Mill Computing, Inc. Forums The Mill Markets Is binary Translating i386/x86_64 to mill code practical? Reply To: Is binary Translating i386/x86_64 to mill code practical?

Ivan Godard
Post count: 627

Binary translation is as practical to the Mill as to any other architecture; the task is essentially the same for any S-to-T translation, including the Mill on either end. You un-model the source to an abstract representation similar to a compiler’s IR, optimize that to a fair-thee-well to remove redundant state setting (like condition codes), and then do a normal target code gen from the result.

The difficulty, for all translations, is when the source code embeds implicit assumptions about the platform. Self-modifying code is obvious, but code often assumes word and pointer sizes, endianness, the presence (and behavior) of I/O devices, and so on.

There are platform dependencies beyond the ISA too. You may have a Windows x86 binary and translate it to execute on a SPARC or a Mill, but without a Windows OS to run on it’s not going to be able to draw pictures on the screen.

So the issues with binary translation are roughly the same as for any other port even if you have the source to recompile. If a given code can already successfully run on big- and little-endian machines using both 32-bit and 64-bit models then it is probably port-clean enough to translate well. But even with perfect ISA translation, the port may not succeed.