Sema: Use PointerEmbeddedInt instead of Fixnum (#3009)

PointerEmbeddedInt is provided by stock LLVM and serves the same purpose.  This
updates the coersion function to use that rather than the swift specific Fixnum.
Furthermore, this type has been removed in the future in favour of the
PointerEmbeddedInt type, which makes this change something which will be needed
when rebasing to a newer LLVM release.

Author: compnerd

lib/Sema/CSApply.cpp

@@ -23,7 +23,6 @@
 #include "swift/Basic/StringExtras.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/APInt.h"
-#include "llvm/ADT/Fixnum.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/SaveAndRestore.h"
 
@@ -1137,10 +1136,12 @@ namespace {
     /// \param locator Locator used to describe where in this expression we are.
     ///
     /// \returns the coerced expression, which will have type \c ToType.
-    Expr *coerceCallArguments(Expr *arg, Type paramType,
-                              llvm::PointerUnion<ApplyExpr *, llvm::Fixnum<2>>
-                                applyOrLevel,
-                              ConstraintLocatorBuilder locator);
+    using LevelTy = llvm::PointerEmbeddedInt<unsigned, 2>;
+
+    Expr *
+    coerceCallArguments(Expr *arg, Type paramType,
+                        llvm::PointerUnion<ApplyExpr *, LevelTy> applyOrLevel,
+                        ConstraintLocatorBuilder locator);
 
     /// \brief Coerce the given object argument (e.g., for the base of a
     /// member expression) to the given type.
@@ -1209,9 +1210,9 @@ namespace {
       }
 
       // Coerce the index argument.
-      index = coerceCallArguments(index, indexTy, /*level=*/llvm::Fixnum<2>(1),
-                                  locator.withPathElement(
-                                    ConstraintLocator::SubscriptIndex));
+      index = coerceCallArguments(
+          index, indexTy, LevelTy(1),
+          locator.withPathElement(ConstraintLocator::SubscriptIndex));
       if (!index)
         return nullptr;
 
@@ -4563,7 +4564,7 @@ static bool isReferenceToMetatypeMember(Expr *expr) {
 
 Expr *ExprRewriter::coerceCallArguments(
     Expr *arg, Type paramType,
-    llvm::PointerUnion<ApplyExpr *, llvm::Fixnum<2>> applyOrLevel,
+    llvm::PointerUnion<ApplyExpr *, LevelTy> applyOrLevel,
     ConstraintLocatorBuilder locator) {
 
   bool allParamsMatch = arg->getType()->isEqual(paramType);
@@ -4574,9 +4575,9 @@ Expr *ExprRewriter::coerceCallArguments(
 
   // Determine the level,
   unsigned level = 0;
-  if (applyOrLevel.is<llvm::Fixnum<2>>()) {
+  if (applyOrLevel.is<LevelTy>()) {
     // Level specified by caller.
-    level = applyOrLevel.get<llvm::Fixnum<2>>();
+    level = applyOrLevel.get<LevelTy>();
   } else if (callee) {
     // Determine the level based on the application itself.
     auto apply = applyOrLevel.get<ApplyExpr *>();