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llvm-mirror/test/Analysis/BasicAA/dag.ll
Dan Gohman edaf7c535a Fix BasicAA's recursion detection so that it doesn't pessimize
queries in the case of a DAG, where a query reaches a node
visited earlier, but it's not on a cycle. This avoids
MayAlias results in cases where BasicAA is expected to
return MustAlias or PartialAlias in order to protect TBAA.

llvm-svn: 132609
2011-06-04 00:31:50 +00:00

42 lines
1.1 KiB
LLVM

; RUN: opt < %s -basicaa -aa-eval -print-all-alias-modref-info |& FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
; BasicAA's guard against use-def cycles shouldn't prevent it from
; analyzing use-def dags.
; CHECK: MustAlias: i8* %base, i8* %phi
; CHECK: MustAlias: i8* %phi, i8* %wwa
; CHECK: MustAlias: i8* %phi, i8* %wwb
; CHECK: MustAlias: i16* %bigbase, i8* %phi
define i8 @foo(i8* %base, i1 %x, i1 %w) {
entry:
br i1 %w, label %wa, label %wb
wa:
%wwa = bitcast i8* %base to i8*
br label %wc
wb:
%wwb = bitcast i8* %base to i8*
br label %wc
wc:
%first = phi i8* [ %wwa, %wa ], [ %wwb, %wb ]
%fc = bitcast i8* %first to i8*
br i1 %x, label %xa, label %xb
xa:
%xxa = bitcast i8* %fc to i8*
br label %xc
xb:
%xxb = bitcast i8* %fc to i8*
br label %xc
xc:
%phi = phi i8* [ %xxa, %xa ], [ %xxb, %xb ]
store i8 0, i8* %phi
%bigbase = bitcast i8* %base to i16*
store i16 -1, i16* %bigbase
%loaded = load i8* %phi
ret i8 %loaded
}