This repository was archived by the owner on May 20, 2020. It is now read-only.
This repository was archived by the owner on May 20, 2020. It is now read-only.
Early parse error for v8x16.shuffle #44
Description
The SIMD testsuite contains an assert_invalid directive in which v8x16.shuffle uses a negative index. When wasmtime attempts to run this test, it fails with:
running 1 test
test Cranelift::simd::simd_lane ... FAILED
failures:
---- Cranelift::simd::simd_lane stdout ----
Error: invalid u8 number: constant out of range
--> tests/spec_testsuite/proposals/simd/simd_lane.wast:492:18
|
492 | (v8x16.shuffle -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
| ^
thread 'Cranelift::simd::simd_lane' panicked at 'assertion failed: `(left == right)`
left: `1`,
right: `0`: the test returned a termination value with a non-zero status code (1) which indicates a failure', src/libtest/lib.rs:196:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
In wast, I can alter V8x16Shuffle to use i8 as the index type (patch at bottom), but this then allows negative indexes to flow to Cranelift, which promptly fails with:
running 1 test
thread '<unnamed>' panicked at 'assertion failed: lane > 0 && lane <= 3', /home/abrown/.cargo/registry/src/github.com-1ecc6299db9ec823/cranelift-codegen-0.54.0/src/isa/x86/enc_tables.rs:1176:21
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
test Cranelift::simd::simd_lane ... FAILED
How should we fix this? And why isn't wasmparser's validation catching this invalid index beforehand?
Patch wast's V8x16Shuffle to use `i8`:
diff --git a/crates/wast/src/ast/expr.rs b/crates/wast/src/ast/expr.rs
index 6d55f6f..b8454e8 100644
--- a/crates/wast/src/ast/expr.rs
+++ b/crates/wast/src/ast/expr.rs
@@ -1008,7 +1008,7 @@ impl<'a> Parse<'a> for V128Const {
#[derive(Debug)]
pub struct V8x16Shuffle {
#[allow(missing_docs)]
- pub lanes: [u8; 16],
+ pub lanes: [i8; 16],
}
impl<'a> Parse<'a> for V8x16Shuffle {
diff --git a/crates/wast/src/binary.rs b/crates/wast/src/binary.rs
index baa0188..1b4d6e2 100644
--- a/crates/wast/src/binary.rs
+++ b/crates/wast/src/binary.rs
@@ -668,7 +668,8 @@ impl Encode for V128Const {
impl Encode for V8x16Shuffle {
fn encode(&self, dst: &mut Vec<u8>) {
- dst.extend_from_slice(&self.lanes);
+ let indexes: Vec<u8> = self.lanes.iter().map(|&i| i as u8).collect();
+ dst.extend_from_slice(&indexes);
}
}