We present a retargetable, machine-level framework that tightly integrates the three primary functions performed by an optimizer: code generation, register allocation and code improvements. This framework is highly retargetable, able to fully exploit unique architectural features and, unlike most integrated frameworks, easily extended to include a comprehensive set of local and global optimizations. A unique approach to performing transformations improves register allocation, reduces interactions between the code improvement phases and enhances retargetability by eliminating the need to determine an effective phase ordering for each target architecture. 1 Introduction Many retargetable optimizing compilers perform code improvements on fixed, high-level intermediate representations [TSK+83] [CH84]. While these representations promote retargetability by allowing much of the optimizer to be machine-independent, they make it difficult to exploit the unique architectural features of each ...

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