Package harpoon.IR.LowQuad

A low-level quadruple-based IR with explicit pointers.

See:
Description

Class Summary

Code	LowQuad.Code is an abstract superclass of codeviews using the components in IR.LowQuad.
DerivationMap<HCE extends HCodeElement>	DerivationMap is a simple map-based implementation of common Derivation functionality.
LowQuad	The LowQuad interface identifies subclasses of harpoon.IR.Quads.Quad as being members of the LowQuad representation.
LowQuadFactory	LowQuadFactory is a trivial subclass of QuadFactory which assigns unique numbers to the Quads and LowQuads in LowQuad form.
LowQuadKind	LowQuadKind is an enumerated type for the various kinds of LowQuads.
LowQuadNoSSA	The LowQuadNoSSA codeview exposes a lowquad-based representation.
LowQuadSSA	The LowQuadSSA codeview exposes a lowquad based representation in SSA form.
LowQuadSSI	The LowQuadSSI codeview exposes a lowquad based representation in SSI form.
LowQuadValueVisitor<T>	LowQuadValueVisitor is a visitor class for low quads that returns a parameterized value.
LowQuadVisitor	LowQuadVisitor is another design pattern.
LQop	LQop is an enumerated type for the various kinds of OPER opcodes in LowQuad form.
PAOFFSET	PAOFFSET computes the POINTER offset needed to access a given array element.
PARRAY	PARRAY converts an array object reference into a POINTER value that can be used to access array elements.
PCALL	PCALL objects represent a method pointer dereference and invocation.
PCONST	PCONST is an abstract superclass of the LowQuads that encode symbolic offsets or constants for array elements, fields, and methods.
PFCONST	PFCONST computes the POINTER constant needed to access a given static field.
PFIELD	PFIELD converts an object reference into a POINTER value that can be used to access non-static object fields.
PFOFFSET	PFOFFSET computes the POINTER offset needed to access a given non-static field.
PGET	PGET represents a POINTER dereference to get a field or array element.
PMCONST	PMCONST computes the POINTER constant needed to invoke a given non-virtual method.
PMETHOD	PMETHOD converts an object reference into a POINTER value that can be used to invoke object methods.
PMOFFSET	PMOFFSET computes the POINTER offset needed to invoke a given virtual method.
POPER	POPER is an extended version of harpoon.IR.Quads.OPER, with new opcodes defined in LQop.
PPTR	PPTR is an abstract superclass of the LowQuads that convert object references into POINTER types.
PSET	PSET represents a POINTER dereference to set a field or array element.

Package harpoon.IR.LowQuad Description

A low-level quadruple-based IR with explicit pointers.

Low-quad form allows pointer-based optimizations that are impossible to perform in hi-quad form. As an example, low-quad form allows the optimization of:

void foo(int arr[]) { for (int i=0; i<arr.length; i++) arr[i] = 42; } which is implemented as something like: void foo(int arr[]) { for (int i=0; i<arr.length; i++) *(arr+i) = 42; } to the more efficient: void foo(int arr[]) { for (int *i=arr; i<arr+arr.length; i++) *i = 42; } Note that there is also pointer-scaling going on here which it is difficult to write in C.

Note that a harpoon.Analysis.Maps.Derivation must be maintained in low-quad form to allow compiler-supported garbage collection in the back-end.

Author:

C. Scott Ananian <cananian@alumni.princeton.edu>