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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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22
crates/environ/src/func_environ.rs
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@@ -362,8 +362,10 @@ impl<'module_environment> TargetEnvironment for FuncEnvironment<'module_environm
}
impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'module_environment> {
fn is_wasm_parameter(&self, signature: &ir::Signature, index: usize) -> bool {
signature.params[index].purpose == ir::ArgumentPurpose::Normal
fn is_wasm_parameter(&self, _signature: &ir::Signature, index: usize) -> bool {
// The first two parameters are the vmctx and caller vmctx. The rest are
// the wasm parameters.
index >= 2
}
fn make_table(&mut self, func: &mut ir::Function, index: TableIndex) -> WasmResult<ir::Table> {
@@ -615,7 +617,8 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
}
}
let mut real_call_args = Vec::with_capacity(call_args.len() + 1);
let mut real_call_args = Vec::with_capacity(call_args.len() + 2);
let caller_vmctx = pos.func.special_param(ArgumentPurpose::VMContext).unwrap();
// First append the callee vmctx address.
let vmctx = pos.ins().load(
@@ -625,6 +628,7 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
i32::from(self.offsets.vmcaller_checked_anyfunc_vmctx()),
);
real_call_args.push(vmctx);
real_call_args.push(caller_vmctx);
// Then append the regular call arguments.
real_call_args.extend_from_slice(call_args);
@@ -639,12 +643,17 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
callee: ir::FuncRef,
call_args: &[ir::Value],
) -> WasmResult<ir::Inst> {
let mut real_call_args = Vec::with_capacity(call_args.len() + 1);
let mut real_call_args = Vec::with_capacity(call_args.len() + 2);
let caller_vmctx = pos.func.special_param(ArgumentPurpose::VMContext).unwrap();
// Handle direct calls to locally-defined functions.
if !self.module.is_imported_function(callee_index) {
// First append the callee vmctx address.
real_call_args.push(pos.func.special_param(ArgumentPurpose::VMContext).unwrap());
// First append the callee vmctx address, which is the same as the caller vmctx in
// this case.
real_call_args.push(caller_vmctx);
// Then append the caller vmctx address.
real_call_args.push(caller_vmctx);
// Then append the regular call arguments.
real_call_args.extend_from_slice(call_args);
@@ -671,6 +680,7 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
i32::try_from(self.offsets.vmctx_vmfunction_import_vmctx(callee_index)).unwrap();
let vmctx = pos.ins().load(pointer_type, mem_flags, base, vmctx_offset);
real_call_args.push(vmctx);
real_call_args.push(caller_vmctx);
// Then append the regular call arguments.
real_call_args.extend_from_slice(call_args);