Merge pull request #4546 from trentxintong/wireup-FSO

Wire up the new epilogue retain matcher with FSO

Author: trentxintong

include/swift/SILOptimizer/Analysis/ARCAnalysis.h

@@ -455,6 +455,16 @@ class EpilogueARCContext {
   /// The exit blocks of the function.
   llvm::SmallPtrSet<SILBasicBlock *, 2> ExitBlocks;
 
+  /// Return true if this is a function exitting block this epilogue ARC
+  /// matcher is interested in. 
+  bool isInterestedFunctionExitingBlock(SILBasicBlock *BB) {
+    if (EpilogueARCKind::Release == Kind)  
+      return BB->getTerminator()->isFunctionExiting();
+
+    return BB->getTerminator()->isFunctionExiting() &&
+           BB->getTerminator()->getTermKind() != TermKind::ThrowInst;
+  }
+
   /// Return true if this is a function exit block.
   bool isExitBlock(SILBasicBlock *BB) {
     return ExitBlocks.count(BB);
@@ -489,7 +499,8 @@ class EpilogueARCContext {
     // Initialize the epilogue arc data flow context.
     initializeDataflow();
     // Converge the data flow.
-    convergeDataflow();
+    if (!convergeDataflow())
+      return false;
     // Lastly, find the epilogue ARC instructions.
     return computeEpilogueARC();
   }
@@ -504,7 +515,7 @@ class EpilogueARCContext {
   void initializeDataflow();
 
   /// Keep iterating until the data flow is converged.
-  void convergeDataflow();
+  bool convergeDataflow();
 
   /// Find the epilogue ARC instructions.
   bool computeEpilogueARC();

lib/SILOptimizer/Analysis/ARCAnalysis.cpp

@@ -1173,7 +1173,7 @@ SILInstruction *swift::findReleaseToMatchUnsafeGuaranteedValue(
 void EpilogueARCContext::initializeDataflow() {
   for (auto &B : *F) {
     // Find the exit blocks.
-    if (B.getTerminator()->isFunctionExiting()) {
+    if (isInterestedFunctionExitingBlock(&B)) {
       ExitBlocks.insert(&B);
     }
     // Allocate the storage.
@@ -1186,11 +1186,13 @@ void EpilogueARCContext::initializeDataflow() {
   llvm::DenseSet<SILValue> Processed;
   ToProcess.push_back(Arg);
   while (!ToProcess.empty()) {
-    SILValue Arg = ToProcess.pop_back_val();
-    if (Processed.find(Arg) != Processed.end())
+    SILValue CArg = ToProcess.pop_back_val();
+    if (!CArg)
+      continue;
+    if (Processed.find(CArg) != Processed.end())
        continue;
-    Processed.insert(Arg);
-    SILArgument *A = dyn_cast<SILArgument>(Arg);
+    Processed.insert(CArg);
+    SILArgument *A = dyn_cast<SILArgument>(CArg);
     if (A && !A->isFunctionArg()) {
       // Find predecessor and break the SILArgument to predecessors.
       for (auto X : A->getParent()->getPreds()) {
@@ -1204,7 +1206,7 @@ void EpilogueARCContext::initializeDataflow() {
   }
 }
 
-void EpilogueARCContext::convergeDataflow() {
+bool EpilogueARCContext::convergeDataflow() {
   // Keep iterating until Changed is false.
   bool Changed = false;
   do {
@@ -1238,9 +1240,10 @@ void EpilogueARCContext::convergeDataflow() {
             break;
           }
           // This is a transition from 1 to 0 due to a blocking instruction.
+          // at this point, its OK to abort the data flow as we have one path
+          // which we did not find an epilogue retain before getting blocked.
           if (mayBlockEpilogueARC(&*I, RCFI->getRCIdentityRoot(Arg))) {
-            BBSetOut = false;
-            break;
+            return false;
           }
         }
       }
@@ -1250,6 +1253,7 @@ void EpilogueARCContext::convergeDataflow() {
       BS->BBSetIn = BBSetOut;
     }
   } while(Changed);
+  return true;
 }
 
 bool EpilogueARCContext::computeEpilogueARC() {

lib/SILOptimizer/Transforms/FunctionSignatureOpts.cpp

@@ -62,6 +62,15 @@ using ArgumentIndexMap = llvm::SmallDenseMap<int, int>;
 //                           Utilities
 //===----------------------------------------------------------------------===//
 
