By the end of the week in February the secret had been revealed to me: he was working on a C compiler and was in the final stages of polishing the optimizer. I was 22 years old at the time, and I still harbored a dream that I might someday write “The Great American Compiler”. I was thrilled to have a chance to see how a master like Stallman would write such a thing, and I was terrified that I would never create something worthy of recognition if he had been there first. When Stallman announced version 1.0, 20 years ago to this day (more or less), I had a decision to make: I could join him, I could compete with him, or I could pick a new dream. I downloaded GCC version 1.0 and began a collaboration that would last for ten years (when, due to RSI, I gave up programming as a mainstream activity.)
GCC version 1.0 was a watershed event in my life. The first day I was intent on just learning how it worked–the parser, the lexical analyzer, the intermediate code generator, the optimizers, and the machine-dependent assembly output routines. I printed all the files (consuming three reams of paper) and proceeded to lay them out in piles across my extra-large dining table and any other horizontal surfaces I could see from my central position. I brought out the colored pencils I’d used when learning the art and science of integrated circuit design (red for polycilicon, green for n-diffusion, blue for metal, yellow for n-well, and black for vias and contacts) and gave the colors new meanings to track data, code, and other relationships relevant to compilers. After five days and nights, something “clicked” and I no longer needed the printouts–the data structures and basic organization suddenly became “obvious”. I put away the pencils and began to itch with the desire to hack GCC, and not lightly.
I decided to take the next step–to write a completely new port of the compiler to a microprocessor that had always fascinated me: the National Semiconductor 32032. I already had the manual from my days at the Moore School of Engineering at the University of Pennsylvania, and so I began the process of replacing templates used for the VAX and Motorola 68020 processors with templates appropriate for the National chip. I immediately ran into problems–but they were small problems and easily fixed. I had GCC generating code for the National chip within a few days, and I had it generating correct code a few days after that.
When I did this work, the typical compiler company charged millions of dollars for the service of delivering a compiler in 12-18 months, and sometimes longer. Two weeks to the day after I downloaded the compiler from the Free Software Foundation, I had it generating code that was 20% faster that the code coming from the National compiler. If I compared the $3000/month salary I earned at the time with what these companies charged, I delivered a product that was 20% better (6-9 months in Moore’s Law time) for 1/1000th the cost in 1/30th the time. It was a heck of a 23rd birthday present to myself!
Within hours of posting an announcement of this new port, it became obvious to me and to others that there were many optimizations I had not yet implemented. After another two weeks of work, I was generated code that was 40% faster than the National compiler. 40% was an important number because the 32032 was marketed as a “1 MIPS” chip (meaning able to execute one million instructions per second), but it only benchmarked at 0.75 MIPS and was headed for commercial irrelevancy. With my 32032 port, the chip benchmarked above 1 MIPS, proving to me that the hardware guys had delivered, but the software guys had not. I also realized that even in 1987, there were already sufficiently many people to make a collaborative process very successful.
I went on to write many other ports that summer, demonstrating with remarkable consistency that by hacking on GNU, I could routinely generate better product faster than whole teams of compiler-writers employed by much larger companies. By the end of that year I went on to achieve a new goal, which was to write the GNU C++ compiler. To me, GNU C++ was “The Great American C++ Compiler”, a new, improved version of my original goal. And because I benefited so much, both by what others shared with me before I started hacking, and by the helpful suggestions and bugfixes I received after I started hacking, I, too, shared freely the knowledge I had gained. I wrote and delivered the first comprehensive training on the GNU compiler internals, giving my 100+ LaTeX slides to Stallman so he, too, could earn money by teaching others how to hack. Two years later, I formally commercialized the commercial advantages of GNU software, and the rest, as they say, is history.
I wonder what the next 20 years will bring…