cmpxchg

    pub fn cmpxchg(
        self: *WipFunction,
        kind: Instruction.CmpXchg.Kind,
        access_kind: MemoryAccessKind,
        ptr: Value,
        cmp: Value,
        new: Value,
        sync_scope: SyncScope,
        success_ordering: AtomicOrdering,
        failure_ordering: AtomicOrdering,
        alignment: Alignment,
        name: []const u8,
    ) Allocator.Error!Value {
        assert(ptr.typeOfWip(self).isPointer(self.builder));
        const ty = cmp.typeOfWip(self);
        assert(ty == new.typeOfWip(self));
        assert(success_ordering != .none);
        assert(failure_ordering != .none);

        _ = try self.builder.structType(.normal, &.{ ty, .i1 });
        try self.ensureUnusedExtraCapacity(1, Instruction.CmpXchg, 0);
        const instruction = try self.addInst(name, .{
            .tag = switch (kind) {
                .strong => .cmpxchg,
                .weak => .@"cmpxchg weak",
            },
            .data = self.addExtraAssumeCapacity(Instruction.CmpXchg{
                .info = .{
                    .access_kind = access_kind,
                    .sync_scope = sync_scope,
                    .success_ordering = success_ordering,
                    .failure_ordering = failure_ordering,
                    .alignment = alignment,
                },
                .ptr = ptr,
                .cmp = cmp,
                .new = new,
            }),
        });
        return instruction.toValue();
    }