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

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; Test that GCSE uses basicaa to do alias analysis, which is capable of
; disambiguating some obvious cases. All loads should be removable in
; this testcase.
; RUN: llvm-as < %s | opt -basicaa -gvn -instcombine -dce \
; RUN: | llvm-dis | not grep load
@A = global i32 7
@B = global i32 8
define i32 @test() {
%A1 = load i32* @A
store i32 123, i32* @B ; Store cannot alias @A
%A2 = load i32* @A
%X = sub i32 %A1, %A2
ret i32 %X
}
define i32 @test2() {
%A1 = load i32* @A
br label %Loop
Loop:
%AP = phi i32 [0, %0], [%X, %Loop]
store i32 %AP, i32* @B ; Store cannot alias @A
%A2 = load i32* @A
%X = sub i32 %A1, %A2
%c = icmp eq i32 %X, 0
br i1 %c, label %out, label %Loop
out:
ret i32 %X
}
declare void @external()
define i32 @test3() {
%X = alloca i32
store i32 7, i32* %X
call void @external()
%V = load i32* %X
ret i32 %V
}