Sam Thomas



Futil is the Fused Temporal Intermediate Language. It is a novel self-contained intermediate representation for High-level Synthesis. HLS is the process of compiling languages that are semantically close to traditional software languages (C, C++ are the languages typically chosen for this) into digital circuit designs that can be run on an FPGA or fabricated. The goal is to speed up the time-consuming process of digital circuit design by raising the level of abstraction.

However, there is a large semantic gap between software languages and digital circuits. The most popular HLS compilers today work by first using existing tools to transform an input C++ program into LLVM. LLVM programs are in SSA and so basic blocks describe dataflow graphs. These graphs basically look like hardware graphs where dataflow edges represent either a register or a wire, but all the operations are logical and untimed. Scheduling transforms the logical untimed operations to logical timed operations and binding assigns each logical operation physical resources. These stages can potentially affect each other, and so they are performed some number of times until we are left with a timed program that uses physical resources.

At it’s core, Futil is a self-contained representation that allows these standard algorithms to be expressed as a series of modular passes. We believe that this will make HLS compilers both easier to write and easier to extend. We think that extensibility is especially important because it can accelerate the speed of HLS research by making it much easier to test out new algorithms and explore new input languages.

Here is a paper that we wrote that goes into more depth on that language. You can even play around with the compiler online: Demo.


Polka is a simple and extensible framework for keeping a single set of dot files