[LifetimeCompletion] Flag instructions dead_end.

Author: nate-chandler

include/swift/SIL/OSSALifetimeCompletion.h

@@ -34,6 +34,8 @@
 
 namespace swift {
 
+class DeadEndBlocks;
+
 enum class LifetimeCompletion { NoLifetime, AlreadyComplete, WasCompleted };
 
 class OSSALifetimeCompletion {
@@ -42,13 +44,17 @@ class OSSALifetimeCompletion {
   // create a new phi would result in an immediately redundant phi.
   const DominanceInfo *domInfo = nullptr;
 
+  DeadEndBlocks &deadEndBlocks;
+
   // Cache intructions already handled by the recursive algorithm to avoid
   // recomputing their lifetimes.
   ValueSet completedValues;
 
 public:
-  OSSALifetimeCompletion(SILFunction *function, const DominanceInfo *domInfo)
-    : domInfo(domInfo), completedValues(function) {}
+  OSSALifetimeCompletion(SILFunction *function, const DominanceInfo *domInfo,
+                         DeadEndBlocks &deadEndBlocks)
+      : domInfo(domInfo), deadEndBlocks(deadEndBlocks),
+        completedValues(function) {}
 
   // The kind of boundary at which to complete the lifetime.
   //
@@ -139,16 +145,19 @@ class UnreachableLifetimeCompletion {
   // If domInfo is nullptr, lifetime completion may attempt to recreate
   // redundant phis, which should be immediately discarded.
   const DominanceInfo *domInfo = nullptr;
+  DeadEndBlocks &deadEndBlocks;
 
   BasicBlockSetVector unreachableBlocks;
   InstructionSet unreachableInsts; // not including those in unreachableBlocks
   ValueSetVector incompleteValues;
   bool updatingLifetimes = false;
 
 public:
-  UnreachableLifetimeCompletion(SILFunction *function, DominanceInfo *domInfo)
-      : function(function), domInfo(domInfo), unreachableBlocks(function),
-        unreachableInsts(function), incompleteValues(function) {}
+  UnreachableLifetimeCompletion(SILFunction *function, DominanceInfo *domInfo,
+                                DeadEndBlocks &deadEndBlocks)
+      : function(function), domInfo(domInfo), deadEndBlocks(deadEndBlocks),
+        unreachableBlocks(function), unreachableInsts(function),
+        incompleteValues(function) {}
 
   /// Record information about this unreachable instruction and return true if
   /// ends any simple OSSA lifetimes.

lib/SIL/Utils/OSSALifetimeCompletion.cpp

@@ -49,8 +49,9 @@
 ///
 //===----------------------------------------------------------------------===//
 
-#include "swift/Basic/Assertions.h"
 #include "swift/SIL/OSSALifetimeCompletion.h"
+#include "swift/Basic/Assertions.h"
+#include "swift/SIL/BasicBlockUtils.h"
 #include "swift/SIL/SILBuilder.h"
 #include "swift/SIL/SILFunction.h"
 #include "swift/SIL/SILInstruction.h"
@@ -61,23 +62,26 @@ using namespace swift;
 
 static SILInstruction *endOSSALifetime(SILValue value,
                                        OSSALifetimeCompletion::LifetimeEnd end,
-                                       SILBuilder &builder) {
+                                       SILBuilder &builder,
+                                       DeadEndBlocks &deb) {
   auto loc =
     RegularLocation::getAutoGeneratedLocation(builder.getInsertionPointLoc());
   if (end == OSSALifetimeCompletion::LifetimeEnd::Loop) {
     return builder.createExtendLifetime(loc, value);
   }
+  auto isDeadEnd = IsDeadEnd_t(deb.isDeadEnd(builder.getInsertionBB()));
   if (value->getOwnershipKind() == OwnershipKind::Owned) {
     if (value->getType().is<SILBoxType>()) {
-      return builder.createDeallocBox(loc, value);
+      return builder.createDeallocBox(loc, value, isDeadEnd);
     }
-    return builder.createDestroyValue(loc, value);
+    return builder.createDestroyValue(loc, value, DontPoisonRefs, isDeadEnd);
   }
-  return builder.createEndBorrow(loc, value);
+  return builder.createEndBorrow(loc, value, isDeadEnd);
 }
 
 static bool endLifetimeAtLivenessBoundary(SILValue value,
-                                          const SSAPrunedLiveness &liveness) {
+                                          const SSAPrunedLiveness &liveness,
+                                          DeadEndBlocks &deb) {
   PrunedLivenessBoundary boundary;
   liveness.computeBoundary(boundary);
 
