llvm-project

Commit Graph

Author	SHA1	Message	Date
Benjamin Kramer	a79c1e0589	Update test. llvm-svn: 136170	2011-07-26 22:45:39 +00:00
Benjamin Kramer	124ac2b997	Add a neat little two's complement hack for x86. On x86 we can't encode an immediate LHS of a sub directly. If the RHS comes from a XOR with a constant we can fold the negation into the xor and add one to the immediate of the sub. Then we can turn the sub into an add, which can be commuted and encoded efficiently. This code is generated for __builtin_clz and friends. llvm-svn: 136167	2011-07-26 22:42:13 +00:00

Author

SHA1

Message

Date

Benjamin Kramer

a79c1e0589

Update test.

llvm-svn: 136170

2011-07-26 22:45:39 +00:00

Benjamin Kramer

124ac2b997

Add a neat little two's complement hack for x86.

On x86 we can't encode an immediate LHS of a sub directly. If the RHS comes from a XOR with a constant we can
fold the negation into the xor and add one to the immediate of the sub. Then we can turn the sub into an add,
which can be commuted and encoded efficiently.

This code is generated for __builtin_clz and friends.

llvm-svn: 136167

2011-07-26 22:42:13 +00:00

2 Commits