` might cause unintended consequences, for example,
```
DTU(Lazy) and Edge A->B exists.
1. DTU.applyUpdates({{Delete, A, B}, {Insert, A, B}}) // User expects these 2 updates result in a no-op, but {Insert, A, B} is queued
2. Remove A->B
3. DTU.applyUpdates({{Delete, A, B}}) // DTU cancels this update with {Insert, A, B} mentioned above together (Unintended)
```
But by restricting the precondition that updates of an edge need to be strictly ordered as how CFG changes were made, we can infer the initial status of this edge to resolve this issue.
Interface changes:
The second semantic of `applyUpdates` is separated to `applyUpdatesPermissive`.
These changes enable DTU(Lazy) to use the first semantic if needed, which is quite useful in `transforms/utils`.
Reviewers: kuhar, brzycki, dmgreen, grosser
Reviewed By: brzycki
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58170
llvm-svn: 354669
diff --git a/llvm/include/llvm/Analysis/DomTreeUpdater.h b/llvm/include/llvm/Analysis/DomTreeUpdater.h
index 9497a31..5ccce2e 100644
--- a/llvm/include/llvm/Analysis/DomTreeUpdater.h
+++ b/llvm/include/llvm/Analysis/DomTreeUpdater.h
@@ -103,8 +103,24 @@
/// Although GenericDomTree provides several update primitives,
/// it is not encouraged to use these APIs directly.
- /// Submit updates to all available trees. Under Eager UpdateStrategy with
- /// ForceRemoveDuplicates enabled or under Lazy UpdateStrategy, it will
+ /// Submit updates to all available trees.
+ /// The Eager Strategy flushes updates immediately while the Lazy Strategy
+ /// queues the updates.
+ ///
+ /// Note: The "existence" of an edge in a CFG refers to the CFG which DTU is
+ /// in sync with + all updates before that single update.
+ ///
+ /// CAUTION!
+ /// 1. It is required for the state of the LLVM IR to be updated
+ /// *before* submitting the updates because the internal update routine will
+ /// analyze the current state of the CFG to determine whether an update
+ /// is valid.
+ /// 2. It is illegal to submit any update that has already been submitted,
+ /// i.e., you are supposed not to insert an existent edge or delete a
+ /// nonexistent edge.
+ void applyUpdates(ArrayRef<DominatorTree::UpdateType> Updates);
+
+ /// Submit updates to all available trees. It will also
/// 1. discard duplicated updates,
/// 2. remove invalid updates. (Invalid updates means deletion of an edge that
/// still exists or insertion of an edge that does not exist.)
@@ -122,8 +138,10 @@
/// 2. It is illegal to submit any update that has already been submitted,
/// i.e., you are supposed not to insert an existent edge or delete a
/// nonexistent edge.
- void applyUpdates(ArrayRef<DominatorTree::UpdateType> Updates,
- bool ForceRemoveDuplicates = false);
+ /// 3. It is only legal to submit updates to an edge in the order CFG changes
+ /// are made. The order you submit updates on different edges is not
+ /// restricted.
+ void applyUpdatesPermissive(ArrayRef<DominatorTree::UpdateType> Updates);
/// Notify DTU that the entry block was replaced.
/// Recalculate all available trees and flush all BasicBlocks
@@ -149,7 +167,7 @@
/// submitted. }
LLVM_ATTRIBUTE_DEPRECATED(void insertEdgeRelaxed(BasicBlock *From,
BasicBlock *To),
- "Use applyUpdates() instead.");
+ "Use applyUpdatesPermissive() instead.");
/// \deprecated { Submit an edge deletion to all available trees. The Eager
/// Strategy flushes this update immediately while the Lazy Strategy queues
@@ -171,7 +189,7 @@
/// submitted. }
LLVM_ATTRIBUTE_DEPRECATED(void deleteEdgeRelaxed(BasicBlock *From,
BasicBlock *To),
- "Use applyUpdates() instead.");
+ "Use applyUpdatesPermissive() instead.");
/// Delete DelBB. DelBB will be removed from its Parent and
/// erased from available trees if it exists and finally get deleted.
@@ -260,11 +278,6 @@
/// Returns true if at least one BasicBlock is deleted.
bool forceFlushDeletedBB();
- /// Deduplicate and remove unnecessary updates (no-ops) when using Lazy
- /// UpdateStrategy. Returns true if the update is queued for update.
