International Business Machines Corporation

Rohini Nair

Thomas James Christopher Ward

A method and system for evaluating a call to a library function at compile time. A first call included in a program being compiled by a compiler is identified. The first call is a call to a library function included in a pre-defined list of library functions external to the program. The first call includes one or more arguments associated with one or more formal arguments of a library function in the pre-defined list. The identification of the first call includes searching the pre-defined list of library functions for the library function. The arguments are determined to be constants. A second call to the library function is constructed in an optimizer of the compiler. A result of the second call is statically computed in the optimizer by issuing the second call with the constants as arguments. During compile time, the first call is replaced with the result.

Compile time evaluation of library functions

A method and system for substituting array values (i.e., expressions) in a program at compile time. An initialization of an array is identified in a loop. The initialization is an assignment of an expression (i.e., a constant or a function of an induction variable to elements of the array). The expression is stored in a table that associates the expression with the array and indices of the array. An assignment statement is detected that is to assign at least one element of the initialized elements. The expression is retrieved from the table based on the expression being associated with the array and corresponding indices. The expression is substituted for the at least one element so that the expression is to be assigned by the assignment statement. The process of substituting array values is extended to interprocedural analysis.

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Rohini Nair