forked from OSchip/llvm-project
80 lines
2.1 KiB
LLVM
80 lines
2.1 KiB
LLVM
; RUN: opt -S -globalopt < %s | FileCheck %s
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; This test is hint, what could globalOpt optimize and what it can't
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; FIXME: @tmp and @tmp2 can be safely set to 42
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; CHECK: @tmp = global i32 0
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; CHECK: @tmp2 = global i32 0
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; CHECK: @tmp3 = global i32 0
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@tmp = global i32 0
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@tmp2 = global i32 0
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@tmp3 = global i32 0
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@ptrToTmp3 = global i32* null
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@llvm.global_ctors = appending global [1 x { i32, void ()* }] [{ i32, void ()* } { i32 65535, void ()* @_GLOBAL__I_a }]
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define i32 @TheAnswerToLifeTheUniverseAndEverything() {
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ret i32 42
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}
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define void @_GLOBAL__I_a() {
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enter:
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call void @_optimizable()
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call void @_not_optimizable()
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ret void
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}
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define void @_optimizable() {
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enter:
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%valptr = alloca i32
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%val = call i32 @TheAnswerToLifeTheUniverseAndEverything()
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store i32 %val, i32* @tmp
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store i32 %val, i32* %valptr
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%0 = bitcast i32* %valptr to i8*
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%barr = call i8* @llvm.invariant.group.barrier(i8* %0)
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%1 = bitcast i8* %barr to i32*
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%val2 = load i32, i32* %1
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store i32 %val2, i32* @tmp2
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ret void
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}
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; We can't step through invariant.group.barrier here, because that would change
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; this load in @usage_of_globals()
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; val = load i32, i32* %ptrVal, !invariant.group !0
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; into
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; %val = load i32, i32* @tmp3, !invariant.group !0
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; and then we could assume that %val and %val2 to be the same, which coud be
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; false, because @changeTmp3ValAndCallBarrierInside() may change the value
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; of @tmp3.
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define void @_not_optimizable() {
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enter:
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store i32 13, i32* @tmp3, !invariant.group !0
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%0 = bitcast i32* @tmp3 to i8*
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%barr = call i8* @llvm.invariant.group.barrier(i8* %0)
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%1 = bitcast i8* %barr to i32*
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store i32* %1, i32** @ptrToTmp3
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store i32 42, i32* %1, !invariant.group !0
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ret void
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}
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define void @usage_of_globals() {
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entry:
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%ptrVal = load i32*, i32** @ptrToTmp3
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%val = load i32, i32* %ptrVal, !invariant.group !0
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call void @changeTmp3ValAndCallBarrierInside()
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%val2 = load i32, i32* @tmp3, !invariant.group !0
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ret void;
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}
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declare void @changeTmp3ValAndCallBarrierInside()
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declare i8* @llvm.invariant.group.barrier(i8*)
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!0 = !{!"something"}
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