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| author | Dan Gohman <gohman@apple.com> | 2010-04-08 18:11:50 +0000 |
|---|---|---|
| committer | Dan Gohman <gohman@apple.com> | 2010-04-08 18:11:50 +0000 |
| commit | b57b6f1575ec87b22dc793fe03539cae9df0e586 (patch) | |
| tree | d44d7805422c7d31c9e45681edcf0b5c7ee1e8bc | |
| parent | 29e13e0c18de57209170d5cd2c3dd1311f5e2a40 (diff) | |
| download | external_llvm-b57b6f1575ec87b22dc793fe03539cae9df0e586.zip external_llvm-b57b6f1575ec87b22dc793fe03539cae9df0e586.tar.gz external_llvm-b57b6f1575ec87b22dc793fe03539cae9df0e586.tar.bz2 | |
Pointers to zero-sized objects don't point to overlapping objects.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100789 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Analysis/BasicAliasAnalysis.cpp | 5 | ||||
| -rw-r--r-- | test/Analysis/BasicAA/empty.ll | 10 |
2 files changed, 15 insertions, 0 deletions
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp index 31a649d..cfe7a1c 100644 --- a/lib/Analysis/BasicAliasAnalysis.cpp +++ b/lib/Analysis/BasicAliasAnalysis.cpp @@ -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(); diff --git a/test/Analysis/BasicAA/empty.ll b/test/Analysis/BasicAA/empty.ll new file mode 100644 index 0000000..689efec --- /dev/null +++ b/test/Analysis/BasicAA/empty.ll @@ -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 +} |