+/// Return the single return value of the function.
+static SILValue findReturnValue(SILFunction *F) {
+  auto RBB = F->findReturnBB();
+  if (RBB == F->end())
+    return SILValue();
+  auto Term = dyn_cast<ReturnInst>(RBB->getTerminator());
+  return Term->getOperand();
+}
+
 /// Return the single apply found in this function.
 static SILInstruction *findOnlyApply(SILFunction *F) {
   SILInstruction *OnlyApply = nullptr;
@@ -103,6 +112,9 @@ class FunctionSignatureTransform {
   /// The RC identity analysis we are using.
   RCIdentityAnalysis *RCIA;
 
+  /// Post order analysis we are using.
+  PostOrderAnalysis *PO;
+
   // The function signature mangler we are using.
   FunctionSignatureSpecializationMangler &FM;
 
@@ -220,11 +232,12 @@ class FunctionSignatureTransform {
   /// Constructor.
   FunctionSignatureTransform(SILFunction *F,
                              AliasAnalysis *AA, RCIdentityAnalysis *RCIA,
+                             PostOrderAnalysis *PO,
                              FunctionSignatureSpecializationMangler &FM,
                              ArgumentIndexMap &AIM,
                              llvm::SmallVector<ArgumentDescriptor, 4> &ADL,
                              llvm::SmallVector<ResultDescriptor, 4> &RDL)
-    : F(F), NewF(nullptr), AA(AA), RCIA(RCIA), FM(FM),
+    : F(F), NewF(nullptr), AA(AA), RCIA(RCIA), PO(PO), FM(FM),
       AIM(AIM), shouldModifySelfArgument(false), ArgumentDescList(ADL),
       ResultDescList(RDL) {}
 
@@ -646,10 +659,14 @@ bool FunctionSignatureTransform::OwnedToGuaranteedAnalyzeResults() {
 
   bool SignatureOptimize = false;
   if (ResultDescList[0].hasConvention(ResultConvention::Owned)) {
+    auto RV = findReturnValue(F);
+    if (!RV)
+      return false;
     auto &RI = ResultDescList[0];
     // We have an @owned return value, find the epilogue retains now.
-    ConsumedResultToEpilogueRetainMatcher ReturnRetainMap(RCIA->get(F), AA, F);
-    auto Retains = ReturnRetainMap.getEpilogueRetains();
+    auto Retains = 
+     computeEpilogueARCInstructions(EpilogueARCContext::EpilogueARCKind::Retain,
+          RV, F, PO->get(F), AA, RCIA->get(F));
     // We do not need to worry about the throw block, as the return value is only
     // going to be used in the return block/normal block of the try_apply
     // instruction.
@@ -880,6 +897,7 @@ class FunctionSignatureOpts : public SILFunctionTransform {
     auto *AA = PM->getAnalysis<AliasAnalysis>();
     auto *RCIA = getAnalysis<RCIdentityAnalysis>();
     CallerAnalysis *CA = PM->getAnalysis<CallerAnalysis>();
+    auto *PO = PM->getAnalysis<PostOrderAnalysis>();
 
     const CallerAnalysis::FunctionInfo &FuncInfo = CA->getCallerInfo(F);
 
@@ -910,7 +928,7 @@ class FunctionSignatureOpts : public SILFunctionTransform {
     }
 
     // Owned to guaranteed optimization.
-    FunctionSignatureTransform FST(F, AA, RCIA, FM, AIM,
+    FunctionSignatureTransform FST(F, AA, RCIA, PO, FM, AIM,
                                    ArgumentDescList, ResultDescList);
 
     bool Changed = false;