AOT building and usage

AOT_build_instructions.md

Boostrapping Shell with AOT:

1. An empty AOTBaselineStub.S scaffold is checked in, but not attached as build input. AOT dumps direct into AOTBaseline.S, which is a build input. First step is: cp js/src/jit/AOTBaselineStub.S js/src/jit/AOTBaseline.S

2. I have some mozconfigs here, but the only option necessary is: ac_add_options --enable-aot. Then ./mach configure && ./mach build

3. Dumping AOT:

   IONFLAGS=bl-aot ./js --aot-dump-baseline --aot-dump-ics --aot-dump-self-hosted -e 'quit(0);'
   

   Should see 0 ics for now, one interp and all the self-hosted functions.

4. Bootstrap: Run ./mach build, you should see: js/src/jit/AOTBaseline.o compiled

5. Running shell tests: python3 ./jit-test/jit_test.py --args="--aot" ../../js Two expected failures: blinterp-trial-inlining.js and ion/recover-objects.js. Former due to baked in blinterp options from the dump, the later due to a broken assertion.

6. Collecting AOT ics: I have some corpi here but ICs can also be collected from the shell:

   AOT_ICS_DUMP_MISSING_DIR=js/src/ics AOT_ICS_KEEP_GOING=1 \
    ./js --aot --aot-ics-enforce -f {{FILE}}
   

   Then mv IC-* js/src/ics and rebuilding will produced the generated AOT CacheIR files (Chris Fallins infra)

Bootstrapping Browser:

1. First bootstrap AOTBaseline.s against the shell same as before
2. Building the browser will automatically pickup the AOT object
3. Instruct usage of AOT with:

   JIT_OPTION_useAOTInterp=true JIT_OPTION_useAOTSelfHosted=true JIT_OPTION_useAOTICs=true \
    ./build-browser-release-aot/dist/bin/firefox --no-remote