Split Memory

Split memory is a compilation mode that splits the normal single typed array of memory into multiple chunks. It is a non-asm.js mode, enabled by building with -s SPLIT_MEMORY=N where N is the chunk size.

Model

Each split chunk gets an independent malloc/free space, implemented by a dlmalloc mspace. That means we assume each malloc is provided by a single chunk, and therefore allocations cannot span chunks. It also means the chunk size must be big enough for the single largest allocation.

We implement HEAP*.subarray by returning a slice into the proper chunk. When an end offset is not provided, we slice to the end of the current chunk, relying on the fact that no allocation can span chunks.