[LLVMdev] Flag operands and load/store DAG nodes

Burke, Max mburke at ea.com
Mon Nov 17 20:10:30 PST 2008


On Nov 17, 2008, at 6:03 PM, Evan Cheng wrote:

> On Nov 17, 2008, at 11:12 AM, Burke, Max wrote:
>
> > I notice that many DAG nodes like the copy-to-register operation
have
> > the ability to take an optional flag parameter, but that the load/ 
> > store
> > nodes do not (at least as of 2.3). Is it possible to pass flag  
> > operands
> > through load/store DAG nodes?
>
> No there isn't. What are you trying to accomplish? Are you trying to  
> force a load / store to be scheduled right after another instruction?

> Is this meant for correctness or performance?
>
> Evan

Yes, I'm trying to add a load/store before and after an indirect branch
on the PowerPC for the purposes of ABI conformance, specifically to use
function descriptors instead of direct function pointers.

(ref: http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.txt
though for this case the third field, the environment pointer, isn't
used)

-Max




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