[Bug c++/122782] New: UBSAN: trunk/gcc/ext-dce.cc:838:38: runtime error: shift exponent 96 is too large for 64-bit type 'long unsigned int'

[dcb314 at hotmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122782

            Bug ID: 122782
           Summary: UBSAN: trunk/gcc/ext-dce.cc:838:38: runtime error:
                    shift exponent 96 is too large for 64-bit type 'long
                    unsigned int'
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

Created attachment 62863
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=62863&action=edit
gzipped C++ source code

I just tried a bootstrap build of gcc trunk with UBSAN 
switched on.

Configure line is

CFLAGS="-g1 -O3 -march=znver3 " \
CXXFLAGS="-g1 -O3 -march=znver3 " \
../trunk/configure --prefix=$HOME/gcc/results.$DATE \
    --disable-doc \
    --disable-multilib \
    --disable-werror \
    --with-pkgversion=$HASH \
    --enable-checking=yes \
    --with-build-config="bootstrap-ubsan" \
    --enable-languages="c,c++"

I get:

../../trunk/gcc/ext-dce.cc:838:38: runtime error: shift exponent 96 is too
large for 64-bit type 'long unsigned int'

I attach the results of the crash. 

The configure line worked a week ago, so the problem is recent.