1 files changed, 34 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/wasm/regress/baseline-extend8.js b/js/src/jit-test/tests/wasm/regress/baseline-extend8.js
new file mode 100644
index 0000000000..6e637e97c9
--- /dev/null
+++ b/js/src/jit-test/tests/wasm/regress/baseline-extend8.js
@@ -0,0 +1,34 @@
+// This attempts to test that we can do an 8-bit sign extend no matter what the
+// source register.  This test is arguably somewhat tied to the baseline
+// compiler's register allocator, but is still appropriate for most simple
+// register allocators.  It works by filling an increasing number of registers
+// with values so as eventually to force the source operand for extend8_s into a
+// register that does not have a byte personality.
+
+for ( let i=0; i < 8; i++) {
+    let txt =
+        `(module
+           (func (export "f") (param i32) (result i32)
+           ${adds(i)}
+           (local.set 0 (i32.extend8_s (i32.add (local.get 0) (i32.const 1))))
+           ${drops(i)}
+           (local.get 0)))`;
+    let ins = new WebAssembly.Instance(new WebAssembly.Module(wasmTextToBinary(txt)));
+    assertEq(ins.exports.f(254), -1);
+}
+
+function adds(n) {
+    let s = ""
+    for ( let i=0; i < n; i++ )
+        s += "(i32.add (local.get 0) (i32.const 1))\n";
+    return s;
+}
+
+function drops(n) {
+    let s = "";
+    for ( let i=0; i < n; i++ )
+        s += "drop\n";
+    return s;
+}
+
+