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Don't create Static memories larger than the Tunables' static bound size.

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Dan Gohman
2018-12-24 21:57:43 -08:00
parent 57a1618742
commit f997cde2db
1 changed files with 16 additions and 15 deletions
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19
lib/environ/src/module.rs
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@@ -54,23 +54,24 @@ impl MemoryStyle {
/// Decide on an implementation style for the given `Memory`. /// Decide on an implementation style for the given `Memory`.
pub fn for_memory(memory: Memory, tunables: &Tunables) -> (Self, u64) { pub fn for_memory(memory: Memory, tunables: &Tunables) -> (Self, u64) {
if let Some(maximum) = memory.maximum { if let Some(maximum) = memory.maximum {
// A heap with a declared maximum is prepared to be used with if maximum <= tunables.static_memory_bound {
// threads and therefore be immovable, so make it static. // A heap with a declared maximum can be immovable, so make
( // it static.
return (
MemoryStyle::Static { MemoryStyle::Static {
bound: cmp::max(tunables.static_memory_bound, maximum), bound: tunables.static_memory_bound,
}, },
tunables.static_memory_offset_guard_size, tunables.static_memory_offset_guard_size,
) );
} else { }
// A heap without a declared maximum is likely to want to be small }
// at least some of the time, so make it dynamic.
// Otherwise, make it dynamic.
( (
MemoryStyle::Dynamic, MemoryStyle::Dynamic,
tunables.dynamic_memory_offset_guard_size, tunables.dynamic_memory_offset_guard_size,
) )
} }
}
} }
/// A WebAssembly linear memory description along with our chosen style for /// A WebAssembly linear memory description along with our chosen style for