@@ -86,17 +90,18 @@ static bool endLifetimeAtLivenessBoundary(SILValue value,
     if (liveness.isInterestingUser(lastUser)
         != PrunedLiveness::LifetimeEndingUse) {
       changed = true;
-      SILBuilderWithScope::insertAfter(lastUser, [value](SILBuilder &builder) {
+      SILBuilderWithScope::insertAfter(lastUser, [value,
+                                                  &deb](SILBuilder &builder) {
         endOSSALifetime(value, OSSALifetimeCompletion::LifetimeEnd::Boundary,
-                        builder);
+                        builder, deb);
       });
     }
   }
   for (SILBasicBlock *edge : boundary.boundaryEdges) {
     changed = true;
     SILBuilderWithScope builder(edge->begin());
     endOSSALifetime(value, OSSALifetimeCompletion::LifetimeEnd::Boundary,
-                    builder);
+                    builder, deb);
   }
   for (SILNode *deadDef : boundary.deadDefs) {
     SILInstruction *next = nullptr;
@@ -108,7 +113,7 @@ static bool endLifetimeAtLivenessBoundary(SILValue value,
     changed = true;
     SILBuilderWithScope builder(next);
     endOSSALifetime(value, OSSALifetimeCompletion::LifetimeEnd::Boundary,
-                    builder);
+                    builder, deb);
   }
   return changed;
 }
@@ -395,14 +400,14 @@ void OSSALifetimeCompletion::visitAvailabilityBoundary(
       });
 }
 
-static bool
-endLifetimeAtAvailabilityBoundary(SILValue value,
-                                  const SSAPrunedLiveness &liveness) {
+static bool endLifetimeAtAvailabilityBoundary(SILValue value,
+                                              const SSAPrunedLiveness &liveness,
+                                              DeadEndBlocks &deb) {
   bool changed = false;
   OSSALifetimeCompletion::visitAvailabilityBoundary(
       value, liveness, [&](auto *unreachable, auto end) {
         SILBuilderWithScope builder(unreachable);
-        endOSSALifetime(value, end, builder);
+        endOSSALifetime(value, end, builder, deb);
         changed = true;
       });
   return changed;
@@ -424,10 +429,12 @@ bool OSSALifetimeCompletion::analyzeAndUpdateLifetime(SILValue value,
   bool changed = false;
   switch (boundary) {
   case Boundary::Liveness:
-    changed |= endLifetimeAtLivenessBoundary(value, liveness.getLiveness());
+    changed |= endLifetimeAtLivenessBoundary(value, liveness.getLiveness(),
+                                             deadEndBlocks);
     break;
   case Boundary::Availability:
-    changed |= endLifetimeAtAvailabilityBoundary(value, liveness.getLiveness());
+    changed |= endLifetimeAtAvailabilityBoundary(value, liveness.getLiveness(),
+                                                 deadEndBlocks);
     break;
   }
   // TODO: Rebuild outer adjacent phis on demand (SILGen does not currently
@@ -453,9 +460,10 @@ static FunctionTest OSSALifetimeCompletionTest(
               .Case("liveness", OSSALifetimeCompletion::Boundary::Liveness)
               .Case("availability",
                     OSSALifetimeCompletion::Boundary::Availability);
+      auto *deb = test.getDeadEndBlocks();
       llvm::outs() << "OSSA lifetime completion on " << kind
                    << " boundary: " << value;
-      OSSALifetimeCompletion completion(&function, /*domInfo*/ nullptr);
+      OSSALifetimeCompletion completion(&function, /*domInfo*/ nullptr, *deb);
       completion.completeOSSALifetime(value, kind);
       function.print(llvm::outs());
     });
@@ -532,7 +540,7 @@ bool UnreachableLifetimeCompletion::completeLifetimes() {
     }
   }
 
