[WIP] Paths mutations

[FedeLoch]

Path's mutations

This is an experiment where we attempt to extend the diversity of inconsistencies between the interpreter and the compiler—differences found by the current path explorer. This experiment aims to introduce path mutations on our current path explorer. To avoid always exploring the same deterministic paths, during the exploration time, we will be introducing several mutations on the path's constraints.

The focus of this experiment is to explore the availability of constraint mutations as a technique to embrace new possible paths on the compiler, and therefore, find new checks if there are undiscovered inconsistencies.

Path constraints

Nowadays Ranger supports a series of different path constraints. These constraints are used inside the path representation to moderate the current path taken inside the interpreter.

The currently supported constraints are separated into five groups:

• Logic Constraints ( AND, OR )
• Comp/Ord Constraints ( =, !=, >, >=, <, <= )
• Arithmetic Constraints ( **+, -, /, %, //, *** )
• Bit Constraints ( <<, ADD, AND, OR )
• VM Constraints ( isNotInt, isInt, isNotChar, isChar, isIntToFloat, intObjOf, floatObjOf, boolObjOf, isClassIndexOf, isContextObj )

Mutations

To encompass several variants, we thought of several different mutations:

LessIntMutation

GreaterIntMutation

...

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