https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89588
Bug ID: 89588
Summary: [8/9 Regression] ICE in
unroll_loop_constant_iterations, at loop-unroll.c:498
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Keywords: ice-on-valid-code
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: asolokha at gmx dot com
Target Milestone: ---
gcc-9.0.0-alpha20190303 snapshot (r269357) ICEs when compiling the following
testcase w/ -O1 -fno-tree-loop-optimize:
void
bb (void)
{
int nv;
#pragma GCC unroll 2
for (nv = 0; nv <= 2; nv += 2)
{
}
}
% gcc-9.0.0-alpha20190303 -O1 -fno-tree-loop-optimize -c hiz1wdrt.c
during RTL pass: loop2_unroll
hiz1wdrt.c: In function 'bb':
hiz1wdrt.c:10:1: internal compiler error: in unroll_loop_constant_iterations,
at loop-unroll.c:498
10 | }
| ^
0x65443d unroll_loop_constant_iterations
/var/tmp/portage/sys-devel/gcc-9.0.0_alpha20190303/work/gcc-9-20190303/gcc/loop-unroll.c:498
0x65443d unroll_loops(int)
/var/tmp/portage/sys-devel/gcc-9.0.0_alpha20190303/work/gcc-9-20190303/gcc/loop-unroll.c:295
0xbcbf0f execute
/var/tmp/portage/sys-devel/gcc-9.0.0_alpha20190303/work/gcc-9-20190303/gcc/loop-init.c:584
0xbcbf0f execute
/var/tmp/portage/sys-devel/gcc-9.0.0_alpha20190303/work/gcc-9-20190303/gcc/loop-init.c:571
Even though I cannot reproduce the ICE w/ gcc older than 8, it seems the firing
assert has been there forever. -fno-tree-loop-optimize breaks the designed-in
assumption on this this particular transformation is based.
