[Bug c/65628] New: valgrind error in improve_allocation

[dcb314 at hotmail dot com]

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

            Bug ID: 65628
           Summary: valgrind error in improve_allocation
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com

Created attachment 35182
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35182&action=edit
C source code

The attached code, when compiled by gcc trunk dated 20150329
under valgrind, and flags -O, does this

==14429== Conditional jump or move depends on uninitialised value(s)
==14429==    at 0xA0579C: improve_allocation() (ira-color.c:2774)
==14429==    by 0xA0CA83: color_allocnos (ira-color.c:3098)
==14429==    by 0xA0CA83: color_pass(ira_loop_tree_node*) (ira-color.c:3207)
==14429==    by 0x9F1200: ira_traverse_loop_tree(bool, ira_loop_tree_node*,
void (*)(ira_loop_tree_node*), void (*)(ira_loop_tree_node*)) (i
ra-build.c:1820)

ira-color.c:2774 is

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