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[SandboxVec][DAG] Implement DAG maintainance on Instruction removal #127361

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Merged
merged 1 commit into from
Feb 18, 2025
Merged

[SandboxVec][DAG] Implement DAG maintainance on Instruction removal #127361

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28 changes: 23 additions & 5 deletions llvm/lib/Transforms/Vectorize/SandboxVectorizer/DependencyGraph.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -483,19 +483,37 @@ void DependencyGraph::notifyEraseInstr(Instruction *I) {
if (Ctx->getTracker().getState() == Tracker::TrackerState::Reverting)
// We don't maintain the DAG while reverting.
return;
// Update the MemDGNode chain if this is a memory node.
if (auto *MemN = dyn_cast_or_null<MemDGNode>(getNodeOrNull(I))) {
auto *N = getNode(I);
if (N == nullptr)
// Early return if there is no DAG node for `I`.
return;
if (auto *MemN = dyn_cast<MemDGNode>(getNode(I))) {
// Update the MemDGNode chain if this is a memory node.
auto *PrevMemN = getMemDGNodeBefore(MemN, /*IncludingN=*/false);
auto *NextMemN = getMemDGNodeAfter(MemN, /*IncludingN=*/false);
if (PrevMemN != nullptr)
PrevMemN->NextMemN = NextMemN;
if (NextMemN != nullptr)
NextMemN->PrevMemN = PrevMemN;
}

// Drop the memory dependencies from both predecessors and successors.
while (!MemN->memPreds().empty()) {
auto *PredN = *MemN->memPreds().begin();
MemN->removeMemPred(PredN);
}
while (!MemN->memSuccs().empty()) {
auto *SuccN = *MemN->memSuccs().begin();
SuccN->removeMemPred(MemN);
}
// NOTE: The unscheduled succs for MemNodes get updated be setMemPred().
} else {
// If this is a non-mem node we only need to update UnscheduledSuccs.
if (!N->scheduled())
for (auto *PredN : N->preds(*this))
PredN->decrUnscheduledSuccs();
}
// Finally erase the Node.
InstrToNodeMap.erase(I);

// TODO: Update the dependencies.
}

void DependencyGraph::notifySetUse(const Use &U, Value *NewSrc) {
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53 changes: 48 additions & 5 deletions llvm/unittests/Transforms/Vectorize/SandboxVectorizer/DependencyGraphTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -940,10 +940,11 @@ define void @foo(ptr %ptr, i8 %v1, i8 %v2, i8 %v3, i8 %new1, i8 %new2) {

TEST_F(DependencyGraphTest, EraseInstrCallback) {
parseIR(C, R"IR(
define void @foo(ptr %ptr, i8 %v1, i8 %v2, i8 %v3, i8 %arg) {
define void @foo(ptr %ptr, i8 %v1, i8 %v2, i8 %v3, i8 %v4, i8 %arg) {
store i8 %v1, ptr %ptr
store i8 %v2, ptr %ptr
store i8 %v3, ptr %ptr
store i8 %v4, ptr %ptr
ret void
}
)IR");
Expand All @@ -955,25 +956,67 @@ define void @foo(ptr %ptr, i8 %v1, i8 %v2, i8 %v3, i8 %arg) {
auto *S1 = cast<sandboxir::StoreInst>(&*It++);
auto *S2 = cast<sandboxir::StoreInst>(&*It++);
auto *S3 = cast<sandboxir::StoreInst>(&*It++);
auto *S4NotInDAG = cast<sandboxir::StoreInst>(&*It++);

// Check erase instruction callback.
sandboxir::DependencyGraph DAG(getAA(*LLVMF), Ctx);
DAG.extend({S1, S3});
auto *S1MemN = cast<sandboxir::MemDGNode>(DAG.getNode(S1));
auto *S2MemN = cast<sandboxir::MemDGNode>(DAG.getNode(S2));
auto *S3MemN = cast<sandboxir::MemDGNode>(DAG.getNode(S3));
EXPECT_EQ(S1MemN->getNumUnscheduledSuccs(), 2u);
EXPECT_EQ(S2MemN->getNumUnscheduledSuccs(), 1u);
EXPECT_EQ(S3MemN->getNumUnscheduledSuccs(), 0u);
S2->eraseFromParent();
auto *DeletedN = DAG.getNodeOrNull(S2);
// Check that the DAG Node for S2 no longer exists.
auto *DeletedN = DAG.getNode(S2);
EXPECT_TRUE(DeletedN == nullptr);
// Check that dependencies are maintained.
EXPECT_THAT(S3MemN->preds(DAG), testing::UnorderedElementsAre(S1MemN));
// Also check that UnscheduledSuccs was updated for S1.
EXPECT_EQ(S1MemN->getNumUnscheduledSuccs(), 1u);

// Check the MemDGNode chain.
auto *S1MemN = cast<sandboxir::MemDGNode>(DAG.getNode(S1));
auto *S3MemN = cast<sandboxir::MemDGNode>(DAG.getNode(S3));
EXPECT_EQ(S1MemN->getNextNode(), S3MemN);
EXPECT_EQ(S3MemN->getPrevNode(), S1MemN);

// Check the chain when we erase the top node.
S1->eraseFromParent();
EXPECT_EQ(S3MemN->getPrevNode(), nullptr);

// TODO: Check the dependencies to/from NewSN after they land.
// Check that we don't crash if we erase a node not in the DAG.
S4NotInDAG->eraseFromParent();
}

// Same but check that we don't update UnscheduledSuccs when Node is scheduled.
TEST_F(DependencyGraphTest, EraseInstrCallbackScheduled) {
parseIR(C, R"IR(
define void @foo(ptr %ptr, i8 %v1, i8 %v2, i8 %v3, i8 %v4, i8 %arg) {
store i8 %v1, ptr %ptr
store i8 %v2, ptr %ptr
ret void
}
)IR");
llvm::Function *LLVMF = &*M->getFunction("foo");
sandboxir::Context Ctx(C);
auto *F = Ctx.createFunction(LLVMF);
auto *BB = &*F->begin();
auto It = BB->begin();
auto *S1 = cast<sandboxir::StoreInst>(&*It++);
auto *S2 = cast<sandboxir::StoreInst>(&*It++);

sandboxir::DependencyGraph DAG(getAA(*LLVMF), Ctx);
DAG.extend({S1, S2});
auto *S1MemN = cast<sandboxir::MemDGNode>(DAG.getNode(S1));
auto *S2MemN = cast<sandboxir::MemDGNode>(DAG.getNode(S2));
EXPECT_EQ(S1MemN->getNumUnscheduledSuccs(), 1u);
EXPECT_EQ(S2MemN->getNumUnscheduledSuccs(), 0u);
// Mark S2 as scheduled and erase it.
S2MemN->setScheduled(true);
S2->eraseFromParent();
EXPECT_EQ(DAG.getNode(S2), nullptr);
// Check that we did not update S1's UnscheduledSuccs
EXPECT_EQ(S1MemN->getNumUnscheduledSuccs(), 1u);
}

TEST_F(DependencyGraphTest, MoveInstrCallback) {
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