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Add heap_load, heap_store, and heap_addr instructions.

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These are used when lowering WebAssembly sandbox code.
This commit is contained in:
Jakob Stoklund Olesen
2017-04-10 15:03:10 -07:00
parent e78e4ea4ec
commit b474485c0d
9 changed files with 110 additions and 46 deletions
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42
cranelift/docs/langref.rst
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@@ -533,49 +533,13 @@ than the native pointer size, for example unsigned :type:`i32` offsets on a
:arg Name: String identifying the heap in the runtime environment.
:result H: Heap identifier.
.. inst:: a = heap_load H, p, Offset
Load a value at the address ``p + Offset`` in the heap H.
Trap if the heap access would be out of bounds.
:arg H: Heap identifier created by :inst:`heap`.
:arg iN p: Unsigned base address in heap.
:arg Offset: Immediate signed offset.
:flag align(N): Expected alignment of ``p + Offset``. Power of two.
:flag aligntrap: Always trap if the memory access is misaligned.
:result T a: Loaded value.
.. inst:: a = heap_store H, x, p, Offset
Store a value at the address ``p + Offset`` in the heap H.
Trap if the heap access would be out of bounds.
:arg H: Heap identifier created by :inst:`heap`.
:arg T x: Value to be stored.
:arg iN p: Unsigned base address in heap.
:arg Offset: Immediate signed offset.
:flag align(N): Expected alignment of ``p + Offset``. Power of two.
:flag aligntrap: Always trap if the memory access is misaligned.
.. autoinst:: heap_load
.. autoinst:: heap_store
When optimizing heap accesses, Cretonne may separate the heap bounds checking
and address computations from the memory accesses.
.. inst:: a = heap_addr H, p, Size
Bounds check and compute absolute address of heap memory.
Verify that the address range ``p .. p + Size - 1`` is valid in the heap H,
and trap if not.
Convert the heap-relative address in ``p`` to a real absolute address and
return it.
:arg H: Heap identifier created by :inst:`heap`.
:arg iN p: Unsigned base address in heap.
:arg Size: Immediate unsigned byte count for range to verify.
:result iPtr a: Absolute address corresponding to ``p``.
.. autoinst:: heap_addr
A small example using heaps::