New functionality for instcombine:
* New ReplaceInstUsesWith function to factor out tons of common code
This needs to be used more in the future still, but it's a good start
* New InsertNewInstBefore to allow multi-instruction replacements
* Change getMaxValue functions to isAllOnesValue function, which doesn't
have to CREATE/lookup a new constant. Also the name is accurate
* Add new isMaxValue, isMinValue, isMaxValueMinusOne, isMinValuePlusOne
functions: This should be moved to Constant* classes eventually
* Implement xor X, ALLONES -> not X
* Fold ALL setcc's of booleans away
* Handle various SetCC's for integers against values at the end of their
ranges, possibly off by one. This implements the setcc-strength-reduce.ll
testcase.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3286
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