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Use guard pages rather than heap checks

By mmap'ing memory using MAP_ANONYMOUS (or /dev/zero) as PROT_NONE (Windows has an equivalent functionality with VirtualAlloc), it's possible to create a page that will fault when read or written to. It may be possible to remove the heap checks in the runtime, speeding up allocations, and instead expand the heap when a fault is raised.

This is likely cheaper for large pages full of many small allocations than the cost of the heap checking branch.

Trac metadata
Trac field Value
Version
Type FeatureRequest
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Runtime System
Test case
Differential revisions
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CC simonmar
Operating system
Architecture
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