The experiments demonstrate the ability of the proposed technique to efficiently exploit parallelism not explicitly specified in the input description.

-This paper describes a symbolic formulation that allows incorporation of speculative operation execution (preexecution) in an exact control-dependent scheduling of arbitrary forward branching control/data paths. The technique provides a closed form solution set in which all satisfying schedules are encapsulated in a compressed OBDD-based representation. To extract parallelism implicit in the input specification Boolean 'guard' functions are used to identify paths where operations have to be scheduled and the execution order of the conditionals is dynamically resolved. An efficient and systematic iterative construction method is presented along with benchmark results.

Optimkation of hardware resources for conditional data-jiow graph behavior is particularly important when conditional behavior occurs in cyclic loops and " i z ation of throughput is desired. In this paper, an exact and efficient conditional resource sharing analysis using a guardbased control representation is presented. The analysis is transparent to a scheduler implementation. The proposed technique systematically handles complex conditional resource sharing for cases when folded (software pipelined) loops include conditional behavior within the loop body.Resource constraints play a crucial role in high-level synthesis of digital systems. Conditional resource sharing enhances resource usage by enabling simultaneous operations on different control paths to share physical resources. For example, operations belonging to "then" and "else" branches of an if-then-else statement are mutually exclusive when the choice of branch to execute is made prior to the execution of the branches. However, it has been shown [ll that superior scheduling results are possible if operations belonging to branch arcs are executed before the branching decision is made (speculative execution). In this case, static exclusivity analysis @erformed before scheduling) is not sufficient for optimal use of resources.A recent approach [Z] successfully detects a static pairwise mutual exclusiveness. In tree scheduling [3], a tree representation allows code motion and sub-trees induced by a branch can share resources. CVLS [ 11 uses condition vectors [4] to dynamically track exclusiveness of pre-executed operations. However, a case was reported wherein condition vector analysis can lead to an erroneous conclusion on mutual exclusion between the operations [5]. The representation from [5] handles nested if-then-else structures correctly, but is not applicable to some other forms of conditional behavior (e.g. gotu). These representations are all restricted to conditional tree structures. Parallel trees are addressed in [ 11, but the trees are either scheduled sequentially or tree duplication is performed. Most importantly, * Supported in part by a fellowship donation from Mentor Gra~hcs Corp.1063-640495 $4.00 0 1995 IEEE Forrest Brewer and Computer Engineering Santa Barbara, CA, U.S.A. none of these approaches discusses conditional resource sharing in cyclic controVdata flow graphs (CDFGs) with loop pipelining. Numerous techniques for cyclic data-flow graph (DFG) optimizations have been proposed, ranging from heuristics [61[71[8] to ILP methods [9] [ 101. However, none of them discusses cases in which conditional behavior occurs within the loop body. Semantics-preserving techniques and the BFSM-based approaches are applicable to cyclic CDFGs, but they either lack a formal treatment of conditional resource sharing [11][12] or introduce an excessive number of 0/1 variables to model resource and exclusivity constraints 1131. Recently, rotation scheduling [61 has been extended to pipelining of CDFGs [14]. This technique is based on a condition j a g rep...

No abstract

No abstract