iWAPT 2024 Keynote Talk: What Happens to a Dream Deferred? Chasing Automatic Offloading in Fortran 2023
Damian W. I. Rouson · 2024
In 1951, Harlem Renaissance poet Langston Hughes asked this talk's titular question at the outset of a poem entitled “Harlem.” Six years later, IBM mathematician John Backus developed Fortran, the world's first widely used high-level programming language. Backus went on to explore functional programming and to highlight the functional style in his Turing Award lecture in 1977, a year that also demarcates what one might consider the end of the classical era of Fortran. This talk will demonstrate how modern Fortran began to deliver on Backus's functional programming dream, starting with pure procedures in the 1995 standard. The talk will further demonstrate how this style culminated in a powerful and flexible facility for expressing independent iterations via the “do concurrent” construct, which the Fortran standard committee included in Fortran 2008 with the intention to facilitate automatic Graphics Processing Unit (GPU) programming. Fortran 2008 was published in 2010, but it took another decade for compilers to deliver on the promise of automatic GPU offloading. This talk will detail the trials and tribulations of Berkeley Lab's Fortran team in chasing the automatic offloading dream in our Inference-Engine deep learning library and Matcha highperformance computing (HPC) application.