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Virtual Machine
Source publication
This paper describes the implementation of a garbage collector as an undergraduate research project. The garbage collector is a continuation of a project where an Assembler, Virtual Machine and Compiler were implemented as a capstone project. The project required modifying the compiler to allocate memory compatible with a mark and sweep algorithm,...
Contexts in source publication
Context 1
... mark phase of the algorithm must know the of every by-reference parameter within a function calls' activation record. See the ordering of variables in the current Activation Record of Figure 1. Because the variables are segregated, references are easily located based on offsets. ...
Context 2
... field was added in the activation record in such a way that the mark phase could iterate over each by-reference parameter and set the mark bit in the corresponding block for each object allocated on the heap. The field is referred to as the Reference Counter in Figure 1. The reference counter in this activation record tells us that there are 2 references. ...
Context 3
... this way, lists, trees and even recursive data structures allocated on the heap can all be traversed and marked. In Figure 1, the mark phase will follow all references inside of Small Block A, so Small Block B is also marked. ...
Context 4
... means that the block has a live reference to it which originated in an activation record that is currently on the run-time stack. Blocks A, B and D in Figure 1 have references pointing to them. These blocks will be un-marked and will remain allocated. ...
Context 5
... the mark bit is not set, the algorithm clears the relevant marker in the vector of available blocks, freeing the block for reuse (See Small Block C in Figure 1) [2]. This allocated block will be freed during the sweep phase because it has no references pointing to it on the run-time stack. ...
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