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; If we have an 'and' of the result of an 'or', and one of the 'or' operands
; cannot have contributed any of the resultant bits, delete the or. This
; occurs for very common C/C++ code like this:
;
; struct foo { int A : 16; int B : 16; };
; void test(struct foo *F, int X, int Y) {
; F->A = X; F->B = Y;
; }
;
; Which corresponds to test1.
; RUN: opt < %s -instcombine -S | \
; RUN: not grep "or "
define i32 @test1(i32 %X, i32 %Y) {
%A = and i32 %X, 7 ; <i32> [#uses=1]
%B = and i32 %Y, 8 ; <i32> [#uses=1]
%C = or i32 %A, %B ; <i32> [#uses=1]
;; This cannot include any bits from %Y!
%D = and i32 %C, 7 ; <i32> [#uses=1]
ret i32 %D
}
define i32 @test2(i32 %X, i8 %Y) {
%B = zext i8 %Y to i32 ; <i32> [#uses=1]
%C = or i32 %X, %B ; <i32> [#uses=1]
;; This cannot include any bits from %Y!
%D = and i32 %C, 65536 ; <i32> [#uses=1]
ret i32 %D
}
define i32 @test3(i32 %X, i32 %Y) {
%B = shl i32 %Y, 1 ; <i32> [#uses=1]
%C = or i32 %X, %B ; <i32> [#uses=1]
;; This cannot include any bits from %Y!
%D = and i32 %C, 1 ; <i32> [#uses=1]
ret i32 %D
}
define i32 @test4(i32 %X, i32 %Y) {
%B = lshr i32 %Y, 31 ; <i32> [#uses=1]
%C = or i32 %X, %B ; <i32> [#uses=1]
;; This cannot include any bits from %Y!
%D = and i32 %C, 2 ; <i32> [#uses=1]
ret i32 %D
}
define i32 @or_test1(i32 %X, i32 %Y) {
%A = and i32 %X, 1 ; <i32> [#uses=1]
;; This cannot include any bits from X!
%B = or i32 %A, 1 ; <i32> [#uses=1]
ret i32 %B
}
define i8 @or_test2(i8 %X, i8 %Y) {
%A = shl i8 %X, 7 ; <i8> [#uses=1]
;; This cannot include any bits from X!
%B = or i8 %A, -128 ; <i8> [#uses=1]
ret i8 %B
}
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