[LLVMdev] Enabling MI Scheduler on x86 (was Experimental Evaluation of the Schedulers in LLVM 3.3)

Andrew Trick atrick at apple.com
Thu Sep 26 08:41:04 PDT 2013

On Sep 26, 2013, at 12:41 AM, Tim Northover <t.p.northover at gmail.com> wrote:

> On 26 September 2013 08:30, Ghassan Shobaki <ghassan_shobaki at yahoo.com> wrote:
>> So, when the MI scheduler is enabled, will SD scheduling be totally disabled
>> or the SD scheduler will be automatically set to do source scheduling?

It’s set to source scheduling to emulate what will happen when it’s disabled.

> The latter. The SD scheduler is where the DAG is converted into the
> linear MachineInstr representation. Some kind of scheduling *has* to
> happen.

Right. We want to replace the expensive SD scheduler, which builds yet another SUnit DAG on top of the SD DAG with a routine that orders the SD nodes and breaks physical register interference.


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