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ARCSequenceOpts: Add LoopSummary verifier #33810

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Merged
merged 1 commit into from
Sep 15, 2020
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ARCSequenceOpts: Add LoopSummary verifier #33810

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29 changes: 29 additions & 0 deletions lib/SILOptimizer/ARC/ARCRegionState.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -18,10 +18,15 @@
#include "swift/SILOptimizer/Analysis/LoopRegionAnalysis.h"
#include "swift/SILOptimizer/Analysis/AliasAnalysis.h"
#include "swift/SILOptimizer/Analysis/RCIdentityAnalysis.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"

using namespace swift;

llvm::cl::opt<bool> verifyARCLoopSummary(
"verify-arc-loop-summary", llvm::cl::init(false),
llvm::cl::desc("Verify if loop summary is correct in ARCLoopsOpts"));

//===----------------------------------------------------------------------===//
// ARCRegionState
//===----------------------------------------------------------------------===//
Expand Down Expand Up @@ -282,6 +287,18 @@ bool ARCRegionState::processLoopBottomUp(
OtherState->second.checkAndResetKnownSafety(
I, OtherState->first, checkIfRefCountInstIsMatched, RCIA, AA);
}
#ifndef NDEBUG
// Verify updateForDifferentLoopInst is conservative enough that the flow
// sensitive native of the loop summarized instructions does not matter.
if (verifyARCLoopSummary) {
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Is this verification inside the loop over SummarizedInterestingInsts? Shouldn't it be outside? Otherwise it's unnecessarily quadratic

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Thanks. I fixed it.

auto NewRefCountState = OtherState->second;
for (auto *I : State->getSummarizedInterestingInsts()) {
NewRefCountState.updateForDifferentLoopInst(I, AA);
}
assert(NewRefCountState.getLatticeState() ==
OtherState->second.getLatticeState());
}
#endif
}

return false;
Expand Down Expand Up @@ -420,6 +437,18 @@ bool ARCRegionState::processLoopTopDown(
OtherState->second.checkAndResetKnownSafety(
I, OtherState->first, checkIfRefCountInstIsMatched, RCIA, AA);
}
#ifndef NDEBUG
// Verify updateForDifferentLoopInst is conservative enough that the flow
// sensitive native of the loop summarized instructions does not matter.
if (verifyARCLoopSummary) {
auto NewRefCountState = OtherState->second;
for (auto *I : State->getSummarizedInterestingInsts()) {
NewRefCountState.updateForDifferentLoopInst(I, AA);
}
assert(NewRefCountState.getLatticeState() ==
OtherState->second.getLatticeState());
}
#endif
}

return false;
Expand Down
8 changes: 8 additions & 0 deletions lib/SILOptimizer/ARC/RefCountState.cpp
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Expand Up @@ -493,13 +493,17 @@ void BottomUpRefCountState::checkAndResetKnownSafety(
clearKnownSafe();
}

// This function is conservative enough that the flow sensitive nature of
// loop summarized instructions does not matter.
void BottomUpRefCountState::updateForDifferentLoopInst(SILInstruction *I,
AliasAnalysis *AA) {
// If we are not tracking anything, bail.
if (!isTrackingRefCount())
return;

if (valueCanBeGuaranteedUsedGivenLatticeState()) {
// Any instruction that may need guaranteed use or may decrement the
// refcount will turn off CodeMotionSafety
if (mayGuaranteedUseValue(I, getRCRoot(), AA) ||
mayDecrementRefCount(I, getRCRoot(), AA)) {
LLVM_DEBUG(llvm::dbgs() << " Found potential guaranteed use:\n "
Expand Down Expand Up @@ -917,12 +921,16 @@ void TopDownRefCountState::checkAndResetKnownSafety(
clearKnownSafe();
}

// This function is conservative enough that the flow sensitive nature of
// loop summarized instructions does not matter.
void TopDownRefCountState::updateForDifferentLoopInst(SILInstruction *I,
AliasAnalysis *AA) {
// If we are not tracking anything, bail.
if (!isTrackingRefCount())
return;

// Any instruction that may need guaranteed use or may decrement the
// refcount will turn off CodeMotionSafety
if (valueCanBeGuaranteedUsedGivenLatticeState()) {
if (mayGuaranteedUseValue(I, getRCRoot(), AA) ||
mayDecrementRefCount(I, getRCRoot(), AA)) {
Expand Down
10 changes: 10 additions & 0 deletions lib/SILOptimizer/ARC/RefCountState.h
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Original file line number Diff line number Diff line change
Expand Up @@ -178,6 +178,9 @@ class BottomUpRefCountState : public RefCountState {
BottomUpRefCountState(BottomUpRefCountState &&) = default;
BottomUpRefCountState &operator=(BottomUpRefCountState &&) = default;

/// Getter for LatticeState
LatticeState getLatticeState() const {return LatState;}

/// Return true if the release can be moved to the retain.
bool isCodeMotionSafe() const {
return LatState != LatticeState::MightBeDecremented;
Expand Down Expand Up @@ -205,6 +208,8 @@ class BottomUpRefCountState : public RefCountState {
/// The main difference in between this routine and update for same loop inst
/// is that if we see any decrements on a value, we treat it as being
/// guaranteed used. We treat any uses as regular uses.
/// This function is conservative enough that the flow sensitive nature of
/// loop summarized instructions does not matter.
void updateForDifferentLoopInst(
SILInstruction *I,
AliasAnalysis *AA);
Expand Down Expand Up @@ -312,6 +317,9 @@ class TopDownRefCountState : public RefCountState {
TopDownRefCountState(TopDownRefCountState &&) = default;
TopDownRefCountState &operator=(TopDownRefCountState &&) = default;

/// Getter for LatticeState
LatticeState getLatticeState() const {return LatState;}

/// Return true if the retain can be moved to the release.
bool isCodeMotionSafe() const {
return LatState != LatticeState::MightBeUsed;
Expand Down Expand Up @@ -350,6 +358,8 @@ class TopDownRefCountState : public RefCountState {
/// The main difference in between this routine and update for same loop inst
/// is that if we see any decrements on a value, we treat it as being
/// guaranteed used. We treat any uses as regular uses.
/// This function is conservative enough that the flow sensitive nature of
/// loop summarized instructions does not matter.
void updateForDifferentLoopInst(
SILInstruction *I,
AliasAnalysis *AA);
Expand Down