Data processing: software development – installation – and managem – Software program development tool – Translation of code
Reexamination Certificate
1998-09-08
2001-04-24
Powell, Mark R. (Department: 2122)
Data processing: software development, installation, and managem
Software program development tool
Translation of code
C717S152000, C717S152000
Reexamination Certificate
active
06223339
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention generally relates to computer systems or computer-implemented systems employing translating or optimizing compilers and methods, and, more particularly, to dynamic translating compilers and methods.
2. Related Art
A variety of techniques are known for static translation of the executable instructions of a computer software program. Such known techniques are implemented by static compilers, i.e., compilers that translate a program prior to execution. One disadvantage of such techniques is that the dynamic behavior of a program typically is more readily and accurately ascertained while it is being executed than while it is being compiled prior to execution. The term “dynamic behavior” in this context generally refers to the flow of control through a computer program as it is being executed.
Some systems and methods exist that avoid this disadvantage by a process generally referred to as dynamic translation. That is, a dynamic compiler operates upon an executable image of the original software program as it is being executed at run time. Typically, the dynamic compiler is thus better able to deduce those paths that execution is most likely to take through particular portions of the program (that is, the control flow through the instructions of the program).
Such known dynamic translation systems may be designed to accomplish one or more of a number of tasks. One task is referred to as cross-platform translation, in which a program designed and written for execution on a computer system having a particular architecture and operating system is translated so that the translated program may be executed on another type of computer system. Some existing dynamic translation systems include “Daisy” by International Business Machine Corporation, “fx!32” from Digital Equipment Corporation, and “Wabi” from Sun Microsystems.
Dynamic translation systems are also used for instrumentation and profiling of programs without the need for recompilation. The term “instrumentation” refers generally to the insertion of special code to detect or record various parameters of execution, and “profiling” refers generally to reporting such parameters. Such use may also be referred to as “monitoring.” Examples of existing products intended for such uses include “Shade” from Sun Microsystems and “ATOM” from Digital Equipment Corporation.
Such tasks of dynamic translation systems generally are also undertaken by static translation systems, albeit with the noted disadvantage. However, another task traditionally carried out by static translation systems is not adequately carried out by known dynamic translation systems. Such task is optimization; that is, the alteration, deletion, rearrangement, or other revision of instructions, or the addition of new instructions, with the specific objectives of increasing the speed of execution of executable instructions, decreasing the amount of computer resources needed for such execution, or both. Therefore, what is needed is a system, method, and product for increasing the opportunities for, and efficiencies of, dynamic optimization of executable instructions. More generally, what is needed is a system, method, and product for increasing the efficiencies of dynamic translation systems irrespective of their purpose.
SUMMARY OF THE INVENTION
The present invention is a system, method, and product for improving the speed of dynamic translation systems by efficiently positioning translated instructions in a computer memory unit. The verb “position,” and its grammatical variants, may refer herein to placement, moving, replication, replacement, or similar actions. Also, as used herein, the term “instruction”refers broadly to a computer instruction word or words that may specify an operation, such as jump, add, compare, another operation, or any combination thereof; may specify an address; or may perform another of a variety of known functions. Generally, one instruction occupies one memory location in the computer memory unit, and each memory location contains only one instruction. Optionally, such translated instructions may also be dynamically instrumented, dynamically optimized, and/or otherwise processed for any purpose now implemented by the use of translated instructions or other such purposes to be developed in the future. The terms “dynamically instrumented,” “dynamically optimized,” and their grammatical variants, refer respectively herein to the application of any of a variety of instrumentation and optimization techniques, now known or to be developed in the future, to instructions or groups of instructions at run time.
More specifically, the speed of execution of dynamically translated instructions, which is a factor of particular relevance to dynamic optimization systems, may be adversely affected by inefficient jumping between various sections of the translated instructions. The present invention reduces the slowing effect of such inefficient jumping by efficiently positioning the sections of translated instructions with respect to each other and with respect to specialized instructions (referred to herein as “trampoline instructions”) that redirect control flow from the translated instructions.
In one embodiment of the invention, a method for positioning translated traces and their trampoline instructions in a computer memory unit is disclosed. The term “translated trace” is used herein to refer to any group of one or more translated instructions having a common control path. A translated trace may be, but is not necessarily, a “hot trace.” The term “hot trace” is used herein to refer to a group of translated instructions through which control frequently passes, or, in some embodiments, has passed more than a predetermined number of times. That is, the term “hot” signifies that the common control path through the group of instructions of the trace is frequently executed. For convenience, the term “frequent,” and its grammatical variants, are used herein to refer both to control passing through instructions either at a rate, or for a number of times, greater than a threshold value.
It typically is advantageous to translate hot traces of original instructions, particularly with respect to a dynamic optimization system, because such selective optimization increases the likelihood that the time saved by translation (and optimization) generally will be greater than the time spent translating (and optimizing) instructions and positioning them efficiently in memory. This result is due to the fact that, once translated, translated instructions typically are available for execution without the need to repeat the translation process. Thus, assuming the translated (and typically optimized) instructions execute faster than the original instructions from which they were translated, the more frequently a translated group of instructions is executed, the greater the time savings achieved. Alternatively stated, if a trace of instructions is translated that is not frequently executed, the likelihood increases that the time spent in such translation may exceed the time saved by infrequently executing the translated trace.
In applications of dynamic translation systems in which purposes other than, or in addition to, optimization are implemented, it may be desirable to translate all instructions, or instructions in addition to those that are frequently executed. For convenience, embodiments of the invention are described herein generally with respect to the translation of hot traces in the context of dynamic optimization. However, it will be understood that the invention is not so limited. In particular, the term “hot trace” as used herein with respect to the description of some embodiments may, in alternative embodiments, be replaced by the broader term “translated trace.” For example, in the context of a dynamic translation system used for cross-platform translation, all instructions in the original executable file may be translated as they are executed or otherwise, and thus the translated instructions oper
Buzbee William B.
Mattson, Jr. James S.
Shah Lacky V.
Hewlett--Packard Company
Khatri Anil
Powell Mark R.
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