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| author | Nick Lewycky <nicholas@mxc.ca> | 2009-11-14 06:15:14 +0000 |
|---|---|---|
| committer | Nick Lewycky <nicholas@mxc.ca> | 2009-11-14 06:15:14 +0000 |
| commit | 20162ac5662a45388911ef1d35ba7559aae368f5 (patch) | |
| tree | fc493f6cbfa5e37bdc5d329f85d483aeabe14328 /lib | |
| parent | fae3e923452b85e72b2c03dd6eacc063f59d81b1 (diff) | |
| download | external_llvm-20162ac5662a45388911ef1d35ba7559aae368f5.zip external_llvm-20162ac5662a45388911ef1d35ba7559aae368f5.tar.gz external_llvm-20162ac5662a45388911ef1d35ba7559aae368f5.tar.bz2 | |
Teach BasicAA that a constant expression can't alias memory provably not
allocated until runtime (such as an alloca). Patch by Hans Wennborg!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@88760 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Analysis/BasicAliasAnalysis.cpp | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp index ea10a83..b8d69f4 100644 --- a/lib/Analysis/BasicAliasAnalysis.cpp +++ b/lib/Analysis/BasicAliasAnalysis.cpp @@ -659,7 +659,12 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, unsigned V1Size, // If V1/V2 point to two different objects we know that we have no alias. if (isIdentifiedObject(O1) && isIdentifiedObject(O2)) return NoAlias; - + + // Constant pointers can't alias with non-const isIdentifiedObject objects. + if ((isa<Constant>(O1) && isIdentifiedObject(O2) && !isa<Constant>(O2)) || + (isa<Constant>(O2) && isIdentifiedObject(O1) && !isa<Constant>(O1))) + return NoAlias; + // Arguments can't alias with local allocations or noalias calls. if ((isa<Argument>(O1) && (isa<AllocaInst>(O2) || isNoAliasCall(O2))) || (isa<Argument>(O2) && (isa<AllocaInst>(O1) || isNoAliasCall(O1)))) |