[PATCH] D18866: [X86] Fix PR23155 by turning on X86FixupBWInsts by default

[Kevin B. Smith via llvm-commits]

kbsmith1 added a comment.

Yes, I have run perf results locally on a number of different kinds of boxes.  As stated this does generate exactly the code desired
for PR23155 (modulo the alignment differences noted as having some performance effect in that PR).

Some highlights
+8% on EEMBC/viterb  (this was what motivated PR23155)
+3% on spec2000 parser
+2% on spec2000 twolf
+3% on EEMBC/ip_reassemblyIT,tcpbulk,tcpmixed
+2% on EEMBC/qos,natIT

a couple of minor degrades as well
-3 on EEMBC/puwmod01
-2 on coremark/zip-test
-2 on spec2006/libquantum -O2,but +1% -O2 +Haswell specific cpu tuning flags.

So, generally this doesn't make a big difference on benchmarks, but is more positive than negative.


http://reviews.llvm.org/D18866