SIL: verify forwarding conformances

Verify that the C++ view of forwarding instructions agrees with the swift ForwardInstruction conformances.

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/Utilities/Verifier.swift

@@ -27,6 +27,9 @@ extension Function {
   func verify(_ context: FunctionPassContext) {
     for block in blocks {
       for inst in block.instructions {
+
+        inst.checkForwardingConformance()
+
         if let verifyableInst = inst as? VerifyableInstruction {
           verifyableInst.verify(context)
         }
@@ -35,6 +38,16 @@ extension Function {
   }
 }
 
+private extension Instruction {
+  func checkForwardingConformance() {
+    if bridged.shouldBeForwarding() {
+      require(self is ForwardingInstruction, "instruction \(self)\nshould conform to ForwardingInstruction")
+    } else {
+      require(!(self is ForwardingInstruction), "instruction \(self)\nshould not conform to ForwardingInstruction")
+    }
+  }
+}
+
 func registerVerifier() {
   BridgedUtilities.registerVerifier(
     { (bridgedCtxt: BridgedPassContext, bridgedFunction: BridgedFunction) in

include/swift/SIL/SILBridging.h

@@ -770,6 +770,7 @@ struct BridgedInstruction {
   bool mayLoadWeakOrUnowned() const;
   bool maySynchronize() const;
   bool mayBeDeinitBarrierNotConsideringSideEffects() const;
+  BRIDGED_INLINE bool shouldBeForwarding() const;
 
   // =========================================================================//
   //                   Generalized instruction subclasses

include/swift/SIL/SILBridgingImpl.h

@@ -846,6 +846,12 @@ bool BridgedInstruction::maySuspend() const {
   return unbridged()->maySuspend();
 }
 
+bool BridgedInstruction::shouldBeForwarding() const {
+  return llvm::isa<swift::OwnershipForwardingSingleValueInstruction>(unbridged()) ||
+         llvm::isa<swift::OwnershipForwardingTermInst>(unbridged()) ||
+         llvm::isa<swift::OwnershipForwardingMultipleValueInstruction>(unbridged());
+}
+
 SwiftInt BridgedInstruction::MultipleValueInstruction_getNumResults() const {
   return getAs<swift::MultipleValueInstruction>()->getNumResults();
 }