Merge pull request #2398 from saagarjha/master

Rename the JIT

.github/workflows/ci.yml

@@ -29,7 +29,7 @@ jobs:
         run: deps/clone-linux.sh
       - name: Build
         run: |
-          meson build -Dengine=jit -Dkernel=${{matrix.kernel}}
+          meson build -Dengine=asbestos -Dkernel=${{matrix.kernel}}
           ninja -C build
         env:
           CC: ${{matrix.cc}}

README.md

@@ -59,9 +59,9 @@ Available channels:
 - `verbose`: Debug logs that don't fit into another category.
 - Grep for `DEFAULT_CHANNEL` to see if more log channels have been added since this list was updated.
 
-# A note on the JIT
+# A note on the interpreter
 
-Possibly the most interesting thing I wrote as part of iSH is the JIT. It's not actually a JIT since it doesn't target machine code. Instead it generates an array of pointers to functions called gadgets, and each gadget ends with a tailcall to the next function; like the threaded code technique used by some Forth interpreters. The result is a speedup of roughly 3-5x compared to pure emulation.
+Possibly the most interesting thing I wrote as part of iSH is the interpreter. It's not quite a JIT since it doesn't target machine code. Instead it generates an array of pointers to functions called gadgets, and each gadget ends with a tailcall to the next function; like the threaded code technique used by some Forth interpreters. The result is a speedup of roughly 3-5x compared to emulation using a simpler switch dispatch.
 
 Unfortunately, I made the decision to write nearly all of the gadgets in assembly language. This was probably a good decision with regards to performance (though I'll never know for sure), but a horrible decision with regards to readability, maintainability, and my sanity. The amount of bullshit I've had to put up with from the compiler/assembler/linker is insane. It's like there's a demon in there that makes sure my code is sufficiently deformed, and if not, makes up stupid reasons why it shouldn't compile. In order to stay sane while writing this code, I've had to ignore best practices in code structure and naming. You'll find macros and variables with such descriptive names as `ss` and `s` and `a`. Assembler macros nested beyond belief. And to top it off, there are almost no comments.