llvm-6502/test/Analysis/BasicAA/featuretest.ll

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; This testcase tests for various features the basicaa test should be able to
; determine, as noted in the comments.
; RUN: opt < %s -basicaa -gvn -instcombine -dce -S | not grep REMOVE
@Global = external global { i32 }
; Array test: Test that operations on one local array do not invalidate
; operations on another array. Important for scientific codes.
;
define i32 @different_array_test(i64 %A, i64 %B) {
%Array1 = alloca i32, i32 100
%Array2 = alloca i32, i32 200
%pointer = getelementptr i32* %Array1, i64 %A
%val = load i32* %pointer
%pointer2 = getelementptr i32* %Array2, i64 %B
store i32 7, i32* %pointer2
%REMOVE = load i32* %pointer ; redundant with above load
%retval = sub i32 %REMOVE, %val
ret i32 %retval
}
; Constant index test: Constant indexes into the same array should not
; interfere with each other. Again, important for scientific codes.
;
define i32 @constant_array_index_test() {
%Array = alloca i32, i32 100
%P1 = getelementptr i32* %Array, i64 7
%P2 = getelementptr i32* %Array, i64 6
%A = load i32* %P1
store i32 1, i32* %P2 ; Should not invalidate load
%BREMOVE = load i32* %P1
%Val = sub i32 %A, %BREMOVE
ret i32 %Val
}
; Test that if two pointers are spaced out by a constant getelementptr, that
; they cannot alias.
define i32 @gep_distance_test(i32* %A) {
%REMOVEu = load i32* %A
%B = getelementptr i32* %A, i64 2 ; Cannot alias A
store i32 7, i32* %B
%REMOVEv = load i32* %A
%r = sub i32 %REMOVEu, %REMOVEv
ret i32 %r
}
; Test that if two pointers are spaced out by a constant offset, that they
; cannot alias, even if there is a variable offset between them...
define i32 @gep_distance_test2({i32,i32}* %A, i64 %distance) {
%A1 = getelementptr {i32,i32}* %A, i64 0, i32 0
%REMOVEu = load i32* %A1
%B = getelementptr {i32,i32}* %A, i64 %distance, i32 1
store i32 7, i32* %B ; B cannot alias A, it's at least 4 bytes away
%REMOVEv = load i32* %A1
%r = sub i32 %REMOVEu, %REMOVEv
ret i32 %r
}
; Test that we can do funny pointer things and that distance calc will still
; work.
define i32 @gep_distance_test3(i32 * %A) {
%X = load i32* %A
%B = bitcast i32* %A to i8*
%C = getelementptr i8* %B, i64 4
%Y = load i8* %C
ret i32 8
}
; Test that we can disambiguate globals reached through constantexpr geps
define i32 @constexpr_test() {
%X = alloca i32
%Y = load i32* %X
store i32 5, i32* getelementptr ({ i32 }* @Global, i64 0, i32 0)
%REMOVE = load i32* %X
%retval = sub i32 %Y, %REMOVE
ret i32 %retval
}