Add nop instruction to Winch (#6449)

fuzz/fuzz_targets/differential.rs

@@ -309,6 +309,7 @@ fn winch_supports_module(module: &[u8]) -> bool {
  | LocalGet { .. }
  | LocalSet { .. }
  | Call { .. }
+ | Nop { .. }
  | End { .. } => {}
  _ => {
  supported = false;

winch/codegen/src/visitor.rs

@@ -53,6 +53,7 @@ macro_rules! def_unsupported {
  (emit LocalSet $($rest:tt)*) => {};
  (emit Call $($rest:tt)*) => {};
  (emit End $($rest:tt)*) => {};
+ (emit Nop $($rest:tt)*) => {};
 
  (emit $unsupported:tt $($rest:tt)*) => {$($rest)*};
 }
@@ -203,6 +204,8 @@ where
  self.emit_call(FuncIndex::from_u32(index));
  }
 
+ fn visit_nop(&mut self) {}
+
  wasmparser::for_each_operator!(def_unsupported);
 }
 

winch/filetests/filetests/aarch64/nop/nop.wat

@@ -0,0 +1,17 @@
+;;! target = "aarch64"
+
+(module
+ (func
+ nop
+ )
+)
+;; 0: fd7bbfa9 stp x29, x30, [sp, #-0x10]!
+;; 4: fd030091 mov x29, sp
+;; 8: fc030091 mov x28, sp
+;; c: ff2300d1 sub sp, sp, #8
+;; 10: fc030091 mov x28, sp
+;; 14: 890300f8 stur x9, [x28]
+;; 18: ff230091 add sp, sp, #8
+;; 1c: fc030091 mov x28, sp
+;; 20: fd7bc1a8 ldp x29, x30, [sp], #0x10
+;; 24: c0035fd6 ret 

winch/filetests/filetests/x64/nop/nop.wat

@@ -0,0 +1,15 @@
+;;! target = "x86_64"
+
+(module
+ (func
+ nop
+ )
+)
+
+;; 0: 55 push rbp
+;; 1: 4889e5 mov rbp, rsp
+;; 4: 4883ec08 sub rsp, 8
+;; 8: 4c893424 mov qword ptr [rsp], r14
+;; c: 4883c408 add rsp, 8
+;; 10: 5d pop rbp
+;; 11: c3 ret