摘要:
A method, system, and computer product uses a hashed static single assignment (SSA) form as a program representation and a medium for performing global scalar optimization. A compiler, after expressing the computer program in SSA form, can perform one or more static single assignment (SSA)-based, SSA-preserving global scalar optimization procedures on the SSA representation. Such a procedure modifies, (i.e., optimizes) the SSA representation of the program while preserving the utility of its embedded use-deprogram information for purposes of subsequent SSA-based, SSA-preserving global scalar optimizations. This saves the overhead expense of having to explicitly regenerate use-def program information for successive SSA-based, SSA-preserving global scalar optimizations.
摘要:
Partial redundancy elimination of a computer program is described that operates using a static single assignment (SSA) representation of a computer program. The SSA representation of the computer program is processed to eliminate partially redundant expressions in the computer program. This processing involves inserting .PHI. functions for expressions where different values of the expressions reach common points in the computer program. A result of each of the .PHI. functions is stored in a hypothetical variable h. The processing also involves a renaming step where SSA versions are assigned to hypothetical variables h in the computer program, a down safety step of determining whether each .PHI. function in the computer program is down safe, and a will be available step of determining whether each expression in the computer program will be available at each .PHI. function following eventual insertion of code into the computer program for purposes of partial redundancy elimination. The processing also includes a finalize step of transforming the SSA representation of the computer program having hypothetical variables h to a SSA graph that includes some insertion information reflecting eventual insertions of code into the computer program for purposes of partial redundancy elimination, and a code motion step of updating the SSA graph based on the insertion information to introduce real temporary variables t for the hypothetical variables h.
摘要:
A system and method for an optimizer of a compilation suite for representing aliases and indirect memory operations in static single assignment (SSA) during compilation of a program having one or more basic blocks of source code. The optimizer converts all scalar variables of said program to SSA form, wherein said SSA form includes a plurality of variable versions, zero or more occurrences of a .chi. function, zero or more occurences of a .phi. function, and zero or more occurrences of a .mu. function. The .chi. function, .phi. function, and .mu. function are inserted for the variable versions. The optimizer also determines whether a variable version can be renamed to a zero version, and upon such a determination, the optimizer renames the variable version to a zero version. The optimizer further converts all indirect variables of a program to SSA form, wherein the SSA form includes a plurality of virtual variable versions such that a virtual variable is assigned to an indirect variable, zero or more occurrences of a .chi. function, zero or more occurences of a .phi. function, and zero or more occurrences of a .mu. function. The .chi. function, .phi. function, and .mu. function are inserted for the virtual variables. The optimizer hashes a unique value number and creates a corresponding hash table entry for each variable version and each virtual variable remaining after renaming all zero versions. The optimizer also applies global value numbering to each basic block of the program.
摘要:
A system and method for an optimizer of a compilation suite for representing aliases and indirect memory operations in static single assignment (SSA) during compilation of a program having one or more basic blocks of source code. The optimizer converts all scalar variables of said program to SSA form, wherein said SSA form includes a plurality of variable versions, zero or more occurrences of a .chi. function, zero or more occurences of a .phi. function, and zero or more occurrences of a .mu. function. The .chi. function, .phi. function, and .mu. function are inserted for the variable versions. The optimizer also determines whether a variable version can be renamed to a zero version, and upon such a determination, the optimizer renames the variable version to a zero version. The optimizer further converts all indirect variables of a program to SSA form, wherein the SSA form includes a plurality of virtual variable versions such that a virtual variable is assigned to an indirect variable, zero or more occurrences of a .chi. function, zero or more occurences of a .phi. function, and zero or more occurrences of a .mu. function. The .chi. function, .phi. function, and .mu. function are inserted for the virtual variables. The optimizer hashes a unique value number and creates a corresponding hash table entry for each variable version and each virtual variable remaining after renaming all zero versions. The optimizer also applies global value numbering to each basic block of the program.
