[Bug ipa/96059] New: ICE: in remove_unreachable_nodes, at ipa.c:575 with -fdevirtualize-at-ltrans

["krzysztof.a.nowicki+gcc at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96059

            Bug ID: 96059
           Summary: ICE: in remove_unreachable_nodes, at ipa.c:575 with
                    -fdevirtualize-at-ltrans
           Product: gcc
           Version: 10.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ipa
          Assignee: unassigned at gcc dot gnu.org
          Reporter: krzysztof.a.nowicki+gcc at gmail dot com
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

When building the ktexteditor-5.71 from the KDE Frameworks with LTO enabled I'm
seeing an ICE when linking libKF5TextEditor.so:

during IPA pass: inline
lto1: internal compiler error: in remove_unreachable_nodes, at ipa.c:575
0xa7e802 symbol_table::remove_unreachable_nodes(_IO_FILE*)
        /var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/ipa.c:575
0x19cb14f ipa_inline
       
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/ipa-inline.c:2696
0x19cb702 execute
       
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/ipa-inline.c:3091
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://bugs.gentoo.org/> for instructions.

GDB backtrace:

#0  internal_error (gmsgid=gmsgid@entry=0x233d39a "in %s, at %s:%d") at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/diagnostic.c:1706
#1  0x0000000001b09d9a in fancy_abort (file=file@entry=0x1c07468
"/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/ipa.c",
line=line@entry=575, function=function@entry=0x1c073fc
"remove_unreachable_nodes")
    at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/diagnostic.c:1778
#2  0x0000000000a7e803 in symbol_table::remove_unreachable_nodes
(this=0x7ffff6e8d100, file=0x0) at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/ipa.c:577
#3  0x00000000019cb150 in ipa_inline () at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/ipa-inline.c:2696
#4  0x00000000019cb703 in (anonymous namespace)::pass_ipa_inline::execute
(this=<optimized out>) at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/ipa-inline.c:3091
#5  0x0000000000c047a3 in execute_one_pass (pass=pass@entry=0x3edc4a0) at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/passes.c:2502
#6  0x0000000000c06052 in execute_ipa_pass_list (pass=0x3edc4a0) at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/passes.c:2929
#7  0x00000000006442ac in do_whole_program_analysis () at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/context.h:48
#8  0x00000000006445f7 in lto_main () at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/lto/lto.c:637
#9  0x0000000000d1844d in compile_file () at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/toplev.c:458
#10 0x0000000000d1b891 in do_compile () at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/toplev.c:2277
#11 0x0000000000d1c1fd in toplev::main (this=this@entry=0x7fffffffd7f6,
argc=<optimized out>, argc@entry=36, argv=<optimized out>,
argv@entry=0x7fffffffd8f8) at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/toplev.c:2416
#12 0x0000000001ae9eeb in main (argc=36, argv=0x7fffffffd8f8) at
/var/tmp/portage/sys-devel/gcc-10.1.0-r1/work/gcc-10.1.0/gcc/main.c:39

CXXFLAGS: -O2 -pipe -march=skylake -flto=3 -fgraphite-identity
-floop-nest-optimize -fdevirtualize-at-ltrans -fipa-pta
-fno-semantic-interposition

The ICE goes away after removing the -fdevirtualize-at-ltrans flag.

The backtrace above was generated from Gentoo-patched version of GCC, but it's
also reproducible with a vanilla version compiled directly from sources.

This is a regression since GCC 10 (reproducible also with latest GCC 11 trunk),
as GCC 9 compiles this package with the same CXXFLAGS without issues.

I've bisected the regression to the following commit:

commit 2bc2379be5c98d34ecbb347b2abf059aa6d94499
Author: Jan Hubicka <jh@suse.cz>
Date:   Mon Nov 4 20:39:52 2019 +0100

    ipa-inline-transform.c: Include ipa-utils.h


            * ipa-inline-transform.c: Include ipa-utils.h
            (inline_call): Set thunk_expansion flag.
            * ipa-utils.h (thunk_expansion): Declare.
            * ipa-devirt.c (thunk_expansion): New global var.
            (devirt_node_removal_hook): Do not invalidate cache while
            doing thunk expansion.

    From-SVN: r277789

Maybe the "HACK alert" in the commit diff has something to do with it :)