| ; This file contains various testcases that require tracking whether bits are |
| ; set or cleared by various instructions. |
| ; XFAIL: * |
| ; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep %ELIM |
| |
| ; test1 - Eliminating the casts in this testcase (by narrowing the AND |
| ; operation) allows instcombine to realize the function always returns false. |
| ; |
| bool %test1(int %A, int %B) { |
| %C1 = setlt int %A, %B |
| %ELIM1 = cast bool %C1 to uint |
| %C2 = setgt int %A, %B |
| %ELIM2 = cast bool %C2 to uint |
| %C3 = and uint %ELIM1, %ELIM2 |
| %ELIM3 = cast uint %C3 to bool |
| ret bool %ELIM3 |
| } |
| |
| ; See if we can eliminate the shifts... |
| int %test2(int %B) { |
| %ELIM1 = shl int %B, ubyte 31 |
| %ELIM2 = shr int %ELIM1, ubyte 31 |
| %inc = add int %ELIM2, 1 ; == xor int %B, 1 |
| ret int %inc |
| } |
| |
| ; 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 |
| } |
| |