https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116357
Bug ID: 116357
Summary: The item's address of the array is not correct if
aligned is used
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: alwin.zhang at sap dot com
Target Milestone: ---
Created attachment 58922
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58922&action=edit
Test code to reproduce the issue.
The item's address of the array is not correct if aligned is used on the type
of array item. The debug version (without gcc optimization) doesn't have the
issue, but if we enable optimization like -O1/O2, all the items of the array
are using the same address.
Attached file is the test code to reproduce the issue. This issue could be
reproduced from gcc 7.1 to latest 14.2.
>From following asm code we can see that the items of the array are using the
same address.
C code is -
------------------
u64 * l1;
u64 * l2;
void align_test(chn_t * p)
{
l1 = (u64*)(&(p->lock[0]));
l2 = (u64*)(&(p->lock[99]));
printf("addr is [0]=%llu, [99]=%llu\n", l1, l2);
}
------------------
asm code is -
------------------
align_test:
sub rsp, 8
mov rsi, rdi
mov QWORD PTR l1[rip], rdi
mov QWORD PTR l2[rip], rdi
mov rdx, rdi
mov edi, OFFSET FLAT:.LC0
mov eax, 0
call printf
add rsp, 8
ret
------------------
Please download the test code and compile with gcc optimization like -O2 to
check the issue.
Bug 65204 appears to be the same as this issue, but it's resolved.
Thanks!
