[Bug target/114993] New: ICE when using bpf-unknown-g++

[Bug target/114993] New: ICE when using bpf-unknown-g++

[dkm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114993

            Bug ID: 114993
           Summary: ICE when using bpf-unknown-g++
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dkm at gcc dot gnu.org
  Target Milestone: ---

bpf-unknown-none-g++ always ICE when using -g:

https://c.godbolt.org/z/EabsM3xjq

Using -g0 builds fine.

```
int square(int num) {
    return num * num;
}
```

Using built-in specs.
COLLECT_GCC=/opt/compiler-explorer/bpf/gcc-trunk/bpf-unknown-none/bin/bpf-unknown-none-g++
Target: bpf-unknown-none
Configured with: /opt/.build/bpf-unknown-none/src/gcc/configure
--build=x86_64-build_pc-linux-gnu --host=x86_64-build_pc-linux-gnu
--target=bpf-unknown-none
--prefix=/opt/compiler-explorer/bpf/gcc-trunk-20240508/bpf-unknown-none
--exec_prefix=/opt/compiler-explorer/bpf/gcc-trunk-20240508/bpf-unknown-none
--with-local-prefix=/opt/compiler-explorer/bpf/gcc-trunk-20240508/bpf-unknown-none/bpf-unknown-none
--with-headers=/opt/compiler-explorer/bpf/gcc-trunk-20240508/bpf-unknown-none/bpf-unknown-none/include
--with-newlib --enable-threads=no --disable-shared
--with-pkgversion='crosstool-NG UNKNOWN' --disable-__cxa_atexit
--disable-libgomp --disable-libmudflap --disable-libmpx --disable-libssp
--disable-libquadmath --disable-libquadmath-support --disable-libstdcxx-verbose
--disable-libstdcxx --with-gmp=/opt/.build/bpf-unknown-none/buildtools
--with-mpfr=/opt/.build/bpf-unknown-none/buildtools
--with-mpc=/opt/.build/bpf-unknown-none/buildtools
--with-isl=/opt/.build/bpf-unknown-none/buildtools --enable-lto
--enable-target-optspace --disable-nls --disable-multilib
--enable-languages=c,c++
Thread model: single
Supported LTO compression algorithms: zlib zstd
gcc version 15.0.0 20240507 (experimental) (crosstool-NG UNKNOWN) 
COLLECT_GCC_OPTIONS='-fdiagnostics-color=always' '-g' '-o' '/app/output.s' '-S'
'-v' '-dumpdir' '/app/'

/opt/compiler-explorer/bpf/gcc-trunk-20240508/bpf-unknown-none/libexec/gcc/bpf-unknown-none/15.0.0/cc1plus
-quiet -v <source> -quiet -dumpdir /app/ -dumpbase output.cpp -dumpbase-ext
.cpp -g -version -fdiagnostics-color=always -o /app/output.s
GNU C++17 (crosstool-NG UNKNOWN) version 15.0.0 20240507 (experimental)
(bpf-unknown-none)
        compiled by GNU C version 14.1.0, GMP version 6.2.1, MPFR version
4.2.1, MPC version 1.3.1, isl version isl-0.24-GMP

GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
ignoring nonexistent directory
"/opt/compiler-explorer/bpf/gcc-trunk-20240508/bpf-unknown-none/lib/gcc/bpf-unknown-none/15.0.0/../../../../bpf-unknown-none/include/c++/15.0.0"
ignoring nonexistent directory
"/opt/compiler-explorer/bpf/gcc-trunk-20240508/bpf-unknown-none/lib/gcc/bpf-unknown-none/15.0.0/../../../../bpf-unknown-none/include/c++/15.0.0/bpf-unknown-none"
ignoring nonexistent directory
"/opt/compiler-explorer/bpf/gcc-trunk-20240508/bpf-unknown-none/lib/gcc/bpf-unknown-none/15.0.0/../../../../bpf-unknown-none/include/c++/15.0.0/backward"
#include "..." search starts here:
#include <...> search starts here:

/opt/compiler-explorer/bpf/gcc-trunk-20240508/bpf-unknown-none/lib/gcc/bpf-unknown-none/15.0.0/include

/opt/compiler-explorer/bpf/gcc-trunk-20240508/bpf-unknown-none/lib/gcc/bpf-unknown-none/15.0.0/include-fixed

/opt/compiler-explorer/bpf/gcc-trunk-20240508/bpf-unknown-none/lib/gcc/bpf-unknown-none/15.0.0/../../../../bpf-unknown-none/sys-include

/opt/compiler-explorer/bpf/gcc-trunk-20240508/bpf-unknown-none/lib/gcc/bpf-unknown-none/15.0.0/../../../../bpf-unknown-none/include
End of search list.
Compiler executable checksum: ed25500f957a8d770dd6c33cfdac0a0b
during RTL pass: final
<source>: In function 'int square(int)':
<source>:4:1: internal compiler error: Segmentation fault
    4 | }
      | ^
0x1e609e8 internal_error(char const*, ...)
        ???:0
0x16d7834 btf_ext_add_string
        ???:0
0x16d7b19 btf_add_func_info_for
        ???:0
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
Compiler returned: 1

[Bug target/114993] ICE when using bpf-unknown-g++

[dkm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114993

--- Comment #1 from Marc Poulhiès <dkm at gcc dot gnu.org> ---
After discussing on IRC, C++ (or anything != C) is not supported by BPF.
The fix is probably to display an error when using anything else than the C FE.

The Rust FE gives another error:
https://c.godbolt.org/z/TeWa3cshd

bpf-unknown-gcc: warning: <source>: linker input file unused because linking
not done

Not sure why it does not even use crab1 in this case.

[Bug target/114993] ICE when using bpf-unknown-g++

[dkm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114993

Marc Poulhiès <dkm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |jemarch at gcc dot gnu.org

--- Comment #2 from Marc Poulhiès <dkm at gcc dot gnu.org> ---
After discussing on IRC, C++ (or anything != C) is not supported by BPF.
The fix is probably to display an error when using anything else than the C FE.

The Rust FE gives another error:
https://c.godbolt.org/z/TeWa3cshd

bpf-unknown-gcc: warning: <source>: linker input file unused because linking
not done

Not sure why it does not even use crab1 in this case.

[Bug target/114993] ICE when using bpf-unknown-g++

[dkm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114993

--- Comment #3 from Marc Poulhiès <dkm at gcc dot gnu.org> ---
The gccrs cross compiler is not working because of the missing cargo/rustc dep,
disabling the frontend, so not a real issue.