Semantic constant folding

Overview

The Semantic constant folding plug-in produces an output program where C expressions which are established as constant by the Eva plug-in are replaced by their value. Because it relies on Eva, it is able to do more of these simplifications than a syntactic analysis would. The output program is guaranteed to be compilable C code, and to have the same semantics as the original program.

Usage

The command-line options related to constant folding are:

• -semantic-const-folding: Activates semantic constant folding and pretty print the new source code.

• -semantic-const-fold f1,...,fn: Replaces constant expressions in functions f1,...,fn.

• -cast-from-constant: Allows introduction of new casts from a folded constant.

Example

Consider the code fragment:

p = &x;
x = 3;
send(*p+4);

The Semantic constant folding plug-in produces:

p = &x;
x = 3;
send(7);

If you need to remove the (now useless) first two statements, you may make use of the Spare Code analysis plug-in.

Technical Notes

The plug-in performs propagation of constant integers and addresses, but at this time, it does not handle floating-point values.

Dependencies

This plug-in depends on results of the Eva plug-in.