[SwiftCompiler] Make BridgedArrayRef.data nullable

ArrayRef.data() can be nullptr when the array is empty.

Author: rintaro

SwiftCompilerSources/Sources/Basic/Utils.swift

@@ -70,7 +70,7 @@ extension Optional where Wrapped == UnsafeMutablePointer<BridgedSwiftObject> {
 
 extension BridgedArrayRef {
   public func withElements<T, R>(ofType ty: T.Type, _ c: (UnsafeBufferPointer<T>) -> R) -> R {
-    let start = data.bindMemory(to: ty, capacity: numElements);
+    let start = data?.bindMemory(to: ty, capacity: numElements);
     let buffer = UnsafeBufferPointer(start: start, count: numElements);
     return c(buffer)
   }

SwiftCompilerSources/Sources/SIL/BasicBlock.swift

@@ -96,7 +96,7 @@ public struct SuccessorArray : RandomAccessCollection, FormattedLikeArray {
 
   public subscript(_ index: Int) -> BasicBlock {
     precondition(index >= 0 && index < endIndex)
-    let s = BridgedSuccessor(succ: succArray.data + index &* BridgedSuccessorSize);
+    let s = BridgedSuccessor(succ: succArray.data! + index &* BridgedSuccessorSize);
     return SILSuccessor_getTargetBlock(s).block
   }
 }

SwiftCompilerSources/Sources/SIL/Operand.swift

@@ -67,11 +67,11 @@ public struct OperandArray : RandomAccessCollection, CustomReflectable {
 
   public subscript(_ index: Int) -> Operand {
     precondition(index >= 0 && index < endIndex)
-    return Operand(BridgedOperand(op: opArray.data + index &* BridgedOperandSize))
+    return Operand(BridgedOperand(op: opArray.data! + index &* BridgedOperandSize))
   }
 
   public func getIndex(of operand: Operand) -> Int {
-    let idx = (operand.bridged.op - UnsafeRawPointer(opArray.data)) /
+    let idx = (operand.bridged.op - UnsafeRawPointer(opArray.data!)) /
                 BridgedOperandSize
     precondition(self[idx].bridged.op == operand.bridged.op)
     return idx
@@ -86,7 +86,7 @@ public struct OperandArray : RandomAccessCollection, CustomReflectable {
     precondition(bounds.lowerBound >= 0)
     precondition(bounds.upperBound <= endIndex)
     return OperandArray(opArray: BridgedArrayRef(
-      data: opArray.data + bounds.lowerBound &* BridgedOperandSize,
+      data: opArray.data! + bounds.lowerBound &* BridgedOperandSize,
       numElements: bounds.upperBound - bounds.lowerBound))
   }
 }

include/swift/Basic/BasicBridging.h

@@ -31,7 +31,7 @@ typedef struct {
 } BridgedStringRef;
 
 typedef struct {
-  const void * _Nonnull data;
+  const void * _Nullable data;
   size_t numElements;
 } BridgedArrayRef;