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Add initial support for the multi-memory proposal (#2263)

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This commit adds initial (gated) support for the multi-memory wasm
proposal. This was actually quite easy since almost all of wasmtime
already expected multi-memory to be implemented one day. The only real
substantive change is the `memory.copy` intrinsic changes, which now
accounts for the source/destination memories possibly being different.
This commit is contained in:
Alex Crichton
2020-10-13 19:13:52 -05:00
committed by GitHub
parent c2d01fe56f
commit e659d5cecd
14 changed files with 246 additions and 107 deletions
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35
crates/runtime/src/instance.rs
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@@ -604,29 +604,31 @@ impl Instance {
// dropping a non-passive element is a no-op (not a trap).
}
/// Do a `memory.copy` for a locally defined memory.
/// Do a `memory.copy`
///
/// # Errors
///
/// Returns a `Trap` error when the source or destination ranges are out of
/// bounds.
pub(crate) fn defined_memory_copy(
pub(crate) fn memory_copy(
&self,
memory_index: DefinedMemoryIndex,
dst_index: MemoryIndex,
dst: u32,
src_index: MemoryIndex,
src: u32,
len: u32,
) -> Result<(), Trap> {
// https://webassembly.github.io/reference-types/core/exec/instructions.html#exec-memory-copy
let memory = self.memory(memory_index);
let src_mem = self.get_memory(src_index);
let dst_mem = self.get_memory(dst_index);
if src
.checked_add(len)
.map_or(true, |n| n as usize > memory.current_length)
.map_or(true, |n| n as usize > src_mem.current_length)
|| dst
.checked_add(len)
.map_or(true, |m| m as usize > memory.current_length)
.map_or(true, |m| m as usize > dst_mem.current_length)
{
return Err(Trap::wasm(ir::TrapCode::HeapOutOfBounds));
}
@@ -637,31 +639,14 @@ impl Instance {
// Bounds and casts are checked above, by this point we know that
// everything is safe.
unsafe {
let dst = memory.base.add(dst);
let src = memory.base.add(src);
let dst = dst_mem.base.add(dst);
let src = src_mem.base.add(src);
ptr::copy(src, dst, len as usize);
}
Ok(())
}
/// Perform a `memory.copy` on an imported memory.
pub(crate) fn imported_memory_copy(
&self,
memory_index: MemoryIndex,
dst: u32,
src: u32,
len: u32,
) -> Result<(), Trap> {
let import = self.imported_memory(memory_index);
unsafe {
let foreign_instance = (&*import.vmctx).instance();
let foreign_memory = &*import.from;
let foreign_index = foreign_instance.memory_index(foreign_memory);
foreign_instance.defined_memory_copy(foreign_index, dst, src, len)
}
}
/// Perform the `memory.fill` operation on a locally defined memory.
///
/// # Errors