Bug 184187 – Online version of the LLInt

• Status: RESOLVED
• Resolution: WONTFIX
• Component: JavaScriptCore

[JF Bastien]

The LLInt is currently entirely generated at JSC compile time, assembled with the binary, and doesn't JIT anything. That's great for when there aren't any JIT privileges and we want to keep that property! However, there are neat fancy things that we could do if, when we can JIT, we generated the LLInt on the fly. In other words, we want an online offline assembler.

So we'd still have say x86 and ARM LLInt codegen, but we'd *also* have LLInt codegen to the macro assembler, which we then would compile into JSC. At VM startup we'd then try to JIT that compiled macro assembler code, into actual assembly (either x86 or ARM). What we want is therefore a compiler compiler that generates native code for a JavaScript interpreter.

[JF Bastien]

Created attachment 336873 [details]
patch

Here's a patch which goes most of the way to this working. There's a bug still which I haven't tracked down, and a bit of debug logging too.

[JF Bastien]

Some of the macro assembler changes I should split out and commit as their own thing.

[JF Bastien]

<rdar://problem/36451201>

[JF Bastien]

Separate macro assembler improvements in https://bugs.webkit.org/show_bug.cgi?id=185106