- bool applyLazyUpdate(DominatorTree::UpdateKind Kind, BasicBlock *From,
- BasicBlock *To);
-
/// Helper function to apply all pending DomTree updates.
void applyDomTreeUpdates();
diff --git a/llvm/lib/Analysis/DomTreeUpdater.cpp b/llvm/lib/Analysis/DomTreeUpdater.cpp
index e4d505b..4921588 100644
--- a/llvm/lib/Analysis/DomTreeUpdater.cpp
+++ b/llvm/lib/Analysis/DomTreeUpdater.cpp
@@ -12,11 +12,13 @@
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/DomTreeUpdater.h"
+#include "llvm/ADT/SmallSet.h"
#include "llvm/Analysis/PostDominators.h"
#include "llvm/IR/Dominators.h"
#include "llvm/Support/GenericDomTree.h"
#include <algorithm>
#include <functional>
+#include <utility>
namespace llvm {
@@ -53,41 +55,6 @@
return Update.getFrom() == Update.getTo();
}
-bool DomTreeUpdater::applyLazyUpdate(DominatorTree::UpdateKind Kind,
- BasicBlock *From, BasicBlock *To) {
- assert((DT || PDT) &&
- "Call applyLazyUpdate() when both DT and PDT are nullptrs.");
- assert(Strategy == DomTreeUpdater::UpdateStrategy::Lazy &&
- "Call applyLazyUpdate() with Eager strategy error");
- // Analyze pending updates to determine if the update is unnecessary.
- const DominatorTree::UpdateType Update = {Kind, From, To};
- const DominatorTree::UpdateType Invert = {Kind != DominatorTree::Insert
- ? DominatorTree::Insert
- : DominatorTree::Delete,
- From, To};
- // Only check duplicates in updates that are not applied by both trees.
- auto I =
- PendUpdates.begin() + std::max(PendDTUpdateIndex, PendPDTUpdateIndex);
- const auto E = PendUpdates.end();
-
- assert(I <= E && "Iterator out of range.");
-
- for (; I != E; ++I) {
- if (Update == *I)
- return false; // Discard duplicate updates.
-
- if (Invert == *I) {
- // Update and Invert are both valid (equivalent to a no-op). Remove
- // Invert from PendUpdates and discard the Update.
- PendUpdates.erase(I);
- return false;
- }
- }
-
- PendUpdates.push_back(Update); // Save the valid update.
- return true;
-}
-
void DomTreeUpdater::applyDomTreeUpdates() {
// No pending DomTreeUpdates.
if (Strategy != UpdateStrategy::Lazy || !DT)
@@ -261,31 +228,15 @@
new UnreachableInst(DelBB->getContext(), DelBB);
}
-void DomTreeUpdater::applyUpdates(ArrayRef<DominatorTree::UpdateType> Updates,
- bool ForceRemoveDuplicates) {
+void DomTreeUpdater::applyUpdates(ArrayRef<DominatorTree::UpdateType> Updates) {
if (!DT && !PDT)
return;
- if (Strategy == UpdateStrategy::Lazy || ForceRemoveDuplicates) {
- SmallVector<DominatorTree::UpdateType, 8> Seen;
+ if (Strategy == UpdateStrategy::Lazy) {
for (const auto U : Updates)
- // For Lazy UpdateStrategy, avoid duplicates to applyLazyUpdate() to save
- // on analysis.
- if (llvm::none_of(
- Seen,
- [U](const DominatorTree::UpdateType S) { return S == U; }) &&
- isUpdateValid(U) && !isSelfDominance(U)) {
- Seen.push_back(U);
- if (Strategy == UpdateStrategy::Lazy)
- applyLazyUpdate(U.getKind(), U.getFrom(), U.getTo());
- }
- if (Strategy == UpdateStrategy::Lazy)
- return;
+ if (!isSelfDominance(U))
+ PendUpdates.push_back(U);
- if (DT)
- DT->applyUpdates(Seen);
- if (PDT)
- PDT->applyUpdates(Seen);
return;
}
@@ -295,6 +246,60 @@
PDT->applyUpdates(Updates);
}
+void DomTreeUpdater::applyUpdatesPermissive(
+ ArrayRef<DominatorTree::UpdateType> Updates) {
+ if (!DT && !PDT)
+ return;
+
+ SmallSet<std::pair<BasicBlock *, BasicBlock *>, 8> Seen;
+ SmallVector<DominatorTree::UpdateType, 8> DeduplicatedUpdates;
+ for (const auto U : Updates) {
+ auto Edge = std::make_pair(U.getFrom(), U.getTo());
+ // Because it is illegal to submit updates that have already been applied
+ // and updates to an edge need to be strictly ordered,
+ // it is safe to infer the existence of an edge from the first update
+ // to this edge.
