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Pointers to zero-sized objects don't point to overlapping objects.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100789 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-04-08 18:11:50 +00:00
parent 29e13e0c18
commit b57b6f1575
2 changed files with 15 additions and 0 deletions
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5
lib/Analysis/BasicAliasAnalysis.cpp
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@ -655,6 +655,11 @@ BasicAliasAnalysis::aliasPHI(const PHINode *PN, unsigned PNSize,
AliasAnalysis::AliasResult
BasicAliasAnalysis::aliasCheck(const Value *V1, unsigned V1Size,
const Value *V2, unsigned V2Size) {
// If either of the memory references is empty, it doesn't matter what the
// pointer values are.
if (V1Size == 0 || V2Size == 0)
return NoAlias;
// Strip off any casts if they exist.
V1 = V1->stripPointerCasts();
V2 = V2->stripPointerCasts();

10
test/Analysis/BasicAA/empty.ll Normal file
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@ -0,0 +1,10 @@
; RUN: opt < %s -aa-eval -print-all-alias-modref-info -disable-output \
; RUN: |& grep {NoAlias: \{\}\\* \[%\]p, \{\}\\* \[%\]q}
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"
define void @foo({}* %p, {}* %q) {
store {} {}, {}* %p
store {} {}, {}* %q
ret void
}