[Bug c++/82338] New: valgrind error in inherit_in_ebb

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82338

            Bug ID: 82338
           Summary: valgrind error in inherit_in_ebb
           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: ---

Created attachment 42242
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42242&action=edit
C++ source code

I built a recent trunk version of gcc with valgrind.

I compiled the attached C++ code with flags -O3 -fPIC -fno-strict-aliasing -c
and got the following:

$ ~/gcc/results.253187.valgrind/bin/gcc -O3 -fPIC -fno-strict-aliasing -c
bug386.cc
==17152== Conditional jump or move depends on uninitialised value(s)
==17152==    at 0x9DCE01: inherit_in_ebb (lra-constraints.c:6224)
==17152==    by 0x9DCE01: lra_inheritance() (lra-constraints.c:6474)
==17152==    by 0x9C8518: lra(_IO_FILE*) (lra.c:2430)
==17152==    by 0x986161: do_reload (ira.c:5440)

The bug seems to have been introduced sometime before revision 249539.

svn blame claims that lra-constraints.c:6224 is as follows:

192719   vmakarov         && usage_insns[regno].calls_num == calls_num - 1

I'll have a go at reducing the code.