Update SemanticARCOpts for @guaranteed forwarding phi support

Author: meg-gupta

lib/SILOptimizer/SemanticARC/OwnedToGuaranteedPhiOpt.cpp

@@ -242,11 +242,6 @@ bool swift::semanticarc::tryConvertOwnedPhisToGuaranteedPhis(Context &ctx) {
       originalIncomingValues[pair.second] = pair.first;
     }
 
-    // Then convert the phi's live range to be guaranteed.
-    std::move(joinedLiveRange)
-        .convertJoinedLiveRangePhiToGuaranteed(
-            ctx.getDeadEndBlocks(), ctx.lifetimeFrontier, ctx.instModCallbacks);
-
     // Now if our phi operand consumes/forwards its guaranteed input, insert a
     // begin_borrow along the incoming value edges. We have to do this after
     // converting the incoming values to be guaranteed to avoid tripping
@@ -257,14 +252,20 @@ bool swift::semanticarc::tryConvertOwnedPhisToGuaranteedPhis(Context &ctx) {
       auto incomingValueOperand = incomingValueOperandList.pop_back_val();
       SILValue originalValue = originalIncomingValues.pop_back_val();
       if (incomingValueOperand.isGuaranteedConsuming() &&
-          originalValue->getOwnershipKind() != OwnershipKind::None) {
+          isa<SILFunctionArgument>(originalValue) &&
+          originalValue->getOwnershipKind() == OwnershipKind::Guaranteed) {
         auto loc = RegularLocation::getAutoGeneratedLocation();
         SILBuilderWithScope builder(incomingValueOperand.getInst());
         originalValue = builder.createBeginBorrow(loc, originalValue);
       }
       incomingValueOperand.getOperand()->set(originalValue);
     }
 
+    // Then convert the phi's live range to be guaranteed.
+    std::move(joinedLiveRange)
+        .convertJoinedLiveRangePhiToGuaranteed(
+            ctx.getDeadEndBlocks(), ctx.lifetimeFrontier, ctx.instModCallbacks);
+
     madeChange = true;
     ctx.verify();
   }

lib/SILOptimizer/SemanticARC/OwnershipLiveRange.cpp

@@ -315,8 +315,10 @@ void OwnershipLiveRange::convertJoinedLiveRangePhiToGuaranteed(
   // 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 (introducer.hasConsumingGuaranteedOperands()) {
-    insertEndBorrowsAtDestroys(phiValue, deadEndBlocks, scratch);
+  if (auto *phi = dyn_cast<SILPhiArgument>(phiValue)) {
+    if (!isGuaranteedForwardingPhi(phi)) {
+      insertEndBorrowsAtDestroys(phiValue, deadEndBlocks, scratch);
+    }
   }
 
   // Then eliminate all of the destroys...

test/SILOptimizer/semantic-arc-opts-canonical.sil

@@ -455,8 +455,7 @@ bb3:
 //
 // CHECK: bb1([[CAST:%.*]] : @guaranteed $Klass):
 // CHECK:   [[SOME:%.*]] = enum $FakeOptional<Klass>, #FakeOptional.some!enumelt, [[CAST]] : $Klass
-// CHECK:   [[BORROW:%.*]] = begin_borrow [[SOME]] : $FakeOptional<Klass>
-// CHECK:   br bb3([[BORROW]] : $FakeOptional<Klass>)
+// CHECK:   br bb3([[SOME]] : $FakeOptional<Klass>)
 //
 // CHECK: bb2([[FAIL:%.*]] : @guaranteed $Klass):
 // CHECK-NEXT: [[NONE:%.*]] = enum $FakeOptional<Klass>, #FakeOptional.none!enumelt
@@ -466,11 +465,9 @@ bb3:
 // CHECK:   switch_enum [[PHI]] : $FakeOptional<Klass>, case #FakeOptional.some!enumelt: bb5, case #FakeOptional.none!enumelt: bb4
 //
 // CHECK: bb4:
-// CHECK-NEXT: end_borrow [[PHI]] : $FakeOptional<Klass>
 // CHECK-NEXT: br bb6
 //
 // CHECK: bb5(%{{.*}} : @guaranteed $Klass):
-// CHECK-NEXT:   end_borrow [[PHI]] : $FakeOptional<Klass>
 // CHECK-NEXT:   br bb6
 // CHECK-LABEL: } // end sil function 'testTypeDependentCheckCast'
 sil [ossa] @testTypeDependentCheckCast : $@convention(thin) (@guaranteed Klass, @thick @dynamic_self Klass.Type) -> () {

test/SILOptimizer/semantic-arc-opts.sil

@@ -1630,3 +1630,30 @@ exit:
     %res = tuple ()
     return %res : $()
 }
+
+// CHECK-LABEL: sil [ossa] @test_owned_to_guaranteed_phi : 
+// CHECK-NOT: copy_value
+// CHECK-LABEL: } // end sil function 'test_owned_to_guaranteed_phi'
+sil [ossa] @test_owned_to_guaranteed_phi : $@convention(thin) (@guaranteed Klass, @guaranteed Klass) -> () {
+bb0(%0 : @guaranteed $Klass, %1 : @guaranteed $Klass):
+  %some = enum $FakeOptional<Klass>, #FakeOptional.some!enumelt, %0 : $Klass
+  %copysome = copy_value %some : $FakeOptional<Klass>
+  switch_enum %copysome : $FakeOptional<Klass>, case #FakeOptional.some!enumelt: bb2, case #FakeOptional.none!enumelt: bb3
+
+bb2(%2 : @owned $Klass):
+  br bb4(%2 : $Klass)
+
+bb3:
+  %3 = copy_value %1 : $Klass
+  br bb4(%3 : $Klass)
+
+bb4(%4 : @owned $Klass):
+  %b = begin_borrow %4 : $Klass
+  %f = function_ref @guaranteed_klass_user : $@convention(thin) (@guaranteed Klass) -> ()
+  apply %f(%b) : $@convention(thin) (@guaranteed Klass) -> ()
+  end_borrow %b : $Klass
+  destroy_value %4 : $Klass
+  %t = tuple ()
+  return %t : $()
+}
+