[Bug c/83086] New: valgrind error in recent build

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83086

            Bug ID: 83086
           Summary: valgrind error in recent build
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

I tried a valgrind build of recent gcc trunk with -O3 and got this:

==26140== Conditional jump or move depends on uninitialised value(s)
==26140==    at 0x145D303: (anonymous
namespace)::imm_store_chain_info::try_coalesce_bswap((anonymous
namespace)::merged_store_group*, unsigned int, unsigned int)
(gimple-ssa-store-merging.c:2393)
==26140==    by 0x146390F: coalesce_immediate_stores
(gimple-ssa-store-merging.c:2575)
==26140==    by 0x146390F: terminate_and_process_chain
(gimple-ssa-store-merging.c:3726)

Source code is

254948      jakub       if (n.base_addr && vuse_store)

Configure is

../trunk/configure --prefix=/home/dcb/gcc/results.254990.valgrind \
        --disable-bootstrap \
        --disable-multilib \
        --disable-werror \
        --enable-checking=valgrind \
        --enable-languages=c,c++,fortran

sed 's/-O2/-O3 -funroll-loops -Wtautological-compare/' < Makefile >
Makefile.tmp
mv Makefile.tmp Makefile