Optimizing stack frame accesses for processors with restricted addressing modes
Software—Practice & Experience
Register allocation for software pipelined loops
PLDI '92 Proceedings of the ACM SIGPLAN 1992 conference on Programming language design and implementation
Register connection: a new approach to adding registers into instruction set architectures
ISCA '93 Proceedings of the 20th annual international symposium on computer architecture
Software pipelining with register allocation and spilling
MICRO 27 Proceedings of the 27th annual international symposium on Microarchitecture
Storage assignment to decrease code size
PLDI '95 Proceedings of the ACM SIGPLAN 1995 conference on Programming language design and implementation
ACM Transactions on Programming Languages and Systems (TOPLAS)
Software pipelining showdown: optimal vs. heuristic methods in a production compiler
PLDI '96 Proceedings of the ACM SIGPLAN 1996 conference on Programming language design and implementation
Heuristics for register-constrained software pipelining
Proceedings of the 29th annual ACM/IEEE international symposium on Microarchitecture
MICRO 31 Proceedings of the 31st annual ACM/IEEE international symposium on Microarchitecture
Proceedings of the eighth international conference on Architectural support for programming languages and operating systems
Improved spill code generation for software pipelined loops
PLDI '00 Proceedings of the ACM SIGPLAN 2000 conference on Programming language design and implementation
Two-level hierarchical register file organization for VLIW processors
Proceedings of the 33rd annual ACM/IEEE international symposium on Microarchitecture
Optimal spilling for CISC machines with few registers
Proceedings of the ACM SIGPLAN 2001 conference on Programming language design and implementation
Profile guided selection of ARM and thumb instructions
Proceedings of the joint conference on Languages, compilers and tools for embedded systems: software and compilers for embedded systems
A Systolic Array Optimizing Compiler
A Systolic Array Optimizing Compiler
Stack Value File: Custom Microarchitecture for the Stack
HPCA '01 Proceedings of the 7th International Symposium on High-Performance Computer Architecture
Increasing the number of effective registers in a low-power processor using a windowed register file
Proceedings of the 2003 international conference on Compilers, architecture and synthesis for embedded systems
Hardware-managed register allocation for embedded processors
Proceedings of the 2004 ACM SIGPLAN/SIGBED conference on Languages, compilers, and tools for embedded systems
Differential register allocation
Proceedings of the 2005 ACM SIGPLAN conference on Programming language design and implementation
MiBench: A free, commercially representative embedded benchmark suite
WWC '01 Proceedings of the Workload Characterization, 2001. WWC-4. 2001 IEEE International Workshop
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Micro-architecture designers are very cautious about expanding the number of architected and exposed registers in the instruction set because increasing the register field adds to the code size, raises the I-cache and memory pressure, and may complicate the processor pipeline. Especially for low-end processors, encoding space could be extremely limited due to area and power considerations. On the other hand, the number of architected registers exposed to the compiler could directly affect the effectiveness of compiler analysis and optimization. For high-performance computers, register pressure can be higher than the available registers in some regions. This could be due to optimizations like aggressive function inlining, software pipelining, etc. The compiler cannot effectively perform compilation and optimization if only a small number of registers are exposed through the ISA. Therefore, it is crucial that more architected registers are available at the compiler's disposal, without expanding the code size significantly. In this article, we devise a new register encoding scheme, called differential encoding, that allows more registers to be addressed in the operand field of instructions than the direct encoding currently being used. We show that this can be implemented with very low overhead. Based upon differential encoding, we apply it in several ways such that the extra architected registers can benefit the performance. Three schemes are devised to integrate differential encoding with register allocation. We demonstrate that differential register allocation is helpful in improving the performance of both high-end and low-end processors. Moreover, we can combine it with software pipelining to provide more registers and reduce spills. Our results show that differential encoding significantly reduces the number of spills and speeds-up program execution. For a low-end configuration, we achieve over 14% speedup while keeping code size almost unaffected. For a high-end VLIW in-order machine, it can significantly speed-up loops with high register pressure (about 80% speedup) and the overall speedup is about 15%. Moreover, our scheme can be applied in an adaptive manner, making its overhead much smaller.