Merge pull request swiftlang#83741 from nate-chandler/rdar158353230

[OSSA] Fix borrowCopyOverGuaranteedUsers at dead-ends.

Author: nate-chandler

include/swift/SILOptimizer/Utils/OwnershipOptUtils.h

@@ -79,11 +79,6 @@ void extendLocalBorrow(BeginBorrowInst *beginBorrow,
 /// newly created phis do not yet have a borrow scope.
 bool createBorrowScopeForPhiOperands(SILPhiArgument *newPhi);
 
-SILValue
-makeGuaranteedValueAvailable(SILValue value, SILInstruction *user,
-                             DeadEndBlocks &deBlocks,
-                             InstModCallbacks callbacks = InstModCallbacks());
-
 /// Compute the liveness boundary for a guaranteed value. Returns true if no
 /// uses are pointer escapes. If pointer escapes are present, the liveness
 /// boundary is still valid for all known uses.

lib/SILOptimizer/Utils/OwnershipOptUtils.cpp

@@ -805,10 +805,6 @@ struct OwnershipLifetimeExtender {
   /// the BorrowedValue that begins the scope.
   SILValue borrowOverSingleUse(SILValue newValue,
                                Operand *singleGuaranteedUse);
-
-  SILValue
-  borrowOverSingleNonLifetimeEndingUser(SILValue newValue,
-                                        SILInstruction *nonLifetimeEndingUser);
 };
 
 } // end anonymous namespace
@@ -973,7 +969,14 @@ BeginBorrowInst *OwnershipLifetimeExtender::borrowCopyOverGuaranteedUsers(
   // Create destroys at the end of copy's lifetime. This only needs to consider
   // uses that end the borrow scope.
   {
-    ValueLifetimeAnalysis lifetimeAnalysis(copy, borrow->getEndBorrows());
+    SmallVector<SILInstruction *, 16> users;
+    for (auto *user : guaranteedUsers) {
+      users.push_back(user);
+    }
+    for (auto *user : borrow->getEndBorrows()) {
+      users.push_back(user);
+    }
+    ValueLifetimeAnalysis lifetimeAnalysis(copy, users);
     ValueLifetimeBoundary copyBoundary;
     lifetimeAnalysis.computeLifetimeBoundary(copyBoundary);
 
@@ -1092,27 +1095,6 @@ OwnershipLifetimeExtender::borrowOverSingleUse(SILValue newValue,
   return newBeginBorrow;
 }
 
-SILValue OwnershipLifetimeExtender::borrowOverSingleNonLifetimeEndingUser(
-    SILValue newValue, SILInstruction *nonLifetimeEndingUser) {
-  // Avoid borrowing guaranteed function arguments.
-  if (isa<SILFunctionArgument>(newValue) &&
-      newValue->getOwnershipKind() == OwnershipKind::Guaranteed) {
-    return newValue;
-  }
-  auto borrowPt = newValue->getNextInstruction()->getIterator();
-  return borrowCopyOverGuaranteedUsers(
-      newValue, borrowPt, ArrayRef<SILInstruction *>(nonLifetimeEndingUser));
-}
-
-SILValue swift::makeGuaranteedValueAvailable(SILValue value,
-                                             SILInstruction *user,
-                                             DeadEndBlocks &deBlocks,
-                                             InstModCallbacks callbacks) {
-  OwnershipFixupContext ctx{callbacks, deBlocks};
-  OwnershipLifetimeExtender extender{ctx};
-  return extender.borrowOverSingleNonLifetimeEndingUser(value, user);
-}
-
 //===----------------------------------------------------------------------===//
 //                OwnershipRAUWUtility - RAUW + fix ownership
 //===----------------------------------------------------------------------===//

test/SILOptimizer/cse_ossa_nontrivial.sil

@@ -1164,3 +1164,38 @@ bb0:
   %13 = tuple ()
   return %13
 }
+
+/// A scenario where a borrow of a copy is introduced but the cfg is such that
+/// no end_borrows are inserted for the borrow.  The copy must still be
+/// destroyed.
+// CHECK-LABEL: sil [ossa] @no_boundary_for_end_borrows : {{.*}} {
+// TODO: There shouldn't actually be a copy_value here, but lifetime transfer
+//       APIs are written and OSSARAUWHelper is in use, there will be.
+//       Even then, this test case shouldn't crash.
+// CHECK:         copy_value
+// CHECK:         destroy_value
+// CHECK-LABEL: } // end sil function 'no_boundary_for_end_borrows'
+sil [ossa] @no_boundary_for_end_borrows : $@convention(thin) (@guaranteed NonTrivialStruct) -> () {
+entry(%s : @guaranteed $NonTrivialStruct):
+  %c1 = struct_extract %s : $NonTrivialStruct, #NonTrivialStruct.val
+  cond_br undef, loop_entry, exit
+
+exit:
+  apply undef(%c1) : $@convention(thin) (@guaranteed Klass) -> ()
+  return undef : $()
+
+loop_entry:
+  %c2 = struct_extract %s : $NonTrivialStruct, #NonTrivialStruct.val
+  apply undef(%c2) : $@convention(thin) (@guaranteed Klass) -> ()
+  br loop_header
+
+loop_header:
+  apply undef(%c2) : $@convention(thin) (@guaranteed Klass) -> ()
+  cond_br undef, die, loop_backedge
+
+loop_backedge:
+  br loop_header
+
+die:
+  unreachable
+}