+ // If the first update to an edge is "Delete", it means that the edge
+ // existed before. If the first update to an edge is "Insert", it means
+ // that the edge didn't exist before.
+ //
+ // For example, if the user submits {{Delete, A, B}, {Insert, A, B}},
+ // because
+ // 1. it is illegal to submit updates that have already been applied,
+ // i.e., user cannot delete an nonexistent edge,
+ // 2. updates to an edge need to be strictly ordered,
+ // So, initially edge A -> B existed.
+ // We can then safely ignore future updates to this edge and directly
+ // inspect the current CFG:
+ // a. If the edge still exists, because the user cannot insert an existent
+ // edge, so both {Delete, A, B}, {Insert, A, B} actually happened and
+ // resulted in a no-op. DTU won't submit any update in this case.
+ // b. If the edge doesn't exist, we can then infer that {Delete, A, B}
+ // actually happened but {Insert, A, B} was an invalid update which never
+ // happened. DTU will submit {Delete, A, B} in this case.
+ if (!isSelfDominance(U) && Seen.count(Edge) == 0) {
+ Seen.insert(Edge);
+ // If the update doesn't appear in the CFG, it means that
+ // either the change isn't made or relevant operations
+ // result in a no-op.
+ if (isUpdateValid(U)) {
+ if (isLazy())
+ PendUpdates.push_back(U);
+ else
+ DeduplicatedUpdates.push_back(U);
+ }
+ }
+ }
+
+ if (Strategy == UpdateStrategy::Lazy)
+ return;
+
+ if (DT)
+ DT->applyUpdates(DeduplicatedUpdates);
+ if (PDT)
+ PDT->applyUpdates(DeduplicatedUpdates);
+}
+
DominatorTree &DomTreeUpdater::getDomTree() {
assert(DT && "Invalid acquisition of a null DomTree");
applyDomTreeUpdates();
@@ -331,7 +336,7 @@
return;
}
- applyLazyUpdate(DominatorTree::Insert, From, To);
+ PendUpdates.push_back({DominatorTree::Insert, From, To});
}
void DomTreeUpdater::insertEdgeRelaxed(BasicBlock *From, BasicBlock *To) {
@@ -352,7 +357,7 @@
return;
}
- applyLazyUpdate(DominatorTree::Insert, From, To);
+ PendUpdates.push_back({DominatorTree::Insert, From, To});
}
void DomTreeUpdater::deleteEdge(BasicBlock *From, BasicBlock *To) {
@@ -377,7 +382,7 @@
return;
}
- applyLazyUpdate(DominatorTree::Delete, From, To);
+ PendUpdates.push_back({DominatorTree::Delete, From, To});
}
void DomTreeUpdater::deleteEdgeRelaxed(BasicBlock *From, BasicBlock *To) {
@@ -398,7 +403,7 @@
return;
}
- applyLazyUpdate(DominatorTree::Delete, From, To);
+ PendUpdates.push_back({DominatorTree::Delete, From, To});
}
void DomTreeUpdater::dropOutOfDateUpdates() {
diff --git a/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp b/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp
index 8463ceb..6b74923 100644
--- a/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp
+++ b/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp
@@ -366,7 +366,7 @@
assert(Splits.size() == 2 && "Expected exactly 2 splits!");
for (unsigned i = 0; i < Splits.size(); i++) {
Splits[i]->getTerminator()->eraseFromParent();
- DTU.applyUpdates({{DominatorTree::Delete, Splits[i], TailBB}});
