International Business Machines Corporation

Infineon Technologies Ag

Georgia Tech Research Corporation

Barcelona Supercomputing Center-centro Nacional De Supercomputacion

Barcelona Supercomputing Center

Tao Zhang

Tong Chen

Kathryn Mary O'Brien

Mark Richard Nutter

Brian King Flachs

Brad William Michael

John K P O'Brien

Zehra Noman Sura

John Kevin O'Brien

Marc Gonzalez Tallada

Alexandre E Eichenberger

John Kevin Patrick O'Brien

Haibo Lin

Byoungro So

Eduard Ayguade

Xavier Martorell

Santosh Pande

Andre Dos Santos

Franz Josef Bruecklmayr

Mechanisms are provided for arranging binary code to reduce instruction cache conflict misses. These mechanisms generate a call graph of a portion of code. Nodes and edges in the call graph are weighted to generate a weighted call graph. The weighted call graph is then partitioned according to the weights, affinities between nodes of the call graph, and the size of cache lines in an instruction cache of the data processing system, so that binary code associated with one or more subsets of nodes in the call graph are combined into individual cache lines based on the partitioning. The binary code corresponding to the partitioned call graph is then output for execution in a computing device.

Arranging binary code based on call graph partitioning

Mechanisms are provided for evicting cache lines from an instruction cache of the data processing system. The mechanisms store, for a portion of code in a current cache line, a linked list of call sites that directly or indirectly target the portion of code in the current cache line. A determination is made as to whether the current cache line is to be evicted from the instruction cache. The linked list of call sites is processed to identify one or more rewritten branch instructions having associated branch stubs, that either directly or indirectly target the portion of code in the current cache line. In addition, the one or more rewritten branch instructions are rewritten to restore the one or more rewritten branch instructions to an original state based on information in the associated branch stubs.

Dynamically rewriting branch instructions in response to cache line eviction

Reducing coherency problems in a data processing system is provided. Source code that is to be compiled is received and analyzed to identify at least one of a plurality of loops that contain a memory reference. A determination is made as to whether the memory reference is an access to a global memory that should be handled by a direct buffer. Responsive to an indication that the memory reference is an access to the global memory that should be handled by the direct buffer, the memory reference is marked for direct buffer transformation. The direct buffer transformation is then applied to the memory reference.

Dynamically maintaining coherency within live ranges of direct buffers

Prefetching irregular memory references into a software controlled cache is provided. A compiler analyzes source code to identify at least one of a plurality of loops that contain an irregular memory reference. The compiler determines if the irregular memory reference within the at least one loop is a candidate for optimization. Responsive to an indication that the irregular memory reference may be optimized, the compiler determines if the irregular memory reference is valid for prefetching. Responsive to an indication that the irregular memory reference is valid for prefetching, a store statement for an address of the irregular memory reference is inserted into the at least one loop. A runtime library call is inserted into a prefetch runtime library for the irregular memory reference. Data associated with the irregular memory reference is prefetched into the software controlled cache when the runtime library call is invoked.

Prefetching irregular data references for software controlled caches

Mechanisms are provided for rewriting branch instructions in a portion of code. The mechanisms receive a portion of source code having an original branch instruction. The mechanisms generate a branch stub for the original branch instruction. The branch stub stores information about the original branch instruction including an original target address of the original branch instruction. Moreover, the mechanisms rewrite the original branch instruction so that a target of the rewritten branch instruction references the branch stub. In addition, the mechanisms output compiled code including the rewritten branch instruction and the branch stub for execution by a computing device. The branch stub is utilized by the computing device at runtime to determine if execution of the rewritten branch instruction can be redirected directly to a target instruction corresponding to the original target address in an instruction cache of the computing device without intervention by an instruction cache runtime system.

Rewriting branch instructions using branch stubs

Mechanisms are provided for dynamically rewriting branch instructions in a portion of code. The mechanisms execute a branch instruction in the portion of code. The mechanisms determine if a target instruction of the branch instruction, to which the branch instruction branches, is present in an instruction cache associated with the processor. Moreover, the mechanisms directly branch execution of the portion of code to the target instruction in the instruction cache, without intervention from an instruction cache runtime system, in response to a determination that the target instruction is present in the instruction cache. In addition, the mechanisms redirect execution of the portion of code to the instruction cache runtime system in response to a determination that the target instruction cannot be determined to be present in the instruction cache.

Dynamically rewriting branch instructions to directly target an instruction cache location

Mechanisms are provided for optimizing irregular memory references in computer code. These mechanisms may parse the computer code to identify memory references in the computer code. These mechanisms may further classify the memory references in the computer code as either regular memory references or irregular memory references. Moreover, the mechanisms may transform the computer code, by a compiler, to generate transformed computer code in which irregular memory references access a storage of a software cache of a data processing system through a transactional cache mechanism of the software cache.

Data transfer optimized software cache for irregular memory references

Mechanisms for optimized code generation targeting a high locality software cache are provided. Original computer code is parsed to identify memory references in the original computer code. Memory references are classified as either regular memory references or irregular memory references. Regular memory references are controlled by a high locality cache mechanism. Original computer code is transformed, by a compiler, to generate transformed computer code in which the regular memory references are grouped into one or more memory reference streams, each memory reference stream having a leading memory reference, a trailing memory reference, and one or more middle memory references. Transforming of the original computer code comprises inserting, into the original computer code, instructions to execute initialization, lookup, and cleanup operations associated with the leading memory reference and trailing memory reference in a different manner from initialization, lookup, and cleanup operations for the one or more middle memory references.

Optimized code generation targeting a high locality software cache

Mechanisms are provided for optimizing regular memory references in computer code. These mechanisms may parse the computer code to identify memory references in the computer code. These mechanisms may further classify the memory references in the computer code as either regular memory references or irregular memory references. Moreover, the mechanisms may transform the computer code, by a compiler, to generate transformed computer code in which regular memory references access a storage of a software cache of a data processing system through a high locality cache mechanism of the software cache.

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Tao Zhang