[ORC] Allow construction of an ExecutorAddrRange from an addr and a size.

llvm/include/llvm/ExecutionEngine/Orc/Shared/ExecutorAddress.h

@@ -135,6 +135,8 @@ struct ExecutorAddrRange {
   ExecutorAddrRange() = default;
   ExecutorAddrRange(ExecutorAddr Start, ExecutorAddr End)
       : Start(Start), End(End) {}
+  ExecutorAddrRange(ExecutorAddr Start, ExecutorAddrDiff Size)
+      : Start(Start), End(Start + Size) {}
 
   bool empty() const { return Start == End; }
   ExecutorAddrDiff size() const { return End - Start; }

llvm/unittests/ExecutionEngine/Orc/ExecutorAddressTest.cpp

@@ -58,6 +58,7 @@ TEST(ExecutorAddrTest, AddrRanges) {
   // R4:  ##    -- Overlaps R1 end
 
   EXPECT_EQ(R1, ExecutorAddrRange(A1, A2));
+  EXPECT_EQ(R1, ExecutorAddrRange(A1, ExecutorAddrDiff(1)));
   EXPECT_NE(R1, R2);
 
   EXPECT_TRUE(R1.contains(A1));