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