I wonder if it is possible to program that D87C51 using regular SDCC...
There was around 2001 a patched version of SDCC, indirectly promoted by Dallas Semiconductors/Maxim Integrated, for the new (well it was a "new" event in 2001)
DS80C390, a fast 8051-compatible redesigned processor core able to executes 8051 instructions up to 3X faster than the original for the same crystal speed, and able to support a maximum crystal speed of 40MHz, resulting in apparent execution speeds of 100MHz.
This monster was the core of their TiniJava(1), a Waba embedded platform coupled with a Java1 compiler and a technology called "Jump51", which was able to automatically "adapt" the JavaByteCode to the natural intel 51 code for all the critical low level sections that need some "speedup".
It intriguing, and interesting, but it was not a success, hence they pushed their effort to SDCC, which was then "reloaded" by their marketing office for the next gen: the
DS80C400 chip!
So, around 2001-2004, as far as I remember, SDCC was able to compile for both of them
What I mean is: we are on Gcc-v9, and GNU is going to drop the support for Itanium starting from Gcc-v11 as well as GNU dropped the 68HC11 support around Gcc v3.4.6, dunno what SDCC did with 51 after 2004.
(1) if you want to see a pic, I have one board in my lab. It's used as weather station. The manual is about 400 pages of Java1, while the development machine is a Windows95 laptop