Evan Cheng d99d68bcee Fix two-address pass's aggressive instruction commuting heuristics. It's meant
to catch cases like:
 %reg1024<def> = MOV r1
 %reg1025<def> = MOV r0
 %reg1026<def> = ADD %reg1024, %reg1025
 r0            = MOV %reg1026

By commuting ADD, it let coalescer eliminate all of the copies. However, there
was a bug in the heuristics where it ended up commuting the ADD in:

 %reg1024<def> = MOV r0
 %reg1025<def> = MOV 0
 %reg1026<def> = ADD %reg1024, %reg1025
 r0            = MOV %reg1026

That did no benefit but rather ensure the last MOV would not be coalesced.

rdar://11355268


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156048 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-03 01:45:13 +00:00
..
2012-04-24 10:45:44 +00:00
2012-04-08 11:53:54 +00:00
2012-04-08 11:00:38 +00:00
2012-04-03 23:09:22 +00:00