PROGRAM STRUCTURE TREES - Software Systems Lab

More documents

Recommendations

Info

a b t_1 entry a entry b entry c T F T c F d e d e t_2 exit exit exit g g (a) Refined region (b) After transformation Figure 3: Transform an extended region to a plain region Every region is also a refined region. The definitions for trivial and canonical regions also apply to refined regions. An analysis of the Polyhedron 1 benchmark showed that only about 30% of all refined regions are simple regions. The complete analysis can be found in Table 2. 2.4 Program structure tree In general there are multiple canonical regions in every CFG. Two canonical regions A and B may contain the same basic blocks. In this case either region A is completely contained in region B, such as all basic blocks in A are also in B, or B is completely contained in A. This relationship is represented as a program structure tree, where a region B is an ancestor of A, if B is completely contained in A. The example in 4 shows a CFG where the simple regions are marked with blue and the refined regions with orange borders. 3 different algorithms There are different algorithms available, that can be used to analyze a CFG and build a region tree. They differ in the CFGs they can analyze, the kind of region they can detect, as well as the implementation afford necessary, the runtime complexity and/or the required prerequisites. 1 http://www.polyhedron.com 4
a g h b l j i f k c d e Figure 4: Program structure tree with simple regions (blue) and refined regions (orange). 5
Page 1 and 2: P R O G R A M S T R U C T U R E T R
Page 3: int i, a, b i = 0 if (i != 100) T F
Page 7 and 8: Analysis PST RPST DRPST Applicable
Page 9 and 10: a b a b c_1 i = 100 i=100 if (b ==

PROGRAM STRUCTURE TREES - Software Systems Lab

Create successful ePaper yourself

Delete template?

Save as template?