[llvm] r190773 - Implement function prefix data as an IR feature.

Richard Mitton richard at codersnotes.com
Mon Sep 23 13:14:05 PDT 2013


I have a small question about this -

Why does the prefix data have to begin with a jump?
Couldn't you just make the entry point label appear after the prefix 
data? And then use negative offsets to access it given the function's 
address? It seems like the jump adds a performance hit which isn't needed.


.word 0x1234 // prefix data
     push rbp
     // etc

Richard Mitton
richard at codersnotes.com

On 09/23/2013 01:07 PM, Peter Collingbourne wrote:
> On Mon, Sep 23, 2013 at 10:01:18AM -0700, Chris Lattner wrote:
>> On Sep 15, 2013, at 6:08 PM, Peter Collingbourne <peter at pcc.me.uk> wrote:
>>> Author: pcc
>>> Date: Sun Sep 15 20:08:15 2013
>>> New Revision: 190773
>>> URL: http://llvm.org/viewvc/llvm-project?rev=190773&view=rev
>>> Log:
>>> Implement function prefix data as an IR feature.
>>> Previous discussion:
>>> http://lists.cs.uiuc.edu/pipermail/llvmdev/2013-July/063909.html
>>> Differential Revision: http://llvm-reviews.chandlerc.com/D1191
>> Cool, thanks Peter.
>> Can I entice you to write a blog post about this? :-)
> Please ask me again in a couple of weeks.  There are a number of
> higher priority tasks that I have to take care of this week...
> Thanks,

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