-  OSSALifetimeCompletion completion(function, domInfo);
+  OSSALifetimeCompletion completion(function, domInfo, deadEndBlocks);
 
   bool changed = false;
   for (auto value : incompleteValues) {

lib/SILOptimizer/Mandatory/MoveOnlyAddressCheckerTester.cpp

@@ -90,6 +90,7 @@ class MoveOnlyAddressCheckerTesterPass : public SILFunctionTransform {
     auto *dominanceAnalysis = getAnalysis<DominanceAnalysis>();
     DominanceInfo *domTree = dominanceAnalysis->get(fn);
     auto *poa = getAnalysis<PostOrderAnalysis>();
+    auto *deba = getAnalysis<DeadEndBlocksAnalysis>();
 
     DiagnosticEmitter diagnosticEmitter(fn);
     llvm::SmallSetVector<MarkUnresolvedNonCopyableValueInst *, 32>
@@ -108,8 +109,8 @@ class MoveOnlyAddressCheckerTesterPass : public SILFunctionTransform {
       LLVM_DEBUG(llvm::dbgs() << "No move introducers found?!\n");
     } else {
       borrowtodestructure::IntervalMapAllocator allocator;
-      MoveOnlyAddressChecker checker{getFunction(), diagnosticEmitter,
-                                     allocator, domTree, poa};
+      MoveOnlyAddressChecker checker{
+          getFunction(), diagnosticEmitter, allocator, domTree, poa, deba};
       madeChange = checker.completeLifetimes();
       madeChange |= checker.check(moveIntroducersToProcess);
     }

lib/SILOptimizer/Mandatory/MoveOnlyAddressCheckerUtils.cpp

@@ -4030,7 +4030,8 @@ bool MoveOnlyAddressChecker::completeLifetimes() {
 
   // Lifetimes must be completed inside out (bottom-up in the CFG).
   PostOrderFunctionInfo *postOrder = poa->get(fn);
-  OSSALifetimeCompletion completion(fn, domTree);
+  OSSALifetimeCompletion completion(fn, domTree,
+                                    *deadEndBlocksAnalysis->get(fn));
   for (auto *block : postOrder->getPostOrder()) {
     for (SILInstruction &inst : reverse(*block)) {
       for (auto result : inst.getResults()) {

lib/SILOptimizer/Mandatory/MoveOnlyAddressCheckerUtils.h

@@ -18,6 +18,7 @@
 namespace swift {
 
 class PostOrderAnalysis;
+class DeadEndBlocksAnalysis;
 
 namespace siloptimizer {
 
@@ -39,6 +40,7 @@ struct MoveOnlyAddressChecker {
   borrowtodestructure::IntervalMapAllocator &allocator;
   DominanceInfo *domTree;
   PostOrderAnalysis *poa;
+  DeadEndBlocksAnalysis *deadEndBlocksAnalysis;
 
   /// \returns true if we changed the IR. To see if we emitted a diagnostic, use
   /// \p diagnosticEmitter.getDiagnosticCount().

lib/SILOptimizer/Mandatory/MoveOnlyChecker.cpp

@@ -79,13 +79,13 @@ struct MoveOnlyChecker {
   SILFunction *fn;
   DominanceInfo *domTree;
   PostOrderAnalysis *poa;
+  DeadEndBlocksAnalysis *deba;
   bool madeChange = false;
   borrowtodestructure::IntervalMapAllocator allocator;
 
   MoveOnlyChecker(SILFunction *fn, DominanceInfo *domTree,
-                  PostOrderAnalysis *poa)
-      : diagnosticEmitter(fn), fn(fn), domTree(domTree), poa(poa) {
-  }
+                  PostOrderAnalysis *poa, DeadEndBlocksAnalysis *deba)
+      : diagnosticEmitter(fn), fn(fn), domTree(domTree), poa(poa), deba(deba) {}
 
   void checkObjects();
   void completeObjectLifetimes(ArrayRef<MarkUnresolvedNonCopyableValueInst *>);
@@ -122,13 +122,13 @@ void MoveOnlyChecker::checkObjects() {
 void MoveOnlyChecker::completeObjectLifetimes(
     ArrayRef<MarkUnresolvedNonCopyableValueInst *> insts) {
 // TODO: Delete once OSSALifetimeCompletion is run as part of SILGenCleanup.
-  OSSALifetimeCompletion completion(fn, domTree);
+OSSALifetimeCompletion completion(fn, domTree, *deba->get(fn));
 
