Nick Lewycky
4333f49afe
Reinstate this optimization to fold icmp of xor when possible. Don't try to
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turn icmp eq a+x, b+x into icmp eq a, b if a+x or b+x has other uses. This
may have been increasing register pressure leading to the bzip2 slowdown.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@63487 91177308-0d34-0410-b5e6-96231b3b80d8
2009-01-31 21:30:05 +00:00
Nick Lewycky
5d52c4501a
Revert r54876 r54877 r54906 and r54907. Evan found that these caused a 20%
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slowdown in bzip2.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@55113 91177308-0d34-0410-b5e6-96231b3b80d8
2008-08-21 05:56:10 +00:00
Nick Lewycky
91a0f78265
Consider the case where xor by -1 and xor by 128 have been combined already to
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produce an xor by 127.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54906 91177308-0d34-0410-b5e6-96231b3b80d8
2008-08-17 19:58:24 +00:00
Nick Lewycky
1b344bc986
Xor'ing both sides of icmp by sign-bit is equivalent to swapping signedness of
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the predicate.
Also, make this optz'n apply in more cases where it's safe to do so.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54876 91177308-0d34-0410-b5e6-96231b3b80d8
2008-08-17 07:34:14 +00:00