+ DTU.applyUpdatesPermissive({{DominatorTree::Delete, Splits[i], TailBB}});
}
// Erase the tail block once done with musttail patching
diff --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 755bf34..e6dd42d 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -373,7 +373,7 @@
++NumDeadCases;
Changed = true;
if (--SuccessorsCount[Succ] == 0)
- DTU.applyUpdates({{DominatorTree::Delete, BB, Succ}});
+ DTU.applyUpdatesPermissive({{DominatorTree::Delete, BB, Succ}});
continue;
}
if (State == LazyValueInfo::True) {
diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index 80b3cd7..7d6ffa0 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -1091,7 +1091,7 @@
<< "' folding undef terminator: " << *BBTerm << '\n');
BranchInst::Create(BBTerm->getSuccessor(BestSucc), BBTerm);
BBTerm->eraseFromParent();
- DTU->applyUpdates(Updates);
+ DTU->applyUpdatesPermissive(Updates);
return true;
}
@@ -1159,7 +1159,8 @@
ConstantInt::getFalse(CondCmp->getType());
ReplaceFoldableUses(CondCmp, CI);
}
- DTU->applyUpdates({{DominatorTree::Delete, BB, ToRemoveSucc}});
+ DTU->applyUpdatesPermissive(
+ {{DominatorTree::Delete, BB, ToRemoveSucc}});
return true;
}
@@ -1246,7 +1247,7 @@
RemoveSucc->removePredecessor(BB);
BranchInst::Create(KeepSucc, BI);
BI->eraseFromParent();
- DTU->applyUpdates({{DominatorTree::Delete, BB, RemoveSucc}});
+ DTU->applyUpdatesPermissive({{DominatorTree::Delete, BB, RemoveSucc}});
return true;
}
CurrentBB = CurrentPred;
@@ -1676,7 +1677,7 @@
Instruction *Term = BB->getTerminator();
BranchInst::Create(OnlyDest, Term);
Term->eraseFromParent();
- DTU->applyUpdates(Updates);
+ DTU->applyUpdatesPermissive(Updates);
// If the condition is now dead due to the removal of the old terminator,
// erase it.
@@ -2018,9 +2019,9 @@
}
// Enqueue required DT updates.
- DTU->applyUpdates({{DominatorTree::Insert, NewBB, SuccBB},
- {DominatorTree::Insert, PredBB, NewBB},
- {DominatorTree::Delete, PredBB, BB}});
+ DTU->applyUpdatesPermissive({{DominatorTree::Insert, NewBB, SuccBB},
+ {DominatorTree::Insert, PredBB, NewBB},
+ {DominatorTree::Delete, PredBB, BB}});
// If there were values defined in BB that are used outside the block, then we
// now have to update all uses of the value to use either the original value,
@@ -2114,7 +2115,7 @@
BFI->setBlockFreq(NewBB, NewBBFreq.getFrequency());
}
- DTU->applyUpdates(Updates);
+ DTU->applyUpdatesPermissive(Updates);
return NewBBs[0];
}
@@ -2387,7 +2388,7 @@
// Remove the unconditional branch at the end of the PredBB block.
OldPredBranch->eraseFromParent();
- DTU->applyUpdates(Updates);
+ DTU->applyUpdatesPermissive(Updates);
++NumDupes;
return true;
@@ -2423,8 +2424,8 @@
// The select is now dead.
SI->eraseFromParent();
- DTU->applyUpdates({{DominatorTree::Insert, NewBB, BB},
- {DominatorTree::Insert, Pred, NewBB}});
+ DTU->applyUpdatesPermissive({{DominatorTree::Insert, NewBB, BB},
+ {DominatorTree::Insert, Pred, NewBB}});
// Update any other PHI nodes in BB.
