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:
4;
5; struct foo { int A : 16; int B : 16; };
6; void test(struct foo *F, int X, int Y) {
7;        F->A = X; F->B = Y;
8; }
9;
10; Which corresponds to test1.
11
12; RUN: opt < %s -instcombine -S | \
13; RUN:   not grep "or "
14
15define i32 @test1(i32 %X, i32 %Y) {
16        %A = and i32 %X, 7              ; <i32> [#uses=1]
17        %B = and i32 %Y, 8              ; <i32> [#uses=1]
18        %C = or i32 %A, %B              ; <i32> [#uses=1]
19        ;; This cannot include any bits from %Y!
20        %D = and i32 %C, 7              ; <i32> [#uses=1]
21        ret i32 %D
22}
23
24define i32 @test2(i32 %X, i8 %Y) {
25        %B = zext i8 %Y to i32          ; <i32> [#uses=1]
26        %C = or i32 %X, %B              ; <i32> [#uses=1]
27        ;; This cannot include any bits from %Y!
28        %D = and i32 %C, 65536          ; <i32> [#uses=1]
29        ret i32 %D
30}
31
32define i32 @test3(i32 %X, i32 %Y) {
33        %B = shl i32 %Y, 1              ; <i32> [#uses=1]
34        %C = or i32 %X, %B              ; <i32> [#uses=1]
35        ;; This cannot include any bits from %Y!
36        %D = and i32 %C, 1              ; <i32> [#uses=1]
37        ret i32 %D
38}
39
40define i32 @test4(i32 %X, i32 %Y) {
41        %B = lshr i32 %Y, 31            ; <i32> [#uses=1]
42        %C = or i32 %X, %B              ; <i32> [#uses=1]
43        ;; This cannot include any bits from %Y!
44        %D = and i32 %C, 2              ; <i32> [#uses=1]
45        ret i32 %D
46}
47
48define i32 @or_test1(i32 %X, i32 %Y) {
49        %A = and i32 %X, 1              ; <i32> [#uses=1]
50        ;; This cannot include any bits from X!
51        %B = or i32 %A, 1               ; <i32> [#uses=1]
52        ret i32 %B
53}
54
55define i8 @or_test2(i8 %X, i8 %Y) {
56        %A = shl i8 %X, 7               ; <i8> [#uses=1]
57        ;; This cannot include any bits from X!
58        %B = or i8 %A, -128             ; <i8> [#uses=1]
59        ret i8 %B
60}
61
62