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| author | Bob Wilson <bob.wilson@apple.com> | 2012-09-04 03:30:13 +0000 |
|---|---|---|
| committer | Bob Wilson <bob.wilson@apple.com> | 2012-09-04 03:30:13 +0000 |
| commit | 2d5c28da0d14883cd0cd6fcf38d7e28040b634c0 (patch) | |
| tree | e419212e537f573bf782c8455019e2d58faa4fd3 | |
| parent | 2dc88d94c34294184368ef0d9663342be2d42811 (diff) | |
| download | external_llvm-2d5c28da0d14883cd0cd6fcf38d7e28040b634c0.zip external_llvm-2d5c28da0d14883cd0cd6fcf38d7e28040b634c0.tar.gz external_llvm-2d5c28da0d14883cd0cd6fcf38d7e28040b634c0.tar.bz2 | |
Be conservative about allocations that may alias the accessed pointer.
If an allocation has a must-alias relation to the access pointer, we treat it
as a Def. Otherwise, without this check, the code here was just skipping over
the allocation call and ignoring it. I noticed this by inspection and don't
have a specific testcase that it breaks, but it seems like we need to treat
a may-alias allocation as a Clobber.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163127 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Analysis/MemoryDependenceAnalysis.cpp | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp index 804217a..5736c35 100644 --- a/lib/Analysis/MemoryDependenceAnalysis.cpp +++ b/lib/Analysis/MemoryDependenceAnalysis.cpp @@ -485,6 +485,9 @@ getPointerDependencyFrom(const AliasAnalysis::Location &MemLoc, bool isLoad, if (AccessPtr == Inst || AA->isMustAlias(Inst, AccessPtr)) return MemDepResult::getDef(Inst); + // Be conservative if the accessed pointer may alias the allocation. + if (AA->alias(Inst, AccessPtr) != AliasAnalysis::NoAlias) + return MemDepResult::getClobber(Inst); // If the allocation is not aliased and does not read memory (like // strdup), it is safe to ignore. if (isa<AllocaInst>(Inst) || |