Safe, Multiphase Bounds Check Elimination in Java

Download Now Date Added: Jan 2010
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As part of its type-safety regime, the Java semantics require precise exceptions at runtime when programs attempt out-of-bound array accesses. This paper describes a Java implementation that utilizes a multiphase approach to identifying safe array accesses. This approach reduces runtime overhead by spreading the out-of-bounds checking effort across three phases of compilation and execution: Production of mobile code from source code, JIT compilation in the virtual machine, and application code execution. The code producer uses multiple passes (including common subexpression elimination, load elimination, induction variable substitution, speculation of dynamically-verified invariants, and inequality constraint analysis) to identify and prove redundancy of bounds checks.