llvm dev - Nov 2011 - [LLVMdev] Scheduler information

[LLVMdev] tag added, sorry for duplicated message.

Hi list,

Could someone help me to understand the internal data dependecy 
structure used by the scheduler ?
As far as I can see in /lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp, 
SUnit nodes are created to wrap SDNodes with scheduling related 
information and SDeps represent all kind of dependencies between them.

Nevertheless, I cannot figure out the graphical form of such structure. 
For example, in a simple SDep::Data dependency like the following one:

Node1: def reg1
Node2: use reg1

Is Node1 the predecessor of Node2 or viceversa ?

Regards,
Ivan

On Nov 24, 2011, at 2:21 PM, Ivan Llopard <ivanllopard at gmail.com>
wrote:
> [LLVMdev] tag added, sorry for duplicated message.
> 
> Hi list,
> 
> Could someone help me to understand the internal data dependecy 
> structure used by the scheduler ?
> As far as I can see in /lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp, 
> SUnit nodes are created to wrap SDNodes with scheduling related 
> information and SDeps represent all kind of dependencies between them.
> 
> Nevertheless, I cannot figure out the graphical form of such structure. 
> For example, in a simple SDep::Data dependency like the following one:
> 
> Node1: def reg1
> Node2: use reg1
> 
> Is Node1 the predecessor of Node2 or viceversa ?
> 
> Regards,
> Ivan
> ______________________________
Node1is the predecessor. Look at an example using llc -view-sched-dags.