Expand description
Runtime library calls.
Note that Wasm compilers may sometimes perform these inline rather than calling them, particularly when CPUs have special instructions which compute them directly.
These functions are called by compiled Wasm code, and therefore must take certain care about some things:
-
They must always be
pub extern "C"
and should only contain basic, raw i32/i64/f32/f64/pointer parameters that are safe to pass across the system ABI! -
If any nested function propagates an
Err(trap)
out to the library function frame, we need to raise it. This involves some nasty and quite unsafe code under the covers! Notable, after raising the trap, drops will not be run for local variables! This can lead to things like leakingVMInstance
s which leads to never deallocating JIT code, instances, and modules! Therefore, always use nested blocks to ensure drops run before raising a trap:ⓘpub extern "C" fn my_lib_function(...) { let result = { // Do everything in here so drops run at the end of the block. ... }; if let Err(trap) = result { // Now we can safely raise the trap without leaking! raise_lib_trap(trap); } }
Enums§
- The name of a runtime library routine.
Statics§
- Probestack check
Functions§
- The function pointer to a libcall
- Implementation of
data.drop
. - Implementation of
elem.drop
. - Implementation of f32.ceil
- Implementation of f32.floor
- Implementation of f32.nearest
- Implementation of f32.trunc
- Implementation of f64.ceil
- Implementation of f64.floor
- Implementation of f64.nearest
- Implementation of f64.trunc
- Implementation of
func.ref
. - Implementation of memory.notfy for imported 32-bit memories.
- Implementation of memory.wait32 for imported 32-bit memories.
- Implementation of memory.wait64 for imported 32-bit memories.
- Implementation of
memory.copy
for imported memories. - Implementation of
memory.fill
for imported memories. - Implementation of memory.grow for imported 32-bit memories.
- Implementation of memory.size for imported 32-bit memories.
- Implementation of
table.get
for imported tables. - Implementation of
table.grow
for imported tables. - Implementation of
table.set
for imported tables. - Implementation of
table.size
for imported tables. - Implementation of memory.notfy for locally-defined 32-bit memories.
- Implementation of memory.wait32 for locally-defined 32-bit memories.
- Implementation of memory.wait64 for locally-defined 32-bit memories.
- Implementation of
memory.copy
for locally defined memories. - Implementation of
memory.fill
for locally defined memories. - Implementation of memory.grow for locally-defined 32-bit memories.
- Implementation of
memory.init
. - Implementation of memory.size for locally-defined 32-bit memories.
- Implementation for raising a trap
- Implementation of
table.copy
. - Implementation of
table.fill
. - Implementation of
table.get
. - Implementation of
table.grow
for locally-defined tables. - Implementation of
table.init
. - Implementation of
table.set
. - Implementation of
table.size
.