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llvm-mirror/test/Analysis/BasicAA/full-store-partial-alias.ll
Dan Gohman df668227fb Teach BasicAA to return PartialAlias in cases where both pointers
are pointing to the same object, one pointer is accessing the entire
object, and the other is access has a non-zero size. This prevents
TBAA from kicking in and saying NoAlias in such cases.

llvm-svn: 123775
2011-01-18 21:16:06 +00:00

34 lines
1.2 KiB
LLVM

; RUN: opt -S -tbaa -basicaa -gvn < %s | grep {ret i32 %}
; RUN: opt -S -tbaa -gvn < %s | grep {ret i32 0}
; rdar://8875631
; BasicAA should notice that the store stores to the entire %u object,
; so the %tmp5 load is PartialAlias with the store and suppress TBAA.
; Without BasicAA, TBAA should say that %tmp5 is NoAlias with the store.
target datalayout = "e-p:64:64:64"
%union.anon = type { double }
@u = global %union.anon { double -2.500000e-01 }, align 8
@endianness_test = global i64 1, align 8
define i32 @signbit(double %x) nounwind {
entry:
%u = alloca %union.anon, align 8
%tmp9 = getelementptr inbounds %union.anon* %u, i64 0, i32 0
store double %x, double* %tmp9, align 8, !tbaa !0
%tmp2 = load i32* bitcast (i64* @endianness_test to i32*), align 8, !tbaa !3
%idxprom = sext i32 %tmp2 to i64
%tmp4 = bitcast %union.anon* %u to [2 x i32]*
%arrayidx = getelementptr inbounds [2 x i32]* %tmp4, i64 0, i64 %idxprom
%tmp5 = load i32* %arrayidx, align 4, !tbaa !3
%tmp5.lobit = lshr i32 %tmp5, 31
ret i32 %tmp5.lobit
}
!0 = metadata !{metadata !"double", metadata !1}
!1 = metadata !{metadata !"omnipotent char", metadata !2}
!2 = metadata !{metadata !"Simple C/C++ TBAA", null}
!3 = metadata !{metadata !"int", metadata !1}