llvm-6502/test/Transforms/InstCombine/2008-08-17-ICmpXorSignbit.ll
Nick Lewycky 1b344bc986 Xor'ing both sides of icmp by sign-bit is equivalent to swapping signedness of
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

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402 B
LLVM

; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep -v xor
define i1 @test1(i8 %x, i8 %y) {
%X = xor i8 %x, 128
%Y = xor i8 %y, 128
%tmp = icmp slt i8 %X, %Y
ret i1 %tmp
}
define i1 @test2(i8 %x, i8 %y) {
%X = xor i8 %x, 128
%Y = xor i8 %y, 128
%tmp = icmp ult i8 %X, %Y
ret i1 %tmp
}
define i1 @test3(i8 %x) {
%X = xor i8 %x, 128
%tmp = icmp uge i8 %X, 15
ret i1 %tmp
}