Package com.ibm.wala.ssa
Class SSAPiInstruction
- java.lang.Object
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- com.ibm.wala.ssa.SSAInstruction
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- com.ibm.wala.ssa.SSAAbstractUnaryInstruction
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- com.ibm.wala.ssa.SSAUnaryOpInstruction
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- com.ibm.wala.ssa.SSAPiInstruction
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public class SSAPiInstruction extends SSAUnaryOpInstruction
A Pi instruction is a dummy assignment inserted at the tail of a basic block, in order to get a new variable name to associate with some flow-insensitive dataflow fact. You can build anIR
with or without Pi instructions, depending onSSAOptions
selected. A Pi instruction is linked to its "cause" instruction, which is usually a conditional branch. for example, the following pseudo-codeboolean condition = (x instanceof Integer); if (condition) { S1; else { S2; } could be translated roughly as follows:boolean condition = (x instanceof Integer); LABEL1: if (condition) { x_1 = pi(x, LABEL1); S1; else { x_2 = pi(x, LABEL2); S2; }
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Nested Class Summary
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Nested classes/interfaces inherited from class com.ibm.wala.ssa.SSAInstruction
SSAInstruction.IVisitor, SSAInstruction.Visitor
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Field Summary
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Fields inherited from class com.ibm.wala.ssa.SSAAbstractUnaryInstruction
result, val
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Fields inherited from class com.ibm.wala.ssa.SSAInstruction
iindex, NO_INDEX
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Constructor Summary
Constructors Constructor Description SSAPiInstruction(int iindex, int result, int val, int piBlock, int successorBlock, SSAInstruction cause)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description SSAInstruction
copyForSSA(SSAInstructionFactory insts, int[] defs, int[] uses)
This method is meant to be used during SSA conversion for an IR that is not in SSA form.SSAInstruction
getCause()
int
getPiBlock()
int
getSuccessor()
int
getVal()
String
toString(SymbolTable symbolTable)
void
visit(SSAInstruction.IVisitor v)
Apply an IVisitor to this instruction.-
Methods inherited from class com.ibm.wala.ssa.SSAUnaryOpInstruction
getOpcode
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Methods inherited from class com.ibm.wala.ssa.SSAAbstractUnaryInstruction
getDef, getDef, getNumberOfDefs, getNumberOfUses, getUse, hasDef, hashCode, isFallThrough
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Methods inherited from class com.ibm.wala.ssa.SSAInstruction
equals, getExceptionTypes, getValueString, isPEI, toString
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Constructor Detail
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SSAPiInstruction
public SSAPiInstruction(int iindex, int result, int val, int piBlock, int successorBlock, SSAInstruction cause)
- Parameters:
successorBlock
- the successor block; this PI assignment happens on the transition between this basic block and the successor block.
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Method Detail
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copyForSSA
public SSAInstruction copyForSSA(SSAInstructionFactory insts, int[] defs, int[] uses)
Description copied from class:SSAInstruction
This method is meant to be used during SSA conversion for an IR that is not in SSA form. It creates a new SSAInstruction of the same type as the receiver, with a combination of the receiver's uses and defs and those from the method parameters. In particular, if the 'defs' parameter is null, then the new instruction has the same defs as the receiver. If 'defs' is not null, it must be an array with a size equal to the number of defs that the receiver instruction has. In this case, the new instruction has defs taken from the array. The uses of the new instruction work in the same way with the 'uses' parameter. Note that this only applies to CAst-based IR translation, since Java bytecode-based IR generation uses a different SSA construction mechanism. TODO: move this into the SSAInstructionFactory- Overrides:
copyForSSA
in classSSAUnaryOpInstruction
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toString
public String toString(SymbolTable symbolTable)
- Overrides:
toString
in classSSAUnaryOpInstruction
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visit
public void visit(SSAInstruction.IVisitor v)
Description copied from class:SSAInstruction
Apply an IVisitor to this instruction. We invoke the appropriate IVisitor method according to the type of this instruction.- Overrides:
visit
in classSSAUnaryOpInstruction
- See Also:
SSAInstruction.visit(IVisitor)
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getSuccessor
public int getSuccessor()
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getPiBlock
public int getPiBlock()
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getCause
public SSAInstruction getCause()
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getVal
public int getVal()
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