International Business Machines Corporation

Patrick R Doyle

Vijay Sundaresan

Andrew James Craik

Pramod Ramarao

Daniel J Heidinga

Sathiskumar Palaniappan

Rachel E Craik

Prashanth S Krishna

Marcel Mitran

Reid T Copeland

Kevin Alexander Stoodley

Allan Henry Kielstra

Ali Ijaz Sheikh

Andrew Johnson

Derek Bruce Inglis

Marius Pirvu

Charles Brian Hall

Bjoern Vaardal

James I A Gartley

A method and system for enhanced local communing optimization of compilation of a program. Within a first pass of a two pass approach, a determination is made as to where in the program to evaluate volatile expressions that can be commoned. In a second pass of the two pass approach, all remaining expressions that are not volatile expressions are commoned.

Enhanced local commoning

In an approach for decreasing an execution time of a computer code, one or more processors identify a long-form conditional branch that is included in a first region of a computer code. The one or more processors generate a long-form unconditional branch with a target that is a target of a long-form conditional branch. The one or more processors modify the long-form conditional branch to be a short-form conditional branch. The one or more processors insert the long-form unconditional branch into the computer code within a branch distance of the short-form conditional branch. The one or more processors modify a target of the short-form conditional branch to be a location of the long-form unconditional branch in the computer code.

Conditional branch instruction compaction for regional code size reduction

A method for expanding inline function calls in inlining scenarios includes receiving an ordered list of inlining options for a computer program and a relational data structure representing dependencies between the inlining options, wherein each inlining option includes an associated cost value and an associated benefit value. A maximum-benefit inlining plan for a selected inlining option of the ordered list is then determined, wherein the maximum-benefit inlining plan includes a set of inlining options from the ordered list that provide a maximum combined benefit value for a combined cost value that is equal to or less than a maximum cost budget, subject to the following conditions: each inlining option of the set precedes, or is, the selected inlining option in the ordered list, and for each inlining option of the set, the set also includes each inlining option that the respective inlining option is dependent on.

Expanding inline function calls in nested inlining scenarios

Embodiments of the present invention provide methods, computer program products, and systems for optimizing virtual calls. Embodiments of the present invention can be used to receive a virtual call associated with a first implementation method and identify a virtual call associated with a second implementation method that appears to have similar functionality to the first implementation method. Embodiments of the present invention can determine whether the virtual call associated with the first implementation method and the virtual call associated with the second implementation method produce the same result and, responsive to determining that the virtual call associated with the first implementation method and the virtual call associated with the second implementation method produce the same result, use a result of the virtual call associated with the first implementation method as a result of the virtual call associated with the second implementation method.

Avoiding guard test invalidation for virtual and interface calls

A computer-implemented method for class load optimizing. The method determines whether a caller method within the class has a specific signature call using the context of the class. The method determines a callee method within the class using the context of the class. Furthermore, the method retrieves a class object of the class and converts the callee method to a second method, in response to the caller method having the specific signature, the callee method being of the specific signature and callee method being the first argument of the caller method.

Optimizing latest user defined class loader

A method and system for enhanced local commoning optimization of compilation of a program. Commoning of volatiles within an extended block for a particular memory model associated with a particular programming language is performed, using a two pass approach. Within a first pass, a determination is made as to where in the program to evaluate volatile expressions that can be commoned. In a second pass, all remaining expressions that are not volatile expressions are commoned.

A computer-implemented method includes receiving an invocation of an invoked interface associated with a class, identifying, based on the class, a plurality of interface lookup artifacts and a cached interface lookup artifact, and comparing the invoked interface with a cache interface. The cache interface is associated with the cached interface artifact. The computer-implemented method further includes, responsive to the invoked interface matching the cache interface, returning the cached interface artifact, and responsive to the invoked interface not matching the cache interface, searching the plurality of interface lookup artifacts until finding a matching interface lookup artifact. The matching interface lookup artifact is associated with a matching interface that matches the invoked interface. Responsive to finding the matching interface lookup artifact, returning the matching interface lookup artifact and updating the cached interface lookup artifact to the matching interface lookup artifact. A corresponding computer program product and computer system are also disclosed.

Interface method resolution in object oriented programming models

A computer-implemented method for class load optimizing. The method identifies a class in which a context can be determined at a compile time, using a compiler. The method determines whether a caller method within the class has a specific signature call using the context of the class. The method determines a callee method within the class using the context of the class. The method determines whether the callee method's receiver is a first argument of the caller method. Furthermore, the method retrieves a class object of the class and converts the callee method to a second method, in response to the caller method having the specific signature, the callee method being of the specific signature and callee method being the first argument of the caller method.

A computer-implemented method, system, and computer program product for performing object collocation on a computer system are provided. The method includes analyzing a sequence of computer instructions for object allocations and uses of the allocated objects. The method further includes creating an allocation interference graph of object allocation nodes with edges indicating pairs of allocations to be omitted from collocation. The method also includes coloring the allocation interference graph such that adjacent nodes are assigned different colors, and creating an object allocation at a program point prior to allocations of a selected color from the allocation interference graph. The method additionally includes storing an address associated with the created object allocation in a collocation pointer, and replacing a use of each allocation of the selected color with a use of the collocation pointer to collocate multiple objects.

Optimizing compiler performance by object collocation

In an approach for decreasing an execution time of a computer code, one or more processors receive a computer code and identify a frequently executed region of the computer code. One or more processors identify a long-form conditional branch in the frequently executed region of the computer code that is infrequently taken. One or more processors generate a long-form unconditional branch with a target that is a target of the long-form conditional branch. One or more processors modify the long-form conditional branch to be a short-form conditional branch. One or more processors insert the long-form unconditional branch in the computer code within a branch distance of the short-form conditional branch. One or more processors modify a target of the short-form conditional branch to be a location of the long-form unconditional branch in the computer code.

A process, a computer program product, and a computer system for efficient code cache management implemented by a just-in-time compiler are provided. Embodiments of the present invention provide a practical approach to compile effectively for methods that are frequently executed over a short time period but are subsequently not executed frequently. The disclosed approach reduces the detrimental effects of compilation of such infrequently executed methods on throughput and garbage collection pause times.

Efficient code cache management in presence of infrequently used complied code fragments

Emulation of source machine instructions is provided in which target machine CPU condition codes are employed to produce emulated condition code settings without the use, encoding or generation of branching instructions.

Efficiently emulating computer architecture condition code settings without executing branch instructions

A compiler and method of optimizing code by partial inlining of a subset of blocks of called blocks of code into calling blocks of code. A restart of the called blocks of code is provided for the case where non-inlined blocks of code are reached at run time. Blocks selected for partial inlining may include global side effects depending on the computer program environment. Global side effects in the selected blocks of code leading to a restart are sanitized in order to defer changes to the global state of the computer program.

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Toronto, Canada

Patrick R Doyle