Add Matt's 2026 Q1 Update

Author: mborland

_posts/2026-04-06-Matts2026Q1Update.md

@@ -0,0 +1,69 @@
+---
+layout: post
+nav-class: dark
+categories: matt
+title: Speed and Safety
+author-id: matt
+author-name: Matt Borland
+---
+
+In my [last post](https://cppalliance.org/matt/2026/01/15/Matts2025Q4Update.html) I mentioned that [int128](https://github.com/cppalliance/int128) library would be getting CUDA support in the future.
+The good news is that the future is now!
+Nearly all the functions in the library are available on both host and device.
+Any function that has `BOOST_INT128_HOST_DEVICE` in its signature in the [documentation](https://develop.int128.cpp.al/overview.html) is available for usage.
+[An example](https://develop.int128.cpp.al/examples.html#examples_cuda) of how to use the types in the CUDA kernels has been added as well.
+These can be as simple as: 
+
+```cpp
+using test_type = boost::int128::uint128_t;
+
+__global__ void cuda_mul(const test_type* in1, const test_type* in2, test_type* out, int num_elements)
+{
+    int i = blockDim.x * blockIdx.x + threadIdx.x;
+
+    if (i < num_elements)
+    {
+        out[i] = in1[i] * in2[i];
+    }
+}
+```
+
+Other Boost libraries are or will be beneficiaries of this effort as well.
+First, Boost.Charconv now supports `boost::charconv::from_chars` and `boost::charconv::to_chars` for integers being run on device.
+This can give you up to an order of magnitude improvement in performance.
+These results and benchmarks are available in the [Boost.Charconv documentation](https://www.boost.org/doc/libs/develop/libs/charconv/doc/html/charconv.html).
+Next, in the coming months Boost.Decimal will gain CUDA support as part of this effort.
+We think users will benefit greatly from being able to perform massively parallel parsing, serialization, and calculations on decimal numbers.
+Stay tuned for this likely in Boost 1.92.
+In the meantime, enjoy the initial release of Decimal coming in Boost 1.91!
+
+On the other side of the performance that we're looking to deliver in coming versions of Boost, we must not forget the importance of safety.
+There exist plenty of [examples of damage and death](https://en.wikipedia.org/wiki/Integer_overflow#Examples) caused by arithmetic errors in computer programs.
+Can we create a library that provides guaranteed safety in arithmetic while minimizing performance losses and integration friction?
+How does one guarantee the behavior of their types?
+In our implementation, [Boost.Safe_Numbers](https://github.com/cppalliance/safe_numbers), we are investigating the usage of the [Why3](https://why3.org) platform for deductive program verification.
+By pursuing these formal methods, safety can have real meaning.
+We will continue to provide additional details as part of the [formal verification page](https://develop.safe-numbers.cpp.al/verification.html) of our documentation.
+Since inevitably the library will cause an increase in the number of errors (which is a good thing), we aim to fail as early as possible, and when we do provide the most helpful error message that we can.
+For example, we have some static arithmetic errors reported in as few as three lines:
+
+```cpp
+clang-darwin.compile.c++ ../../../bin.v2/libs/safe_numbers/test/compile_fail_basic_usage_constexpr.test/clang-darwin-21/debug/arm_64/cxxstd-20-iso/threading-multi/visibility-hidden/compile_fail_basic_usage_constexpr.o
+../examples/compile_fail_basic_usage_constexpr.cpp:18:22: error: constexpr variable 'z' must be initialized by a constant expression
+   18 |         constexpr u8 z {x + y};
+      |                      ^ ~~~~~~~
+../../../boost/safe_numbers/detail/unsigned_integer_basis.hpp:397:17: note: subexpression not valid in a constant expression
+  397 |                 throw std::overflow_error("Overflow detected in u8 addition");
+      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+../examples/compile_fail_basic_usage_constexpr.cpp:18:25: note: in call to 'operator+<unsigned char>({255}, {2})'
+   18 |         constexpr u8 z {x + y};
+      |                         ^~~~~
+1 error generated.
+```
+
+Our runtime error reporting system fundamentally uses Boost.Throw_Exception so it can report not only the type, operation, file and line, but also up to an entire stack trace when leveraging the optional linking with Boost.Stacktrace.
+Not to forget our discussion of CUDA so quickly, the Safe_Numbers library will have CUDA support.
+One thing that we will continue to refine is synchronizing error reporting on device as one cannot throw an exception on device.
+
+We are always looking for users of all the libraries discussed.
+If you are a current or prospective user, feel free to reach out and let us know what you're using it for, or any issues that you find.