cetus.analysis

Class ArrayParameterAnalysis

java.lang.Object

cetus.analysis.AnalysisPass

cetus.analysis.ArrayParameterAnalysis

public class ArrayParameterAnalysis
extends AnalysisPass

This analysis detects array- or pointer-type formal parameters that can be safely expressed in terms of the argument arrays. The result of analysis keeps, for each call site, maps from each formal parameters to their equivalent expression in terms of caller's arrays. The analysis is basically * based on pattern-matching but gives useful information for inlining and for alias analysis.

 void func1(double b[][8][8]) {} // or double (*b)[8][8]
 void func2(double b[][8]) {}    // or double (*b)[8]
 void func3(double b[]) {}       // or double *b
 int main() {
   double a[8][8][8];
   func1(a);        // or func1(&a[0]);
   func2(a[0]);     // or func2(&a[0][0]);
   func3(a[0][0]);  // or func3(&a[0][0][0]);
   return 0;
 }
 Result:
 func1(a) =       { b=>a }
 func2(a[0]) =    { b=>a[0] }
 func3(a[0][0]) = { b=>a[0][0] }
 

In inliner this information is useful when expressing the array access through "b" in terms of "a", keeping the transformed code as easy-to-read as possible. In alias analysis, together with points-to information, the result of this analysis can compute more precise alias-free relationship between two formal parameters if they are equivalent to different portion of one array in the callers.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ArrayParameterAnalysis.Option Available safety options

Constructor Summary

Constructors

Constructor and Description
ArrayParameterAnalysis(Program prog, ArrayParameterAnalysis.Option... opts) Constructs a new analyzer with the given program.

Method Summary

Methods

Modifier and Type	Method and Description
Expression	getCompatibleArgument(FunctionCall fcall, Symbol param) Returns caller's expression that is equivalent to the given parameter.
java.lang.String	getPassName() Returns the pass name.
static void	invalidate() Invalidates the analysis result.
boolean	isDisjoint(Symbol symbol1, Symbol symbol2, Procedure procedure) Checks if the two symbols are alias-free between themselves.
void	start() Starts the analysis; it visits each callee and performs the analysis.

Methods inherited from class cetus.analysis.AnalysisPass

run

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ArrayParameterAnalysis

public ArrayParameterAnalysis(Program prog,
                      ArrayParameterAnalysis.Option... opts)

Constructs a new analyzer with the given program.

Parameters:

prog - the input program.

Method Detail

invalidate

public static void invalidate()

Invalidates the analysis result. This method needs to be invoked after applying any IR-changing transformations.

getPassName

public java.lang.String getPassName()

Returns the pass name.

Specified by:

getPassName in class AnalysisPass

Returns:

the pass name "[ArrayParameter]".

start

public void start()

Starts the analysis; it visits each callee and performs the analysis.

Specified by:

start in class AnalysisPass

isDisjoint

public boolean isDisjoint(Symbol symbol1,
                 Symbol symbol2,
                 Procedure procedure)

Checks if the two symbols are alias-free between themselves. This assumes that the only source of the alias is from the call site. Hence, this method should always be used with more general alias/pointer analysis.

getCompatibleArgument

public Expression getCompatibleArgument(FunctionCall fcall,
                               Symbol param)

Returns caller's expression that is equivalent to the given parameter. Inliner can just copy the return expression of this method (if not null), and insert the all subscripts used with the parameter to the returning expression which is either an identifier or an array access.

Parameters:

fcall - the function call of interest.

param - the formal parameter of interest.

Returns:

the compatible expression with param, or null if not compatible.