Sanjay Patel 2d477e59e8 [InstCombine] fold add(zext(xor X, C), C) --> sext X when C is INT_MIN in the source type ...

The pattern may look more obviously like a sext if written as:

  define i32 @g(i16 %x) {
    %zext = zext i16 %x to i32
    %xor = xor i32 %zext, 32768
    %add = add i32 %xor, -32768
    ret i32 %add
  }

We already have that fold in visitAdd().

Differential Revision: https://reviews.llvm.org/D22477

llvm-svn: 276035

2016-07-19 22:09:34 +00:00

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