Execution interval analysis under resource constraints

Conflict Modelling and Instruction Scheduling in Code Generation for In-House DSP Cores

“…However, because in general the number of times a certain resource is occupied is not known beforehand (see the previous subsection), it is very cumbersome and difficult to calculate the MEIs per separate resource, see [Timm95b]. For the same reason, such a calculation will inevitably be less accurate than the original approach of [Timm93]. As the objective of the matching formulation we present in this section is to model the combination of resource and timing conflicts between different RTs as accurately as possible, the formulation would not be as powerful as the original approach.…”

“…The formulation prunes the scheduling search space in polynomial time without limiting the solution space by exploiting combinations of resource and timing constraints. The method is based on the execution interval analysis of [Timm93], but is completely changed for our code generation. Because of the large number and the tightness of the different resource constraints, the approach is highly suitable for the retargetable code generation problem.…”

“…If resource constraints are not considered, then an OEI is given by the ASAP and ALAP cycles of the RT under the assumption of unlimited resources. Recent research [Timm93] showed, that the search space of schedulers that are both resource and time constrained can be pruned considerably by reducing the OEIs. That (polynomial run time) approach is based on a graph matching formulation exploiting both resource and time constraints and does not exclude any possible schedule.…”

“…Cyclic signal flow graphs were not considered in [Timm93], and loop folding also results in extra timing constraints for the RTs because the consumption of a value must occur before a new version of the value is produced.…”

Comprehensive Lower Bound Estimation From Behavioral Descriptions

“…In a similar way, we can adjust the ALAP times of the operations. More sophisticated methods, which restrict the time frames effectively under the resource constraints, can be found in [13] and [14]. Figure 5 shows the time frames of the operations modified by this update procedure.…”