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Instantiate fewer instances when fuzzing (#2768)

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This commit fixes an issue where when module linking was enabled for
fuzzing (which it is) import types of modules show as imports of
instances. In an attempt to satisfy the dummy values of such imports the
fuzzing integration would create instances for each import. This would,
however, count towards instance limits and isn't always desired.

This commit refactors the creation of dummy import values to decompose
imports of instances into imports of each individual item. This should
retain the pre-module-linking behavior of dummy imports for various
fuzzers.
This commit is contained in:
Alex Crichton
2021-03-25 13:35:38 -05:00
committed by GitHub
parent 30d9164b6e
commit 9476581ae6
3 changed files with 78 additions and 40 deletions
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14
crates/fuzzing/src/oracles.rs
View File

@@ -13,7 +13,7 @@
pub mod dummy;
use arbitrary::Arbitrary;
use dummy::dummy_imports;
use dummy::dummy_linker;
use log::debug;
use std::cell::Cell;
use std::rc::Rc;
@@ -118,9 +118,9 @@ pub fn instantiate_with_config(
Err(_) if !known_valid => return,
Err(e) => panic!("failed to compile module: {:?}", e),
};
let imports = dummy_imports(&store, module.imports());
let linker = dummy_linker(&store, &module);
match Instance::new(&store, &module, &imports) {
match linker.instantiate(&module) {
Ok(_) => {}
// Allow traps which can happen normally with `unreachable` or a timeout
Err(e) if e.downcast_ref::<Trap>().is_some() => {}
@@ -190,13 +190,13 @@ pub fn differential_execution(
// in and with what values. Like the results of exported functions,
// calls to imports should also yield the same values for each
// configuration, and we should assert that.
let imports = dummy_imports(&store, module.imports());
let linker = dummy_linker(&store, &module);
// Don't unwrap this: there can be instantiation-/link-time errors that
// aren't caught during validation or compilation. For example, an imported
// table might not have room for an element segment that we want to
// initialize into it.
let instance = match Instance::new(&store, &module, &imports) {
let instance = match linker.instantiate(&module) {
Ok(instance) => instance,
Err(e) => {
eprintln!(
@@ -354,13 +354,13 @@ pub fn make_api_calls(api: crate::generators::api::ApiCalls) {
};
let store = store.as_ref().unwrap();
let imports = dummy_imports(store, module.imports());
let linker = dummy_linker(store, module);
// Don't unwrap this: there can be instantiation-/link-time errors that
// aren't caught during validation or compilation. For example, an imported
// table might not have room for an element segment that we want to
// initialize into it.
if let Ok(instance) = Instance::new(store, &module, &imports) {
if let Ok(instance) = linker.instantiate(&module) {
instances.insert(id, instance);
}
}