> Am 21.07.2026 um 16:45 schrieb Kyrylo Tkachov <[email protected]>:
>
>
>
>> On 21 Jul 2026, at 16:05, Richard Biener <[email protected]> wrote:
>>
>>> On Tue, 21 Jul 2026, [email protected] wrote:
>>>
>>> From: Kyrylo Tkachov <[email protected]>
>>>
>>> create_tmp_var_raw marks a replacement declaration as ignored. At -O0,
>>> this can change use_register_for_decl from memory for the original user
>>> declaration to a pseudo for the replacement. A partition can already own
>>> memory from a parameter default definition, which then makes set_rtl reject
>>> that memory for another name in the partition.
>>>
>>> If the replacement would use a register, copy DECL_IGNORED_P so it keeps the
>>> storage choice made during coalescing. Keep declarations that already use
>>> memory unchanged. Add a checking assertion for the memory invariant.
>>>
>>> Bootstrapped and tested on aarch64-none-linux-gnu and x86_64-linux.
>>>
>>> Ok for trunk?
>>> Thanks,
>>> Kyrill
>>>
>>> gcc/ChangeLog:
>>>
>>> PR middle-end/126341
>>> * tree-outof-ssa.cc (split_overlapping_partition_decls): Preserve
>>> DECL_IGNORED_P. Check that the replacement uses memory.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>> PR middle-end/126341
>>> * gcc.dg/pr126341.c: New test.
>>>
>>> Signed-off-by: Kyrylo Tkachov <[email protected]>
>>> ---
>>> gcc/testsuite/gcc.dg/pr126341.c | 53 +++++++++++++++++++++++++++++++++
>>> gcc/tree-outof-ssa.cc | 3 ++
>>> 2 files changed, 56 insertions(+)
>>> create mode 100644 gcc/testsuite/gcc.dg/pr126341.c
>>>
>>> diff --git a/gcc/testsuite/gcc.dg/pr126341.c
>>> b/gcc/testsuite/gcc.dg/pr126341.c
>>> new file mode 100644
>>> index 00000000000..76ed1d889e4
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.dg/pr126341.c
>>> @@ -0,0 +1,53 @@
>>> +/* { dg-do compile { target bitint575 } } */
>>> +/* { dg-options "-fnon-call-exceptions -ftree-coalesce-vars" } */
>>> +/* { dg-prune-output "division by zero" } */
>>> +
>>> +/* PR middle-end/126341 */
>>> +
>>> +#define N 0x200000000uwb
>>> +#define DIV0 (1 / 0)
>>> +
>>> +struct {
>>> + char j[8];
>>> +} k;
>>> +char l;
>>> +int m, p, q, r;
>>> +long n;
>>> +_Complex o;
>>> +int s;
>>> +_BitInt (256) aa;
>>> +
>>> +void
>>> +foo (_BitInt (8) t)
>>> +{
>>> + int ah, ai, aj = 1, ak, al = 1, am = 1, an = 1, ao = 1, ap = 1, aq =
>>> DIV0;
>>> + int ar = 1, as = 1, at, au = DIV0;
>>> + int av = 1;
>>> + _BitInt (7) c = ak--;
>>> + char aw = 1, ax = 1, ay = 1, az = 1, a = 1, d = 1, e = 1;
>>> + int bfbg = 1, bh = 1, bi = p += ai -= __sync_add_and_fetch (&s, 1);
>>> + int bj;
>>> + int bk, blbm = 1, bt = 1, bu = 1, bv = __atomic_or_fetch (&aa, 1, 1);
>>> + int bn = 1, bobp = 1, br = 1, bs = 1;
>>> + unsigned b, cc;
>>> + char cf, ce;
>>> +
>>> + if (bj)
>>> + goto ca;
>>> + b = 1, cc = 1;
>>> + for (;;);
>>> + ce = q;
>>> + cf = o ? 1
>>> + :
>>> + __builtin_stdc_rotate_left (__builtin_stdc_rotate_left
>>> + (c - 0x3bfuwb, br), n & 1) ? 3 : 3;
>>> + 1 +
>>> + az & 1 | N << -az & m | ((az & 1 | N) << -az & 1 ? 0 : 7u) & 1 |
>>> + ((az & 1 | N) - az & m | az & 1 | N) < 7 > -c & 1;
>>> +ca:
>>> + s %= __builtin_stdc_rotate_left (cc, ah);
>>> + at /= r ^= ({ __auto_type cg = 0; __auto_type ch = 0; 0; });
>>> +
>>> + long ci = bk % cf;
>>> + _BitInt (8) cj = l ? t : k.j[3];
>>> +}
>>> diff --git a/gcc/tree-outof-ssa.cc b/gcc/tree-outof-ssa.cc
>>> index 918dbbedde3..8a32dab42a5 100644
>>> --- a/gcc/tree-outof-ssa.cc
>>> +++ b/gcc/tree-outof-ssa.cc
>>> @@ -1101,6 +1101,9 @@ split_overlapping_partition_decls (var_map map)
>>> continue;
>>>
>>> tree nvar = create_tmp_var_raw (TREE_TYPE (var));
>>> + if (use_register_for_decl (nvar))
>>
>> I think this warrants a comment in the code.
>>
>> OK with that change.
>
> Thanks, I’ve pushed the fix as g:7459f9136500bfb881902834d56fb110b77909f2 .
> I propose to back port it together with the previous out-of-ssa wrong-code
> fix for 16.2 by the end of the week if no fallout occurs?
Sounds good to me
Richard
> Kyrill
>
>
>> Richard.
>>
>>> + DECL_IGNORED_P (nvar) = DECL_IGNORED_P (var);
>>> + gcc_checking_assert (!use_register_for_decl (nvar));
>>> DECL_CONTEXT (nvar) = DECL_CONTEXT (var);
>>> DECL_SOURCE_LOCATION (nvar) = DECL_SOURCE_LOCATION (var);
>>> SET_DECL_ALIGN (nvar, DECL_ALIGN (var));
>>>
>>
>> --
>> Richard Biener <[email protected]>
>> SUSE Software Solutions Germany GmbH,
>> Frankenstrasse 146, 90461 Nuernberg, Germany;
>> GF: Jochen Jaser, Andrew McDonald, Abhinav Puri; (HRB 36809, AG Nuernberg)
>
