https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97357
Bug ID: 97357
Summary: Unable to coalesce ssa_names which are marked as MUST
COALESCE.
Product: gcc
Version: 10.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: qinzhao at gcc dot gnu.org
Target Milestone: ---
the latest gcc10.2.1 failed with SSA corruption on multiple c modules of our
important application on O3. disabling -fsplit-loops cures the failure.
I was able to reduce the huge routine to the following simple one to reproduce
the failure:
#include <setjmp.h>
#include <stdlib.h>
static void * my_malloc (size_t size);
typedef struct glk {
struct glk *nxt;
} glk;
typedef struct Lock
{
glk ByteLock;
} Lock;
static Lock *l, *lk;
void bytelocks(glk *rethead, jmp_buf jb)
{
glk *cur, *cur_lk;
if (( _setjmp (jb)) == 0)
for (cur = &l->ByteLock; cur != ((glk *)0) ; cur = (cur)->nxt)
for (cur_lk = &lk->ByteLock; cur_lk != ((glk *)0); cur_lk =
cur_lk->nxt)
{
glk *retrng;
if(!rethead)
rethead = (glk *) my_malloc (sizeof(glk));
retrng = (glk *) my_malloc (sizeof(glk));
retrng->nxt = rethead;
}
return;
}
/home/qinzhao/Install/latest/bin/gcc -O3 t.c
t.c:4:15: warning: ‘my_malloc’ used but never defined
4 | static void * my_malloc (size_t size);
| ^~~~~~~~~
Unable to coalesce ssa_names 5 and 6 which are marked as MUST COALESCE.
rethead_5(ab) and rethead_6(ab)
during RTL pass: expand
t.c: In function ‘bytelocks’:
t.c:17:6: internal compiler error: SSA corruption
17 | void bytelocks(glk *rethead, jmp_buf jb)
| ^~~~~~~~~
0xbcca65 fail_abnormal_edge_coalesce
../../latest_gcc/gcc/tree-ssa-coalesce.c:1003
0xbcca65 coalesce_partitions
../../latest_gcc/gcc/tree-ssa-coalesce.c:1425
0xbcca65 coalesce_ssa_name(_var_map*)
../../latest_gcc/gcc/tree-ssa-coalesce.c:1755
0xb7d597 remove_ssa_form
../../latest_gcc/gcc/tree-outof-ssa.c:1065
0xb7d597 rewrite_out_of_ssa(ssaexpand*)
../../latest_gcc/gcc/tree-outof-ssa.c:1323
0x6fb5d5 execute
../../latest_gcc/gcc/cfgexpand.c:6352
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
