Validate alignment in the canonical ABI (#4238)
This commit updates the lifting and lowering done by Wasmtime to validate that alignment is all correct. Previously alignment was ignored because I wasn't sure how this would all work out. To be extra safe I haven't actually modified any loads/stores and they're all still unaligned. If this becomes a performance issue we can investigate aligned loads and stores but otherwise I believe the requisite locations have been guarded with traps and I've also added debug asserts to catch possible future mistakes.
This commit is contained in:
Alex Crichton
@@ -1,3 +1,4 @@
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use super::REALLOC_AND_FREE;
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use anyhow::Result;
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use wasmtime::component::*;
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use wasmtime::{Store, StoreContextMut, Trap};
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@@ -332,3 +333,293 @@ fn attempt_to_reenter_during_host() -> Result<()> {
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func.call(&mut store, ())?;
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Ok(())
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}
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#[test]
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fn stack_and_heap_args_and_rets() -> Result<()> {
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let component = format!(
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r#"
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(component
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(type $many_params (tuple
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string string string string
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string string string string
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string))
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(import "f1" (func $f1 (param u32) (result u32)))
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(import "f2" (func $f2 (param $many_params) (result u32)))
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(import "f3" (func $f3 (param u32) (result string)))
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(import "f4" (func $f4 (param $many_params) (result string)))
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(module $libc
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{REALLOC_AND_FREE}
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(memory (export "memory") 1)
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)
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(instance $libc (instantiate (module $libc)))
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(func $f1_lower (canon.lower (into $libc) (func $f1)))
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(func $f2_lower (canon.lower (into $libc) (func $f2)))
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(func $f3_lower (canon.lower (into $libc) (func $f3)))
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(func $f4_lower (canon.lower (into $libc) (func $f4)))
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(module $m
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(import "host" "f1" (func $f1 (param i32) (result i32)))
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(import "host" "f2" (func $f2 (param i32) (result i32)))
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(import "host" "f3" (func $f3 (param i32 i32)))
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(import "host" "f4" (func $f4 (param i32 i32)))
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(import "libc" "memory" (memory 1))
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(func $run (export "run")
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block
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i32.const 1
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call $f1
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i32.const 2
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i32.eq
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br_if 0
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unreachable
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end
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block
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call $allocate_empty_strings
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call $f2
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i32.const 3
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i32.eq
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br_if 0
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unreachable
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end
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block
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i32.const 8
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i32.const 16000
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call $f3
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(call $validate_string_ret (i32.const 16000))
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end
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block
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call $allocate_empty_strings
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i32.const 20000
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call $f4
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(call $validate_string_ret (i32.const 20000))
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end
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)
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(func $allocate_empty_strings (result i32)
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(local $ret i32)
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(local $offset i32)
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(local $cnt i32)
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(local.set $ret (i32.const 8000))
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(local.set $cnt (i32.const 9))
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loop
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(call $setup_str (i32.add (local.get $ret) (local.get $offset)))
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(local.set $offset (i32.add (local.get $offset) (i32.const 8)))
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(local.tee $cnt (i32.add (local.get $cnt) (i32.const -1)))
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br_if 0
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end
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local.get $ret
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)
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(func $setup_str (param $addr i32)
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(i32.store offset=0 (local.get $addr) (i32.const 1000))
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(i32.store offset=4 (local.get $addr) (i32.const 3))
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)
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(func $validate_string_ret (param $addr i32)
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(local $base i32)
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(local $len i32)
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(local.set $base (i32.load (local.get $addr)))
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(local.set $len (i32.load offset=4 (local.get $addr)))
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block
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local.get $len
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i32.const 3
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i32.eq
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br_if 0
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unreachable
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end
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(i32.load8_u offset=0 (local.get $base))
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i32.const 120 ;; 'x'
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i32.ne
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if unreachable end
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(i32.load8_u offset=1 (local.get $base))
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i32.const 121 ;; 'y'
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i32.ne
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if unreachable end
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(i32.load8_u offset=2 (local.get $base))
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i32.const 122 ;; 'z'
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i32.ne
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if unreachable end
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)
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(data (i32.const 1000) "abc")
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)
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(instance $m (instantiate (module $m)
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(with "libc" (instance $libc))
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(with "host" (instance
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(export "f1" (func $f1_lower))
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(export "f2" (func $f2_lower))
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(export "f3" (func $f3_lower))
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(export "f4" (func $f4_lower))
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))
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))
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(func (export "run")
