[PATCH] [Core] Update references in parallel

[Rafael Espíndola]

> In the meanwhile, Rafael, do you mind to re-run your tests with this patch applied in order to see if it shows up some improvement for you (or if it doesn't) ?

Linking today's build of clang:

master

       2513.543751      task-clock (msec)         #    1.836 CPUs
utilized            ( +-  0.19% )
            68,894      context-switches          #    0.027 M/sec
               ( +-  0.10% )
               537      cpu-migrations            #    0.214 K/sec
               ( +-  1.71% )
           186,760      page-faults               #    0.074 M/sec
               ( +-  0.00% )
     7,441,047,000      cycles                    #    2.960 GHz
               ( +-  0.15% )
     4,815,567,274      stalled-cycles-frontend   #   64.72% frontend
cycles idle     ( +-  0.28% )
   <not supported>      stalled-cycles-backend
     6,277,994,513      instructions              #    0.84  insns per
cycle
                                                  #    0.77  stalled
cycles per insn  ( +-  0.06% )
     1,308,048,483      branches                  #  520.400 M/sec
               ( +-  0.06% )
        29,809,859      branch-misses             #    2.28% of all
branches          ( +-  0.09% )

       1.368777139 seconds time elapsed
          ( +-  0.23% )

master+patch:

       2653.171771      task-clock (msec)         #    1.982 CPUs
utilized            ( +-  0.24% )
            68,537      context-switches          #    0.026 M/sec
               ( +-  0.11% )
               588      cpu-migrations            #    0.222 K/sec
               ( +-  2.27% )
           187,068      page-faults               #    0.071 M/sec
               ( +-  0.00% )
     7,939,751,958      cycles                    #    2.993 GHz
               ( +-  0.29% )
     5,162,486,783      stalled-cycles-frontend   #   65.02% frontend
cycles idle     ( +-  0.53% )
   <not supported>      stalled-cycles-backend
     7,016,657,070      instructions              #    0.88  insns per
cycle
                                                  #    0.74  stalled
cycles per insn  ( +-  0.08% )
     1,581,215,011      branches                  #  595.972 M/sec
               ( +-  0.08% )
        29,727,439      branch-misses             #    1.88% of all
branches          ( +-  0.14% )

       1.338744727 seconds time elapsed
          ( +-  0.30% )

Cheers,
Rafael