Interface SSAIndirectionData<T extends SSAIndirectionData.Name>
- All Known Implementing Classes:
ShrikeIndirectionData
For example, an SSALoadIndirectInstruction
takes as an argument a pointer value. This
map tells which locals that pointer may alias.
So if we have
Example A:
v2 = SSAAddressOf v1; v7 = #1; v3 = SSALoadIndirect v2; (1)Then this map will tell us that instruction (1) indirectly uses whichever source-level entity (in the source or bytecode) v1 represents.
(Don't be confused by AddressOf v1 .. we're not actually taking the address of v1 ... we're taking the address of some source level entity (like a local variable in source code or bytecode) for which v1 is just an SSA name)
As a more complex example, when we have lexical scoping, we can have the following IR generated, which passes a local by reference:
Example B: foo: v3 = AddressOf v2; bar(v3) (1) bar(v1): StoreIndirect v1, #7.
In this case, the instruction (1) potentially defs the locals aliased by v2. The lexical scoping support could/should use this information to rebuild SSA accounting for the fact that (1) defs v2.
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Nested Class Summary
Modifier and TypeInterfaceDescriptionstatic interface
A Name is a mock interface introduced just for strong typing. -
Method Summary
Modifier and TypeMethodDescriptionint
For the instruction at the given index, and a source-level name, return the SSA value number which represents this instruction's def of that name.getNames()
Returns the set of "source" level names (e.g.int
For the instruction at the given index, and a source-level name, return the SSA value number which represents this instruction's use of that name.void
Record the fact that a particular instruction defs a particular SSA value number (newDef), representing the value of a "source" entity "name".void
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Method Details
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getNames
Collection<T> getNames()Returns the set of "source" level names (e.g. local variables in bytecode or source code) for which this map holds information. -
getDef
For the instruction at the given index, and a source-level name, return the SSA value number which represents this instruction's def of that name.For example, in Example B in header comment above, suppose v2 referred to a "source"-entity called "Local1". Since instruction (1) (call to bar) defs "Local1", we introduce in this table a new SSA value number, say v7, which represents the value of "Local1" immediately after this instruction.
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setDef
Record the fact that a particular instruction defs a particular SSA value number (newDef), representing the value of a "source" entity "name".- See Also:
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getUse
For the instruction at the given index, and a source-level name, return the SSA value number which represents this instruction's use of that name.For example, in Example A in header comment above, suppose v1 referred to a "source"-entity called "Local1". Since instruction (1) (LoadIndirect) uses "Local1", we record in this table the SSA value number that represents "Local1" immediately before instruction (1). So if v1 and v7 both refer to "Local1", then (1) uses v7. If v7 does NOT refer to "Local1", then (1) uses v1.
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setUse
- See Also:
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