Cloner: set the cloner's builder insertion point to the entry block when creating a new entry block in the cloned function

This allows clients to directly clone specific instructions into the new entry block

Author: eeckstein

SwiftCompilerSources/Sources/SIL/Utilities/Cloner.swift

@@ -67,7 +67,9 @@ public struct Cloner<Context: MutatingContext> {
     if let entryBlock = targetFunction.blocks.first {
       return entryBlock
     }
-    return targetFunction.appendNewBlock(context)
+    let entryBlock = targetFunction.appendNewBlock(context)
+    bridged.setInsertionBlockIfNotSet(entryBlock.bridged)
+    return entryBlock
   }
 
   public func cloneFunctionBody(from originalFunction: Function, entryBlockArguments: [Value]) {

include/swift/SIL/SILBridging.h

@@ -1549,6 +1549,7 @@ struct BridgedCloner {
   void recordClonedInstruction(BridgedInstruction origInst, BridgedInstruction clonedInst) const;
   void recordFoldedValue(BridgedValue orig, BridgedValue mapped) const;
   BridgedInstruction clone(BridgedInstruction inst) const;
+  void setInsertionBlockIfNotSet(BridgedBasicBlock block) const;
 };
 
 struct BridgedTypeSubstCloner {

lib/SIL/Utils/SILBridging.cpp

@@ -699,6 +699,11 @@ BridgedInstruction BridgedCloner::clone(BridgedInstruction inst) const {
   return {cloner->cloneInst(inst.unbridged())->asSILNode()};
 }
 
+void BridgedCloner::setInsertionBlockIfNotSet(BridgedBasicBlock block) const {
+  if (!cloner->getBuilder().hasValidInsertionPoint())
+    cloner->getBuilder().setInsertionPoint(block.unbridged());
+}
+
 BridgedBasicBlock BridgedCloner::getClonedBasicBlock(BridgedBasicBlock originalBasicBlock) const {
   return { cloner->getOpBasicBlock(originalBasicBlock.unbridged()) };
 }