MrSpidey Analysis Preferences Window

The MrSpidey Analysis preferences window configures MrSpidey's analysis of programs. An example of this window is shown in figure 3.1, and the controls are described below.

Figure 3.1: MrSpidey Analysis preferences window

• Accurate constant types: When this button is off (default), then character, symbolic and numeric constants are given the types char, sym or num respectively. If the button is on, then these constants are typed accurately, i.e. the number 4 is assigned the type 4, etc.
• Constant merge size: Large quoted values in Scheme can yield large types that significantly increase the analysis time. To overcome this problem, MrSpidey generates approximate types for such constants. The Constant merge size slider controls how large constants can get before MrSpidey starts to approximate their type.
• If splitting: If this button is on (default), MrSpidey is smart about conditional expressions such as (if (number? x) ...). MrSpidey only propagates numeric values for x in the then-part, and non-numbers in the else-part.
• Flow sensitivity: If this button is on (default), then after an expression such as (car x), MrSpidey knows that the value of x must be a pair.
• Accurate analysis of numeric operations: When this button is off (default), then numeric operations such as + simply return the type num. If the button is on, then the numeric operations are typed more accurately, as described in subsection 5.1.
• Polymorphism: This radio box controls how polymorphic expressions are analyzed.
  • No polymorphism: polymorphic annotation is ignored;
  • Simplify constraints: The constraint system for the polymorphic expression is simplified (see below); and
  • Reanalyze: The polymorphic expression is re-analyzed for each polymorphic reference.
• Polymorphism simplification algorithms: This radio box controls which constraint simplification algorithm is used to simplify the constraint system of polymorphic expression, provided the Polymorphism control is set to Simplify constraints. These constraint simplification algorithms are described in [4].
• Save .za files in: MrSpidey generates and saves constraint (.za) files during the analysis of multi-file programs. This radio box controls where these constraint files are stored, either in the same directory as the corresponding source file (default), or in a temporary directory.