Which brings up an interesting query - I wonder when/what the last compiler written in assembler was?
Excellent question -- IBM's Fortran-H maybe? circa mid 1970's would be my guess.
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The Fortran H compiler was mostly written in Fortran: 27,415 lines of Fortran and 16,721 lines of assembler according to slide 12 of [1].
There were some language extensions (structures and pointers) to support this, enabled by the secret compiler option XL. They are described in Appendix J of the Program Logic Manual for the compiler [2].
The early-1980s Fortran 77 compiler for the GEC 4090 was written in Babbage, a thin PL/360-like veneer over the raw 4090 instruction set.