exec: "C:\Users\jm**\AppData\Local\Arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.4-gcc10.3-1757bed/bin/xtensa-lx106-elf-g++": file does not exist
Compilation error: exec: "C:\Users\jm**\AppData\Local\Arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.4-gcc10.3-1757bed/bin/xtensa-lx106-elf-g++": file does not exist
I agree with BitSeeker that an re-install will be the best bet to try to solve it. You seem to have a corrupt installation of the board package.
Your original problem in the opening post is about a missing compiler. In above quoted text you're talking about upload; is there a confusion about the terminology?
Can you compile for e.g. an Uno? And if you have a board like that, can you upload to it?
The elf is just part of the file name; it could have been anything. I do not know why the ESP people decided to have elf in the filename. I run Windows and I have a lot of files containing elf in the installation for my ESP8266.
The elf extension is part of the compiler; it creates extensible and linkable files.