1 ; If we have an 'and' of the result of an 'or', and one of the 'or' operands
2 ; cannot have contributed any of the resultant bits, delete the or. This
3 ; occurs for very common C/C++ code like this:
5 ; struct foo { int A : 16; int B : 16; };
6 ; void test(struct foo *F, int X, int Y) {
10 ; Which corresponds to test1.
12 ; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep 'or '
14 int %test1(int %X, int %Y) {
18 %D = and int %C, 7 ;; This cannot include any bits from %Y!
22 int %test2(int %X, ubyte %Y) {
23 %B = cast ubyte %Y to int
25 %D = and int %C, 65536 ;; This cannot include any bits from %Y!
29 int %test3(int %X, int %Y) {
30 %B = shl int %Y, ubyte 1
32 %D = and int %C, 1 ;; This cannot include any bits from %Y!
36 uint %test4(uint %X, uint %Y) {
37 %B = shr uint %Y, ubyte 31
39 %D = and uint %C, 2 ;; This cannot include any bits from %Y!
43 int %or_test1(int %X, int %Y) {
45 %B = or int %A, 1 ;; This cannot include any bits from X!
49 ubyte %or_test2(ubyte %X, ubyte %Y) {
50 %A = shl ubyte %X, ubyte 7
51 %B = or ubyte %A, 128 ;; This cannot include any bits from X!