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Typed Assembly Language (TAL) extends traditional untyped assembly languages with typing annotations, memory management primitives, and a sound set of typing rules. These typing rules guarantee the memory safety, control flow safety, and type safety of TAL programs. Moreover, the typing constructs are expressive enough to encode most source language programming features including records and structures, arrays, higher-order and polymorphic functions, exceptions, abstract data types, subtyping, and modules. Just as importantly, TAL is flexible enough to admit many low-level compiler optimizations. Consequently, TAL is an ideal target platform for type-directed compilers that want to produce verifiably safe code for use in secure mobile code applications or extensible operating system kernels. [Source]
You've met Microsoft research scientist and operating system expert Chris Hawblitzel before. He's the architect and lead researcher of the Verve operating system research project from MSR. As you learned in that interview, typed assembly language and Hoare logic were employed to verify the absence of many kinds of errors in low-level code. Chris et al. use TAL and Hoare logic to achieve highly automated, static verification of the safety of Verve. We didn't spend much time on TAL during the Verve interview, so we decided to remedy that. Enter computer scientist and RiSE team member Juan Chen who did much of the TAL work for Verve. After you watch this video, you should read this paper to go much deeper.
Tune in and get a sense of what TAL is, how type verification works for assembly code, benefits, trade-offs, and much more. Enjoy.
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