Use internal alignment logarithm in aligned sized delete

For valid power-of-two alignments, use `lg_floor()` to encode the
alignment flags in the C++ aligned sized delete helper. This avoids the
public macro's split-word calculation when alignment is a runtime
argument.

src/jemalloc_cpp.cpp

@@ -268,7 +268,8 @@ alignedSizedDeleteImpl(
 	    ptr, size, alignment);
 
 	if (likely(ptr != nullptr)) {
-		je_sdallocx_impl(ptr, size, MALLOCX_ALIGN(alignment));
+		je_sdallocx_impl(
+		    ptr, size, MALLOCX_LG_ALIGN(lg_floor((size_t)alignment)));
 	}
 
 	LOG("core.operator_delete.exit", "");

test/integration/cpp/basic.cpp

@@ -1,3 +1,4 @@
+#include <new>
 #include <type_traits>
 
 #include "test/jemalloc_test.h"
@@ -32,7 +33,37 @@ TEST_BEGIN(test_basic) {
 }
 TEST_END
 
+TEST_BEGIN(test_aligned_sized_delete) {
+#if __cpp_aligned_new >= 201606 && __cpp_sized_deallocation >= 201309
+	const size_t alignments[] = {1, 64, 256, 4096, ZU(1) << 20};
+	const size_t sizes[] = {1, 42, 4096, 65536};
+	for (size_t alignment : alignments) {
+		auto al = static_cast<std::align_val_t>(alignment);
+		for (size_t size : sizes) {
+			void *ptr = ::operator new(size, al);
+			expect_ptr_not_null(
+			    ptr, "Unexpected aligned new failure");
+			expect_zu_eq((uintptr_t)ptr & (alignment - 1), 0,
+			    "Unexpected allocation alignment");
+			::operator delete(ptr, size, al);
+
+			ptr = ::operator new[](size, al);
+			expect_ptr_not_null(
+			    ptr, "Unexpected aligned array new failure");
+			expect_zu_eq((uintptr_t)ptr & (alignment - 1), 0,
+			    "Unexpected allocation alignment");
+			::operator delete[](ptr, size, al);
+		}
+		::operator delete(nullptr, 0, al);
+		::operator delete[](nullptr, 0, al);
+	}
+#else
+	test_skip("Aligned sized deallocation is not enabled");
+#endif
+}
+TEST_END
+
 int
 main() {
-	return test(test_basic);
+	return test(test_basic, test_aligned_sized_delete);
 }