[Bug tree-optimization/98272] New: [11 Regression] ICE: during GIMPLE pass: switchlower: in decompose, at wide-int.h:984 with -O -fno-tree-forwprop

["zsojka at seznam dot cz" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98272

            Bug ID: 98272
           Summary: [11 Regression] ICE: during GIMPLE pass: switchlower:
                    in decompose, at wide-int.h:984 with -O
                    -fno-tree-forwprop
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu

Created attachment 49758
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49758&action=edit
reduced testcase

Compiler output:
$ x86_64-pc-linux-gnu-gcc -O -fno-tree-forwprop testcase.c 
during GIMPLE pass: switchlower
testcase.c: In function 'foo':
testcase.c:4:1: internal compiler error: in decompose, at wide-int.h:984
    4 | foo (unsigned char uc)
      | ^~~
0x61a4c0 wi::int_traits<generic_wide_int<wide_int_ref_storage<false, false> >
>::decompose(long*, unsigned int, generic_wide_int<wide_int_ref_storage<false,
false> > const&)
        /repo/gcc-trunk/gcc/wide-int.h:984
0xac2400 wi::int_traits<generic_wide_int<wide_int_storage> >::decompose(long*,
unsigned int, generic_wide_int<wide_int_storage> const&)
        /repo/gcc-trunk/gcc/wide-int.h:1933
0xac2400 wide_int_ref_storage<true,
false>::wide_int_ref_storage<generic_wide_int<wide_int_storage>
>(generic_wide_int<wide_int_storage> const&, unsigned int)
        /repo/gcc-trunk/gcc/wide-int.h:1034
0xac2400 generic_wide_int<wide_int_ref_storage<true, false>
>::generic_wide_int<generic_wide_int<wide_int_storage>
>(generic_wide_int<wide_int_storage> const&, unsigned int)
        /repo/gcc-trunk/gcc/wide-int.h:790
0xac2400 bool wi::ltu_p<generic_wide_int<wide_int_storage>,
generic_wide_int<wide_int_storage> >(generic_wide_int<wide_int_storage> const&,
generic_wide_int<wide_int_storage> const&)
        /repo/gcc-trunk/gcc/wide-int.h:1937
0x10aa543 bool wi::lt_p<generic_wide_int<wide_int_storage>,
generic_wide_int<wide_int_storage> >(generic_wide_int<wide_int_storage> const&,
generic_wide_int<wide_int_storage> const&, signop)
        /repo/gcc-trunk/gcc/wide-int.h:1963
0x10aa543 tree_switch_conversion::bit_test_cluster::emit(tree_node*,
tree_node*, tree_node*, basic_block_def*)
        /repo/gcc-trunk/gcc/tree-switch-conversion.c:1562
0x10aac3b
tree_switch_conversion::switch_decision_tree::try_switch_expansion(vec<tree_switch_conversion::cluster*,
va_heap, vl_ptr>&)
        /repo/gcc-trunk/gcc/tree-switch-conversion.c:1893
0x10ab413
tree_switch_conversion::switch_decision_tree::analyze_switch_statement()
        /repo/gcc-trunk/gcc/tree-switch-conversion.c:1823
0x10ac217 execute
        /repo/gcc-trunk/gcc/tree-switch-conversion.c:2570
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.

$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-amd64/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r11-5984-20201214092247-gcf7efe2d36f-checking-yes-rtl-df-extra-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/11.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--with-cloog --with-ppl --with-isl --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=x86_64-pc-linux-gnu
--with-ld=/usr/bin/x86_64-pc-linux-gnu-ld
--with-as=/usr/bin/x86_64-pc-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-r11-5984-20201214092247-gcf7efe2d36f-checking-yes-rtl-df-extra-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.0.0 20201214 (experimental) (GCC)