[Bug middle-end/79242] New: ICE in simplify_subreg, at simplify-rtx.c:6029

["jozef.l at somniumtech dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79242

            Bug ID: 79242
           Summary: ICE in simplify_subreg, at simplify-rtx.c:6029
           Product: gcc
           Version: 7.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jozef.l at somniumtech dot com
  Target Milestone: ---

Created attachment 40588
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40588&action=edit
Preprocessed source to reproduce ICE

The attached preprocessed source (tester.ii) causes an ICE when built using the
current GCC trunk (r244903).

This was discovered trying to build the GCC trunk for the msp430 target with C
and C++ support. The attached source is a reduced test case from
libstdc++-v3/libsupc++/vec.cc which fails to build because of the same ICE.

Target: msp430-elf
Configured with: ../configure --target=msp430-elf --enable-languages=c,c++
gcc version 7.0.1 20170125 (experimental) (GCC)

> msp430-elf-gcc -O0 tester.C                    

tester.C: In function 'std::size_t
__cxxabiv1::{anonymous}::compute_size(std::size_t, std::size_t)':
tester.C:22:41: internal compiler error: in simplify_subreg, at
simplify-rtx.c:6029
       if (element_size && element_count > std::size_t(-1) / element_size)
                           ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0xcbfbd4 simplify_subreg(machine_mode, rtx_def*, machine_mode, unsigned int)
        ../../gcc/simplify-rtx.c:6029
0xcbff38 simplify_gen_subreg(machine_mode, rtx_def*, machine_mode, unsigned
int)
        ../../gcc/simplify-rtx.c:6260
0xca7384 gen_lowpart_general(machine_mode, rtx_def*)
        ../../gcc/rtlhooks.c:47
0x9e256f convert_move(rtx_def*, rtx_def*, int)
        ../../gcc/expr.c:530
0x9e2c39 convert_modes(machine_mode, machine_mode, rtx_def*, int)
        ../../gcc/expr.c:685
0xaf6443 expand_arith_overflow_result_store
        ../../gcc/internal-fn.c:606
0xafb06f expand_mul_overflow
        ../../gcc/internal-fn.c:1887
0xafe1c8 expand_arith_overflow
        ../../gcc/internal-fn.c:2179
0x8d2e27 expand_call_stmt
        ../../gcc/cfgexpand.c:2569
0x8d2e27 expand_gimple_stmt_1
        ../../gcc/cfgexpand.c:3571
0x8d2e27 expand_gimple_stmt
        ../../gcc/cfgexpand.c:3737
0x8d47a1 expand_gimple_basic_block
        ../../gcc/cfgexpand.c:5744
0x8d9d66 execute
        ../../gcc/cfgexpand.c:6357