[Bug bootstrap/103974] New: [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[Bug bootstrap/103974] New: [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[hp at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

            Bug ID: 103974
           Summary: [12 Regression] ICE in ira_flattening building
                    libstdc++ with r12-6415-g01f3e6a40e72
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: build, ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hp at gcc dot gnu.org
                CC: rsandifo at gcc dot gnu.org
  Target Milestone: ---
              Host: x86_64-linux
            Target: cris-elf

Commit r12-6415-g01f3e6a40e72, "[PATCH 27/33] ira: Consider modelling
caller-save allocations as loop spills" caused build to break for cris-elf,
when building the v10 multilib of libstdc++-v3, specifically
v10/libstdc++-v3/src/c++17 floating_to_chars.cc, like so:

libtool: compile:  /tmp/X/gccobj/./gcc/xgcc -shared-libgcc
-B/tmp/X/gccobj/./gcc -nostdinc++ -L/tmp/X/gccobj/cris-elf/v10/libstdc++-v3/src
-L/tmp/X/gccobj/cris-elf/v10/libstdc++-v3/src/.libs
-L/tmp/X/gccobj/cris-elf/v10/libstdc++-v3/libsupc++/.libs -nostdinc
-B/tmp/X/gccobj/cris-elf/v10/newlib/ -isystem
/tmp/X/gccobj/cris-elf/v10/newlib/targ-include -isystem
/tmp/X/gcc/newlib/libc/include -B/tmp/X/gccobj/cris-elf/v10/libgloss/cris
-L/tmp/X/gccobj/cris-elf/v10/libgloss/libnosys -L/tmp/X/gcc/libgloss/cris
-B/tmp/X/pre/cris-elf/bin/ -B/tmp/X/pre/cris-elf/lib/ -isystem
/tmp/X/pre/cris-elf/include -isystem /tmp/X/pre/cris-elf/sys-include -march=v10
-mbest-lib-options -I/tmp/X/gcc/libstdc++-v3/../libgcc
-I/tmp/X/gccobj/cris-elf/v10/libstdc++-v3/include/cris-elf
-I/tmp/X/gccobj/cris-elf/v10/libstdc++-v3/include
-I/tmp/X/gcc/libstdc++-v3/libsupc++ -std=gnu++17 -nostdinc++
-fno-implicit-templates -Wall -Wextra -Wwrite-strings -Wcast-qual -Wabi=2
-fdiagnostics-show-location=once -ffunction-sections -fdata-sections
-frandom-seed=floating_to_chars.lo -fimplicit-templates -g -O2 -march=v10
-mbest-lib-options -c /tmp/X/gcc/libstdc++-v3/src/c++17/floating_to_chars.cc -o
floating_to_chars.o
/tmp/X/gcc/libstdc++-v3/src/c++17/floating_to_chars.cc:561:3: warning:
'std::to_chars_result {anonymous}::to_chars(char*, char*, uint128_t)' defined
but not used [-Wunused-function]
  561 |   to_chars(char* first, char* const last, uint128_t x)
      |   ^~~~~~~~
/tmp/X/gcc/libstdc++-v3/src/c++17/floating_to_chars.cc:554:3: warning: 'int
{anonymous}::get_mantissa_length(ryu::generic128::floating_decimal_128)'
defined but not used [-Wunused-function]
  554 |   get_mantissa_length(const ryu::floating_decimal_128 fd)
      |   ^~~~~~~~~~~~~~~~~~~
/tmp/X/gcc/libstdc++-v3/src/c++17/floating_to_chars.cc:127:5: warning: 'int
{anonymous}::ryu::to_chars(generic128::floating_decimal_128, char*)' defined
but not used [-Wunused-function]
  127 |     to_chars(const floating_decimal_128 v, char* const result)
      |     ^~~~~~~~
during RTL pass: ira
/tmp/X/gcc/libstdc++-v3/src/c++17/floating_to_chars.cc: In function
'std::to_chars_result std::__floating_to_chars_shortest(char*, char*, T,
chars_format) [with T = double]':
/tmp/X/gcc/libstdc++-v3/src/c++17/floating_to_chars.cc:1106:3: internal
compiler error: in ira_flattening, at ira-build.c:3213
 1106 |   }
      |   ^
0x708412 ira_flattening(int, int)
        /tmp/X/gcc/gcc/ira-build.c:3213
0xe7c9b8 ira
        /tmp/X/gcc/gcc/ira.c:5807
0xe7c9b8 execute
        /tmp/X/gcc/gcc/ira.c:6075
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.

I'll attach a brief gdb inspection session.

