Revert "Followup for #61505"

Author: compnerd

lib/SIL/Verifier/SILVerifier.cpp

@@ -4881,6 +4881,17 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
   }
 
   void checkBranchInst(BranchInst *BI) {
+    for (auto arg : BI->getArgs()) {
+      auto *borrow = dyn_cast<BeginBorrowInst>(arg);
+      if (!borrow) {
+        continue;
+      }
+      auto op = borrow->getOperand();
+      if (op->getOwnershipKind() != OwnershipKind::Guaranteed) {
+        continue;
+      }
+      assert(!isGuaranteedForwarding(op));
+    }
     require(BI->getArgs().size() == BI->getDestBB()->args_size(),
             "branch has wrong number of arguments for dest bb");
     require(std::equal(BI->getArgs().begin(), BI->getArgs().end(),

lib/SILOptimizer/SemanticARC/OwnedToGuaranteedPhiOpt.cpp

@@ -251,6 +251,13 @@ bool swift::semanticarc::tryConvertOwnedPhisToGuaranteedPhis(Context &ctx) {
     while (!incomingValueOperandList.empty()) {
       auto incomingValueOperand = incomingValueOperandList.pop_back_val();
       SILValue originalValue = originalIncomingValues.pop_back_val();
+      if (incomingValueOperand.isGuaranteedConsuming() &&
+          isa<SILFunctionArgument>(originalValue) &&
+          originalValue->getOwnershipKind() == OwnershipKind::Guaranteed) {
+        auto loc = RegularLocation::getAutoGeneratedLocation();
+        SILBuilderWithScope builder(incomingValueOperand.getInst());
+        originalValue = builder.createBeginBorrow(loc, originalValue);
+      }
       incomingValueOperand.getOperand()->set(originalValue);
     }
 

lib/SILOptimizer/SemanticARC/OwnershipLiveRange.cpp

@@ -310,7 +310,16 @@ void OwnershipLiveRange::convertJoinedLiveRangePhiToGuaranteed(
     InstModCallbacks callbacks) && {
 
   // First convert the phi value itself to be guaranteed.
-  convertIntroducerToGuaranteed(introducer);
+  SILValue phiValue = convertIntroducerToGuaranteed(introducer);
+
+  // Then insert end_borrows at each of our destroys if we are consuming. We
+  // have to convert the phi to guaranteed first since otherwise, the ownership
+  // check when we create the end_borrows will trigger.
+  if (auto *phi = dyn_cast<SILPhiArgument>(phiValue)) {
+    if (!isGuaranteedForwardingPhi(phi)) {
+      insertEndBorrowsAtDestroys(phiValue, deadEndBlocks, scratch);
+    }
+  }
 
   // Then eliminate all of the destroys...
   while (!destroyingUses.empty()) {

lib/SILOptimizer/Transforms/ConditionForwarding.cpp

@@ -202,6 +202,14 @@ bool ConditionForwarding::tryOptimize(SwitchEnumInst *SEI) {
     if (!EI)
       return false;
 
+    if (getFunction()->hasOwnership() && EI->hasOperand()) {
+      auto some = EI->getOperand();
+      if (some->getOwnershipKind() == OwnershipKind::Guaranteed &&
+          isa<SILFunctionArgument>(some)) {
+        return false;
+      }
+    }
+
     if (CommonBranchBlock && PredPred != CommonBranchBlock)
       return false;
     CommonBranchBlock = PredPred;

test/SILOptimizer/conditionforwarding_nontrivial_ossa.sil

@@ -71,8 +71,10 @@ bb6:
   return %r : $()
 }
 
+// Currently, this is not optimized away because enum has @guaranteed function
+// argument, which  will need a borrow scope before being forwarded.
 // CHECK-LABEL: sil [ossa] @simple_forwarding2 :
-// CHECK-NOT: switch_enum
+// CHECK: switch_enum
 // CHECK-LABEL: } // end sil function 'simple_forwarding2'
 sil [ossa] @simple_forwarding2 : $@convention(thin) (Builtin.Int1, @guaranteed Klass) -> () {
 bb0(%0 : $Builtin.Int1, %1 : @guaranteed $Klass):
@@ -183,7 +185,6 @@ bb6:
 
 // CHECK-LABEL: sil [ossa] @simple_switch_enum_forwarding2 : 
 // CHECK: switch_enum
-// CHECK-NOT: switch_enum
 // CHECK-LABEL: } // end sil function 'simple_switch_enum_forwarding2'
 sil [ossa] @simple_switch_enum_forwarding2 : $@convention(thin) (@guaranteed E3) -> () {
 bb0(%0 : @guaranteed $E3):

test/SILOptimizer/ossa_rauw_tests.sil

@@ -673,6 +673,8 @@ bb3:
 //
 // CHECK-LABEL: sil [ossa] @guaranteed_copy_rauw_owned : $@convention(thin) (@guaranteed FakeOptional<Klass>) -> () {
 // CHECK-NOT: copy_value
+// CHECK: begin_borrow
+// CHECK-NOT: copy_value
 // CHECK: } // end sil function 'guaranteed_copy_rauw_owned'
 sil [ossa] @guaranteed_copy_rauw_owned : $@convention(thin) (@guaranteed FakeOptional<Klass>) -> () {
 bb0(%0 : @guaranteed $FakeOptional<Klass>):