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(canon.lift (func) (func $m "run"))
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)
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)
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"#
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);
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let engine = super::engine();
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let mut linker = Linker::new(&engine);
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linker.root().func_wrap("f1", |x: u32| -> Result<u32> {
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assert_eq!(x, 1);
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Ok(2)
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})?;
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linker.root().func_wrap(
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"f2",
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|cx: StoreContextMut<'_, ()>,
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arg: (
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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)|
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-> Result<u32> {
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assert_eq!(arg.0.to_str(&cx).unwrap(), "abc");
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Ok(3)
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},
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)?;
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linker
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.root()
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.func_wrap("f3", |arg: u32| -> Result<String> {
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assert_eq!(arg, 8);
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Ok("xyz".to_string())
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})?;
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linker.root().func_wrap(
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"f4",
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|cx: StoreContextMut<'_, ()>,
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arg: (
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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)|
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-> Result<String> {
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assert_eq!(arg.0.to_str(&cx).unwrap(), "abc");
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Ok("xyz".to_string())
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},
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)?;
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let component = Component::new(&engine, component)?;
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let mut store = Store::new(&engine, ());
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let instance = linker.instantiate(&mut store, &component)?;
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instance
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.get_typed_func::<(), (), _>(&mut store, "run")?
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.call(&mut store, ())?;
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Ok(())
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}
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#[test]
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fn bad_import_alignment() -> Result<()> {
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let component = format!(
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r#"
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(component
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(import "unaligned-retptr" (func $unaligned_retptr (result string)))
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(type $many_arg (tuple
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string string string string
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string string string string
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string
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))
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(import "unaligned-argptr" (func $unaligned_argptr (param $many_arg)))
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(module $libc_panic
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(memory (export "memory") 1)
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(func (export "canonical_abi_realloc") (param i32 i32 i32 i32) (result i32)
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unreachable)
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(func (export "canonical_abi_free") (param i32 i32 i32)
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unreachable)
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)
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(instance $libc_panic (instantiate (module $libc_panic)))
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(func $unaligned_retptr_lower
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(canon.lower (into $libc_panic) (func $unaligned_retptr))
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)
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(func $unaligned_argptr_lower
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(canon.lower (into $libc_panic) (func $unaligned_argptr))
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)
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(module $m
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(import "host" "unaligned-retptr" (func $unaligned_retptr (param i32)))
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(import "host" "unaligned-argptr" (func $unaligned_argptr (param i32)))
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(func (export "unaligned-retptr")
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(call $unaligned_retptr (i32.const 1)))
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(func (export "unaligned-argptr")
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(call $unaligned_argptr (i32.const 1)))
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)
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(instance $m (instantiate (module $m)
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(with "host" (instance
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(export "unaligned-retptr" (func $unaligned_retptr_lower))
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(export "unaligned-argptr" (func $unaligned_argptr_lower))
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))
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))
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(func (export "unaligned-retptr")
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(canon.lift (func) (func $m "unaligned-retptr"))
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)
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(func (export "unaligned-argptr")
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(canon.lift (func) (func $m "unaligned-argptr"))
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)
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)
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"#
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);
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let engine = super::engine();
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let mut linker = Linker::new(&engine);
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linker
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.root()
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.func_wrap("unaligned-retptr", || -> Result<String> {
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Ok(String::new())
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})?;
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linker.root().func_wrap(
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"unaligned-argptr",
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|_: (
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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WasmStr,
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)|
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-> Result<()> { unreachable!() },
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)?;
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let component = Component::new(&engine, component)?;
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let mut store = Store::new(&engine, ());
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let instance = linker.instantiate(&mut store, &component)?;
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let trap = instance
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.get_typed_func::<(), (), _>(&mut store, "unaligned-retptr")?
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.call(&mut store, ())
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.unwrap_err()
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.downcast::<Trap>()?;
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assert!(trap.to_string().contains("pointer not aligned"), "{}", trap);
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let trap = instance
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.get_typed_func::<(), (), _>(&mut store, "unaligned-argptr")?
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.call(&mut store, ())
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.unwrap_err()
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.downcast::<Trap>()?;
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assert!(trap.to_string().contains("pointer not aligned"), "{}", trap);
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Ok(())
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}
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