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[hp at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

--- Comment #1 from Hans-Peter Nilsson <hp at gcc dot gnu.org> ---
Created attachment 52157
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52157&action=edit
gzipped preprocessed (>1 MB) floating_to_chars.ii

Reproduce using the ungzipped file for example like so:

/tmp/X/gccobj/./gcc/cc1plus -fpreprocessed floating_to_chars.ii -march=v10
-quiet -dumpbase floating_to_chars.cc -dumpbase-ext .cc -O2 -std=gnu++17
-frandom-seed=floating_to_chars.lo

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[hp at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

--- Comment #2 from Hans-Peter Nilsson <hp at gcc dot gnu.org> ---
Created attachment 52158
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52158&action=edit
brief gdb inspection session

I had to "rm *ira*.o" and "make all-gcc CXXFLAGS=-g3" and re-start the gdb
session to get a sane inspection context: that's what the "r;
`/tmp/X/gccobj/gcc/cc1plus' has changed; re-reading symbols." is about.  IOW,
business as usual.
BTW, host environment is Debian 11; "gcc --version | head -1" yields
gcc (Debian 10.2.1-6) 10.2.1 20210110

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |12.0
                 CC|                            |pinskia at gcc dot gnu.org

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-01-11

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed, reducing.

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 52159
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52159&action=edit
reduced testcase as much as I could get it

Just needs -O2. It is both a C or C++ testcase even.
I can't reduce it any further really.

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This the steps I needed to reproduce this bug;
mkdir objdir-cris
cd objdir-cris
../configure --target=cris-elf
make -j24 all-gcc
cd gcc
wget https://gcc.gnu.org/bugzilla/attachment.cgi?id=52159
mv attach* t.c
./cc1 t.c -O2

(you can do at this point:
make clean
make -j24 cc1
and get a -O0 built cc1 too if needed).

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

Jeffrey A. Law <law at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |law at gcc dot gnu.org

--- Comment #6 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Richard -- if you need an alternate testcase, reach out -- I've seen what is
likely the same failure on lm32-elf building libgcc.  I have the un-reduced .i
if it'd be useful.

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |rsandifo at gcc dot gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #7 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
(In reply to Jeffrey A. Law from comment #6)
> Richard -- if you need an alternate testcase, reach out -- I've seen what is
> likely the same failure on lm32-elf building libgcc.  I have the un-reduced
> .i if it'd be useful.
It's OK, thanks.  It's a simple “don't do this for old reload”
thing, but first I needed a few attempts to get a full testsuite
run for cris-elf, and then I changed my mind about where exactly
the shortcut should go.  Hope to post a patch later today.

Re one of the things I hit getting the cris-elf testsuite run:
it would be good to make the port rtl-checking clean if possible.
At the moment, building with --enable-checking=yes,extra,rtl
(my usual flags) falls over on cris.c:395:

        insn = as_a <rtx_insn *> XVECEXP (pat, 0, 1);

(missing parens).

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

--- Comment #8 from Jeffrey A. Law <law at gcc dot gnu.org> ---
ACK.  I wandered through the tester this morning, the vast majority of the
current failures are the ira_flattening ICE.  Though I think there's likely one
other ICE in IRA (frv-elf, ICE in check_allocation).

I'll restart everything once you've got your patch ready and file fresh bugs
for anything that's still problematical after the ira_flattening ICE is
resolved.

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Sandiford <rsandifo@gcc.gnu.org>:

https://gcc.gnu.org/g:db8d94a0570dc1f3de10c9eb9fe6e91df804272b

commit r12-6490-gdb8d94a0570dc1f3de10c9eb9fe6e91df804272b
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Tue Jan 11 19:24:59 2022 +0000

    ira: Fix old-reload targets [PR103974]

    The new IRA heuristics would need more work on old-reload targets,
    since flattening needs to be able to undo the cost propagation.
    It's doable, but hardly seems worth it.

    This patch therefore makes all the new calls to
    ira_subloop_allocnos_can_differ_p return false if !ira_use_lra_p.
    The color_pass code that predated the new function (and that was
    the source of ira_subloop_allocnos_can_differ_p) continues to
    behave as before.

    It's a hack, but at least it has the advantage that the new parameter
    would become obviously unused if reload and (!)ira_use_lra_p were
    removed.  The hack should therefore disappear alongside reload.

    gcc/
            PR rtl-optimization/103974
            * ira-int.h (ira_subloop_allocnos_can_differ_p): Take an
            extra argument, default true, that says whether old-reload
            targets should be excluded.
            * ira-color.c (color_pass): Pass false.

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> changed:

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

--- Comment #10 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
Fixed.

[Bug bootstrap/103974] [12 Regression] ICE in ira_flattening building libstdc++ with r12-6415-g01f3e6a40e72

[hp at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974

--- Comment #11 from Hans-Peter Nilsson <hp at gcc dot gnu.org> ---
Yes, thanks for the quick resolution.