test/Transforms/InstCombine/bit-tracking.ll


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26

; This file contains various testcases that require tracking whether bits are
; set or cleared by various instructions.
; RUN: llvm-as < %s | opt -instcombine -instcombine -disable-output &&
; RUN: llvm-as < %s | opt -instcombine -instcombine | llvm-dis | not grep %ELIM

; Reduce down to a single XOR
int %test3(int %B) {
        %ELIMinc = and int %B, 1
        %tmp.5 = xor int %ELIMinc, 1
        %ELIM7 = and int %B, -2
        %tmp.8 = or int %tmp.5, %ELIM7
        ret int %tmp.8
}

; Finally, a bigger case where we chain things together.  This corresponds to
; incrementing a single-bit bitfield, which should become just an xor.
int %test4(int %B) {
        %ELIM3 = shl int %B, ubyte 31
        %ELIM4 = shr int %ELIM3, ubyte 31
        %inc = add int %ELIM4, 1
        %ELIM5 = and int %inc, 1
        %ELIM7 = and int %B, -2
        %tmp.8 = or int %ELIM5, %ELIM7
        ret int %tmp.8
}