Optimizing the java virtual machine instruction set by despecialization and multicode substitution
Notice bibliographique
Résumé
Since its public introduction; Java has grown into one of the most widely used programming languages. Its popularity can be attributed to the wide variety of features that it provides, including platform independence. In order to achieve platform independence, Java applications are represented by a set of binary, platform independent Java class files. Within the class files, the functionality of each Java method is expressed using a sequence of Java bytecodes. This thesis examines the set of Java bytecodes defined by the Java Virtual Machine Specification, and describes two techniques that have been developed for manipulating the set. When the current set of Java bytecodes was analyzed, it was discovered that over one third of the bytecodes were specialized, redundant bytecodes. In many cases, these provided functionality that was easily replicated using one other bytecode. In a small number of other cases, a short sequence of bytecodes was used in order to achieve identical functionality. The Java class files for a set of standard benchmarks were transformed so that uses of specialized bytecodes were removed. Performance testing revealed that this transformation increased average execution Lime by approximately 2.0 percent when 67 specialized bytecodes were replaced with their equivalent general-purpose forms. The impact this transformation had on class file size and the correctness of the class files was also examined. A second transformation, which has come to be known as multicode substitution, was also developed. It employed profiling in order to determine which sequences of bytecodes executed with greatest frequency. A new Java bytecode, known as a multicode, was introduced for each frequently executed bytecode sequence. Performing this transformation reduced the total number of bytecodes executed by the application, improving Java interpreter performance by reducing the number of transfers of control from one bytecode to the next. Furthermore, performing this transformation presented additional optimization opportunities within the implementation of the multicode. Such optimizations could not be exploited previously because of the presence of the intervening transfers of control. When performance testing was conducted using industry standard benchmarks, performing multicode substitution reduced application runtime by as much as 30 percent. Keywords. Java Virtual Machine. Java Bytecode, Instruction Set Design, Optimization, Multicode Substitution, Despecialization
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».