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[arc-opts] After the arc optimizer converges, run another round of the ARC

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optimizer freezing releases in the epilogue of functions that match to
SILArguments. This allows us to treat all such SILArguments throughout the
entire function as having a post dominating release.

<rdar://problem/18923030>

Swift SVN r23253
This commit is contained in:
Michael Gottesman
2014-11-11 23:37:09 +00:00
parent ed9a765d43
commit 7a2e1fb4d3
6 changed files with 75 additions and 18 deletions
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32
lib/SILAnalysis/GlobalARCSequenceDataflow.cpp
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@@ -570,10 +570,9 @@ bool swift::arc::ARCSequenceDataflowEvaluator::processTopDown() {
///
/// NestingDetected will be set to indicate that the block needs to be
/// reanalyzed if code motion occurs.
static bool processBBBottomUp(
ARCBBState &BBState,
BlotMapVector<SILInstruction *, BottomUpRefCountState> &IncToDecStateMap,
AliasAnalysis *AA, RCIdentityAnalysis *RCIA) {
bool
swift::arc::ARCSequenceDataflowEvaluator::
processBBBottomUp(ARCBBState &BBState, bool FreezeOwnedArgEpilogueReleases) {
DEBUG(llvm::dbgs() << ">>>> Bottom Up!\n");
SILBasicBlock &BB = BBState.getBB();
@@ -591,8 +590,13 @@ static bool processBBBottomUp(
continue;
}
SILValue Op;
// If this instruction is a post dominating release, skip it so we don't
// pair it up with anything.
if (FreezeOwnedArgEpilogueReleases &&
ConsumedArgToReleaseMap.isReleaseMatchedToArgument(&I))
continue;
SILValue Op;
// If I is a ref count decrement instruction...
if (isRefCountDecrement(I)) {
// map its operand to a newly initialized or reinitialized ref count
@@ -601,6 +605,11 @@ static bool processBBBottomUp(
BottomUpRefCountState &State = BBState.getBottomUpRefCountState(Op);
NestingDetected |= State.initWithInst(&I);
// If we know that this decrement is on the same SILValue.
if (FreezeOwnedArgEpilogueReleases) {
State.KnownSafe |= ConsumedArgToReleaseMap.argumentHasRelease(Op);
}
DEBUG(llvm::dbgs() << " REF COUNT DECREMENT! Known Safe: "
<< (State.isKnownSafe() ? "yes" : "no") << "\n");
@@ -727,7 +736,8 @@ swift::arc::ARCSequenceDataflowEvaluator::mergeSuccessors(ARCBBState &BBState,
}
}
bool swift::arc::ARCSequenceDataflowEvaluator::processBottomUp() {
bool swift::arc::ARCSequenceDataflowEvaluator::
processBottomUp(bool FreezeOwnedArgEpilogueReleases) {
bool NestingDetected = false;
DEBUG(llvm::dbgs() << "<<<< Processing Bottom Up! >>>>\n");
@@ -744,7 +754,8 @@ bool swift::arc::ARCSequenceDataflowEvaluator::processBottomUp() {
mergeSuccessors(BBState, BB);
// Then perform the basic block optimization.
NestingDetected |= processBBBottomUp(BBState, IncToDecStateMap, AA, RCIA);
NestingDetected |= processBBBottomUp(BBState,
FreezeOwnedArgEpilogueReleases);
}
return NestingDetected;
@@ -759,7 +770,7 @@ void swift::arc::ARCSequenceDataflowEvaluator::init() {
#ifndef NDEBUG
unsigned Count = 0;
for (auto &BB : F) {
BBToBBID[&BB] = Count++;
BBToBBID[&BB] = Count++;
}
#endif
@@ -786,10 +797,9 @@ void swift::arc::ARCSequenceDataflowEvaluator::init() {
TopDownBBStates.sort();
}
bool swift::arc::ARCSequenceDataflowEvaluator::run() {
bool NestingDetected = processBottomUp();
bool swift::arc::ARCSequenceDataflowEvaluator::run(bool FreezeOwnedReleases) {
bool NestingDetected = processBottomUp(FreezeOwnedReleases);
NestingDetected |= processTopDown();
return NestingDetected;
}