for (BasicBlock::iterator BI = BB->begin();
@@ -2601,7 +2602,7 @@
Updates.push_back({DominatorTree::Delete, BB, Succ});
Updates.push_back({DominatorTree::Insert, SplitBB, Succ});
}
- DTU->applyUpdates(Updates);
+ DTU->applyUpdatesPermissive(Updates);
return true;
}
return false;
diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index 0d6d102..0557b7d 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -101,7 +101,7 @@
DetatchDeadBlocks(BBs, DTU ? &Updates : nullptr, KeepOneInputPHIs);
if (DTU)
- DTU->applyUpdates(Updates, /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive(Updates);
for (BasicBlock *BB : BBs)
if (DTU)
@@ -235,7 +235,7 @@
isa<UnreachableInst>(BB->getTerminator()) &&
"The successor list of BB isn't empty before "
"applying corresponding DTU updates.");
- DTU->applyUpdates(Updates, /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive(Updates);
DTU->deleteBB(BB);
}
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 3ef5494..d14384f 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -128,8 +128,7 @@
Builder.CreateBr(Destination);
BI->eraseFromParent();
if (DTU)
- DTU->applyUpdates({{DominatorTree::Delete, BB, OldDest}},
- /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive({{DominatorTree::Delete, BB, OldDest}});
return true;
}
@@ -205,8 +204,8 @@
i = SI->removeCase(i);
e = SI->case_end();
if (DTU)
- DTU->applyUpdates({{DominatorTree::Delete, ParentBB, DefaultDest}},
- /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive(
+ {{DominatorTree::Delete, ParentBB, DefaultDest}});
continue;
}
@@ -254,7 +253,7 @@
if (DeleteDeadConditions)
RecursivelyDeleteTriviallyDeadInstructions(Cond, TLI);
if (DTU)
- DTU->applyUpdates(Updates, /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive(Updates);
return true;
}
@@ -332,7 +331,7 @@
}
if (DTU)
- DTU->applyUpdates(Updates, /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive(Updates);
return true;
}
}
@@ -666,8 +665,7 @@
if (PhiIt != OldPhiIt) PhiIt = &BB->front();
}
if (DTU)
- DTU->applyUpdates({{DominatorTree::Delete, Pred, BB}},
- /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive({{DominatorTree::Delete, Pred, BB}});
}
/// MergeBasicBlockIntoOnlyPred - DestBB is a block with one predecessor and its
@@ -736,7 +734,7 @@
isa<UnreachableInst>(PredBB->getTerminator()) &&
"The successor list of PredBB isn't empty before "
"applying corresponding DTU updates.");
- DTU->applyUpdates(Updates, /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive(Updates);
DTU->deleteBB(PredBB);
// Recalculation of DomTree is needed when updating a forward DomTree and
// the Entry BB is replaced.
@@ -1078,7 +1076,7 @@
"applying corresponding DTU updates.");
if (DTU) {
- DTU->applyUpdates(Updates, /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive(Updates);
DTU->deleteBB(BB);
} else {
BB->eraseFromParent(); // Delete the old basic block.
@@ -1942,7 +1940,7 @@
++NumInstrsRemoved;
}
if (DTU)
- DTU->applyUpdates(Updates, /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive(Updates);
return NumInstrsRemoved;
}
@@ -1970,8 +1968,7 @@
UnwindDestBB->removePredecessor(BB);
II->eraseFromParent();
if (DTU)
- DTU->applyUpdates({{DominatorTree::Delete, BB, UnwindDestBB}},
- /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive({{DominatorTree::Delete, BB, UnwindDestBB}});
}
BasicBlock *llvm::changeToInvokeAndSplitBasicBlock(CallInst *CI,
@@ -2118,8 +2115,8 @@
UnwindDestBB->removePredecessor(II->getParent());
II->eraseFromParent();
if (DTU)
- DTU->applyUpdates({{DominatorTree::Delete, BB, UnwindDestBB}},
- /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive(
+ {{DominatorTree::Delete, BB, UnwindDestBB}});
} else
changeToCall(II, DTU);
Changed = true;
@@ -2208,8 +2205,7 @@
TI->replaceAllUsesWith(NewTI);
TI->eraseFromParent();
if (DTU)
- DTU->applyUpdates({{DominatorTree::Delete, BB, UnwindDest}},
- /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive({{DominatorTree::Delete, BB, UnwindDest}});
}
/// removeUnreachableBlocks - Remove blocks that are not reachable, even
@@ -2274,7 +2270,7 @@
}
if (DTU) {
- DTU->applyUpdates(Updates, /*ForceRemoveDuplicates*/ true);
+ DTU->applyUpdatesPermissive(Updates);
bool Deleted = false;
for (auto *BB : DeadBlockSet) {
if (DTU->isBBPendingDeletion(BB))
diff --git a/llvm/unittests/Analysis/DomTreeUpdaterTest.cpp b/llvm/unittests/Analysis/DomTreeUpdaterTest.cpp
index a1154a3..4a5e2d7 100644
--- a/llvm/unittests/Analysis/DomTreeUpdaterTest.cpp
+++ b/llvm/unittests/Analysis/DomTreeUpdaterTest.cpp
@@ -71,9 +71,9 @@
SwitchInst *SI = dyn_cast<SwitchInst>(BB0->getTerminator());
ASSERT_NE(SI, nullptr) << "Couldn't get SwitchInst.";
- DTU.applyUpdates(
- {{DominatorTree::Insert, BB0, BB0}, {DominatorTree::Delete, BB0, BB0}},
- /*ForceRemoveDuplicates*/ true);
+ DTU.applyUpdatesPermissive(
+ {{DominatorTree::Insert, BB0, BB0}, {DominatorTree::Delete, BB0, BB0}});
+ ASSERT_FALSE(DTU.hasPendingUpdates());
// Delete edge bb0 -> bb3 and push the update twice to verify duplicate
// entries are discarded.
