Package ghidra.pcode.emu.jit.alloc

Record Class ShiftedMpIntHandler

java.lang.Object
java.lang.Record
ghidra.pcode.emu.jit.alloc.ShiftedMpIntHandler
Record Components:
parts - the list of locals spanned by the variable, in little-endian order.
type - the type of the multi-precision integer variable (only considering the varnode, not the whole comprised of the spanned parts). In the diagram, this would be JitType.MpIntJitType(size=11).
vn - the complete varnode accessible to this handler. NOTE: The handler must take care not to modify or permit access to portions of the parts at either end not actually part of its varnode. In the example, the lower 24 bits of parts[0] and the upper 16 bits of parts[3] cannot be accessed. Should a caller to genLoadToOpnd(Emitter, JitCodeGenerator, MpIntJitType, Ext, Scope) specify a type larger than 11 bytes, only the 11-byte value is loaded, then extended to the requested size. We do not load the more sigificant portion of parts[3].
byteShift - the number of least-significant bytes of the handler's least-significant part that are excluded from the variable's least-significant leg. I.e., the number of bytes to shift right when loading the value. In the example, this is 3.
All Implemented Interfaces:
VarHandler
public record ShiftedMpIntHandler(List<JvmLocal<Types.TInt,JitType.IntJitType>> parts, JitType.MpIntJitType type, Varnode vn, int byteShift) extends Record implements VarHandler
The handler used for a varnode requiring allocation of multiple integers, where those integers do not align to the variable's legs.

The below diagram is an example shifted allocation, whose byteShift value is 3, and whose varnode size is 11 (admittedly pathological, but made to illustrate a complicated example). 

 +--*--*--*--+--*--*--*--+--*--*--*--+--*--*--*--+
 | parts[3]  | parts[2]  | parts[1]  | parts[0]  |
 +-----------+-----------+-----------+-----------+
       +--*--*--+--*--*--*--+--*--*--*--+
       |  leg2  |   leg1    |   leg0    |
       +--------+-----------+-----------+

In the unaligned case, all loads and stores require copying the shifted value into a series of temporary locals, representing the legs of the value. Because these are already temporary, the operator may freely use the legs as temporary storage.

  • Constructor Details

  • Method Details

    • genLoadToStack

      public <TT extends Types.BPrim<?>, TJT extends JitType.SimpleJitType<TT, TJT>, N extends Emitter.Next> Emitter<Emitter.Ent<N,TT>> genLoadToStack(Emitter<N> em, JitCodeGenerator<?> gen, TJT type, Opnd.Ext ext)
      Description copied from interface: VarHandler
      Emit bytecode to load the varnode's value onto the JVM stack.
      Specified by:
      genLoadToStack in interface VarHandler
      Type Parameters:
      TT - the JVM type of the value to load onto the stack
      TJT - the p-code type of the value to load onto the stack
      N - the incoming stack
      Parameters:
      em - the emitter typed with the incoming stack
      gen - the code generator
      type - the p-code type of the value expected on the JVM stack by the proceeding bytecode
      ext - the kind of extension to apply when adjusting from JVM size to varnode size
      Returns:
      the emitter typed with the resulting stack

    • genLoadToOpnd

      public <N extends Emitter.Next> Opnd.OpndEm<JitType.MpIntJitType,N> genLoadToOpnd(Emitter<N> em, JitCodeGenerator<?> gen, JitType.MpIntJitType to, Opnd.Ext ext, Scope scope)
      Description copied from interface: VarHandler
      Emit bytecode to load the varnode's value into several locals.
      Specified by:
      genLoadToOpnd in interface VarHandler
      Type Parameters:
      N - the incoming stack
      Parameters:
      em - the emitter typed with the incoming stack
      gen - the code generator
      to - the p-code type of the value expected on the JVM stack by the proceeding bytecode
      ext - the kind of extension to apply
      scope - a scope for generating temporary local storage
      Returns:
      the operand containing the locals, and the emitter typed with the incoming stack

    • genLoadLegToStack

      public <N extends Emitter.Next> Emitter<Emitter.Ent<N,Types.TInt>> genLoadLegToStack(Emitter<N> em, JitCodeGenerator<?> gen, JitType.MpIntJitType type, int leg, Opnd.Ext ext)
      Description copied from interface: VarHandler
      Emit bytecode to load one leg of a multi-precision value from the varnode onto the JVM stack.
      Specified by:
      genLoadLegToStack in interface VarHandler
      Type Parameters:
      N - the incoming stack
      Parameters:
      em - the emitter typed with the incoming stack
      gen - the code generator
      type - the p-code type of the complete multi-precision value
      leg - the index of the leg to load, 0 being least significant
      ext - the kind of extension to apply
      Returns:
      the emitter typed with the resulting stack, i.e., having the int leg pushed onto it

    • genLoadToArray

      public <N extends Emitter.Next> Emitter<Emitter.Ent<N,Types.TRef<int[]>>> genLoadToArray(Emitter<N> em, JitCodeGenerator<?> gen, JitType.MpIntJitType to, Opnd.Ext ext, Scope scope, int slack)
      Description copied from interface: VarHandler
      Emit bytecode to load the varnode's value into an integer array in little-endian order, pushing its ref onto the JVM stack.
      Specified by:
      genLoadToArray in interface VarHandler
      Type Parameters:
      N - the incoming stack
      Parameters:
      em - the emitter typed with the incoming stack
      gen - the code generator
      to - the p-code type of the complete multi-precision value
      ext - the kind of extension to apply
      scope - a scope for generating temporary local storage
      slack - the number of additional, more significant, elements to allocate in the array
      Returns:
      the emitter typed with the resulting stack, i.e., having the ref pushed onto it

