https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95818
Bug ID: 95818
Summary: wrong "used uninitialized" warning
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: ferruh.yigit at intel dot com
Target Milestone: ---
gcc (GCC) 11.0.0 20200621 (experimental)
Sorry, I couldn't able to reproduce with test code, I will copy-paste the real
code that causes the warning hoping it helps.
Warning [1] and code that causes it [2], struct in question [3].
As you can see all the fields of the struct has been set before used, so not
sure why giving used uninitialized warning.
[1]
.../drivers/net/iavf/iavf_ethdev.c: In function ‘iavf_dev_link_update’:
.../drivers/net/iavf/iavf_ethdev.c:641:6: error: ‘new_link’ is used
uninitialized [-Werror=uninitialized]
641 | if (rte_atomic64_cmpset((uint64_t *)&dev->data->dev_link,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
642 | *(uint64_t *)&dev->data->dev_link,
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
643 | *(uint64_t *)&new_link) == 0)
| ~~~~~~~~~~~~~~~~~~~~~~~
.../drivers/net/iavf/iavf_ethdev.c:596:22: note: ‘new_link’ declared here
596 | struct rte_eth_link new_link;
| ^~~~~~~~
cc1: all warnings being treated as error
[2]
iavf_dev_link_update(struct rte_eth_dev *dev,
__rte_unused int wait_to_complete)
{
struct rte_eth_link new_link;
struct iavf_info *vf = IAVF_DEV_PRIVATE_TO_VF(dev->data->dev_private);
/* Only read status info stored in VF, and the info is updated
* when receive LINK_CHANGE evnet from PF by Virtchnnl.
*/
switch (vf->link_speed) {
case 10:
new_link.link_speed = ETH_SPEED_NUM_10M;
break;
case 100:
new_link.link_speed = ETH_SPEED_NUM_100M;
break;
case 1000:
new_link.link_speed = ETH_SPEED_NUM_1G;
break;
case 10000:
new_link.link_speed = ETH_SPEED_NUM_10G;
break;
case 20000:
new_link.link_speed = ETH_SPEED_NUM_20G;
break;
case 25000:
new_link.link_speed = ETH_SPEED_NUM_25G;
break;
case 40000:
new_link.link_speed = ETH_SPEED_NUM_40G;
break;
case 50000:
new_link.link_speed = ETH_SPEED_NUM_50G;
break;
case 100000:
new_link.link_speed = ETH_SPEED_NUM_100G;
break;
default:
new_link.link_speed = ETH_SPEED_NUM_NONE;
break;
}
new_link.link_duplex = ETH_LINK_FULL_DUPLEX;
new_link.link_status = vf->link_up ? ETH_LINK_UP :
ETH_LINK_DOWN;
new_link.link_autoneg = !(dev->data->dev_conf.link_speeds &
ETH_LINK_SPEED_FIXED);
if (rte_atomic64_cmpset((uint64_t *)&dev->data->dev_link,
*(uint64_t *)&dev->data->dev_link,
*(uint64_t *)&new_link) == 0)
return -1;
return 0;
}
[3]
struct rte_eth_link {
uint32_t link_speed; /**< ETH_SPEED_NUM_ */
uint16_t link_duplex : 1; /**< ETH_LINK_[HALF/FULL]_DUPLEX */
uint16_t link_autoneg : 1; /**< ETH_LINK_[AUTONEG/FIXED] */
uint16_t link_status : 1; /**< ETH_LINK_[DOWN/UP] */
} __rte_aligned(8); /**< aligned for atomic64 read/write */