@@ -102,14 +102,13 @@
// queued for deletion.
ASSERT_FALSE(isa<UnreachableInst>(BB3->getTerminator()));
EXPECT_FALSE(DTU.isBBPendingDeletion(BB3));
- DTU.applyUpdates(Updates, /*ForceRemoveDuplicates*/ true);
+ DTU.applyUpdatesPermissive(Updates);
ASSERT_FALSE(DTU.hasPendingUpdates());
// Invalid Insert: no edge bb1 -> bb2 after change to bb0.
// Invalid Delete: edge exists bb0 -> bb1 after change to bb0.
- DTU.applyUpdates(
- {{DominatorTree::Insert, BB1, BB2}, {DominatorTree::Delete, BB0, BB1}},
- /*ForceRemoveDuplicates*/ true);
+ DTU.applyUpdatesPermissive(
+ {{DominatorTree::Insert, BB1, BB2}, {DominatorTree::Delete, BB0, BB1}});
// DTU working with Eager UpdateStrategy does not need to flush.
ASSERT_TRUE(DT.verify());
@@ -184,8 +183,7 @@
EXPECT_EQ(F->begin()->getName(), NewEntry->getName());
EXPECT_TRUE(&F->getEntryBlock() == NewEntry);
- DTU.applyUpdates({{DominatorTree::Insert, NewEntry, BB0}},
- /*ForceRemoveDuplicates*/ true);
+ DTU.applyUpdates({{DominatorTree::Insert, NewEntry, BB0}});
// Changing the Entry BB requires a full recalculation of DomTree.
DTU.recalculate(*F);
@@ -254,7 +252,7 @@
BasicBlock *BB3 = &*FI++;
// Test discards of self-domination update.
- DTU.applyUpdates({{DominatorTree::Delete, BB0, BB0}});
+ DTU.applyUpdatesPermissive({{DominatorTree::Insert, BB0, BB0}});
ASSERT_FALSE(DTU.hasPendingDomTreeUpdates());
// Delete edge bb0 -> bb3 and push the update twice to verify duplicate
@@ -277,7 +275,7 @@
// Verify. Updates to DTU must be applied *after* all changes to the CFG
// (including block deletion).
- DTU.applyUpdates(Updates);
+ DTU.applyUpdatesPermissive(Updates);
ASSERT_TRUE(DTU.getDomTree().verify());
// Deletion of a BasicBlock is an immediate event. We remove all uses to the
@@ -362,9 +360,9 @@
//
// While the final CFG form is functionally identical the updates to
// DTU are not. In the first case we must have
- // DTU.applyUpdates({{DominatorTree::Insert, Pred1, Succ}}) while in the
- // latter case we must *NOT* have DTU.applyUpdates({{DominatorTree::Insert,
- // Pred1, Succ}}).
+ // DTU.applyUpdates({{DominatorTree::Insert, Pred1, Succ}}) while in
+ // the latter case we must *NOT* have
+ // DTU.applyUpdates({{DominatorTree::Insert, Pred1, Succ}}).
// CFG Change: bb0 now only has bb0 -> bb1 and bb0 -> bb3. We are preparing to
// remove bb2.
