In their twilight years Symbolics implemented their own DEC Alpha assembler in Common Lisp to aid the development of their Lisp machine emulator: http://pt.withy.org/publications/VLM.html
You can still find its leaked source code on the internet.
"We built a prototype of the emulator in C, but it quickly became obvious that we could not achieve the level of performance desired in C. Examination of code emitted by the C compiler showed it took very poor advantage of the Alpha's dual-issue capabilities. A second implementation was done in Alpha assembly language and is the basis for the current product.
We built a number of tools (in Lisp, running on Genera) that supported the level of complexity of the assembly language program we were attempting. A translator was built that allowed us to use Lisp as a macro language. One of the primary benefits of using Lisp was that we could use all our normal development tools, including incremental patching, even though we were working in another machine's assembly language. Even more beneficial, however, was that early on in the project, we were able to easily graft on to the translator a cycle-counting tool that allowed one to easily and automatically "preview" any code fragment and see its total cycle cost, dual-issues that were taken or missed, and any free stall slots. Because this tool was integrated directly with the Genera editor, we were able to pro-actively optimize our code, right from the start. The full paper describes this tool in more detail, with examples, and compares it with tools that have recently become available from DEC that attempt to automatically re-organize executable files. It is our claim that our tool, because of its interactive nature, offers many more opportunities for optimization."
In their earlier years, the Symbolics 3600 series machines included a Motorola 68K series Front End Processor (the "FEP") for booting the main processor. And the assembler for that was written in Lisp.
Reminds me of the predecessor for this 6502 assembler: https://www.pagetable.com/?p=848 -- the comments include a note by the author, Chip Morningstar of Habitat, saying the Lisp assembler was terribly slow on a VAX.
You can still find its leaked source code on the internet.
"We built a prototype of the emulator in C, but it quickly became obvious that we could not achieve the level of performance desired in C. Examination of code emitted by the C compiler showed it took very poor advantage of the Alpha's dual-issue capabilities. A second implementation was done in Alpha assembly language and is the basis for the current product.
We built a number of tools (in Lisp, running on Genera) that supported the level of complexity of the assembly language program we were attempting. A translator was built that allowed us to use Lisp as a macro language. One of the primary benefits of using Lisp was that we could use all our normal development tools, including incremental patching, even though we were working in another machine's assembly language. Even more beneficial, however, was that early on in the project, we were able to easily graft on to the translator a cycle-counting tool that allowed one to easily and automatically "preview" any code fragment and see its total cycle cost, dual-issues that were taken or missed, and any free stall slots. Because this tool was integrated directly with the Genera editor, we were able to pro-actively optimize our code, right from the start. The full paper describes this tool in more detail, with examples, and compares it with tools that have recently become available from DEC that attempt to automatically re-organize executable files. It is our claim that our tool, because of its interactive nature, offers many more opportunities for optimization."