# Optimistic register coalescing

@article{Park2004OptimisticRC, title={Optimistic register coalescing}, author={Jinpyo Park and Soo-Mook Moon}, journal={ACM Trans. Program. Lang. Syst.}, year={2004}, volume={26}, pages={735-765} }

Graph-coloring register allocators eliminate copies by coalescing the source and target nodes of a copy if they do not interfere in the interference graph. Coalescing, however, can be harmful to the colorability of the graph because it tends to yield a graph with nodes of higher degrees. Unlike aggressive coalescing, which coalesces any pair of noninterfering copy-related nodes, conservative coalescing or iterated coalescing perform safe coalescing that preserves the colorability. Unfortunately…

## 31 Citations

### Copy coalescing by graph recoloring

- Computer SciencePLDI '08
- 2008

A coalescing technique designed for, but not limited to, SSA-form register allocation that improves upon two long-standing inconveniences of graph coloring register allocation by exploiting that a valid coloring can be easily obtained by an Ssa-based register allocator.

### Live-range Unsplitting for Faster Optimal Coalescing ( extended version )

- Computer Science
- 2008

This report provides all the solutions of the optimal coalescing challenge, including the 3 instances that were previously unsolved, and presents some theoretical properties that give rise to an algorithm for reducing interference graphs, while preserving optimality.

### Graph-coloring and treescan register allocation using repairing

- Computer Science2011 Proceedings of the 14th International Conference on Compilers, Architectures and Synthesis for Embedded Systems (CASES)
- 2011

A decoupled approach that first lowers the register pressure by spilling variables, and then performs live ranges splitting/coalescing /coloring in a separate phase enables the design of simpler, cleaner, and more efficient register allocators.

### Parallel Copy Elimination on Data Dependence Graphs

- Computer Science
- 2011

This work presents an extension of a local recoloring technique called Parallel Copy Motion that performs code motion on data dependence graphs in order to eliminate useless copies and reorder instructions, while at the same time a valid register assignment is preserved.

### Register coalescing techniques for heterogeneous register architecture with copy sifting

- Computer ScienceTECS
- 2009

It is shown that optimistic coalescing is also useful for an embedded processor to better handle such heterogeneity of the register architecture, and a modified algorithm for optimal coalescing that helps a register allocator is developed.

### Elimination of parallel copies using code motion on data dependence graphs

- Computer ScienceComput. Lang. Syst. Struct.
- 2013

### Scratchpad memory allocation for data aggregates via interval coloring in superperfect graphs

- Computer ScienceTECS
- 2011

This article develops an SPM allocation algorithm that places arrays in an interference graph in SPM by examining its maximal cliques and achieves close-to-optimal results and is superior to graph coloring for the benchmarks tested.

### A comparison of graph coloring heuristics for register allocation based on coalescing in interval graphs

- Computer Science2004 IEEE International Symposium on Circuits and Systems (IEEE Cat. No.04CH37512)
- 2004

This paper compares different coloring heuristics in order to obtain minimum register requirements and shows that Chaitin's well known coloring heuristic produces optimum results for interval graphs.

### Optimizing translation out of SSA using renaming constraints

- Computer ScienceInternational Symposium on Code Generation and Optimization, 2004. CGO 2004.
- 2004

This work proposes a method to reduce the /spl Phi/-related copies during the out of SSA translation, thanks to a pinning-based coalescing algorithm that is aware of renaming constraints.

### Graph Coloring vs. Optimal Register Allocation for Optimizing Compilers

- Computer ScienceJMLC
- 2003

This article shows how optimistic graph coloring register allocation can be extended to handle peculiarities and irregularities in their register sets and presents an exponential algorithm which in most cases can compute an optimal solution for register allocation and copy elimination.

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