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Create the wasm-bindgen-wasm-conventions crate

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This tiny crate provides utilities for working with Wasm codegen
conventions (typically established by LLVM or lld) such as getting the shadow
stack pointer.

It also de-duplicates all the places in the codebase where we were implementing
these conventions in one-off ways.
This commit is contained in:
Nick Fitzgerald
2019-09-16 11:18:06 -07:00
parent 68af85d001
commit 2fbb8359e0
7 changed files with 173 additions and 121 deletions
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46
crates/cli-support/src/webidl/standard.rs
View File

@ -53,9 +53,10 @@ use crate::descriptor::VectorKind;
use crate::webidl::{AuxExportKind, AuxImport, AuxValue, JsImport, JsImportName};
use crate::webidl::{NonstandardIncoming, NonstandardOutgoing};
use crate::webidl::{NonstandardWebidlSection, WasmBindgenAux};
use failure::{bail, format_err, Error, ResultExt};
use walrus::{GlobalId, MemoryId, Module};
use failure::{bail, Error, ResultExt};
use walrus::Module;
use wasm_bindgen_multi_value_xform as multi_value_xform;
use wasm_bindgen_wasm_conventions as wasm_conventions;
use wasm_webidl_bindings::ast;
pub fn add_multi_value(
@ -79,8 +80,8 @@ pub fn add_multi_value(
return Ok(());
}
let memory = get_memory(module)?;
let shadow_stack_pointer = get_shadow_stack_pointer(module)?;
let shadow_stack_pointer = wasm_conventions::get_shadow_stack_pointer(module)?;
let memory = wasm_conventions::get_memory(module)?;
multi_value_xform::run(module, memory, shadow_stack_pointer, &to_xform)?;
// Finally, unset `return_via_outptr`, fix up its incoming bindings'
@ -163,43 +164,6 @@ fn fixup_binding_argument_gets(incoming: &mut [NonstandardIncoming]) -> Result<(
}
}
fn get_memory(module: &Module) -> Result<MemoryId, Error> {
let mut memories = module.memories.iter().map(|m| m.id());
let memory = memories.next();
if memories.next().is_some() {
bail!(
"expected a single memory, found multiple; multiple memories \
currently not supported"
);
}
memory.ok_or_else(|| {
format_err!(
"module does not have a memory; must have a memory \
to transform return pointers into Wasm multi-value"
)
})
}
// Get the `__shadow_stack_pointer` global that we stashed in an export early on
// in the pipeline.
fn get_shadow_stack_pointer(module: &mut Module) -> Result<GlobalId, Error> {
let (g, e) = module
.exports
.iter()
.find(|e| e.name == "__shadow_stack_pointer")
.map(|e| {
let g = match e.item {
walrus::ExportItem::Global(g) => g,
_ => unreachable!(),
};
(g, e.id())
})
.ok_or_else(|| format_err!("module does not have a shadow stack pointer"))?;
module.exports.delete(e);
Ok(g)
}
pub fn add_section(
module: &mut Module,
aux: &WasmBindgenAux,