https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105453
Bug ID: 105453
Summary: wrong choice of source in load instruction
Product: gcc
Version: 11.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: absoler at smail dot nju.edu.cn
Target Milestone: ---
Created attachment 52917
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52917&action=edit
concurrent case
Here's the code:
int g_6[2] = {0x67D50F82L,0x67D50F82L};
int g_10 = 0L;
int func_1(void)
{
int *l_9 = &g_10;
(*l_9) = (g_6[0]);
if (g_6[1])
{
return g_10;
}
return 1;
}
and on gcc-11.3.0 with -O1 option, the assembly code are as follows:
0x000000000040114d <+0>: mov 0x2eed(%rip),%eax # 0x404040
<g_6>
0x0000000000401153 <+6>: mov %eax,0x2ef3(%rip) # 0x40404c
<g_10>
0x0000000000401159 <+12>: cmpl $0x0,0x2ee4(%rip) # 0x404044
<g_6+4>
0x0000000000401160 <+19>: mov $0x1,%eax
0x0000000000401165 <+24>: cmovne 0x2ed4(%rip),%eax # 0x404040
<g_6>
0x000000000040116c <+31>: retq
yes, it assert that g_10 = g_6[0] and this may cause problem in concurrent
environment. The case files uploaded can show that the generated code is the
same as above in an environment that g_6 may be modified by other thread.
