Class SSAPhiInstruction
See any modern compiler textbook for the definition of phi and the nature of SSA.
Note: In SSA IR
s, these instructions do not appear in the normal instruction
array returned by IR.getInstructions(); instead these instructions live in ISSABasicBlock
.
getUse(i)
corresponds to the value number from the ith predecessor of the
corresponding ISSABasicBlock
b
in ControlFlowGraph
g
, where
predecessor order is the order of nodes returned by the Iterator
g.getPredNodes(b)
.
Note: if getUse(i) returns AbstractIntStackMachine
.TOP (that is, -1), then that use
represents an edge in the CFG which is infeasible in verifiable bytecode.
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Nested Class Summary
Nested classes/interfaces inherited from class com.ibm.wala.ssa.SSAInstruction
SSAInstruction.IVisitor, SSAInstruction.Visitor
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Field Summary
Fields inherited from class com.ibm.wala.ssa.SSAInstruction
NO_INDEX
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptioncopyForSSA
(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.int
getDef()
int
getDef
(int i) Return the ith defint
int
int
getUse
(int j) protected String
getValueString
(SymbolTable symbolTable, int valueNumber) boolean
hasDef()
Does this instruction define a normal value, as distinct from a set of exceptions possibly thrown by it (e.g.int
hashCode()
boolean
void
setValues
(int[] i) Clients should not call this.toString
(SymbolTable symbolTable) void
Apply an IVisitor to this instruction.Methods inherited from class com.ibm.wala.ssa.SSAInstruction
equals, getExceptionTypes, iIndex, isPEI, setInstructionIndex, toString
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Constructor Details
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SSAPhiInstruction
- Throws:
IllegalArgumentException
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Method Details
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copyForSSA
public SSAInstruction copyForSSA(SSAInstructionFactory insts, int[] defs, int[] uses) throws IllegalArgumentException 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
- Specified by:
copyForSSA
in classSSAInstruction
- Throws:
IllegalArgumentException
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toString
- Specified by:
toString
in classSSAInstruction
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visit
Description copied from class:SSAInstruction
Apply an IVisitor to this instruction. We invoke the appropriate IVisitor method according to the type of this instruction.- Specified by:
visit
in classSSAInstruction
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hasDef
public boolean hasDef()Description copied from class:SSAInstruction
Does this instruction define a normal value, as distinct from a set of exceptions possibly thrown by it (e.g. for invoke instructions).- Overrides:
hasDef
in classSSAInstruction
- Returns:
- true if the instruction does define a proper value.
- See Also:
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getDef
public int getDef()- Overrides:
getDef
in classSSAInstruction
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getDef
public int getDef(int i) Description copied from class:SSAInstruction
Return the ith def- Overrides:
getDef
in classSSAInstruction
- Parameters:
i
- number of the def, starting at 0.
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getNumberOfUses
public int getNumberOfUses()- Overrides:
getNumberOfUses
in classSSAInstruction
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getNumberOfDefs
public int getNumberOfDefs()- Overrides:
getNumberOfDefs
in classSSAInstruction
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getUse
- Overrides:
getUse
in classSSAInstruction
- Returns:
- value number representing the jth use in this instruction. -1 means TOP (i.e., the value doesn't matter)
- Throws:
IllegalArgumentException
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setValues
public void setValues(int[] i) Clients should not call this. only for SSA builders. I hate this. Nuke it someday. -
getValueString
- Overrides:
getValueString
in classSSAInstruction
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hashCode
public int hashCode()- Specified by:
hashCode
in classSSAInstruction
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isFallThrough
public boolean isFallThrough()- Specified by:
isFallThrough
in classSSAInstruction
- Returns:
- true iff this instruction may fall through to the next
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