Package com.ibm.wala.core.util.ssa

Class SSAValueManager

java.lang.Object
com.ibm.wala.core.util.ssa.SSAValueManager
public class SSAValueManager extends Object
Manage SSA-Variables in synthetic methods.
Since:
2013-09-19
Author:
Tobias Blaschke <code@tobiasblaschke.de>

  • Field Details

  • Constructor Details

  • Method Details

    • setAllocation

      public void setAllocation(SSAValue value, SSAInstruction setBy)
      Register a variable _after_ allocation.

      The proper way to add an allocation is to get a Variable using getUnallocated(com.ibm.wala.types.TypeReference, com.ibm.wala.core.util.ssa.SSAValue.VariableKey). Then assign it a value. And at last call this function.

      You can however directly call the function if the type has not been seen before.

      Parameters:
      value - an unallocated SSA-Variable to assign the allocation to
      setBy - The instruction that set the value (optional)
      Throws:
      IllegalStateException - if you set more than one allocation for that type (TODO better check!)
      IllegalArgumentException - if type is null or ssaValue is zero or negative

    • setPhi

      public void setPhi(SSAValue value, SSAInstruction setBy)
      Register a Phi-Instruction _after_ added to the model.
      Parameters:
      value - the number the SSA-Instruction assigns to
      setBy - the Phi-Instruction itself - may be null
      Throws:
      IllegalArgumentException - if you assign to a number requested using getFree(com.ibm.wala.types.TypeReference, com.ibm.wala.core.util.ssa.SSAValue.VariableKey) but types mismatch.
      IllegalStateException - if you forgot to close some Phis

    • getFree

      public SSAValue getFree(TypeReference type, SSAValue.VariableKey key)
      Returns and registers a free SSA-Number to a Type.

      You have to set the type using a Phi-Instruction. Also you don't have to add that instruction immediately it is required that it is added before the Model gets finished.

      You can request the List of unmet Phi-Instructions by using XXX

      Returns:
      an unused SSA-Number
      Throws:
      IllegalArgumentException - if type is null

    • getUnallocated

      public SSAValue getUnallocated(TypeReference type, SSAValue.VariableKey key)
      Get an unused number to assign to.

      There may only be one unallocated value for each type at a time. XXX: Really?

      Returns:
      SSA-Variable
      Throws:
      IllegalStateException - if there is already an unallocated variable of that type
      IllegalArgumentException - if type is null

    • getUnmanaged

      public SSAValue getUnmanaged(TypeReference type, SSAValue.VariableKey key)
      Retrieve a SSA-Value that is not under management.

      Use instead of 'nextLocal++', else SSA-Values will clash!

      Returns:
      SSA-Variable

    • getUnmanaged

      public SSAValue getUnmanaged(TypeReference type, String name)

    • getCurrent

      public SSAValue getCurrent(SSAValue.VariableKey key)
      Retrieve the SSA-Number that is valid for a type in the current scope.

      Either that number origins from an allocation or a PhiInstruction (to be).

      Returns:
      a ssa number
      Throws:
      IllegalStateException - if no number is assignable
      IllegalArgumentException - if type was not seen before or is null

    • getSuper

      public SSAValue getSuper(SSAValue.VariableKey key)
      Retrieve the SSA-Number that is valid for a type in the super-ordinate scope.

      Either that number origins from an allocation or a PhiInstruction (to be).

      Returns:
      a ssa number
      Throws:
      IllegalStateException - if no number is assignable
      IllegalArgumentException - if type was not seen before or is null

    • getAllForPhi

      public List<SSAValue> getAllForPhi(SSAValue.VariableKey key)
      Returns all "free" and "allocated" variables and the invalid ones in a sub-scope.

      This is a suggestion which variables to considder as parameter to a Phi-Function.

      Throws:
      IllegalArgumentException - if type was not seen before or is null

    • isSeen

      public boolean isSeen(SSAValue.VariableKey key, boolean withSuper)
      Return if the type is managed by this class.
      Parameters:
      withSuper - when true return true if a managed key may be cast to type, when false type has to match exactly
      key - the type in question
      Throws:
      IllegalArgumentException - if key is null

    • isSeen

      public boolean isSeen(SSAValue.VariableKey key)
      Return if the type is managed by this class.

      This variant respects super-types. Use isSeen(VariableKey, boolean) with a setting for withSuper of false to enforce exact matches.

      Returns:
      if the type is managed by this class.

    • needsAllocation

      public boolean needsAllocation(SSAValue.VariableKey key)
      Returns if an instance for that type needs to be allocated.

      However this function does not respect weather a PhiInstruction is needed.

      Throws:
      IllegalArgumentException - if type is null

    • needsPhi

      public boolean needsPhi(SSAValue.VariableKey key)
      Returns if a PhiInstruction (still) has to be added.

      This is true if the Value has changed in a deeper scope, has been invalidated or requested using getFree

      Throws:
      IllegalArgumentException - if type is null or has not been seen before

    • invalidate

      public void invalidate(SSAValue.VariableKey key)
      Marks all known instances of VariableKey invalid.

      A call to this method is useful before a call to setAllocation. This methods sets all known instances to invalid, setAllocation will assign the new "current" instance to use.

      Parameters:
      key - Which variables to invalidate.
      Throws:
      IllegalArgumentException - if type was not seen before or is null

    • scopeDown

      public int scopeDown(boolean doesLoop)
      Enter a subordinate scope.

      Call this whenever a new code block starts i.e. when ever you would have to put a left curly-bracket in the java code.

      This function influences the placement of Phi-Functions. Thus if you don't change values you don't have to call it.

      Parameters:
      doesLoop - set to true if the scope is introduced for a loop
      Returns:
      The depth

    • scopeUp

      public int scopeUp()
      Leave a subordinate scope.

      All changes are marked invalid thus to be expected to be collected by a PhiInstruction.

      Throws:
      IllegalStateException - if already at top level

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • getException

      public SSAValue getException()
      Create new SSAValue with UniqueKey and Exception-Type.

      The generated SSAValue will be unmanaged. It is mainly useful for SSAInvokeInstructions.

      Returns:
      new unmanaged SSAValue with Exception-Type

    • makeLocalNames

      public Map<Integer,Atom> makeLocalNames()
      Collect the variable-names of all known variables.