| ; 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 -passes=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 |
| } |
| |