SIL: make unchecked_ref_cast buildable in a global variable initializer

Author: eeckstein

include/swift/SIL/SILBuilder.h

@@ -1279,6 +1279,11 @@ class SILBuilder {
   UncheckedRefCastInst *
   createUncheckedRefCast(SILLocation Loc, SILValue Op, SILType Ty,
                          ValueOwnershipKind forwardingOwnershipKind) {
+    if (isInsertingIntoGlobal()) {
+      return insert(UncheckedRefCastInst::create(
+          getSILDebugLocation(Loc), Op, Ty, getModule(),
+          forwardingOwnershipKind));
+    }
     return insert(UncheckedRefCastInst::create(
         getSILDebugLocation(Loc), Op, Ty, getFunction(),
         forwardingOwnershipKind));

include/swift/SIL/SILInstruction.h

@@ -5964,6 +5964,10 @@ class UncheckedRefCastInst final
   static UncheckedRefCastInst *
   create(SILDebugLocation DebugLoc, SILValue Operand, SILType Ty,
          SILFunction &F, ValueOwnershipKind forwardingOwnershipKind);
+
+  static UncheckedRefCastInst *
+  create(SILDebugLocation DebugLoc, SILValue Operand, SILType Ty,
+         SILModule &Mod, ValueOwnershipKind forwardingOwnershipKind);
 };
 
 /// Convert a value's binary representation to a trivial type of the same size.

lib/SIL/IR/SILInstructions.cpp

@@ -2588,6 +2588,17 @@ BeginCOWMutationInst::create(SILDebugLocation loc, SILValue operand,
                                   isNative);
 }
 
+UncheckedRefCastInst *
+UncheckedRefCastInst::create(SILDebugLocation DebugLoc, SILValue Operand,
+                             SILType Ty, SILModule &Mod,
+                             ValueOwnershipKind forwardingOwnershipKind) {
+  assert(Operand->getType().getCategory() == SILValueCategory::Object);
+  unsigned size = totalSizeToAlloc<swift::Operand>(1);
+  void *Buffer = Mod.allocateInst(size, alignof(UncheckedRefCastInst));
+  return ::new (Buffer) UncheckedRefCastInst(
+      DebugLoc, Operand, {}, Ty, forwardingOwnershipKind);
+}
+
 UncheckedRefCastInst *
 UncheckedRefCastInst::create(SILDebugLocation DebugLoc, SILValue Operand,
                              SILType Ty, SILFunction &F,