https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90197
Bug ID: 90197
Summary: [8/9 Regression] Cannot step through simple loop at -O
-g
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: debug
Assignee: unassigned at gcc dot gnu.org
Reporter: rsandifo at gcc dot gnu.org
Target Milestone: ---
Compiling:
__attribute__((noipa))
void
test (unsigned int *dst, unsigned int base, int count)
{
for (int i = 0; i < count; ++i, base += 15)
dst[i] = base;
}
int
main (void)
{
unsigned int dst[100];
test (dst, 0x4000, 100);
}
with -O -g and launching with recent gdb trunk (and stock gdb):
(gdb) break test
Breakpoint 1 ...
(gdb) run
Starting program: ...
Breakpoint 1, test ...
5 for (int i = 0; i < count; ++i, base += 15)
(gdb) next
6 dst[i] = base;
(gdb) next
__libc_start_main (main=...
i.e. it isn't possible to step through each iteration of the loop. With gcc 7
this worked even for -O2 -g.
The test works with -O -fno-tree-ch -g (and thus also with -Og). For -O2
-fno-tree-ch -g we get:
(gdb) break test
Breakpoint 1 ...
(gdb) run
Starting program: ...
Breakpoint 1, test ...
5 for (int i = 0; i < count; ++i, base += 15)
(gdb) next
__libc_start_main ...
With just -O2 -g we get the same as for -O -g.
A breakpoint on the loop body (line 6) hits for each iteration of the loop
though.
As you can tell, this isn't my area, so I'm not sure whether it's actually a
gdb bug (or a dup).
