chickadee » graph-ssa

graph-ssa

Compute static single assignment form of a graph.

Usage

(require-extension graph-ssa)

Documentation

This code is based on the algorithm from Efficiently computing static single assignment form and the control dependence graph, ACM Transactions on Programming Languages and Systems 1991 13(4), pp. 451-490.

Procedures

graph->ssa-graph:: G -> SSA-GRAPH procedure

Computes the dominance frontiers of the nodes in the graph, and returns the list of nodes augmented with this information.

graph-ssa-find-joins:: SSA-GRAPH -> NODES procedure

Given a list of SSA nodes, returns the list of nodes N for which there are (at least) two paths ... N_0 M_0 ... M_i N and ... N_1 P_0 ... P_j N such that N_0 and N_1 are distinct members of NODES and the M's and P's are disjoint sets.

Examples

(require-extension srfi-1)
(require-extension digraph)
(require-extension graph-dominators)

(define used-by '((a . b) (b . c) (c . d) (c . b) (b . e) (d . d) (d . e) ))

(define g (make-digraph 'cfg "control flow graph"))

(define node-list (delete-duplicates 
		   (concatenate (list (map car used-by) (map cdr used-by)))))

(define node-ids (list-tabulate (length node-list) values))
 
(for-each (lambda (i n) ((g 'add-node!) i (list #f n))) node-ids node-list)
(define node-map (zip node-list node-ids))

(for-each (lambda (e) 
	    (match e ((ni . nj) (let ((i (car (alist-ref ni node-map)))
				      (j (car (alist-ref nj node-map))))
				  ((g 'add-edge!) (list i j (format "~A->~A" ni nj)))))
		   (else (error "invalid edge " e))))
	  used-by)

(define ssa-graph (graph->ssa-graph g))
(graph-ssa-find-joins ssa-graph)

About this egg

Author

Richard Kelsey; ported to Chicken by Ivan Raikov

Version history

1.3
Documentation converted to wiki format
1.2
Ported to Chicken 4
1.0
Initial release

License

Copyright by Richard Kelsey.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

- Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.

- Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided
with the distribution.

- Neither name of the copyright holders nor the names of its
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.

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