[Bug middle-end/112668] New: ICE in bitintlower0 while compiling bitint-42.c

[Bug middle-end/112668] New: ICE in bitintlower0 while compiling bitint-42.c

[fkastl at suse dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112668

            Bug ID: 112668
           Summary: ICE in bitintlower0 while compiling bitint-42.c
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fkastl at suse dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu

Compiling the bitint-42.c file from testsuite:

gcc -fnon-call-exceptions src/gcc/testsuite/gcc.dg/torture/bitint-42.c

results in:

during GIMPLE pass: bitintlower0       
/home/fkastl/gcc/src/gcc/testsuite/gcc.dg/torture/bitint-42.c: In function
‘main’:       
/home/fkastl/gcc/src/gcc/testsuite/gcc.dg/torture/bitint-42.c:50:1: internal
compiler error: Segmentation fault       
   50 | main ()       
      | ^~~~       
0x100d5bf crash_signal       
        ../../src/gcc/toplev.cc:316    
0x10d607e add_phi_arg(gphi*, tree_node*, edge_def*, unsigned int)       
        ../../src/gcc/tree-phinodes.cc:358    
0x1e22438 prepare_data_in_out       
        ../../src/gcc/gimple-lower-bitint.cc:1036    
0x1e323c6 handle_load       
        ../../src/gcc/gimple-lower-bitint.cc:1695    
0x1e323c6 handle_stmt       
        ../../src/gcc/gimple-lower-bitint.cc:1876    
0x1e33bc4 lower_mergeable_stmt       
        ../../src/gcc/gimple-lower-bitint.cc:2406    
0x1e3811d lower_stmt       
        ../../src/gcc/gimple-lower-bitint.cc:5216    
0x1e39dbd gimple_lower_bitint       
        ../../src/gcc/gimple-lower-bitint.cc:6296    
Please submit a full bug report, with preprocessed source.       
Please include the complete backtrace with any bug report.       
See <https://gcc.gnu.org/bugs/> for instructions.

Compiler configuration (nothing non-standard):

Target: x86_64-pc-linux-gnu       
Configured with: ../src/configure --enable-checking --disable-bootstrap
--disable-libsanitizer : (reconfigured) ../src/configure --enable-checking
--disable-bootstrap --disable-libsanitizer : (reconfigured) ../src/configure
--enable-checking --disable-bootstrap --disable-libsanitizer
--enable-languages=c,c++,fortran,lto,objc --no-create --no-recursion   
Thread model: posix       
Supported LTO compression algorithms: zlib zstd       
gcc version 14.0.0 20231122 (experimental) (GCC)

[Bug middle-end/112668] ICE in bitintlower0 while compiling bitint-42.c

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112668

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Reduced:
/* PR middle-end/112668 */
/* { dg-do compile { target bitint } } */
/* { dg-options "-std=c23 -fnon-call-exceptions" } */

#if __BITINT_MAXWIDTH__ >= 495
struct T495 { _BitInt(495) a : 2; unsigned _BitInt(495) b : 471; _BitInt(495) c
: 2; };
extern void foo (struct T495 *r495);

int
bar (void)
{
  struct T495 r495[12];
  foo (r495);
  for (int i = 0; i < 12; ++i)
    if (r495[i].b != 0uwb)
      return 1;
  return 0;
}
#endif

[Bug middle-end/112668] ICE in bitintlower0 while compiling bitint-42.c

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112668

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
No loop is needed:
/* PR middle-end/112668 */
/* { dg-do compile { target bitint } } */
/* { dg-options "-std=c23 -fnon-call-exceptions" } */

#if __BITINT_MAXWIDTH__ >= 495
struct T495 { _BitInt(495) a : 2; unsigned _BitInt(495) b : 471; _BitInt(495) c
: 2; };
extern void foo (struct T495 *r495);

unsigned _BitInt(495)
bar (int i)
{
  struct T495 r495[12];
  foo (r495);
  return r495[i].b;
}
#endif

[Bug middle-end/112668] ICE in bitintlower0 while compiling bitint-42.c

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112668

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2023-11-22
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever confirmed|0                           |1

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 56665
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56665&action=edit
gcc14-pr112668.patch

Untested fix.

[Bug middle-end/112668] ICE in bitintlower0 while compiling bitint-42.c

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112668

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:9a96a9e45b421436ca93efadba0f1901f12fb6c0

commit r14-5815-g9a96a9e45b421436ca93efadba0f1901f12fb6c0
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Nov 24 08:54:40 2023 +0100

    lower-bitint: Fix up -fnon-call-exceptions bit-field load lowering
[PR112668]

    As the following testcase shows, there are some bugs in the
    -fnon-call-exceptions bit-field load lowering.  In particular, there
    is a case where we want to emit a load early in the initialization
    (before m_init_gsi) and because that load might throw exception, need
    to split block after the load so that it has an EH edge.
    Now, across this splitting, we have m_init_gsi, save_gsi (something
    we put back into m_gsi afterwards) statement iterators and m_preheader_bb
    which is used to determine the pre-header edge of a loop (if any).
    As the testcase shows, both of these statement iterators and m_preheader_bb
    as well need adjustments if the block was split.  If the stmt iterators
    refer to a statement, they need to be updated so that if the statement is
    in the bb after the split gsi_bb and gsi_seq is updated, otherwise they
    ought to be the start of the new (second) bb.
    Similarly, m_preheader_bb should be updated to the second bb if it was
    the first before.  Other spots where we insert something before m_init_gsi
    don't split blocks in there and are fine.

    The m_gsi iterator is normal iterator to insert statements before it,
    so gsi_end_p means insert statements at the end of basic block.
    m_init_gsi is on the other side an iterator after which statements should
be
    inserted (so gsi_end_p means insert statements at the start of basic block
    after labels), but the whole pass is written for insertion of statements
before
    iterators, so when in 3 spots it wants to insert something after
m_init_gsi,
    it saves current iterator to save_gsi and sets m_gsi to gsi_after_labels
    if m_init_gsi was gsi_end_p, or to the next statement.  But it actually
wasn't
    updating m_init_gsi back when switching to normal iterator, this patch
changes
    that such that further statements after m_init_gsi will appear after the
    set of statements inserted before m_init_gsi.

    Finally, the pass had a couple of places where it wanted to create a
gsi_end_p
    iterator for a particular basic block, instead of doing
    m_gsi = gsi_last_bb (bb); if (!gsi_end_p (m_gsi)) gsi_next (&m_gsi);
    the pass now uses new m_gsi = gsi_end_bb (bb) function.

    2023-11-24  Jakub Jelinek  <jakub@redhat.com>

            PR middle-end/112668
            * gimple-iterator.h (gsi_end, gsi_end_bb): New inline functions.
            * gimple-lower-bitint.cc (bitint_large_huge::handle_cast): After
            temporarily adding statements after m_init_gsi, update m_init_gsi
            such that later additions after it will be after the added
statements.
            (bitint_large_huge::handle_load): Likewise.  When splitting
            gsi_bb (m_init_gsi) basic block, update m_preheader_bb if needed
            and update saved m_gsi as well if needed.
            (bitint_large_huge::lower_mergeable_stmt,
            bitint_large_huge::lower_comparison_stmt,
            bitint_large_huge::lower_mul_overflow,
            bitint_large_huge::lower_bit_query): Use gsi_end_bb.

            * gcc.dg/bitint-40.c: New test.

[Bug middle-end/112668] ICE in bitintlower0 while compiling bitint-42.c

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112668

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Should be fixed now.