[Bug other/56338] New: register spill caused by loading constant

[neleai at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56338

             Bug #: 56338
           Summary: register spill caused by loading constant
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: neleai@seznam.cz


Consider attached code(smaller testcase has same bug but do not manifest by
spilling). 

gcc-4.7 -O3 spills rbp and rbx. 
  pushq %rbp
  .cfi_def_cfa_offset 16
  .cfi_offset 6, -16
  pxor  %xmm5, %xmm5
  movl  $63, %r10d
  movabsq $-9223372036854775808, %r11
  pushq %rbx
  .cfi_def_cfa_offset 24
  .cfi_offset 3, -24
  movl  $64, %ebx

Only use of rbx is this in loop below.: 
  movq  %rbx, %rdx

Same thing happens with 63 moved to r10d and used to initialize other register.