Add SILArgument::isTerminatorResult() and getTransformingTerminator().

Author: atrick

include/swift/SIL/SILArgument.h

@@ -117,6 +117,9 @@ class SILArgument : public ValueBase {
   /// opposed to a cast or projection.
   bool isPhiArgument() const;
 
+  /// Return true if this block argument is a terminator result.
+  bool isTerminatorResult() const;
+
   /// If this argument is a phi, return the incoming phi value for the given
   /// predecessor BB. If this argument is not a phi, return an invalid SILValue.
   SILValue getIncomingPhiValue(SILBasicBlock *predBlock) const;
@@ -208,6 +211,9 @@ class SILPhiArgument : public SILArgument {
   /// opposed to a cast or projection.
   bool isPhiArgument() const;
 
+  /// Return true if this block argument is a terminator result.
+  bool isTerminatorResult() const { return !isPhiArgument(); }
+
   /// If this argument is a phi, return the incoming phi value for the given
   /// predecessor BB. If this argument is not a phi, return an invalid SILValue.
   ///
@@ -283,6 +289,10 @@ class SILPhiArgument : public SILArgument {
   /// terminator has a single operand, return that terminator.
   TermInst *getSingleTerminator() const;
 
+  /// Return the terminator instruction of which this argument is a result or
+  /// nullptr.
+  TermInst *getTransformingTerminator() const;
+
   static bool classof(const SILInstruction *) = delete;
   static bool classof(const SILUndef *) = delete;
   static bool classof(SILNodePointer node) {
@@ -347,6 +357,16 @@ inline bool SILArgument::isPhiArgument() const {
   llvm_unreachable("Covered switch is not covered?!");
 }
 
+inline bool SILArgument::isTerminatorResult() const {
+  switch (getKind()) {
+  case SILArgumentKind::SILPhiArgument:
+    return cast<SILPhiArgument>(this)->isTerminatorResult();
+  case SILArgumentKind::SILFunctionArgument:
+    return false;
+  }
+  llvm_unreachable("Covered switch is not covered?!");
+}
+
 inline SILValue
 SILArgument::getIncomingPhiValue(SILBasicBlock *predBlock) const {
   switch (getKind()) {

lib/SIL/IR/SILArgument.cpp

@@ -316,6 +316,14 @@ TermInst *SILPhiArgument::getSingleTerminator() const {
   return const_cast<SILBasicBlock *>(predBlock)->getTerminator();
 }
 
+TermInst *getTransformingTerminator() const {
+  if (auto *termInst = getSingleTerminator()) {
+    if (!isa<BranchInst>(termInst) && !isa<CondBranchInst>(termInst))
+      return termInst;
+  }
+  return nullptr;
+}
+
 SILPhiArgument *BranchInst::getArgForOperand(const Operand *oper) {
   assert(oper->getUser() == this);
   return cast<SILPhiArgument>(