data flow analysis

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data flow analysis

[′dad·ə ¦flō ə‚nal·ə·səs]
(computer science)
The development of models for the movement of information within an organization, indicating the sources and destinations of information and where and how information is transmitted, processed, and stored.

data flow analysis

(programming)
A process to discover the dependencies between different data items manipulated by a program. The order of execution in a data driven language is determined solely by the data dependencies. For example, given the equations

1. X = A + B 2. B = 2 + 2 3. A = 3 + 4

a data-flow analysis would find that 2 and 3 must be evaluated before 1. Since there are no data dependencies between 2 and 3, they may be evaluated in any order, including in parallel.

This technique is implemented in hardware in some pipelined processors with multiple functional units. It allows instructions to be executed as soon as their inputs are available, independent of the original program order.
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Information-flow and data-flow analysis of while- programs.
Section 2 discusses issues of accurate interprocedural data-flow analysis and pointer aliasing algorithms.
Iterative data-flow analysis is a fixed-point calculation for recursive equations defined on a graph representing a program that safely approximates the meet over all paths solution of a data-flow problem [Kildall 1973; Marlowe and Ryder 1990b].
Very low percentages indicate that the worst-case [MOD.sub.C] solution is very much larger than what can be calculated using even flow-/context-insensitive data-flow analysis and indicate the significant advantages that inexpensive data-flow analysis can offer.
Then important parts of the lazy code motion optimization are presented, including syntactic equivalence of intermediate expressions (Section 4.2), global data-flow analysis (Section 4.3), and the transformation phase (Section 4.4).
Since the global data-flow analysis can be performed on the classes of equivalent expressions--if define/use/kill information is taken into account--the information about equivalent expressions can be used to reduce the number of objects considered.
All-quantifiers in data-flow analysis can be mimicked with an ESGRS that approaches the greatest fixpoint of the ISOLATED_IN/OUT-relations, starting from the complete relations, subtracting edges step by step.
We present our approach in detail in Section 3 and show how it uses both the linear algebra framework and data-flow analysis. Section 4 discusses the effect of hoisting communication vis-a-vis reducing the number of messages.
DATA-FLOW ANALYSIS USING A LINEAR ALGEBRA FRAMEWORK
In order to make the data-flow analysis task easier, the CFG of the program is traversed prior to the local analysis phase, and for each LHS reference a pointer is stored in the header of all enclosing loop nests.
An interval-based approach to exhaustive and incremental interprocedural data-flow analysis. ACM Transactions on Programming Languages and Systems 12, 3 (July), 341-395.
We will first show how our example functions of Figure 3 are computed using a data-flow analysis. Next, we will show that the example cost function satisfies the two constraints.

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