-  // Collect all values derived from each mark_unresolved_non_copyable_value
-  // instruction via ownership instructions and phis.
-  ValueWorklist transitiveValues(fn);
-  for (auto *inst : insts) {
-    transitiveValues.push(inst);
+// Collect all values derived from each mark_unresolved_non_copyable_value
+// instruction via ownership instructions and phis.
+ValueWorklist transitiveValues(fn);
+for (auto *inst : insts) {
+  transitiveValues.push(inst);
   }
   while (auto value = transitiveValues.pop()) {
     for (auto *use : value->getUses()) {
@@ -203,8 +203,8 @@ void MoveOnlyChecker::checkAddresses() {
     return;
   }
 
-  MoveOnlyAddressChecker checker{fn, diagnosticEmitter, allocator, domTree,
-                                 poa};
+  MoveOnlyAddressChecker checker{
+      fn, diagnosticEmitter, allocator, domTree, poa, deba};
   madeChange |= checker.completeLifetimes();
   madeChange |= checker.check(moveIntroducersToProcess);
 }
@@ -256,9 +256,9 @@ class MoveOnlyCheckerPass : public SILFunctionTransform {
     LLVM_DEBUG(llvm::dbgs()
                << "===> MoveOnly Checker. Visiting: " << fn->getName() << '\n');
 
-    MoveOnlyChecker checker(
-        fn, getAnalysis<DominanceAnalysis>()->get(fn),
-        getAnalysis<PostOrderAnalysis>());
+    MoveOnlyChecker checker(fn, getAnalysis<DominanceAnalysis>()->get(fn),
+                            getAnalysis<PostOrderAnalysis>(),
+                            getAnalysis<DeadEndBlocksAnalysis>());
 
     checker.checkObjects();
     checker.checkAddresses();

lib/SILOptimizer/Mandatory/PredictableMemOpt.cpp

@@ -2664,7 +2664,8 @@ bool AllocOptimize::tryToRemoveDeadAllocation() {
   // post-dominating consuming use sets. This can happen if we have an enum that
   // is known dynamically none along a path. This is dynamically correct, but
   // can not be represented in OSSA so we insert these destroys along said path.
-  OSSALifetimeCompletion completion(TheMemory->getFunction(), domInfo);
+  OSSALifetimeCompletion completion(TheMemory->getFunction(), domInfo,
+                                    deadEndBlocks);
 
   while (!valuesNeedingLifetimeCompletion.empty()) {
     auto optV = valuesNeedingLifetimeCompletion.pop_back_val();

lib/SILOptimizer/Mandatory/SILGenCleanup.cpp

@@ -23,6 +23,7 @@
 #include "swift/SIL/PrettyStackTrace.h"
 #include "swift/SIL/PrunedLiveness.h"
 #include "swift/SIL/SILInstruction.h"
+#include "swift/SILOptimizer/Analysis/DeadEndBlocksAnalysis.h"
 #include "swift/SILOptimizer/Analysis/PostOrderAnalysis.h"
 #include "swift/SILOptimizer/PassManager/Transforms.h"
 #include "swift/SILOptimizer/Utils/CanonicalizeInstruction.h"
@@ -114,7 +115,8 @@ bool SILGenCleanup::completeOSSALifetimes(SILFunction *function) {
   // Lifetimes must be completed inside out (bottom-up in the CFG).
   PostOrderFunctionInfo *postOrder =
       getAnalysis<PostOrderAnalysis>()->get(function);
-  OSSALifetimeCompletion completion(function, /*DomInfo*/nullptr);
+  DeadEndBlocks *deb = getAnalysis<DeadEndBlocksAnalysis>()->get(function);
+  OSSALifetimeCompletion completion(function, /*DomInfo*/ nullptr, *deb);
   for (auto *block : postOrder->getPostOrder()) {
     for (SILInstruction &inst : reverse(*block)) {
       for (auto result : inst.getResults()) {