[LLVMdev] JIT memory manager: NeedsExactSize() ?

Chris Lattner clattner at apple.com
Wed Jul 21 17:25:16 PDT 2010


On Jul 21, 2010, at 5:01 PM, Reid Kleckner wrote:

> Oh god, rip it out.  IIRC it's just a complete parallel
> reimplementation of bunch of instruction encoding stuff just to
> compute the code size.

Yeah, I know.  It's the 3rd and most incorrect copy of the instruction emitter.  I really really want to rip it out, but we do have a unit test for the 'needsexactsize()' stuff, so I figure someone might actually care.  Does vmkit use this?

-Chris


> 
> Reid
> 
> On Wed, Jul 21, 2010 at 3:52 PM, Chris Lattner <clattner at apple.com> wrote:
>> The JIT has a codepath that supports JIT memory managers that return true for NeedsExactSize().  This is particularly bad for X86, because the "exact size" is not exact, and looks completely wrong in a lot of cases.  Is anyone using this?  Can I rip it out?  This stuff should go away with the mc'ization of the JIT in the long term.
>> 
>> -Chris
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