摘要:
A method, system, and computer program product for performing register promotion, that optimizes placement of load and store operations of a computer program within a compiler. Based on the observation that the circumstances for promoting a memory location's value to register coincide with situations where the program exhibits partial redundancy between accesses to the memory location, the system is an approach to register promotion that models the optimization as two separate problems: (1) the partial redundancy elimination (PRE) of loads and (2) the PRE of stores. Both of these problems are solved through a sparse approach to PRE. The static single assignment PRE (SSAPRE) method for eliminating partial redundancy using a sparse SSA representation representations the foundation in eliminating redundancy among memory accesses, enabling the achievement of both computational and live range optimality in register promotion results. A static single use (SSU) representation is defined allowing the dual of the SSAPRE algorithm, called SSUPRE, to perform the partial redundancy elimination of stores. SSUPRE is performed after the PRE of loads, taking advantage of the loads' having been converted into pseudo-register references so that there are fewer barriers to the movement of stores. Consequently, the compiler produces more efficient, register-promoted executable program code from the SSA representation.
摘要:
A method and computer program product, within an optimizing compiler, for the global minimization of sign-extension and zero-extension operations in generated code during compilation. The method and computer program product allows, for example, 64-bit compilers targeting the Intel IA64 architecture to improve their SPECint benchmarks by reducing the number of sign-extension and zero-extension operations in the global and intra-procedural scope, thus, speeding up the execution of the compiled program.
摘要:
A method, system, and computer program product for performing speculative code motion within a sparse partial redundancy elimination (PRE) framework. Speculative code motion (i.e., speculation) refers to the placement of computations by a compiler in positions in the program that results in some paths being executed more efficiently and some being executed less efficiently. A net speed-up is thus achieved when the improved paths are those executed more frequently during the program's execution. Two embodiments for performing speculative code motion within the PRE framework are presented: (1) a conservative speculation method used in the absence of profile data; and (2) a profile-driven speculation method used when profile data are available. In a preferred embodiment, the two methods may be performed within static single assignment PRE (SSAPRE) resulting in better optimized code.
摘要:
A method and computer program product, within an optimizing compiler, for precise feedback data generation and updating. The method and computer program uses instrumentation and annotation of frequency values to allow feedback data to stay current during the multiple optimizations that the program code undergoes during compilation. Global propagation of known precise feedback values are used to replace approximate and unavailable values, and global verification of feedback data after optimization to detect discrepancies is employed. The method and computer program also provides improved instrumentation to anticipate cloning when code is cloned during ceratin compiler optimizations and handles inlined procedures. The result is compiled executables with improved SPECint benchmarks.
摘要:
Improving connectivity in a peer-to-peer (P2P) network involves packet forwarding by infrastructure or peers. A system can achieve full connectivity and a setup for transactions that takes a fraction of a second. The system can include a routing table that is initially configured so that packets to peers are routed via the infrastructure. NAT traversal heuristics can be employed to establish direct connections between peers in parallel with packet forwarding in accordance with the routing table. When a direct connection is ready, the routing table can be updated so that packets are sent P2P. If a direct connection cannot be made, the routing table can be updated so that the packets are sent through a peer intermediary without going through the infrastructure.
摘要:
A power toothbrush appliance (10) which includes a user interface assembly (24) having a hidden interface panel (26) and a method of making same, the appliance including a handle (12, 40) and a brushhead assembly (18) with a brush member (24) for cleaning teeth. The user interface assembly is structured so that when the appliance is in the off condition, the user interface panel is blank, and when the appliance is in an on condition, the indicia associated with the selected operating mode of the toothbrush is illuminated and visible to the user. The interface panel includes a first paint layer of gray or black paint (42) on a translucent handle (40). The mode indicia are etched (44) to the handle in the first paint layer. A second paint layer of white paint (46) is applied over the first layer and is light-transmitting so that when the toothbrush is on, the selected indicia are visible to the user.