@@ -384,9 +382,9 @@
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".
+ // 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);
@@ -407,9 +405,9 @@
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".
+ // 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);
@@ -424,7 +422,7 @@
Updates.push_back({DominatorTree::Delete, BB1, BB3});
// Verify everything.
- DTU.applyUpdates(Updates);
+ DTU.applyUpdatesPermissive(Updates);
ASSERT_EQ(BasicBlocks.size(), static_cast<size_t>(2));
DTU.flush();
ASSERT_EQ(BasicBlocks.size(), static_cast<size_t>(0));
@@ -509,7 +507,7 @@
// Verify. Updates to DTU must be applied *after* all changes to the CFG
// (including block deletion).
- DTU.applyUpdates(Updates);
+ DTU.applyUpdatesPermissive(Updates);
ASSERT_TRUE(DTU.getDomTree().verify());
ASSERT_TRUE(DTU.hasPendingUpdates());
ASSERT_TRUE(DTU.hasPendingPostDomTreeUpdates());
@@ -648,8 +646,7 @@
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.
+ // Delete edge bb0 -> bb3.
std::vector<DominatorTree::UpdateType> Updates;
Updates.reserve(1);
Updates.push_back({DominatorTree::Delete, BB0, BB3});
@@ -694,7 +691,7 @@
++i;
}
- DTU.applyUpdates(Updates);
+ DTU.applyUpdatesPermissive(Updates);
// flush PostDomTree
ASSERT_TRUE(DTU.getPostDomTree().verify());
ASSERT_FALSE(DTU.hasPendingPostDomTreeUpdates());
@@ -729,3 +726,69 @@
DTU.recalculate(*F);
ASSERT_FALSE(DTU.hasPendingDeletedBB());
}
+
+TEST(DomTreeUpdater, LazyUpdateDeduplicationTest) {
+ StringRef FuncName = "f";
+ StringRef ModuleString = R"(
+ define i32 @f() {
+ bb0:
+ br label %bb1
+ bb1:
+ ret i32 1
+ bb2:
+ 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);
+ DomTreeUpdater DTU(&DT, nullptr, DomTreeUpdater::UpdateStrategy::Lazy);
+ ASSERT_TRUE(DTU.getDomTree().verify());
+
+ Function::iterator FI = F->begin();
+ BasicBlock *BB0 = &*FI++;
+ BasicBlock *BB1 = &*FI++;
+ BasicBlock *BB2 = &*FI++;
+
+ // CFG Change: remove bb0 -> bb1 and add back bb0 -> bb1.
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 1u);
+ BB0->getTerminator()->eraseFromParent();
+ BranchInst::Create(BB1, BB0);
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 1u);
+
+ // Update the DTU and simulate duplicates.
+ DTU.applyUpdatesPermissive({{DominatorTree::Delete, BB0, BB1},
+ {DominatorTree::Delete, BB0, BB1},
+ {DominatorTree::Insert, BB0, BB1},
+ {DominatorTree::Insert, BB0, BB1},
+ {DominatorTree::Insert, BB0, BB1}});
+
+ // The above operations result in a no-op.
+ ASSERT_FALSE(DTU.hasPendingUpdates());
+
+ // Update the DTU. Simulate an invalid update.
+ DTU.applyUpdatesPermissive({{DominatorTree::Delete, BB0, BB1}});
+ ASSERT_FALSE(DTU.hasPendingUpdates());
+
+ // CFG Change: remove bb0 -> bb1.
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 1u);
+ BB0->getTerminator()->eraseFromParent();
+
+ // Update the DTU and simulate invalid updates.
+ DTU.applyUpdatesPermissive({{DominatorTree::Delete, BB0, BB1},
+ {DominatorTree::Insert, BB0, BB1},
+ {DominatorTree::Delete, BB0, BB1},
+ {DominatorTree::Insert, BB0, BB1},
+ {DominatorTree::Insert, BB0, BB1}});
+ ASSERT_TRUE(DTU.hasPendingUpdates());
+
+ // CFG Change: add bb0 -> bb2.
+ BranchInst::Create(BB2, BB0);
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 1u);
+ DTU.applyUpdates({{DominatorTree::Insert, BB0, BB2}});
+ ASSERT_TRUE(DTU.getDomTree().verify());
+}