    • genLoadToBool

      public <N extends Emitter.Next> Emitter<Emitter.Ent<N,Types.TInt>> genLoadToBool(Emitter<N> em, JitCodeGenerator<?> gen)
      Description copied from interface: VarHandler
      Emit bytecode to load the varnode's value, interpreted as a boolean, as an integer onto the JVM stack.
      Specified by:
      genLoadToBool in interface VarHandler
      Type Parameters:
      N - the incoming stack
      Parameters:
      em - the emitter typed with the incoming stack
      gen - the code generator
      Returns:
      the emitter typed with the resulting stack, i.e., having the int boolean pushed onto it

    • genStoreFromStack

      public <FT extends Types.BPrim<?>, FJT extends JitType.SimpleJitType<FT, FJT>, N1 extends Emitter.Next, N0 extends Emitter.Ent<N1, FT>> Emitter<N1> genStoreFromStack(Emitter<N0> em, JitCodeGenerator<?> gen, FJT from, Opnd.Ext ext, Scope scope)
      Description copied from interface: VarHandler
      Emit bytecode to store a value into a variable from the JVM stack.
      Specified by:
      genStoreFromStack in interface VarHandler
      Type Parameters:
      FT - the JVM type of the value on the stack
      FJT - the p-code type of the value on the stack
      N1 - the tail of the incoming stack
      N0 - the incoming stack having the value to store on top
      Parameters:
      em - the emitter typed with the incoming stack
      gen - the code generator
      from - the p-code type of the value on the stack
      ext - the kind of extension to apply
      scope - a scope for generating temporary local storage
      Returns:
      the emitter typed with the resulting stack, i.e., having popped the value

    • genStoreFromOpnd

      public <N extends Emitter.Next> Emitter<N> genStoreFromOpnd(Emitter<N> em, JitCodeGenerator<?> gen, Opnd<JitType.MpIntJitType> opnd, Opnd.Ext ext, Scope scope)
      Emit bytecode to store a varnode's value from several locals.

      The general strategy is to load the source operand one leg at a time. In order to put each leg with the remaining portion of the previous leg in position, we use a long on the stack as a temporary. This eases "gluing" the legs together and then writing the shifted portion into each part.

      Specified by:
      genStoreFromOpnd in interface VarHandler
      Type Parameters:
      N - the incoming stack
      Parameters:
      em - the emitter typed with the incoming stack
      gen - the code generator
      opnd - the operand whose locals contain the value to be stored
      ext - the kind of extension to apply
      scope - a scope for generating temporary local storage
      Returns:
      the emitter typed with the incoming stack

    • genStoreFromArray

      public <N1 extends Emitter.Next, N0 extends Emitter.Ent<N1, Types.TRef<int[]>>> Emitter<N1> genStoreFromArray(Emitter<N0> em, JitCodeGenerator<?> gen, JitType.MpIntJitType from, Opnd.Ext ext, Scope scope)
      Emit bytecode to store a varnode's value from an array of integer legs, in little endian order

      The strategy here is the same as for genStoreFromOpnd(Emitter, JitCodeGenerator, Opnd, Ext, Scope)

      Specified by:
      genStoreFromArray in interface VarHandler
      Type Parameters:
      N1 - the tail of the incoming stack
      N0 - the incoming stack having the array ref on top
      Parameters:
      em - the emitter typed with the incoming stack
      gen - the code generator
      from - the p-code type of the value on the stack
      ext - the kind of extension to apply
      scope - a scope for generating temporary local storage
      Returns:
      the emitter typed with the resulting stack, i.e., having popped the array

    • subpiece

      public VarHandler subpiece(Endian endian, int byteOffset, int maxByteSize)
      Description copied from interface: VarHandler
      Create a handler for a PcodeOp.SUBPIECE of a value.

      To implement subpiece, we could load the entire varnode and then extract the designated portion. Or, we could load only the designated portion, averting any code and execution cost of loading the un-designated portions. We accomplish this by re-writing the subpiece op and a load of the sub-varnode.

      Specified by:
      subpiece in interface VarHandler
      Parameters:
      endian - the endianness of the emulation target
      byteOffset - the number of least-significant bytes to remove
      maxByteSize - the maximum size of the resulting variable. In general, a subpiece should never exceed the size of the parent varnode, but if it does, this will truncate that excess.
      Returns:
      the resulting subpiece handler

    • toString

      public final String toString()
      Returns a string representation of this record class. The representation contains the name of the class, followed by the name and value of each of the record components.
      Specified by:
      toString in class Record
      Returns:
      a string representation of this object

    • hashCode

      public final int hashCode()
      Returns a hash code value for this object. The value is derived from the hash code of each of the record components.
      Specified by:
      hashCode in class Record
      Returns:
      a hash code value for this object

    • equals

      public final boolean equals(Object o)
      Indicates whether some other object is "equal to" this one. The objects are equal if the other object is of the same class and if all the record components are equal. Reference components are compared with Objects::equals(Object,Object); primitive components are compared with '=='.
      Specified by:
      equals in class Record
      Parameters:
      o - the object with which to compare
      Returns:
      true if this object is the same as the o argument; false otherwise.

    • parts

      public List<JvmLocal<Types.TInt,JitType.IntJitType>> parts()
      Returns the value of the parts record component.
      Returns:
      the value of the parts record component

    • type

      public JitType.MpIntJitType type()
      Returns the value of the type record component.
      Specified by:
      type in interface VarHandler
      Returns:
      the value of the type record component

    • vn

      public Varnode vn()
      Returns the value of the vn record component.
      Specified by:
      vn in interface VarHandler
      Returns:
      the value of the vn record component

    • byteShift

      public int byteShift()
      Returns the value of the byteShift record component.
      Returns:
      the value of the byteShift record component