[Bug c/78580] New: Segfault in gcc with multilib (-m32) and -ffixed-*

["bugs-gcc at rationality dot eu" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78580

            Bug ID: 78580
           Summary: Segfault in gcc with multilib (-m32) and -ffixed-*
           Product: gcc
           Version: 6.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bugs-gcc at rationality dot eu
  Target Milestone: ---

Created attachment 40187
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40187&action=edit
Minimized testcase exhibiting the issue

First off: the bug sounds slightly related to #68701, but that one is reported
as RESOLVED FIXED and seems to be far more specific and tied to -ffixed-ebx.
Sorry if this still is a duplicate.

The issue:

The compilation is terminated with an `internal compiler error: Segmentation
fault` when trying to compile the attached testcase (foobar-min.0x.fixed.i).
The segfault only happens when the code is compiled with `-ffixed-ebx -m32`.

Compiler output with my distro-gcc (I'm using ArchLinux):

> $ /tmp: gcc -v -ffixed-ebx -m32 -Wall -Wextra -Werror -c foobar-min.0x.fixed.i -o foobar.o
> Using built-in specs.
> COLLECT_GCC=/usr/bin/gcc
> Target: x86_64-pc-linux-gnu
> Configured with: /build/gcc-multilib/src/gcc/configure --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-shared --enable-threads=posix --enable-libmpx --with-system-zlib --with-isl --enable-__cxa_atexit --disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch --disable-libssp --enable-gnu-unique-object --enable-linker-build-id --enable-lto --enable-plugin --enable-install-libiberty --with-linker-hash-style=gnu --enable-gnu-indirect-function --enable-multilib --disable-werror --enable-checking=release
> Thread model: posix
> gcc version 6.2.1 20160830 (GCC) 
> COLLECT_GCC_OPTIONS='-B' '/usr/lib/hardening-wrapper/bin' '-fPIE' '-fstack-check=specific' '-fstack-protector-strong' '-v' '-ffixed-ebx' '-m32' '-Wall' '-Wextra' '-Werror' '-c' '-o' 'foobar.o' '-mtune=generic' '-march=x86-64'
>  /usr/lib/gcc/x86_64-pc-linux-gnu/6.2.1/cc1 -fpreprocessed foobar-min.0x.fixed.i -quiet -dumpbase foobar-min.0x.fixed.i -m32 -mtune=generic -march=x86-64 -auxbase-strip foobar.o -Wall -Wextra -Werror -version -fPIE -fstack-check=specific -fstack-protector-strong -ffixed-ebx -o /tmp/ccPviy6Q.s
> GNU C11 (GCC) version 6.2.1 20160830 (x86_64-pc-linux-gnu)
> 	compiled by GNU C version 6.2.1 20160830, GMP version 6.1.1, MPFR version 3.1.4-p1, MPC version 1.0.3, isl version 0.15
> warning: MPFR header version 3.1.4-p1 differs from library version 3.1.5.
> GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
> GNU C11 (GCC) version 6.2.1 20160830 (x86_64-pc-linux-gnu)
> 	compiled by GNU C version 6.2.1 20160830, GMP version 6.1.1, MPFR version 3.1.4-p1, MPC version 1.0.3, isl version 0.15
> warning: MPFR header version 3.1.4-p1 differs from library version 3.1.5.
> GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
> Compiler executable checksum: 8532c1c062237a3d67fa873459bd34cd
> foobar-min.0x.fixed.i: In function ‘StartOS’:
> foobar-min.0x.fixed.i:4:2: internal compiler error: Segmentation fault
>   int StartOS(signed char f) { return f; }
>   ^~~

To verify, I've built gcc-svn, revision 242936. PATH was modified to point to
the ./build/build/gcc/ directory. Output:

> $ ./gcc/build/gcc/xgcc -v -ffixed-ebx -m32 -Wall -Wextra -Werror -c foobar-min.0x.fixed.i -o foobar.o
> Using built-in specs.
> COLLECT_GCC=/srv/scratch/fo21qixo/gcc/build/gcc/xgcc
> Target: x86_64-pc-linux-gnu
> Configured with: ../gcc-svn/configure --enable-languages=c,c++,lto --enable-shared --enable-threads=posix --enable-libmpx --with-isl --enable-__cxa_atexit --disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch --disable-libssp --enable-gnu-unique-object --enable-linker-build-id --enable-lto --enable-plugin --enable-install-libiberty --with-linker-hash-style=gnu --enable-gnu-indirect-function --enable-multilib --disable-werror --enable-checking=release
> Thread model: posix
> gcc version 7.0.0 20161128 (experimental) (GCC)
> COLLECT_GCC_OPTIONS='-v' '-ffixed-ebx' '-m32' '-Wall' '-Wextra' '-Werror' '-c' '-o' 'foobar.o' '-mtune=generic' '-march=x86-64'
>  cc1 -fpreprocessed foobar-min.0x.fixed.i -quiet -dumpbase foobar-min.0x.fixed.i -m32 -mtune=generic -march=x86-64 -auxbase-strip foobar.o -Wall -Wextra -Werror -version -ffixed-ebx -o /tmp/ccQKFQbs.s
> GNU C11 (GCC) version 7.0.0 20161128 (experimental) (x86_64-pc-linux-gnu)
>         compiled by GNU C version 7.0.0 20161128 (experimental), GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3, isl version 0.15
> GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
> GNU C11 (GCC) version 7.0.0 20161128 (experimental) (x86_64-pc-linux-gnu)
>         compiled by GNU C version 7.0.0 20161128 (experimental), GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3, isl version 0.15
> GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
> Compiler executable checksum: 2801dc23875b542e7454fd26ef7c7556
> foobar-min.0x.fixed.i: In function ‘StartOS’:
> foobar-min.0x.fixed.i:4:2: internal compiler error: Segmentation fault
>   int StartOS(signed char f) { return f; }
>   ^~~
> 0x9b7faf crash_signal
>         ../../gcc-svn/gcc/toplev.c:333
> 0x635708 bitmap_find_bit
>         ../../gcc-svn/gcc/bitmap.c:510
> 0x635708 bitmap_set_bit(bitmap_head*, int)
>         ../../gcc-svn/gcc/bitmap.c:600
> 0x845452 update_bad_spill_attribute
>         ../../gcc-svn/gcc/ira-build.c:2651
> 0x84b84f ira_build()
>         ../../gcc-svn/gcc/ira-build.c:3425
> 0x843246 ira
>         ../../gcc-svn/gcc/ira.c:5217
> 0x843246 execute
>         ../../gcc-svn/gcc/ira.c:5522

Please notify me if you need any further information.

N.B.: The testcase was preprocessed with `delta`. I think this is what you
want. If you however require a more complete input set, I would be happy to
provide one. It was extracted from the Open Source Trampoline OS.