llvm/test/Transforms/InstCombine/2008-11-20-DivMulRem.ll
Nick Lewycky 0c73079855 Optimize (x/y)*y into x-(x%y) in general. Div and rem are about the same, and
a subtract is cheaper than a multiply. This generalizes an existing transform.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59800 91177308-0d34-0410-b5e6-96231b3b80d8
2008-11-21 07:33:58 +00:00

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LLVM

; RUN: llvm-as < %s | opt -instcombine | llvm-dis > %t
; RUN: grep urem %t | count 3
; RUN: grep srem %t | count 1
; RUN: grep sub %t | count 2
; RUN: grep add %t | count 1
; PR3103
define i8 @test1(i8 %x, i8 %y) {
%A = udiv i8 %x, %y
%B = mul i8 %A, %y
%C = sub i8 %x, %B
ret i8 %C
}
define i8 @test2(i8 %x, i8 %y) {
%A = sdiv i8 %x, %y
%B = mul i8 %A, %y
%C = sub i8 %x, %B
ret i8 %C
}
define i8 @test3(i8 %x, i8 %y) {
%A = udiv i8 %x, %y
%B = mul i8 %A, %y
%C = sub i8 %B, %x
ret i8 %C
}
define i8 @test4(i8 %x) {
%A = udiv i8 %x, 3
%B = mul i8 %A, -3
%C = sub i8 %x, %B
ret i8 %C
}