Vpopcnt for x64

build.rs

@@ -191,7 +191,6 @@ fn x64_should_panic(testsuite: &str, testname: &str, strategy: &str) -> bool {
     }
 
     match (testsuite, testname) {
-        ("simd", "simd_i8x16_arith2") => return true, // Unsupported feature: proposed simd operator I8x16Popcnt
         ("simd", "simd_conversions") => return true, // unknown operator or unexpected token: tests/spec_testsuite/proposals/simd/simd_conversions.wast:724:6
         ("simd", "simd_i16x8_extadd_pairwise_i8x16") => return true,
         ("simd", "simd_i16x8_extmul_i8x16") => return true,

cranelift/codegen/meta/src/shared/instructions.rs

@@ -3314,6 +3314,9 @@ pub(crate) fn define(
         .operands_out(vec![a]),
     );
 
+    let x = &Operand::new("x", Int);
+    let a = &Operand::new("a", Int);
+
     ig.push(
         Inst::new(
             "popcnt",

cranelift/codegen/src/isa/aarch64/lower_inst.rs

@@ -3046,6 +3046,7 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
 
         Opcode::TlsValue => unimplemented!("tls_value"),
         Opcode::FcvtLowFromSint => unimplemented!("FcvtLowFromSint"),
+        Opcode::Vpopcnt => unimplemented!("Vpopcnt"),
     }
 
     Ok(())