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Replace the global-exports mechanism with a caller-vmctx mechanism. (#789)

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* Replace the global-exports mechanism with a caller-vmctx mechanism.

This eliminates the global exports mechanism, and instead adds a
caller-vmctx argument to wasm functions so that WASI can obtain the
memory and other things from the caller rather than looking them up in a
global registry.

This replaces #390.

* Fixup some merge conflicts

* Rustfmt

* Ensure VMContext is aligned to 16 bytes

With the removal of `global_exports` it "just so happens" that this
isn't happening naturally any more.

* Fixup some bugs with double vmctx in wasmtime crate

* Trampoline stub needed adjusting
* Use pointer type instead of always using I64 for caller vmctx
* Don't store `ir::Signature` in `Func` since we don't know the pointer
  size at creation time.
* Skip the first 2 arguments in IR signatures since that's the two vmctx
  parameters.

* Update cranelift to 0.56.0

* Handle more merge conflicts

* Rustfmt

Co-authored-by: Alex Crichton <alex@alexcrichton.com>
This commit is contained in:
Dan Gohman
2020-01-21 14:50:59 -08:00
committed by GitHub
parent de72435576
commit 9a88d3d894
33 changed files with 362 additions and 330 deletions
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33
crates/jit/src/compiler.rs
View File

@@ -282,11 +282,15 @@ fn make_trampoline(
let pointer_type = isa.pointer_type();
let mut wrapper_sig = ir::Signature::new(isa.frontend_config().default_call_conv);
// Add the `vmctx` parameter.
// Add the callee `vmctx` parameter.
wrapper_sig.params.push(ir::AbiParam::special(
pointer_type,
ir::ArgumentPurpose::VMContext,
));
// Add the caller `vmctx` parameter.
wrapper_sig.params.push(ir::AbiParam::new(pointer_type));
// Add the `values_vec` parameter.
wrapper_sig.params.push(ir::AbiParam::new(pointer_type));
@@ -302,9 +306,9 @@ fn make_trampoline(
builder.switch_to_block(block0);
builder.seal_block(block0);
let (vmctx_ptr_val, values_vec_ptr_val) = {
let (vmctx_ptr_val, caller_vmctx_ptr_val, values_vec_ptr_val) = {
let params = builder.func.dfg.ebb_params(block0);
(params[0], params[1])
(params[0], params[1], params[2])
};
// Load the argument values out of `values_vec`.
@@ -314,16 +318,19 @@ fn make_trampoline(
.iter()
.enumerate()
.map(|(i, r)| {
match r.purpose {
// i - 1 because vmctx isn't passed through `values_vec`.
ir::ArgumentPurpose::Normal => builder.ins().load(
r.value_type,
mflags,
values_vec_ptr_val,
((i - 1) * value_size) as i32,
),
ir::ArgumentPurpose::VMContext => vmctx_ptr_val,
other => panic!("unsupported argument purpose {}", other),
match i {
0 => vmctx_ptr_val,
1 => caller_vmctx_ptr_val,
_ =>
// i - 2 because vmctx and caller vmctx aren't passed through `values_vec`.
{
builder.ins().load(
r.value_type,
mflags,
values_vec_ptr_val,
((i - 2) * value_size) as i32,
)
}
}
})
.collect::<Vec<_>>();