[Bug rtl-optimization/65628] valgrind error in improve_allocation

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65628

David Binderman <dcb314 at hotmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|WORKSFORME                  |---

--- Comment #5 from David Binderman <dcb314 at hotmail dot com> ---
>David, in the future please use an --enable-checking=valgrind compiler
>for valgrind testing.

Righto. I tried a build of today's (20160620) gcc trunk with this flag you
recommend.

I got

==16199== Conditional jump or move depends on uninitialised value(s)
==16199==    at 0x89001C: improve_allocation() (ira-color.c:2809)
==16199==    by 0x893F3E: color_allocnos (ira-color.c:3140)
==16199==    by 0x893F3E: color_pass(ira_loop_tree_node*) (ira-color.c:3249)
==16199==    by 0x87D136: ira_traverse_loop_tree(bool, ira_loop_tree_node*,
void (*)(ira_loop_tree_node*), void (*)(ira_loop_tree_node*))
(ira-build.c:1780)

Source code is

      if ((hregno = ALLOCNO_HARD_REGNO (a)) < 0)

So it looks to me like the problem is still there.
Configure line is 

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

And it looks like -O3 needs to be switched on in the build.
At the top level Makefile:

sed 's/-O2/-O3 -march=native -Wall -Wlogical-op/' < Makefile > Makefile.tmp
mv Makefile.tmp Makefile

Although I guess make target bootstrap-O3 would also provoke this valgrind
error.