[sil] Add new API to ApplySite called getOperandsWithoutSelf().

Needed this API. Unwrapping the onion to make further commits easier to review.

Author: gottesmm

include/swift/SIL/ApplySite.h

@@ -485,6 +485,21 @@ class ApplySite {
     llvm_unreachable("covered switch");
   }
 
+  /// Return a list of applied operands of the apply without self.
+  ArrayRef<Operand> getOperandsWithoutSelf() const {
+    switch (ApplySiteKind(Inst->getKind())) {
+    case ApplySiteKind::ApplyInst:
+      return cast<ApplyInst>(Inst)->getOperandsWithoutSelf();
+    case ApplySiteKind::BeginApplyInst:
+      return cast<BeginApplyInst>(Inst)->getOperandsWithoutSelf();
+    case ApplySiteKind::TryApplyInst:
+      return cast<TryApplyInst>(Inst)->getOperandsWithoutSelf();
+    case ApplySiteKind::PartialApplyInst:
+      llvm_unreachable("Unhandled case");
+    }
+    llvm_unreachable("covered switch");
+  }
+
   /// Returns true if \p op is an operand that passes an indirect
   /// result argument to the apply site.
   bool isIndirectResultOperand(const Operand &op) const;

include/swift/SIL/SILInstruction.h

@@ -2877,20 +2877,30 @@ class ApplyInstBase<Impl, Base, true>
   void setSelfArgument(SILValue V) {
     assert(hasSelfArgument() && "Must have a self argument");
     assert(getNumArguments() && "Should only be called when Callee has "
-                                      "arguments.");
+                                "arguments.");
     getArgumentOperands()[getNumArguments() - 1].set(V);
   }
 
   OperandValueArrayRef getArgumentsWithoutSelf() const {
-    assert(hasSelfArgument() && "Must have a self argument");
     assert(getNumArguments() && "Should only be called when Callee has "
-           "at least a self parameter.");
+                                "at least a self parameter.");
     ArrayRef<Operand> ops = this->getArgumentOperands();
-    ArrayRef<Operand> opsWithoutSelf = ArrayRef<Operand>(&ops[0],
-                                                         ops.size()-1);
+    if (!hasSelfArgument())
+      return ops;
+    auto opsWithoutSelf = ArrayRef<Operand>(&ops[0], ops.size() - 1);
     return OperandValueArrayRef(opsWithoutSelf);
   }
 
+  ArrayRef<Operand> getOperandsWithoutSelf() const {
+    assert(getNumArguments() && "Should only be called when Callee has "
+                                "at least a self parameter.");
+    ArrayRef<Operand> ops = this->getArgumentOperands();
+    if (!hasSelfArgument())
+      return ops;
+    auto opsWithoutSelf = ArrayRef<Operand>(&ops[0], ops.size() - 1);
+    return opsWithoutSelf;
+  }
+
   llvm::Optional<SILResultInfo> getSingleResult() const {
     auto SubstCallee = getSubstCalleeType();
     if (SubstCallee->getNumResults() != 1)