Store the hash in SectionPiece.
This spreads out computing the hash and using it in a hash table. The
speedups are:
firefox
master 6.
811232891
patch 6.
559280249 1.03841162939x faster
chromium
master 4.
369323666
patch 4.
33171853 1.00868134338x faster
chromium fast
master 1.
856679971
patch 1.
850617741 1.00327578725x faster
the gold plugin
master 0.
32917962
patch 0.
325711944 1.01064645023x faster
clang
master 0.
558015452
patch 0.
550284165 1.01404962652x faster
llvm-as
master 0.
032563515
patch 0.
032152077 1.01279662275x faster
the gold plugin fsds
master 0.
356221362
patch 0.
352772162 1.00977741549x faster
clang fsds
master 0.
635096494
patch 0.
627249229 1.01251060127x faster
llvm-as fsds
master 0.
030183188
patch 0.
029889544 1.00982430511x faster
scylla
master 3.
071448906
patch 2.
938484138 1.04524944215x faster
This seems to be because we don't stall as much. When linking firefox
stalled-cycles-frontend goes from 57.56% to 55.55%.
With -O2 the difference is even more significant since we avoid
recomputing the hash. For firefox we go from 9.
990295265 to
9.
149627521 seconds (1.09x faster).
llvm-svn: 283367