Javascript:SpiderMonkey:OdinMonkey

Active

Move code generation into the parallel compilation tasks: bug 959263
Heap resizing: bug 965880
Add enough try/catch to asm.js to allow compilation of C++ exceptions using the zero-cost implementation strategy
Optimize calls into (bug 962641), out of (bug 1000632), and between (bug 982036) asm.js modules.
Remove async-script requirement for asm.js caching: bug 961057
Fix asm.js caching browser interop (bug 1047098, bug 1047105

General backend optimizations:
- Use callee-saved registers: bug 985065
- Enable backtracking allocator: bug 983580
- Avoid over-recursed check in leaf functions: bug 985130
- Heap access: bug 986981, bug 870743, bug 897425, bug 915157, bug 983131, bug 865523, bug 984478, bug 1056027
- Optimize add-with-overflow: bug 1043365
- Optimize min/max: bug 1060635
Further improve load-time:
- Parse and AOT compile while downloading: bug 1061886
- asm.js parser: Avoid building an intermediate parse tree; type check during recursive descent bug 854061
Further improve caching:
- Compress more than just the source in asm.js cache entries
Improve compile time on pathological functions:
- Break up super-large functions into disjoint regions that can be regalloc'd and optimized separately
- Investigate GVN quadratic behavior : bug 845068
For asm.js->asm.js calls on x86, pass the return value via xmm register, not fp stack
Extend the asm.js signal handler tricks to:
- Remove idiv branching
- Remove double-to-int conversion branching (see also bug 818750)

Extend asm.js to allow proper tail calls for all return types and do the tail-call optimization
Effectively support 'goto' (even computed 'goto') by formalizing a pattern of while+switch that gets compiled as if it was goto
Extend asm.js to better support dynamically linking asm.js modules (a mutable, callable array argument to asm.js module, like the PLT)
Add DataView to avoid the alignment mask on asm.js heap accesses (this is mostly a problem of DataView being slow in all browsers)

ArrayBuffer.prototype.discard (bug 855669): to allow madvise(DONTNEED)
Typed Objects: (Typed Objects)
- This feature comes with float32/uint64/int64 value types, which would be useful as scalar types in asm.js.
- Formalize Typed Object "class declarations" in asm.js which could make asm.js a target for JVM/CLR/TypeScript (and allow these languages to reuse the builtin JS GC)
FunctionPromise: bug 854627, or perhaps just make some functions (asm.js, no-free-variables) structured-cloneable
Add way to programmatically observe whether asm.js validated: bug 952847

Credit to John Howard